Difference between revisions of "Natural Quality"

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The objective of monitoring the Natural Quality is to assess the effects of modern
[[Category:USFS]]
civilization on the integrity of wilderness ecosystems, with a focus on plants, animals,
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air and water, and ecological processes. The Wilderness Act defines wilderness as
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an area that “is protected and managed so as to preserve its natural conditions”
<div class="center">[[USFS Wilderness Character Monitoring Technical Guide]]</div>
and that these areas should be free from the effects of “an increasing population,
[[File:Wilderness character monitoring technical guide - rmrs gtr406.pdf.png|200px|thumb|center]]
accompanied by expanding settlement and growing mechanization” (sections 2(c) and
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2(a), respectively). Human-caused changes to wilderness ecological systems can be
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intentional or unintentional. While managers may have control over some impacts to
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natural ecosystems in wilderness, many threats come from external sources outside
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of their jurisdiction (e.g., air pollutants and nonindigenous species). In contrast
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to the Untrammeled Quality, which monitors actions that manipulate or control
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ecological systems, the Natural Quality monitors the effects on wilderness ecosystems
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from actions as well as external forces. While this quality encompasses all the
naturally occurring species, physical resources, and ecological functions and processes
in wilderness, practical limitations require that a relatively small but significant subset
of possible measures are monitored.


For the Natural Quality, a single monitoring question provides the broad context and
The objective of monitoring the Natural Quality is to assess the effects of modern civilization on the integrity of wilderness ecosystems, with a focus on plants, animals, air and water, and ecological processes. The Wilderness Act defines wilderness as an area that "is protected and managed so as to preserve its natural conditions" and that these areas should be free from the effects of "an increasing population, accompanied by expanding settlement and growing mechanization" (sections 2(c) and 2(a), respectively). Human-caused changes to wilderness ecological systems can be intentional or unintentional. While managers may have control over some impacts to natural ecosystems in wilderness, many threats come from external sources outside of their jurisdiction (e.g., air pollutants and '''nonindigenous species'''). In contrast to the Untrammeled Quality, which monitors actions that manipulate or control ecological systems, the Natural Quality monitors the effects on wilderness ecosystems from actions as well as external forces. While this quality encompasses all the naturally occurring species, physical resources, and ecological functions and processes in wilderness, practical limitations require that a relatively small but significant subset of possible measures are monitored.
four indicators provide the structure for this monitoring (as summarized in table
 
1.3.1).
For the Natural Quality, a single monitoring question provides the broad context and four indicators provide the structure for this monitoring (as summarized in table 1.3.1).


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== 3.1 Monitoring Question ==
== 3.1 Monitoring Question ==
A single monitoring question is used to monitor the Natural Quality: What are the
trends in the natural environment from human-caused change?


This monitoring question assesses the trends in natural wilderness ecosystems
A single monitoring question is used to monitor the Natural Quality: What are the trends in the natural environment from human-caused change?
that result from human-caused threats occurring since designation of the area as
 
wilderness. Importantly, this monitoring question seeks to distinguish between
This monitoring question assesses the trends in natural wilderness ecosystems that result from human-caused threats occurring since designation of the area as wilderness. Importantly, this monitoring question seeks to distinguish between natural variability, which is integral to all ecosystems and does not degrade wilderness character, and human-caused change. In wilderness, the primary goal is to allow ecosystems to function and change without impacts or interference from modern civilization; therefore, the Natural Quality should not be used to set a target to maintain a particular ecological state or condition. In addition, this monitoring question does not include actions taken to restore ecological systems in wilderness. There are several reasons for not including these actions, including: (1) actions are tracked in the Untrammeled Quality, not the Natural Quality that tracks effects; (2) restoration actions are highly site-dependent and no single national protocol to measure such actions and their effects has been developed; (3) restoration actions typically assume static or historical ecological conditions contrary to wilderness as a place where human-determined states are not appropriate; and (4) the effects of restoration actions should eventually show, with monitoring, as an improving trend in the Natural Quality.
natural variability, which is integral to all ecosystems and does not degrade wilderness
character, and human-caused change. In wilderness, the primary goal is to allow
ecosystems to function and change without impacts or interference from modern
civilization; therefore, the Natural Quality should not be used to set a target to
maintain a particular ecological state or condition. In addition, this monitoring
question does not include actions taken to restore ecological systems in wilderness.
There are several reasons for not including these actions, including: (1) actions are
tracked in the Untrammeled Quality, not the Natural Quality that tracks effects;
(2) restoration actions are highly site-dependent and no single national protocol to
measure such actions and their effects has been developed; (3) restoration actions
typically assume static or historical ecological conditions contrary to wilderness as
a place where human-determined states are not appropriate; and (4) the effects of
restoration actions should eventually show, with monitoring, as an improving trend in
the Natural Quality.


Four indicators assess a range of ecosystem components, structures, and functions
Four indicators assess a range of ecosystem components, structures, and functions in wilderness: (1) plants, (2) animals, (3) air and water, and (4) ecological processes. Practical and conceptual constraints mean that not everything important to wilderness ecosystems can be included in this monitoring. Likewise, not all ecological data currently collected by scientists are relevant or necessary to include in WCM. The measures under each indicator are not all encompassing; rather, the measures are selected because they are known human-caused threats to the indicators. Part 2, section 3.6, provides a detailed discussion of the criteria and process used for selecting measures under the Natural Quality; this section should guide local units considering the use of locally developed measures under this quality.
in wilderness: (1) plants, (2) animals, (3) air and water, and (4) ecological processes.
Practical and conceptual constraints mean that not everything important to wilderness
ecosystems can be included in this monitoring. Likewise, not all ecological data
currently collected by scientists are relevant or necessary to include in WCM. The
measures under each indicator are not all encompassing; rather, the measures are
selected because they are known human-caused threats to the indicators. Part 2,
section 3.6, provides a detailed discussion of the criteria and process used for selecting
measures under the Natural Quality; this section should guide local units considering
the use of locally developed measures under this quality.


== 3.2 Indicator: Plants ==
== 3.2 Indicator: Plants ==


This indicator focuses on threats to indigenous plant species and communities.
This indicator focuses on threats to indigenous plant species and communities. Indigenous plant species (also referred to as native plant species) and plant communities are an essential biological component of natural wilderness ecosystems. Indigenous plant species and plant communities are those that evolved in an area and therefore have intrinsic value within a wilderness. In addition, they are critically important to the entire ecosystem by providing food and habitat to indigenous animals, preventing soil erosion, adding soil nutrients, and maintaining the local environmental conditions and biodiversity.
Indigenous plant species (also referred to as native plant species) and plant
communities are an essential biological component of natural wilderness ecosystems.
Indigenous plant species and plant communities are those that evolved in an area
and therefore have intrinsic value within a wilderness. In addition, they are critically
important to the entire ecosystem by providing food and habitat to indigenous
animals, preventing soil erosion, adding soil nutrients, and maintaining the local
environmental conditions and biodiversity.


=== 3.2.1 Measure: Acres of Nonindigenous Plant Species ===
=== 3.2.1 Measure: Acres of Nonindigenous Plant Species ===


This measure assesses the total number of acres, or the estimated percentage of acres,
This measure assesses the total number of acres, or the estimated percentage of acres, occupied by selected nonindigenous plant species in wilderness. The introduction and spread of nonindigenous species (also referred to as '''non-native''', alien, or '''exotic species''') is the second leading cause of plant and animal species endangerment and extinction worldwide (Lowe et al. 2000). Although many nonindigenous species are present throughout the United States, invasive nonindigenous species (i.e., those species that increase quickly in abundance and distribution) are a particular threat to wilderness character and are therefore the focus of this measure.
occupied by selected nonindigenous plant species in wilderness. The introduction and
spread of nonindigenous species (also referred to as non-native, alien, or exotic
species) is the second leading cause of plant and animal species endangerment and
extinction worldwide (Lowe et al. 2000). Although many nonindigenous species are
present throughout the United States, invasive nonindigenous species (i.e., those
species that increase quickly in abundance and distribution) are a particular threat to
wilderness character and are therefore the focus of this measure.


This measure was selected because nonindigenous plants may directly and indirectly
This measure was selected because nonindigenous plants may directly and indirectly alter the composition, structure, and function of natural communities in significant ways by degrading or eliminating habitat for native plant and animal species, and causing multiple cascading effects throughout the entire ecosystem. The adverse impact of these species on the Natural Quality of wilderness character is significant. Because of established concerns about nonindigenous species, this measure is relatively simple and cost effective to monitor.
alter the composition, structure, and function of natural communities in significant
ways by degrading or eliminating habitat for native plant and animal species, and
causing multiple cascading effects throughout the entire ecosystem. The adverse
impact of these species on the Natural Quality of wilderness character is significant.
Because of established concerns about nonindigenous species, this measure is
relatively simple and cost effective to monitor.


This measure is required for all Forest Service wildernesses. A 5-percent or greater
This measure is required for all Forest Service wildernesses. A 5-percent or greater change in the number of measured or estimated acres, or any change in defined "percentage occupied" categories, will result in a change in trend for this measure. An increase in the acreage occupied by nonindigenous species corresponds with a degrading trend.
change in the number of measured or estimated acres, or any change in defined
“percentage occupied” categories, will result in a change in trend for this measure.
An increase in the acreage occupied by nonindigenous species corresponds with a
degrading trend.


Refer to part 2, section 3.2.1, for detailed guidance on data sources and compilation
Refer to part 2, section 3.2.1, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


== 3.3 Indicator: Animals ==
== 3.3 Indicator: Animals ==


This indicator focuses on threats to indigenous animal species and communities.
This indicator focuses on threats to indigenous animal species and communities. Indigenous animal species (also referred to as native animal species) and animal communities are an essential biological component of natural wilderness ecosystems. Indigenous animal species and communities are those that evolved in the area and therefore have intrinsic value within a wilderness. Additionally, they are critically important to the entire ecosystem by providing food and habitat to other animals, digesting plant material and thereby making nutrients available in the soil for plants to use, scavenging carcasses of dead animals, and contributing to a wilderness ecosystem in many other ways.
Indigenous animal species (also referred to as native animal species) and animal
communities are an essential biological component of natural wilderness ecosystems.
Indigenous animal species and communities are those that evolved in the area and
therefore have intrinsic value within a wilderness. Additionally, they are critically
important to the entire ecosystem by providing food and habitat to other animals,
digesting plant material and thereby making nutrients available in the soil for plants
to use, scavenging carcasses of dead animals, and contributing to a wilderness
ecosystem in many other ways.


=== 3.3.1 Measure: Index of Nonindigenous Terrestrial Animal Species ===
=== 3.3.1 Measure: Index of Nonindigenous Terrestrial Animal Species ===


This measure is an index that assesses the geographic distribution and estimated
This measure is an index that assesses the geographic distribution and estimated impact of selected nonindigenous terrestrial animal species. Nonindigenous animal species generally occur inside a wilderness because of human influence, such as intentional and unintentional introductions and transplants. Once nonindigenous species become established outside a wilderness, they may spread naturally or disperse into that wilderness. Nonindigenous animals include livestock that intentionally graze in wilderness, as well as feral domesticated animals, such as feral livestock, horses, goats, and pigs. Examples of nonindigenous terrestrial insects include: Asian longhorned beetle, emerald ash borer, gypsy moth, and hemlock woolly adelgid. Terrestrial pathogens and diseases are included in this measure because even though they are not animals, they are not considered plants either and creating a separate measure for them is not warranted. Examples of terrestrial pathogens and diseases that would be included in this measure are sudden oak death, chronic wasting disease, and whitenose syndrome.
impact of selected nonindigenous terrestrial animal species. Nonindigenous animal
species generally occur inside a wilderness because of human influence, such as intentional and unintentional introductions and transplants. Once nonindigenous species become established outside a wilderness, they may spread naturally or disperse
into that wilderness. Nonindigenous animals include livestock that intentionally graze
in wilderness, as well as feral domesticated animals, such as feral livestock, horses,
goats, and pigs. Examples of nonindigenous terrestrial insects include: Asian longhorned
beetle, emerald ash borer, gypsy moth, and hemlock woolly adelgid. Terrestrial
pathogens and diseases are included in this measure because even though they are
not animals, they are not considered plants either and creating a separate measure for
them is not warranted. Examples of terrestrial pathogens and diseases that would be
included in this measure are sudden oak death, chronic wasting disease, and whitenose
syndrome.


This measure was selected because nonindigenous terrestrial animals, insects, and
This measure was selected because nonindigenous terrestrial animals, insects, and pathogens and diseases may significantly alter the composition, structure, and function of natural communities by degrading or eliminating habitat for '''indigenous species''', and causing multiple cascading effects throughout the entire ecosystem. The adverse impact of these species on the Natural Quality of wilderness character is significant.
pathogens and diseases may significantly alter the composition, structure, and
function of natural communities by degrading or eliminating habitat for indigenous
species, and causing multiple cascading effects throughout the entire ecosystem.
The adverse impact of these species on the Natural Quality of wilderness character is
significant.


Units are required to select either this measure or the following measure, Index of
Units are required to select either this measure or the following measure, Index of Nonindigenous Aquatic Animal Species, or may select both measures if relevant to the individual wilderness. A 5-percent or greater change in the measure value will result in a change in trend for this measure. Once there are five measure values, the threshold for meaningful change will switch to regression analysis, and statistical significance will determine the trend in the measure. An increase in the measure value corresponds with a degrading trend.
Nonindigenous Aquatic Animal Species, or may select both measures if relevant to the
individual wilderness. A 5-percent or greater change in the measure value will result in
a change in trend for this measure. Once there are five measure values, the threshold
for meaningful change will switch to regression analysis, and statistical significance
will determine the trend in the measure. An increase in the measure value corresponds
with a degrading trend.


Refer to part 2, section 3.3.1, for detailed guidance on data sources and compilation
Refer to part 2, section 3.3.1, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


=== 3.3.2 Measure: Index of Nonindigenous Aquatic Animal Species ===
=== 3.3.2 Measure: Index of Nonindigenous Aquatic Animal Species ===


This measure is an index that assesses the geographic distribution and estimated
This measure is an index that assesses the geographic distribution and estimated impact of selected nonindigenous aquatic species (NAS), including amphibians, fish, crustaceans, mollusks, gastropods, aquatic insects, and aquatic pathogens and diseases. NAS are typically introduced into a given wilderness by anthropogenic vectors, although species introductions may also have originated outside of a wilderness and the species subsequently moved into the wilderness by upstream or downstream movement. Aquatic pathogens and diseases are included in this measure because even though they are not animals, they are not considered plants either and creating a separate measure for them is not warranted. Examples of an aquatic pathogens and diseases that would be included in this measure are: whirling disease, iridoviruses, and chytrid fungus.
impact of selected nonindigenous aquatic species (NAS), including amphibians,
fish, crustaceans, mollusks, gastropods, aquatic insects, and aquatic pathogens and
diseases. NAS are typically introduced into a given wilderness by anthropogenic
vectors, although species introductions may also have originated outside of a
wilderness and the species subsequently moved into the wilderness by upstream or
downstream movement. Aquatic pathogens and diseases are included in this measure
because even though they are not animals, they are not considered plants either
and creating a separate measure for them is not warranted. Examples of an aquatic
pathogens and diseases that would be included in this measure are: whirling disease,
iridoviruses, and chytrid fungus.


This measure was selected because nonindigenous aquatic animal species may
This measure was selected because nonindigenous aquatic animal species may alter the composition, structure, and function of natural aquatic communities, and adversely impact indigenous species, reduce biodiversity, and degrade natural aquatic ecosystems.
alter the composition, structure, and function of natural aquatic communities, and
adversely impact indigenous species, reduce biodiversity, and degrade natural aquatic
ecosystems.


Local units are required to select either this measure or the preceding measure, Index
Local units are required to select either this measure or the preceding measure, Index of Nonindigenous Terrestrial Animal Species, or may select both measures if relevant to the individual wilderness. A 5-percent or greater change in the measure value results in a change in trend for this measure. Once there are five measure values, the threshold for meaningful change will switch to regression analysis, and statistical significance will determine the trend in the measure. An increase in the measure value corresponds with a degrading trend.
of Nonindigenous Terrestrial Animal Species, or may select both measures if relevant
to the individual wilderness. A 5-percent or greater change in the measure value
results in a change in trend for this measure. Once there are five measure values, the
threshold for meaningful change will switch to regression analysis, and statistical
significance will determine the trend in the measure. An increase in the measure value
corresponds with a degrading trend.


Refer to part 2, section 3.3.2, for detailed guidance on data sources and compilation
Refer to part 2, section 3.3.2, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


== 3.4 Indicator: Air and Water ==
== 3.4 Indicator: Air and Water ==


This indicator focuses on threats to air and water quality. Air and water are
This indicator focuses on threats to air and water quality. Air and water are fundamental physical resources of wilderness ecosystems, and both are essential to maintain properly functioning natural systems inside wilderness. Both air and water resources are vulnerable to degradation by pollutants produced outside of wilderness as a result of human development and industrial activity.
fundamental physical resources of wilderness ecosystems, and both are essential to
maintain properly functioning natural systems inside wilderness. Both air and water
resources are vulnerable to degradation by pollutants produced outside of wilderness
as a result of human development and industrial activity.


Units are required to select at least one of the five air quality measures included under
Units are required to select at least one of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. The Clean Air Act of 1977 mandates special protections for values related to air quality in both Class I and '''Class II areas''', many of which are also designated wildernesses. The presence of airborne pollutants in soil and water within wilderness can have direct adverse effects on sensitive plant and animal species and can directly impact essential ecosystem functions, such as nutrient cycling. Certain air pollutants also can reduce visibility. The effects of air pollution on plants, animals, soil, and water are important in all wildernesses, regardless of whether a wilderness is designated as Class I or Class II according to the Clean Air Act.
this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than
one air quality measure. The Clean Air Act of 1977 mandates special protections for
values related to air quality in both Class I and Class II areas, many of which are
also designated wildernesses. The presence of airborne pollutants in soil and water
within wilderness can have direct adverse effects on sensitive plant and animal species
and can directly impact essential ecosystem functions, such as nutrient cycling.
Certain air pollutants also can reduce visibility. The effects of air pollution on plants,
animals, soil, and water are important in all wildernesses, regardless of whether a
wilderness is designated as Class I or Class II according to the Clean Air Act.


In addition to air pollutants, water quality and water flows also are vulnerable to the
In addition to air pollutants, water quality and water flows also are vulnerable to the effects of physical manipulations inside and outside of wilderness. For example, dams outside a wilderness can markedly affect water quantity and quality, as well as stream morphology, inside a wilderness. Most existing NFS wildernesses include relatively undeveloped headwater watersheds with few water quality impacts. More recent additions to NFS wildernesses may include areas that are impacted by upstream watershed activities, such as by agriculture, mining, and land development.
effects of physical manipulations inside and outside of wilderness. For example, dams
outside a wilderness can markedly affect water quantity and quality, as well as stream
morphology, inside a wilderness. Most existing NFS wildernesses include relatively
undeveloped headwater watersheds with few water quality impacts. More recent
additions to NFS wildernesses may include areas that are impacted by upstream
watershed activities, such as by agriculture, mining, and land development.


=== 3.4.1 Measure: Concentration of Ambient Ozone ===
=== 3.4.1 Measure: Concentration of Ambient Ozone ===


This measure assesses the 3-year rolling average of ozone concentration (fourth
This measure assesses the 3-year rolling average of ozone concentration (fourth highest daily maximum 8-hour concentration) based on the Forest Service Air Resource Management Program's annual analyses of national ozone monitoring data. '''Ozone''' is a pollutant formed when emissions of nitrogen oxides (NOX) and volatile organic compounds react in the presence of sunlight. Human activities such as the burning of fossil fuels and industrial processes produce these pollutants, which can then travel long distances resulting in elevated ozone levels in wildernesses. In most places in the United States, reductions in human-generated NOX will cause a reduction in ground-level ozone. Ozone is one of the most toxic air pollutants to plants and its effects include visible injury to leaves and needles, premature leaf loss, reduced photosynthesis, and reduced growth in sensitive plant species. Continued exposure of vegetation to ozone over time may also result in increased susceptibility to disease and damage from insects, as well as changes in species diversity and community structure.
highest daily maximum 8-hour concentration) based on the Forest Service Air
Resource Management Program’s annual analyses of national ozone monitoring data.
Ozone is a pollutant formed when emissions of nitrogen oxides (NOX) and volatile
organic compounds react in the presence of sunlight. Human activities such as the
burning of fossil fuels and industrial processes produce these pollutants, which can
then travel long distances resulting in elevated ozone levels in wildernesses. In most
places in the United States, reductions in human-generated NOX will cause a reduction
in ground-level ozone. Ozone is one of the most toxic air pollutants to plants and
its effects include visible injury to leaves and needles, premature leaf loss, reduced
photosythesis, and reduced growth in sensitive plant species. Continued exposure of
vegetation to ozone over time may also result in increased susceptibility to disease and
damage from insects, as well as changes in species diversity and community structure.


This measure of air pollution was selected based on the potential impact of ozone
This measure of air pollution was selected based on the potential impact of ozone on wilderness vegetation and the availability of ozone measurements. Considering all of the potential negative effects on wilderness vegetation, increasing ozone levels in or near a wilderness are a direct human-caused threat to the Natural Quality of wilderness character. A network of long-term air quality monitors measure ambient ground-level ozone concentrations across the United States. The monitors are primarily intended to track whether NAAQS, established to protect human health and natural resources, are being met. Data from this network receive rigorous QA and QC review before being entered into the EPA's Air Quality System (AQS) database available at https://www.epa.gov/aqs. Using these data, staff in the Forest Service Air Resource Management Program calculate a suite of ozone statistics for all monitoring sites in the United States each year.
on wilderness vegetation and the availability of ozone measurements. Considering
all of the potential negative effects on wilderness vegetation, increasing ozone levels
in or near a wilderness are a direct human-caused threat to the Natural Quality of
wilderness character. A network of long-term air quality monitors measure ambient
ground-level ozone concentrations across the United States. The monitors are
primarily intended to track whether NAAQS, established to protect human health and
natural resources, are being met. Data from this network receive rigorous QA and
QC review before being entered into the EPA’s Air Quality System (AQS) database
available at https://www.epa.gov/aqs. Using these data, staff in the Forest Service Air
Resource Management Program calculate a suite of ozone statistics for all monitoring
sites in the United States each year.


If most relevant, local units may select just this measure of the five air quality
If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. A finding of statistical significance results in a change in trend for this measure. An increase in the average ozone concentration corresponds with a degrading trend.
measures included under this indicator (see sections 3.4.1 through 3.4.5), or may
optionally select more than one air quality measure. A finding of statistical significance
results in a change in trend for this measure. An increase in the average ozone
concentration corresponds with a degrading trend.


Refer to part 2, section 3.4.1, for detailed guidance on data sources and compilation
Refer to part 2, section 3.4.1, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


=== 3.4.2 Measure: Deposition of Nitrogen ===
=== 3.4.2 Measure: Deposition of Nitrogen ===


This measure assesses the amount of nitrogen deposition in a wilderness by using
This measure assesses the amount of nitrogen deposition in a wilderness by using either the average '''total deposition''' (based on nationally modeled or measured spatial data) or the trend in '''wet deposition''' (based on the Forest Service Air Program's annual analyses of spatially interpolated data). Nitrogen oxides (NOX) are one of the major pollutants emitted into the atmosphere during the burning of fossil fuels. Agricultural activities, especially livestock management and fertilizer application to soils, are the primary source of ammonia (NH3) released to the atmosphere. These pollutants return to terrestrial and aquatic environments as atmospheric deposition of nitric acids and ammonium. In sensitive ecosystems, these compounds can acidify soil and surface waters, which affects nutrient cycling, impacts the growth of vegetation, and causes the decline or death of aquatic insects and fish. Even in ecosystems that can buffer incoming acid compounds, excess nitrogen deposition can lead to chemical and biological changes that affect plant growth, species composition, and aquatic food webs. Descriptions of the effects of nitrogen deposition on natural resources are available on the Forest Service Air Quality Portal website available at https://www.srs.fs.usda.gov/airqualityportal/critical_loads/atmospheric_deposition.php.
either the average total deposition (based on nationally modeled or measured
spatial data) or the trend in wet deposition (based on the Forest Service Air
Program’s annual analyses of spatially interpolated data). Nitrogen oxides (NOX) are
one of the major pollutants emitted into the atmosphere during the burning of fossil
fuels. Agricultural activities, especially livestock management and fertilizer application
to soils, are the primary source of ammonia (NH3) released to the atmosphere. These
pollutants return to terrestrial and aquatic environments as atmospheric deposition of
nitric acids and ammonium. In sensitive ecosystems, these compounds can acidify soil
and surface waters, which affects nutrient cycling, impacts the growth of vegetation,
and causes the decline or death of aquatic insects and fish. Even in ecosystems that
can buffer incoming acid compounds, excess nitrogen deposition can lead to chemical
and biological changes that affect plant growth, species composition, and aquatic
food webs. Descriptions of the effects of nitrogen deposition on natural resources are
available on the Forest Service Air Quality Portal website available at https://www.srs.
fs.usda.gov/airqualityportal/critical_loads/atmospheric_deposition.php.


Nitrogen deposition was selected as a measure based on potential and observed
Nitrogen deposition was selected as a measure based on potential and observed negative impacts on wilderness ecosystems and the availability of deposition estimates across most wildernesses. While a few wildernesses may have direct nitrogen deposition measurements available, most will rely on estimates created through modeling based on data derived from long-term air quality monitoring stations that record nitrogen deposition across the United States.
negative impacts on wilderness ecosystems and the availability of deposition estimates
across most wildernesses. While a few wildernesses may have direct nitrogen
deposition measurements available, most will rely on estimates created through
modeling based on data derived from long-term air quality monitoring stations that
record nitrogen deposition across the United States.


If most relevant, local units may select just this measure of the five air quality
If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. A finding of statistical significance, or any change in defined categories, results in a change in trend for this measure. An increase in the amount of nitrogen deposition corresponds with a degrading trend.
measures included under this indicator (see sections 3.4.1 through 3.4.5), or
may optionally select more than one air quality measure. A finding of statistical
significance, or any change in defined categories, results in a change in trend for
this measure. An increase in the amount of nitrogen deposition corresponds with a
degrading trend.


Refer to part 2, section 3.4.2, for detailed guidance on data sources and compilation
Refer to part 2, section 3.4.2, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


=== 3.4.3 Measure: Deposition of Sulfur ===
=== 3.4.3 Measure: Deposition of Sulfur ===


This measure assesses the amount of sulfur deposition in a wilderness by using
This measure assesses the amount of sulfur deposition in a wilderness by using either the trend in wet deposition (based on the Forest Service Air Resource Management Program's annual analyses of spatially interpolated data) or the average total deposition (based on nationally modeled spatial data). Sulfur dioxide (SO2) is emitted during the burning of fossil fuels, especially coal, and can be transported long distances through the atmosphere before being deposited in the form of sulfuric acid. In sensitive ecosystems, sulfuric acid can contribute to acidification of soil and surface waters, affect nutrient cycling and impact the growth of vegetation, as well as lead to the decline and death of aquatic insects and fish. These effects have been more prevalent in the eastern United States due to historically high sulfur deposition levels.
either the trend in wet deposition (based on the Forest Service Air Resource
Management Program’s annual analyses of spatially interpolated data) or the average
total deposition (based on nationally modeled spatial data). Sulfur dioxide (SO2) is
emitted during the burning of fossil fuels, especially coal, and can be transported
long distances through the atmosphere before being deposited in the form of sulfuric
acid. In sensitive ecosystems, sulfuric acid can contribute to acidification of soil and
surface waters, affect nutrient cycling and impact the growth of vegetation, as well as
lead to the decline and death of aquatic insects and fish. These effects have been more
prevalent in the eastern United States due to historically high sulfur deposition levels.


Although sulfur deposition has been declining and fish kills from acidification are
Although sulfur deposition has been declining and fish kills from acidification are now infrequent, sulfur bound and held in the soil continues to affect soil chemistry, soil buffering capacity, and the nutrient status of soils. Detailed descriptions of the effects of sulfur deposition on natural resources are available on the Forest Service Air Quality Portal website available at https://www.srs.fs.usda.gov/airqualityportal/critical_loads/atmospheric_deposition.php.
now infrequent, sulfur bound and held in the soil continues to affect soil chemistry,
soil buffering capacity, and the nutrient status of soils. Detailed descriptions of the
effects of sulfur deposition on natural resources are available on the Forest Service
Air Quality Portal website available at https://www.srs.fs.usda.gov/airqualityportal/
critical_loads/atmospheric_deposition.php.


Sulfur deposition was selected as a measure based on observed negative impacts
Sulfur deposition was selected as a measure based on observed negative impacts on wilderness ecosystems and the availability of deposition estimates across most wildernesses. While a few wildernesses may have direct sulfur deposition measurements available, most will rely on estimates created through modeling based on data derived from networks of long-term air quality monitoring stations that record sulfur deposition across the United States. Eastern national forests are likely to be more interested in using the sulfur deposition measure over the nitrogen measure because sulfur continues to exert a stronger influence on many ecosystems in the Eastern United States.
on wilderness ecosystems and the availability of deposition estimates across
most wildernesses. While a few wildernesses may have direct suflur deposition
measurements available, most will rely on estimates created through modeling based
on data derived from networks of long-term air quality monitoring stations that record
sulfur deposition across the United States. Eastern national forests are likely to be
more interested in using the sulfur deposition measure over the nitrogen measure
because sulfur continues to exert a stronger influence on many ecosystems in the
Eastern United States.


If most relevant, local units may select just this measure of the five air quality
If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. A finding of statistical significance, or any change in defined categories, results in a change in trend for this measure. An increase in the amount of sulfur deposition corresponds with a degrading trend.
measures included under this indicator (see sections 3.4.1 through 3.4.5), or
may optionally select more than one air quality measure. A finding of statistical
significance, or any change in defined categories, results in a change in trend for this
measure. An increase in the amount of sulfur deposition corresponds with a degrading
trend.


Refer to part 2, section 3.4.3, for detailed guidance on data sources and compilation
Refer to part 2, section 3.4.3, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


=== 3.4.4 Measure: Amount of Haze ===
=== 3.4.4 Measure: Amount of Haze ===


This measure assesses the trend in average deciview for the 20 percent most
This measure assesses the trend in average '''deciview''' for the 20 percent most impaired days, based on the Forest Service Air Resource Management Program's annual analyses of national visibility monitoring data. Although air quality managers often refer to visibility (or the lack thereof) in terms of its impacts on human perception, visibility is a general indicator of air quality monitored for its inherent value, just as one would monitor the biophysical condition of water quality.
impaired days, based on the Forest Service Air Resource Management Program’s
annual analyses of national visibility monitoring data. Although air quality managers
often refer to visibility (or the lack thereof) in terms of its impacts on human
perception, visibility is a general indicator of air quality monitored for its inherent
value, just as one would monitor the biophysical condition of water quality.


This measure was selected because visual air quality (visibility) measurements
This measure was selected because visual air quality (visibility) measurements provide a direct link between the concentration of pollutants in the atmosphere and degradation of the natural and physical condition of clean air in wilderness. Reduced visibility can affect local climate and photosynthetic activity. Additionally, visibility directly affects many wildlife and insect species that depend on clear, clean air (e.g., foraging raptors, pollinators).
provide a direct link between the concentration of pollutants in the atmosphere and
degradation of the natural and physical condition of clean air in wilderness. Reduced
visibility can affect local climate and photosynthetic activity. Additionally, visibility
directly affects many wildlife and insect species that depend on clear, clean air (e.g.,
foraging raptors, pollinators).


Particles suspended in the atmosphere that absorb and scatter light cause regional
Particles suspended in the atmosphere that absorb and scatter light cause regional '''haze'''. Impairment is operationally defined as the portion of haze which results from human activity. Fine particles (particles less than 2.5 μm in diameter) are routinely split into six distinct categories: (1) sulfates, (2) nitrates, (3) organics, (4) elemental carbon, (5) sea salt, and (6) soil.
haze. Impairment is operationally defined as the portion of haze which results from
human activity. Fine particles (particles less than 2.5 μm in diameter) are routinely
split into six distinct categories: (1) sulfates, (2) nitrates, (3) organics, (4) elemental
carbon, (5) sea salt, and (6) soil.


A simple algorithm is used to identify the 20 percent of sample days each calendar
A simple algorithm is used to identify the 20 percent of sample days each calendar year that are likely to be most affected by anthropogenic pollutants. The visibility conditions on these 20 percent "most impaired" days are converted to deciview and averaged annually.
year that are likely to be most affected by anthropogenic pollutants. The visibility
conditions on these 20 percent “most impaired” days are converted to deciview and
averaged annually.


If most relevant, local units may select just this measure of the five air quality
If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. Any change in defined categories results in a change in trend for this measure. An increase in the amount of haze corresponds with a degrading trend.
measures included under this indicator (see sections 3.4.1 through 3.4.5), or may
optionally select more than one air quality measure. Any change in defined categories
results in a change in trend for this measure. An increase in the amount of haze
corresponds with a degrading trend.


Refer to part 2, section 3.4.4, for detailed guidance on data sources and compilation
Refer to part 2, section 3.4.4, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


=== 3.4.5 Measure: Index of Sensitive Lichen Species ===
=== 3.4.5 Measure: Index of Sensitive Lichen Species ===


This measure assesses the trend in air pollution scores for nitrogen and sulfur derived
This measure assesses the trend in air pollution scores for nitrogen and sulfur derived from the presence and abundance of '''sensitive lichen species''', based on the Forest Service Air Resource Management Program's analyses of local biomonitoring data. Air pollution scores are calculated for each wilderness biomonitoring plot by surveying epiphytic lichen species (i.e., those growing on trees) with varying sensitivities to nitrogen and sulfur air pollution. Lichens are important contributors to critical ecosystem processes, such as nutrient cycling, and they provide food and nesting material for birds and other animals. The composition of an epiphytic lichen community is a well-known biological indicator of air pollution in forested ecosystems because epiphytic lichens rely completely on atmospheric sources of nutrition.
from the presence and abundance of sensitive lichen species, based on the Forest
Service Air Resource Management Program’s analyses of local biomonitoring data. Air
pollution scores are calculated for each wilderness biomonitoring plot by surveying
epiphytic lichen species (i.e., those growing on trees) with varying sensitivities to
nitrogen and sulfur air pollution. Lichens are important contributors to critical
ecosystem processes, such as nutrient cycling, and they provide food and nesting material for birds and other animals. The composition of an epiphytic lichen
community is a well-known biological indicator of air pollution in forested ecosystems
because epiphytic lichens rely completely on atmospheric sources of nutrition.


The lack of a waxy cuticle on the lichen surface permits absorption and leaching of
The lack of a waxy cuticle on the lichen surface permits absorption and leaching of nutrients in very similar proportion to what is present in the atmosphere. Lichen species that are sensitive to nitrogen and sulfur deposition eventually die or diminish from the forest if pollution levels are elevated. Epiphytic lichen communities that retain the species most sensitive to air pollution indicate good air quality. Nitrogen and sulfur air pollutants can cause measurable lichen community changes within a 5-year monitoring period depending on the spatial and temporal extent of deposition.
nutrients in very similar proportion to what is present in the atmosphere. Lichen
species that are sensitive to nitrogen and sulfur deposition eventually die or diminish
from the forest if pollution levels are elevated. Epiphytic lichen communities that
retain the species most sensitive to air pollution indicate good air quality. Nitrogen
and sulfur air pollutants can cause measurable lichen community changes within a
5-year monitoring period depending on the spatial and temporal extent of deposition.


This measure was selected because the presence or absence of sensitive lichens over
This measure was selected because the presence or absence of sensitive lichens over time indicates improving or degrading air quality (Matos et al. 2017). Many Forest Service regions routinely collect data on epiphytic lichen communities; this measure of air pollution may be especially useful for wildernesses that are not near other air pollution monitors, such as in Alaska.
time indicates improving or degrading air quality (Matos et al. 2017). Many Forest
Service regions routinely collect data on epiphytic lichen communities; this measure
of air pollution may be especially useful for wildernesses that are not near other air
pollution monitors, such as in Alaska.


If most relevant, local units may select just this measure of the five air quality
If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. Any change in defined categories results in a change in trend for this measure. A change in the trend category indicating an increase in air pollution corresponds with a degrading trend.
measures included under this indicator (see sections 3.4.1 through 3.4.5), or may
optionally select more than one air quality measure. Any change in defined categories
results in a change in trend for this measure. A change in the trend category indicating
an increase in air pollution corresponds with a degrading trend.


Refer to part 2, section 3.4.5, for detailed guidance on data sources and compilation
Refer to part 2, section 3.4.5, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


=== 3.4.6 Measure: Extent of Waterbodies With Impaired Water Quality ===
=== 3.4.6 Measure: Extent of Waterbodies With Impaired Water Quality ===


This measure assesses the miles of streams or number of lakes inside wilderness
This measure assesses the miles of streams or number of lakes inside wilderness with impaired water quality, based on national or state 303(d) lists of impaired water bodies or local monitoring data. Water quality is influenced by a wide range of biological and physical variables from both inside and outside a wilderness. This measure focuses on human-caused threats to wilderness water quality and not on natural variation in water quality. Despite the general importance of water and a myriad of national water monitoring programs, water monitoring in wilderness is generally conducted only for site-specific threats. For example, impacts from grazing (sediment, manure), mining (sediment, heavy metals, and other toxins), air pollutants (nitrogen, sulfur), and recreation (sediment, fecal coliform bacteria) vary tremendously from wilderness to wilderness and from one site to another within that wilderness.
with impaired water quality, based on national or state 303(d) lists of impaired
water bodies or local monitoring data. Water quality is influenced by a wide range
of biological and physical variables from both inside and outside a wilderness. This
measure focuses on human-caused threats to wilderness water quality and not on
natural variation in water quality. Despite the general importance of water and a
myriad of national water monitoring programs, water monitoring in wilderness
is generally conducted only for site-specific threats. For example, impacts from
grazing (sediment, manure), mining (sediment, heavy metals, and other toxins), air
pollutants (nitrogen, sulfur), and recreation (sediment, fecal coliform bacteria) vary
tremendously from wilderness to wilderness and from one site to another within that
wilderness.


This measure was selected because of the fundamental importance of water quality
This measure was selected because of the fundamental importance of water quality to the Natural Quality of wilderness character. Water quality directly influences the health of plant and animal communities. While many headwater wilderness watersheds have good water quality, degradation from historical activities such as mining or from upstream developments outside a wilderness may impact water quality in wilderness.
to the Natural Quality of wilderness character. Water quality directly influences the health of plant and animal communities. While many headwater wilderness
watersheds have good water quality, degradation from historical activities such as
mining or from upstream developments outside a wilderness may impact water
quality in wilderness.


Measures related to different aspects of water are included in other indicators under
Measures related to different aspects of water are included in other indicators under the Natural Quality. For example, changes to biological aspects of water are monitored under the plants or animals indicators. The measure Watershed Condition Class (see section 3.5.1) uses the Forest Service WCF, which includes water quality as one of 12 indicators that determine watershed condition. While WCF assesses the overall watershed condition of the entire 6th code '''Hydrologic Unit Code (HUC)''', this measure provides a more specific focus on water quality within a wilderness.
the Natural Quality. For example, changes to biological aspects of water are monitored
under the plants or animals indicators. The measure Watershed Condition Class (see
section 3.5.1) uses the Forest Service WCF, which includes water quality as one of
12 indicators that determine watershed condition. While WCF assesses the overall
watershed condition of the entire 6th code Hydrologic Unit Code (HUC), this
measure provides a more specific focus on water quality within a wilderness.


This measure is required for all Forest Service wildernesses. A 5-percent or greater
This measure is required for all Forest Service wildernesses. A 5-percent or greater change in the miles of impaired streams or number of lakes will result in a change in trend for this measure. An increase in the extent of impaired waterbodies corresponds with a degrading trend.
change in the miles of impaired streams or number of lakes will result in a change in
trend for this measure. An increase in the extent of impaired waterbodies corresponds
with a degrading trend.


Refer to part 2, section 3.4.6, for detailed guidance on data sources and compilation
Refer to part 2, section 3.4.6, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
protocols, analysis, data adequacy, and interpreting the threshold for meaningful
change.


== 3.5 Indicator: Ecological Processes ==
== 3.5 Indicator: Ecological Processes ==


This indicator focuses on threats to ecological processes that affect biotic and
This indicator focuses on threats to ecological processes that affect biotic and abiotic components of wilderness ecological systems. Ecological processes are the interactions among the biotic and abiotic components of ecosystems and include disturbance events (e.g., fire and wind storms, insect and pathogen outbreaks), predation, competition, decomposition, symbioses, and nutrient cycling. Ecological processes involve multiple components of wilderness ecosystems and are critical to all aspects of ecosystem composition, structure, and function, resulting in long-term and cascading effects on the natural community in wilderness.
abiotic components of wilderness ecological systems. Ecological processes are the
interactions among the biotic and abiotic components of ecosystems and include
disturbance events (e.g., fire and wind storms, insect and pathogen outbreaks),
predation, competition, decomposition, symbioses, and nutrient cycling. Ecological
processes involve multiple components of wilderness ecosystems and are critical to all
aspects of ecosystem composition, structure, and function, resulting in long-term and
cascading effects on the natural community in wilderness.


The integrity of ecological processes within wilderness is crucial to maintaining the
The integrity of ecological processes within wilderness is crucial to maintaining the Natural Quality of wilderness character. Ecological processes are complex and difficult to quantify. Of the vast number of threats to ecological processes that could be used for WCM, this technical guide includes only those that take advantage of existing datasets and provide an overall synthesis of the condition of an ecological process within wilderness. This indicator does not include measures on the effects of climate change on ecological processes in wilderness because of the difficulty in separating the localized effects of natural change from climate change, combined with the general lack of wilderness-specific data on the natural variability of ecological processes (see section 3.6 in part 2, and Appendix 2).
Natural Quality of wilderness character. Ecological processes are complex and difficult
to quantify. Of the vast number of threats to ecological processes that could be used
for WCM, this technical guide includes only those that take advantage of existing
datasets and provide an overall synthesis of the condition of an ecological process
within wilderness. This indicator does not include measures on the effects of climate
change on ecological processes in wilderness because of the difficulty in separating the
localized effects of natural change from climate change, combined with the general
lack of wilderness-specific data on the natural variability of ecological processes (see
section 3.6 in part 2, and Appendix 2).


=== 3.5.1 Measure: Watershed Condition Class ===
=== 3.5.1 Measure: Watershed Condition Class ===


This measure assesses the average wilderness watershed condition class, based
This measure assesses the average wilderness '''watershed condition class''', based on Forest Service Watershed Condition Classification (WCC) data. The WCF is a nationally consistent, reconnaissance-level approach for classifying NFS watershed conditions that uses a comprehensive set of 12 indicators to represent the underlying ecological, hydrological, and geomorphic functions and processes that affect watershed condition (USDA Forest Service 2011b,c). WCC maps generated from the WCF characterize the health and condition of NFS lands in more than 15,000 watersheds across the country. These maps, instituted in 2011, established watershed baseline conditions along with information on ecological, social, and economic factors, as well as partnership opportunities to establish watershed restoration priorities.
on Forest Service Watershed Condition Classification (WCC) data. The WCF is a
nationally consistent, reconnaissance-level approach for classifying NFS watershed
conditions that uses a comprehensive set of 12 indicators to represent the underlying
ecological, hydrological, and geomorphic functions and processes that affect watershed
condition (USDA Forest Service 2011b,c). WCC maps generated from the WCF
characterize the health and condition of NFS lands in more than 15,000 watersheds
across the country. These maps, instituted in 2011, established watershed baseline
conditions along with information on ecological, social, and economic factors, as well
as partnership opportunities to establish watershed restoration priorities.


This measure was selected because it reflects the integrity and ecological importance
This measure was selected because it reflects the integrity and ecological importance of watersheds, including biotic integrity, resiliency, connectivity, and important ecosystem services such as high-quality water, the recharge of streams and aquifers, maintenance of riparian communities, and the moderation of climate variability and change. Updating the WCC ratings for each watershed is planned at five-year intervals with the next update initiated in 2016.
of watersheds, including biotic integrity, resiliency, connectivity, and important
ecosystem services such as high-quality water, the recharge of streams and aquifers,
maintenance of riparian communities, and the moderation of climate variability and
change. Updating the WCC ratings for each watershed is planned at five-year intervals
with the next update initiated in 2016.


There is some redundancy between this measure and the Extent of Waterbodies With
There is some redundancy between this measure and the Extent of Waterbodies With Impaired Water Quality measure. While this measure uses all 12 WCF indicators, including the indicator for water quality, the Extent of Waterbodies With Impaired Water Quality measure relies heavily on EPA and individual state 303(d) lists of streams or lakes with impaired water quality. The Extent of Waterbodies With Impaired Water Quality is appropriate as a measure under the Air and Water indicator as it provides a site-specific assessment of water quality in wilderness. Using all 12 WCF indicators in this measure provides a more complete overall assessment of watershed condition because it includes additional aquatic and terrestrial physical and biological information. This measure is therefore located under the Ecological Processes indicator rather than the Air and Water indicator.
Impaired Water Quality measure. While this measure uses all 12 WCF indicators,
including the indicator for water quality, the Extent of Waterbodies With Impaired
Water Quality measure relies heavily on EPA and individual state 303(d) lists of
streams or lakes with impaired water quality. The Extent of Waterbodies With
Impaired Water Quality is appropriate as a measure under the Air and Water
indicator as it provides a site-specific assessment of water quality in wilderness. Using
all 12 WCF indicators in this measure provides a more complete overall assessment
of watershed condition because it includes additional aquatic and terrestrial physical
and biological information. This measure is therefore located under the Ecological
Processes indicator rather than the Air and Water indicator.


Local units are required to select either this measure or the following measure,
Local units are required to select either this measure or the following measure, Number of Animal Unit Months of Commercial Livestock Use, or may select both measures if relevant to the individual wilderness. Any change in the average wilderness watershed condition class results in a change in trend for this measure. An increase in the watershed condition class corresponds with a degrading trend.
Number of Animal Unit Months of Commercial Livestock Use, or may select
both measures if relevant to the individual wilderness. Any change in the average
wilderness watershed condition class results in a change in trend for this measure. An
increase in the watershed condition class corresponds with a degrading trend.


Refer to part 2, section 3.5.1, for more detailed guidance on data sources and
Refer to part 2, section 3.5.1, for more detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
compilation protocols, analysis, data adequacy, and interpreting the threshold for
meaningful change.


=== 3.5.2 Measure: Number of Animal Unit Months of Commercial Livestock Use ===
=== 3.5.2 Measure: Number of Animal Unit Months of Commercial Livestock Use ===


This measure assesses the 3-year rolling average of commercial livestock use, based
This measure assesses the 3-year rolling average of commercial livestock use, based on an annual count of wilderness '''animal unit months''' (AUMs) within a wilderness. The Wilderness Act states that, "The grazing of livestock, where established prior to the effective date of this act, shall be permitted to continue subject to reasonable regulations as are deemed necessary by the Secretary of Agriculture" (Section 4(d) (4)(2)). Subsequent wilderness legislation and the Congressional Grazing Guidelines (House Reports 96–617 and 96–1126 that are included in the Colorado Wilderness Act of 1980) uphold this mandate from the Wilderness Act. In practice, this means that livestock grazing cannot be reduced or phased out simply because an area is designated as wilderness—any adjustments in livestock grazing must be made through revisions in the normal rangeland management and land management planning and policy-setting processes. These processes consider legal mandates, range condition, and protection of the range resource from deterioration.
on an annual count of wilderness animal unit months (AUMs) within a wilderness.
The Wilderness Act states that, “The grazing of livestock, where established prior
to the effective date of this act, shall be permitted to continue subject to reasonable
regulations as are deemed necessary by the Secretary of Agriculture” (Section 4(d)
(4)(2)). Subsequent wilderness legislation and the Congressional Grazing Guidelines
(House Reports 96–617 and 96–1126 that are included in the Colorado Wilderness
Act of 1980) uphold this mandate from the Wilderness Act. In practice, this means
that livestock grazing cannot be reduced or phased out simply because an area is
designated as wilderness—any adjustments in livestock grazing must be made through
revisions in the normal rangeland management and land management planning and
policy-setting processes. These processes consider legal mandates, range condition,
and protection of the range resource from deterioration.


This measure was selected because the presence of livestock, even though allowed
This measure was selected because the presence of livestock, even though allowed under the Wilderness Act, represents a nonindigenous, domestic animal that impacts many aspects of the Natural Quality of wilderness character (Belsky et al. 1999; Beschta et al. 2014). Livestock grazing may impact indigenous plant and animal communities, soil, and watershed conditions within a wilderness. This measure does not directly monitor the ecological impacts of livestock grazing; rather it is based on the assumption that a declining number of AUMs results in an improving trend in ecological processes within wilderness, even though the adverse ecological effects of livestock may persist (Nussle et al. 2017).
under the Wilderness Act, represents a nonindigenous, domestic animal that impacts
many aspects of the Natural Quality of wilderness character (Belsky et al. 1999;
Beschta et al. 2014). Livestock grazing may impact indigenous plant and animal
communities, soil, and watershed conditions within a wilderness. This measure does
not directly monitor the ecological impacts of livestock grazing; rather it is based on
the assumption that a declining number of AUMs results in an improving trend in
ecological processes within wilderness, even though the adverse ecological effects of
livestock may persist (Nussle et al. 2017).


The amount of annual livestock use is based on the AUMs of livestock grazing
The amount of annual livestock use is based on the AUMs of livestock grazing authorized by a grazing permit for allotments located wholly or partially within a wilderness. AUMs are the preferred unit of measurement instead of head months and should be used if available.
authorized by a grazing permit for allotments located wholly or partially within a
wilderness. AUMs are the preferred unit of measurement instead of head months and
should be used if available.


Local units are required to select either this measure or the preceding measure,
Local units are required to select either this measure or the preceding measure, Watershed Condition Class, or may select both measures if relevant to the individual wilderness. A 5-percent change in the 3-year rolling average amount of commercial livestock use will result in a change in trend for this measure. Once there are five measure values, the threshold for meaningful change will switch to regression analysis, and statistical significance will determine the trend in the measure. An increase in the average amount of commercial livestock use corresponds with a degrading trend.
Watershed Condition Class, or may select both measures if relevant to the individual
wilderness. A 5-percent change in the 3-year rolling average amount of commercial
livestock use will result in a change in trend for this measure. Once there are five
measure values, the threshold for meaningful change will switch to regression
analysis, and statistical significance will determine the trend in the measure. An
increase in the average amount of commercial livestock use corresponds with a
degrading trend.


Refer to part 2, section 3.5.2, for more detailed guidance on data sources and
Refer to part 2, section 3.5.2, for more detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.
compilation protocols, analysis, data adequacy, and interpreting the threshold for
meaningful change.

Latest revision as of 20:17, 5 March 2023

The objective of monitoring the Natural Quality is to assess the effects of modern civilization on the integrity of wilderness ecosystems, with a focus on plants, animals, air and water, and ecological processes. The Wilderness Act defines wilderness as an area that "is protected and managed so as to preserve its natural conditions" and that these areas should be free from the effects of "an increasing population, accompanied by expanding settlement and growing mechanization" (sections 2(c) and 2(a), respectively). Human-caused changes to wilderness ecological systems can be intentional or unintentional. While managers may have control over some impacts to natural ecosystems in wilderness, many threats come from external sources outside of their jurisdiction (e.g., air pollutants and nonindigenous species). In contrast to the Untrammeled Quality, which monitors actions that manipulate or control ecological systems, the Natural Quality monitors the effects on wilderness ecosystems from actions as well as external forces. While this quality encompasses all the naturally occurring species, physical resources, and ecological functions and processes in wilderness, practical limitations require that a relatively small but significant subset of possible measures are monitored.

For the Natural Quality, a single monitoring question provides the broad context and four indicators provide the structure for this monitoring (as summarized in table 1.3.1).

Table 1.3.1—Monitoring question, indicators, measures, and measure types for the Natural Quality.
Natural Quality
Monitoring question: What are the trends in the natural environment from human-caused change?
Indicator Measure Measure type
Plants Acres of nonindigenous plants Required
Animals Index of nonindigenous terrestrial animal species Required to select at least one
Index of nonindigenous aquatic animal species
Air and water Concentration of ambient ozone Required to select at least one
Deposition of nitrogen
Deposition of sulfur
Amount of haze
Index of sensitive lichen species
Extent of waterbodies with impaired water quality Required
Ecological processes Watershed condition class Required to select at least one
Number of animal unit months of commercial livestock use

3.1 Monitoring Question

A single monitoring question is used to monitor the Natural Quality: What are the trends in the natural environment from human-caused change?

This monitoring question assesses the trends in natural wilderness ecosystems that result from human-caused threats occurring since designation of the area as wilderness. Importantly, this monitoring question seeks to distinguish between natural variability, which is integral to all ecosystems and does not degrade wilderness character, and human-caused change. In wilderness, the primary goal is to allow ecosystems to function and change without impacts or interference from modern civilization; therefore, the Natural Quality should not be used to set a target to maintain a particular ecological state or condition. In addition, this monitoring question does not include actions taken to restore ecological systems in wilderness. There are several reasons for not including these actions, including: (1) actions are tracked in the Untrammeled Quality, not the Natural Quality that tracks effects; (2) restoration actions are highly site-dependent and no single national protocol to measure such actions and their effects has been developed; (3) restoration actions typically assume static or historical ecological conditions contrary to wilderness as a place where human-determined states are not appropriate; and (4) the effects of restoration actions should eventually show, with monitoring, as an improving trend in the Natural Quality.

Four indicators assess a range of ecosystem components, structures, and functions in wilderness: (1) plants, (2) animals, (3) air and water, and (4) ecological processes. Practical and conceptual constraints mean that not everything important to wilderness ecosystems can be included in this monitoring. Likewise, not all ecological data currently collected by scientists are relevant or necessary to include in WCM. The measures under each indicator are not all encompassing; rather, the measures are selected because they are known human-caused threats to the indicators. Part 2, section 3.6, provides a detailed discussion of the criteria and process used for selecting measures under the Natural Quality; this section should guide local units considering the use of locally developed measures under this quality.

3.2 Indicator: Plants

This indicator focuses on threats to indigenous plant species and communities. Indigenous plant species (also referred to as native plant species) and plant communities are an essential biological component of natural wilderness ecosystems. Indigenous plant species and plant communities are those that evolved in an area and therefore have intrinsic value within a wilderness. In addition, they are critically important to the entire ecosystem by providing food and habitat to indigenous animals, preventing soil erosion, adding soil nutrients, and maintaining the local environmental conditions and biodiversity.

3.2.1 Measure: Acres of Nonindigenous Plant Species

This measure assesses the total number of acres, or the estimated percentage of acres, occupied by selected nonindigenous plant species in wilderness. The introduction and spread of nonindigenous species (also referred to as non-native, alien, or exotic species) is the second leading cause of plant and animal species endangerment and extinction worldwide (Lowe et al. 2000). Although many nonindigenous species are present throughout the United States, invasive nonindigenous species (i.e., those species that increase quickly in abundance and distribution) are a particular threat to wilderness character and are therefore the focus of this measure.

This measure was selected because nonindigenous plants may directly and indirectly alter the composition, structure, and function of natural communities in significant ways by degrading or eliminating habitat for native plant and animal species, and causing multiple cascading effects throughout the entire ecosystem. The adverse impact of these species on the Natural Quality of wilderness character is significant. Because of established concerns about nonindigenous species, this measure is relatively simple and cost effective to monitor.

This measure is required for all Forest Service wildernesses. A 5-percent or greater change in the number of measured or estimated acres, or any change in defined "percentage occupied" categories, will result in a change in trend for this measure. An increase in the acreage occupied by nonindigenous species corresponds with a degrading trend.

Refer to part 2, section 3.2.1, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.3 Indicator: Animals

This indicator focuses on threats to indigenous animal species and communities. Indigenous animal species (also referred to as native animal species) and animal communities are an essential biological component of natural wilderness ecosystems. Indigenous animal species and communities are those that evolved in the area and therefore have intrinsic value within a wilderness. Additionally, they are critically important to the entire ecosystem by providing food and habitat to other animals, digesting plant material and thereby making nutrients available in the soil for plants to use, scavenging carcasses of dead animals, and contributing to a wilderness ecosystem in many other ways.

3.3.1 Measure: Index of Nonindigenous Terrestrial Animal Species

This measure is an index that assesses the geographic distribution and estimated impact of selected nonindigenous terrestrial animal species. Nonindigenous animal species generally occur inside a wilderness because of human influence, such as intentional and unintentional introductions and transplants. Once nonindigenous species become established outside a wilderness, they may spread naturally or disperse into that wilderness. Nonindigenous animals include livestock that intentionally graze in wilderness, as well as feral domesticated animals, such as feral livestock, horses, goats, and pigs. Examples of nonindigenous terrestrial insects include: Asian longhorned beetle, emerald ash borer, gypsy moth, and hemlock woolly adelgid. Terrestrial pathogens and diseases are included in this measure because even though they are not animals, they are not considered plants either and creating a separate measure for them is not warranted. Examples of terrestrial pathogens and diseases that would be included in this measure are sudden oak death, chronic wasting disease, and whitenose syndrome.

This measure was selected because nonindigenous terrestrial animals, insects, and pathogens and diseases may significantly alter the composition, structure, and function of natural communities by degrading or eliminating habitat for indigenous species, and causing multiple cascading effects throughout the entire ecosystem. The adverse impact of these species on the Natural Quality of wilderness character is significant.

Units are required to select either this measure or the following measure, Index of Nonindigenous Aquatic Animal Species, or may select both measures if relevant to the individual wilderness. A 5-percent or greater change in the measure value will result in a change in trend for this measure. Once there are five measure values, the threshold for meaningful change will switch to regression analysis, and statistical significance will determine the trend in the measure. An increase in the measure value corresponds with a degrading trend.

Refer to part 2, section 3.3.1, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.3.2 Measure: Index of Nonindigenous Aquatic Animal Species

This measure is an index that assesses the geographic distribution and estimated impact of selected nonindigenous aquatic species (NAS), including amphibians, fish, crustaceans, mollusks, gastropods, aquatic insects, and aquatic pathogens and diseases. NAS are typically introduced into a given wilderness by anthropogenic vectors, although species introductions may also have originated outside of a wilderness and the species subsequently moved into the wilderness by upstream or downstream movement. Aquatic pathogens and diseases are included in this measure because even though they are not animals, they are not considered plants either and creating a separate measure for them is not warranted. Examples of an aquatic pathogens and diseases that would be included in this measure are: whirling disease, iridoviruses, and chytrid fungus.

This measure was selected because nonindigenous aquatic animal species may alter the composition, structure, and function of natural aquatic communities, and adversely impact indigenous species, reduce biodiversity, and degrade natural aquatic ecosystems.

Local units are required to select either this measure or the preceding measure, Index of Nonindigenous Terrestrial Animal Species, or may select both measures if relevant to the individual wilderness. A 5-percent or greater change in the measure value results in a change in trend for this measure. Once there are five measure values, the threshold for meaningful change will switch to regression analysis, and statistical significance will determine the trend in the measure. An increase in the measure value corresponds with a degrading trend.

Refer to part 2, section 3.3.2, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.4 Indicator: Air and Water

This indicator focuses on threats to air and water quality. Air and water are fundamental physical resources of wilderness ecosystems, and both are essential to maintain properly functioning natural systems inside wilderness. Both air and water resources are vulnerable to degradation by pollutants produced outside of wilderness as a result of human development and industrial activity.

Units are required to select at least one of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. The Clean Air Act of 1977 mandates special protections for values related to air quality in both Class I and Class II areas, many of which are also designated wildernesses. The presence of airborne pollutants in soil and water within wilderness can have direct adverse effects on sensitive plant and animal species and can directly impact essential ecosystem functions, such as nutrient cycling. Certain air pollutants also can reduce visibility. The effects of air pollution on plants, animals, soil, and water are important in all wildernesses, regardless of whether a wilderness is designated as Class I or Class II according to the Clean Air Act.

In addition to air pollutants, water quality and water flows also are vulnerable to the effects of physical manipulations inside and outside of wilderness. For example, dams outside a wilderness can markedly affect water quantity and quality, as well as stream morphology, inside a wilderness. Most existing NFS wildernesses include relatively undeveloped headwater watersheds with few water quality impacts. More recent additions to NFS wildernesses may include areas that are impacted by upstream watershed activities, such as by agriculture, mining, and land development.

3.4.1 Measure: Concentration of Ambient Ozone

This measure assesses the 3-year rolling average of ozone concentration (fourth highest daily maximum 8-hour concentration) based on the Forest Service Air Resource Management Program's annual analyses of national ozone monitoring data. Ozone is a pollutant formed when emissions of nitrogen oxides (NOX) and volatile organic compounds react in the presence of sunlight. Human activities such as the burning of fossil fuels and industrial processes produce these pollutants, which can then travel long distances resulting in elevated ozone levels in wildernesses. In most places in the United States, reductions in human-generated NOX will cause a reduction in ground-level ozone. Ozone is one of the most toxic air pollutants to plants and its effects include visible injury to leaves and needles, premature leaf loss, reduced photosynthesis, and reduced growth in sensitive plant species. Continued exposure of vegetation to ozone over time may also result in increased susceptibility to disease and damage from insects, as well as changes in species diversity and community structure.

This measure of air pollution was selected based on the potential impact of ozone on wilderness vegetation and the availability of ozone measurements. Considering all of the potential negative effects on wilderness vegetation, increasing ozone levels in or near a wilderness are a direct human-caused threat to the Natural Quality of wilderness character. A network of long-term air quality monitors measure ambient ground-level ozone concentrations across the United States. The monitors are primarily intended to track whether NAAQS, established to protect human health and natural resources, are being met. Data from this network receive rigorous QA and QC review before being entered into the EPA's Air Quality System (AQS) database available at https://www.epa.gov/aqs. Using these data, staff in the Forest Service Air Resource Management Program calculate a suite of ozone statistics for all monitoring sites in the United States each year.

If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. A finding of statistical significance results in a change in trend for this measure. An increase in the average ozone concentration corresponds with a degrading trend.

Refer to part 2, section 3.4.1, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.4.2 Measure: Deposition of Nitrogen

This measure assesses the amount of nitrogen deposition in a wilderness by using either the average total deposition (based on nationally modeled or measured spatial data) or the trend in wet deposition (based on the Forest Service Air Program's annual analyses of spatially interpolated data). Nitrogen oxides (NOX) are one of the major pollutants emitted into the atmosphere during the burning of fossil fuels. Agricultural activities, especially livestock management and fertilizer application to soils, are the primary source of ammonia (NH3) released to the atmosphere. These pollutants return to terrestrial and aquatic environments as atmospheric deposition of nitric acids and ammonium. In sensitive ecosystems, these compounds can acidify soil and surface waters, which affects nutrient cycling, impacts the growth of vegetation, and causes the decline or death of aquatic insects and fish. Even in ecosystems that can buffer incoming acid compounds, excess nitrogen deposition can lead to chemical and biological changes that affect plant growth, species composition, and aquatic food webs. Descriptions of the effects of nitrogen deposition on natural resources are available on the Forest Service Air Quality Portal website available at https://www.srs.fs.usda.gov/airqualityportal/critical_loads/atmospheric_deposition.php.

Nitrogen deposition was selected as a measure based on potential and observed negative impacts on wilderness ecosystems and the availability of deposition estimates across most wildernesses. While a few wildernesses may have direct nitrogen deposition measurements available, most will rely on estimates created through modeling based on data derived from long-term air quality monitoring stations that record nitrogen deposition across the United States.

If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. A finding of statistical significance, or any change in defined categories, results in a change in trend for this measure. An increase in the amount of nitrogen deposition corresponds with a degrading trend.

Refer to part 2, section 3.4.2, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.4.3 Measure: Deposition of Sulfur

This measure assesses the amount of sulfur deposition in a wilderness by using either the trend in wet deposition (based on the Forest Service Air Resource Management Program's annual analyses of spatially interpolated data) or the average total deposition (based on nationally modeled spatial data). Sulfur dioxide (SO2) is emitted during the burning of fossil fuels, especially coal, and can be transported long distances through the atmosphere before being deposited in the form of sulfuric acid. In sensitive ecosystems, sulfuric acid can contribute to acidification of soil and surface waters, affect nutrient cycling and impact the growth of vegetation, as well as lead to the decline and death of aquatic insects and fish. These effects have been more prevalent in the eastern United States due to historically high sulfur deposition levels.

Although sulfur deposition has been declining and fish kills from acidification are now infrequent, sulfur bound and held in the soil continues to affect soil chemistry, soil buffering capacity, and the nutrient status of soils. Detailed descriptions of the effects of sulfur deposition on natural resources are available on the Forest Service Air Quality Portal website available at https://www.srs.fs.usda.gov/airqualityportal/critical_loads/atmospheric_deposition.php.

Sulfur deposition was selected as a measure based on observed negative impacts on wilderness ecosystems and the availability of deposition estimates across most wildernesses. While a few wildernesses may have direct sulfur deposition measurements available, most will rely on estimates created through modeling based on data derived from networks of long-term air quality monitoring stations that record sulfur deposition across the United States. Eastern national forests are likely to be more interested in using the sulfur deposition measure over the nitrogen measure because sulfur continues to exert a stronger influence on many ecosystems in the Eastern United States.

If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. A finding of statistical significance, or any change in defined categories, results in a change in trend for this measure. An increase in the amount of sulfur deposition corresponds with a degrading trend.

Refer to part 2, section 3.4.3, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.4.4 Measure: Amount of Haze

This measure assesses the trend in average deciview for the 20 percent most impaired days, based on the Forest Service Air Resource Management Program's annual analyses of national visibility monitoring data. Although air quality managers often refer to visibility (or the lack thereof) in terms of its impacts on human perception, visibility is a general indicator of air quality monitored for its inherent value, just as one would monitor the biophysical condition of water quality.

This measure was selected because visual air quality (visibility) measurements provide a direct link between the concentration of pollutants in the atmosphere and degradation of the natural and physical condition of clean air in wilderness. Reduced visibility can affect local climate and photosynthetic activity. Additionally, visibility directly affects many wildlife and insect species that depend on clear, clean air (e.g., foraging raptors, pollinators).

Particles suspended in the atmosphere that absorb and scatter light cause regional haze. Impairment is operationally defined as the portion of haze which results from human activity. Fine particles (particles less than 2.5 μm in diameter) are routinely split into six distinct categories: (1) sulfates, (2) nitrates, (3) organics, (4) elemental carbon, (5) sea salt, and (6) soil.

A simple algorithm is used to identify the 20 percent of sample days each calendar year that are likely to be most affected by anthropogenic pollutants. The visibility conditions on these 20 percent "most impaired" days are converted to deciview and averaged annually.

If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. Any change in defined categories results in a change in trend for this measure. An increase in the amount of haze corresponds with a degrading trend.

Refer to part 2, section 3.4.4, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.4.5 Measure: Index of Sensitive Lichen Species

This measure assesses the trend in air pollution scores for nitrogen and sulfur derived from the presence and abundance of sensitive lichen species, based on the Forest Service Air Resource Management Program's analyses of local biomonitoring data. Air pollution scores are calculated for each wilderness biomonitoring plot by surveying epiphytic lichen species (i.e., those growing on trees) with varying sensitivities to nitrogen and sulfur air pollution. Lichens are important contributors to critical ecosystem processes, such as nutrient cycling, and they provide food and nesting material for birds and other animals. The composition of an epiphytic lichen community is a well-known biological indicator of air pollution in forested ecosystems because epiphytic lichens rely completely on atmospheric sources of nutrition.

The lack of a waxy cuticle on the lichen surface permits absorption and leaching of nutrients in very similar proportion to what is present in the atmosphere. Lichen species that are sensitive to nitrogen and sulfur deposition eventually die or diminish from the forest if pollution levels are elevated. Epiphytic lichen communities that retain the species most sensitive to air pollution indicate good air quality. Nitrogen and sulfur air pollutants can cause measurable lichen community changes within a 5-year monitoring period depending on the spatial and temporal extent of deposition.

This measure was selected because the presence or absence of sensitive lichens over time indicates improving or degrading air quality (Matos et al. 2017). Many Forest Service regions routinely collect data on epiphytic lichen communities; this measure of air pollution may be especially useful for wildernesses that are not near other air pollution monitors, such as in Alaska.

If most relevant, local units may select just this measure of the five air quality measures included under this indicator (see sections 3.4.1 through 3.4.5), or may optionally select more than one air quality measure. Any change in defined categories results in a change in trend for this measure. A change in the trend category indicating an increase in air pollution corresponds with a degrading trend.

Refer to part 2, section 3.4.5, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.4.6 Measure: Extent of Waterbodies With Impaired Water Quality

This measure assesses the miles of streams or number of lakes inside wilderness with impaired water quality, based on national or state 303(d) lists of impaired water bodies or local monitoring data. Water quality is influenced by a wide range of biological and physical variables from both inside and outside a wilderness. This measure focuses on human-caused threats to wilderness water quality and not on natural variation in water quality. Despite the general importance of water and a myriad of national water monitoring programs, water monitoring in wilderness is generally conducted only for site-specific threats. For example, impacts from grazing (sediment, manure), mining (sediment, heavy metals, and other toxins), air pollutants (nitrogen, sulfur), and recreation (sediment, fecal coliform bacteria) vary tremendously from wilderness to wilderness and from one site to another within that wilderness.

This measure was selected because of the fundamental importance of water quality to the Natural Quality of wilderness character. Water quality directly influences the health of plant and animal communities. While many headwater wilderness watersheds have good water quality, degradation from historical activities such as mining or from upstream developments outside a wilderness may impact water quality in wilderness.

Measures related to different aspects of water are included in other indicators under the Natural Quality. For example, changes to biological aspects of water are monitored under the plants or animals indicators. The measure Watershed Condition Class (see section 3.5.1) uses the Forest Service WCF, which includes water quality as one of 12 indicators that determine watershed condition. While WCF assesses the overall watershed condition of the entire 6th code Hydrologic Unit Code (HUC), this measure provides a more specific focus on water quality within a wilderness.

This measure is required for all Forest Service wildernesses. A 5-percent or greater change in the miles of impaired streams or number of lakes will result in a change in trend for this measure. An increase in the extent of impaired waterbodies corresponds with a degrading trend.

Refer to part 2, section 3.4.6, for detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.5 Indicator: Ecological Processes

This indicator focuses on threats to ecological processes that affect biotic and abiotic components of wilderness ecological systems. Ecological processes are the interactions among the biotic and abiotic components of ecosystems and include disturbance events (e.g., fire and wind storms, insect and pathogen outbreaks), predation, competition, decomposition, symbioses, and nutrient cycling. Ecological processes involve multiple components of wilderness ecosystems and are critical to all aspects of ecosystem composition, structure, and function, resulting in long-term and cascading effects on the natural community in wilderness.

The integrity of ecological processes within wilderness is crucial to maintaining the Natural Quality of wilderness character. Ecological processes are complex and difficult to quantify. Of the vast number of threats to ecological processes that could be used for WCM, this technical guide includes only those that take advantage of existing datasets and provide an overall synthesis of the condition of an ecological process within wilderness. This indicator does not include measures on the effects of climate change on ecological processes in wilderness because of the difficulty in separating the localized effects of natural change from climate change, combined with the general lack of wilderness-specific data on the natural variability of ecological processes (see section 3.6 in part 2, and Appendix 2).

3.5.1 Measure: Watershed Condition Class

This measure assesses the average wilderness watershed condition class, based on Forest Service Watershed Condition Classification (WCC) data. The WCF is a nationally consistent, reconnaissance-level approach for classifying NFS watershed conditions that uses a comprehensive set of 12 indicators to represent the underlying ecological, hydrological, and geomorphic functions and processes that affect watershed condition (USDA Forest Service 2011b,c). WCC maps generated from the WCF characterize the health and condition of NFS lands in more than 15,000 watersheds across the country. These maps, instituted in 2011, established watershed baseline conditions along with information on ecological, social, and economic factors, as well as partnership opportunities to establish watershed restoration priorities.

This measure was selected because it reflects the integrity and ecological importance of watersheds, including biotic integrity, resiliency, connectivity, and important ecosystem services such as high-quality water, the recharge of streams and aquifers, maintenance of riparian communities, and the moderation of climate variability and change. Updating the WCC ratings for each watershed is planned at five-year intervals with the next update initiated in 2016.

There is some redundancy between this measure and the Extent of Waterbodies With Impaired Water Quality measure. While this measure uses all 12 WCF indicators, including the indicator for water quality, the Extent of Waterbodies With Impaired Water Quality measure relies heavily on EPA and individual state 303(d) lists of streams or lakes with impaired water quality. The Extent of Waterbodies With Impaired Water Quality is appropriate as a measure under the Air and Water indicator as it provides a site-specific assessment of water quality in wilderness. Using all 12 WCF indicators in this measure provides a more complete overall assessment of watershed condition because it includes additional aquatic and terrestrial physical and biological information. This measure is therefore located under the Ecological Processes indicator rather than the Air and Water indicator.

Local units are required to select either this measure or the following measure, Number of Animal Unit Months of Commercial Livestock Use, or may select both measures if relevant to the individual wilderness. Any change in the average wilderness watershed condition class results in a change in trend for this measure. An increase in the watershed condition class corresponds with a degrading trend.

Refer to part 2, section 3.5.1, for more detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.

3.5.2 Measure: Number of Animal Unit Months of Commercial Livestock Use

This measure assesses the 3-year rolling average of commercial livestock use, based on an annual count of wilderness animal unit months (AUMs) within a wilderness. The Wilderness Act states that, "The grazing of livestock, where established prior to the effective date of this act, shall be permitted to continue subject to reasonable regulations as are deemed necessary by the Secretary of Agriculture" (Section 4(d) (4)(2)). Subsequent wilderness legislation and the Congressional Grazing Guidelines (House Reports 96–617 and 96–1126 that are included in the Colorado Wilderness Act of 1980) uphold this mandate from the Wilderness Act. In practice, this means that livestock grazing cannot be reduced or phased out simply because an area is designated as wilderness—any adjustments in livestock grazing must be made through revisions in the normal rangeland management and land management planning and policy-setting processes. These processes consider legal mandates, range condition, and protection of the range resource from deterioration.

This measure was selected because the presence of livestock, even though allowed under the Wilderness Act, represents a nonindigenous, domestic animal that impacts many aspects of the Natural Quality of wilderness character (Belsky et al. 1999; Beschta et al. 2014). Livestock grazing may impact indigenous plant and animal communities, soil, and watershed conditions within a wilderness. This measure does not directly monitor the ecological impacts of livestock grazing; rather it is based on the assumption that a declining number of AUMs results in an improving trend in ecological processes within wilderness, even though the adverse ecological effects of livestock may persist (Nussle et al. 2017).

The amount of annual livestock use is based on the AUMs of livestock grazing authorized by a grazing permit for allotments located wholly or partially within a wilderness. AUMs are the preferred unit of measurement instead of head months and should be used if available.

Local units are required to select either this measure or the preceding measure, Watershed Condition Class, or may select both measures if relevant to the individual wilderness. A 5-percent change in the 3-year rolling average amount of commercial livestock use will result in a change in trend for this measure. Once there are five measure values, the threshold for meaningful change will switch to regression analysis, and statistical significance will determine the trend in the measure. An increase in the average amount of commercial livestock use corresponds with a degrading trend.

Refer to part 2, section 3.5.2, for more detailed guidance on data sources and compilation protocols, analysis, data adequacy, and interpreting the threshold for meaningful change.