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Below is a cache of http://www.wbdg.org/ccb/ARMYCOE/PWTB/pwtb_200_1_37.pdf. It's a snapshot of the page taken as our search engine crawled the Web.
The web site itself may have changed. You can check the current page or check for previous versions at the Internet Archive. Yahoo! is not affiliated with the authors of this page or responsible for its content. PWTB 200-1-37 Method to Estimate Vegetative Cover on Army Training Lands PUBLIC WORKS TECHNICAL BULLETIN 200-1-37 25 OCTOBER 2005 METHOD TO ESTIMATE VEGETATIVE COVER ON ARMY TRAINING LANDS Public Works Technical Bulletins are published by the U.S. Army Corps of Engineers, 441 G
Street, NW, Washington, DC 20314-1000. They are intended to provide information on specific
topics in areas of Facilities Engineering and Public Works. They are not intended to
establish new DA policy. 2 DEPARTMENT OF THE ARMY U.S. Army Corps of Engineers 441 G Street, NW Washington, DC 20314-1000 CEMP-CE Public Works Technical Bulletin 25 October 2005 No. 200-1-37 Facilities Engineering Environmental METHOD TO ESTIMATE VEGETATIVE COVER ON ARMY TRAINING LANDS 1. Purpose. This Public Works Technical Bulletin (PWTB)
describes a method for estimating percent ground cover and environmental damage caused by off-road vehicle traffic at U.S.
Army installations. 2. Applicability. This PWTB applies to all continental U.S.
(CONUS) and outside CONUS (OCONUS) Army training and testing
facilities. 3. References. a. Army Regulation (AR) 200-1, Environmental Protection and Enhancement, 21 February 1997. b. See additional references in Appendix E. 4. Discussion. a. The U.S. Army manages over 12 million acres of land in
order to support mission readiness through military training and testing activities (Houston et al. 2001). The training lands at
most Army installations are in use constantly for ground training and tracked vehicle maneuvers that result in damage to
ecosystem structure and function (Dale et al. 2002). The loss of Army training lands to severe soil erosion due to mission
impacts has resulted in increasing investments in land monitoring and rehabilitation (Vachta and Hutchinson 1990;
Althoff et al. 2004). PWTB 200-1-37
25 October 2005
b. Models that predict the effects of training on land are based on a narrow timeframe and often do not calculate
cumulative effects over long time periods. Temporal variations due to military training are extreme and difficult to predict.
The cumulative effects of damages caused by military training
can affect ecosystem health and the potential for successful rehabilitation. Removal of vegetation can increase the
amplitude of soil moisture oscillations, for example, which will impact revegetation and recovery over time (Milton 1995).
Ecological sustainability is related to a broad time frame (Smyth and Dumanski 1995), so predictions based only on current
conditions are unreliable. In addition, field tests on Army installations have shown collection of field data to be labor-
and time-intensive, and, often, excessive amounts of data are
collected for sites that require only minimal recovery effort (Vachta and Hutchinson 1990). c. Assessing the sustainability of training lands is further complicated because of heavy land use by vehicles that results
in excessive loss of vegetative cover (Foster et al. 2004). The evaluation of ground cover is a necessary component of land
management models, since it is a primary indicator of a stable
and sustainable soil base that is needed for protection from soil erosion (OBrien et al. 2003). Visual cover estimates are
often used as a rapid method for erosion control projects. Percent plant cover can also be determined using the point-
intercept method (Stocking 1994; Vachta and Riggins 1990) with frequent sampling during defined times of the growing season
(Herrick and Whitford 1995). These methods to obtain estimates of vegetative cover are labor-intensive, which may decrease the
ability of land managers to take repeated samples during the
same year (Althoff et al. 2004). d. A simpler method would decrease time and labor
requirements of data collection to estimate vegetative cover on Army training and testing lands. Analysis of digital images can
be a useful technique (Fransen et al. 1998; Althoff et al. 2004) because the images can be randomly and quickly acquired along
transects or grids. Digital imagery processing software can be
used to determine the relative amount of pixels within the image that represent percent cover. A database of images can be kept
to provide a temporal record of vegetative cover of a sampling site. e. This report summarizes efforts to develop an effective method to estimate ground cover on Army installations using
digital imagery. A cost-effective method to estimate vegetative 2 PWTB 200-1-37
25 October 2005 APPENDIX A INTRODUCTION The U.S. Army manages over 12 million acres of land (Houston et al. 2001), most of which is in constant use by military trainers
to meet mission requirements (Fang et al. 2002; Milchunas et al.
2000). These large expanses of land are used to conduct deployment, tactical positioning, camouflage, and offensive and
defensive maneuver operations. Environmental impacts on ecosystems from military training are similar to consequences
from military actions during wartime (Austin and Bruch 2000; Whitecotten et al. 2000; Dudley et al. 2002). Plant populations
may be greatly reduced or altered due to vehicle operations that can result in the clearing of vegetation and severe soil
compaction. Soil conditions are changed due to the removal of
vegetation, the erosion of topsoil and the mixing and compaction of soil horizons. These changes can result in erosion, water
pollution, and loss of habitat for species (Jansen 1997). Degradation of soils in military training areas can result in
significant reductions in plant diversity (Dale et al. 2002) with negative impacts to ecosystems. Installation land managers must inventory and monitor vegetative
cover in order to estimate erosion potential and ecological health of training lands. The Universal Soil Loss Equation
(USLE) provides a rough estimate of erosion (Tiwari et al. 2000) and is used by land managers to determine erosion potential of
selected areas of concern. The USLE includes a cover management factor, C, or the ratio of soil loss from an area with specified
vegetative cover. The Army Training and Testing Area Carrying Capacity (ATTACC) program is a software model used to determine
land rehabilitation and maintenance costs associated with land-
based military training. ATTACC is part of the Army's Integrated Training Area Management (ITAM) Program, mandated for
all Department of Defense (DOD) installations. The ATTACC model uses the C factor from the USLE to calculate current land
condition as a means to estimate the erosion status of soils (U.S. Army Environmental Center 1999). The Army currently uses
vegetative cover surveys to monitor land condition; however,
methodologies for determining vegetative cover are not universal and vary among installations. These methods can be so labor-
intensive and time consuming that repeated estimates per plot during the year become unrealistic (Althoff et al. 2004).
Quantitative, accurate, and inexpensive techniques that do not require extensive technical skills are needed to estimate ground
cover and vegetative damage on training lands. A-1 PWTB 200-1-37
25 October 2005
Two methods commonly used to assess plant growth are estimates of cover and biomass production. Biomass estimates are more
exact measures of how much growth has occurred within an area; however, the methods require the destructive harvest of plants
and are prone to large yearly variations dependent on
precipitation amounts. Cover estimates are often used to describe vegetative conditions because they do not involve
clipping of plants, and are, therefore, less destructive than biomass production techniques. Plant density and frequency may
also be used as additional growth measurements, with frequency representing plant community structure and plant density
representing the number of plants per unit area (Stocking 1994). Cover is an important ecological characteristic and is generally
calculated as the percentage of ground surface covered by
vegetation. Cover can be expressed in absolute terms (square meters/hectares) but is most often expressed simply as a
percentage. Researchers use several types of cover to classify erosion potential, but the most common examples are foliar,
canopy, ground, and basal covers. Foliar cover is the area covered by the aerial portions of plants, canopy cover is the
area covered by the outer perimeter of foliage, ground cover is
the percentage of ground covered by plants, litter, rocks and gravel at a site, and, basal cover is the area of ground covered
by the basal (new growth) portion of the plants (NARSC 1996). The cover types that are most relevant to erosion potential are
ground cover and basal cover, since these estimates reflect the amount of plant materials situated directly on the soil surface. Visual plant cover estimates are often used because they are more rapid (Sykes et al. 1983). Visual methods estimate the
percent of ground cover of different classes of vegetation
within an area or quadrant. The percent cover in each vegetation class is then summed together to obtain a total
estimate of plant cover. Aerial photography and Geographic Information System (GIS) vegetative layers are useful for
overall resource surveys, but they are not detailed enough in their resolution to provide accurate estimates of cover. The
simplest, most practical and least costly techniques for direct
measure of vegetative cover are vertical photography and the use of a quadrant sighting frame (Stocking 1994). An analysis of
digital photographs randomly taken to document vegetative cover is described and the results are compared with two other common
methods, visual ground cover estimates and basal cover estimates using the point-intercept method. A-2 PWTB 200-1-37
25 October 2005
The digital photography method described is less labor intensive than the point-intercept method, while providing a temporal
record of ground cover conditions. Estimation of basal cover by this method produced the best results, especially in the early
and late phases of the growing season when plant growth is more
distinct from background colors. The method also allows for the standardization of ground cover estimates between sites,
something that cannot be accomplished when using gross visual estimates. A-3 PWTB 200-1-37
25 October 2005 APPENDIX B PROJECT DETAILS AND DATA COLLECTION For the purpose of testing the efficacy of using digital photography for ground cover estimations, photographs from two
installations were obtained for analysis. Photographic
documentation of vegetative conditions was obtained from Fort Hood, TX, and Fort Benning, GA. The analyses of the digital
images determined the number of pixels that fall within certain color classes that represent vegetation, litter, or bare ground.
Since data collection and analyses from each installation varied slightly, sampling procedures will be discussed separately. Fort Hood, Texas Fort Hood data were collected at regular intervals spaced 2,000
meters apart, based on a sampling grid laid out over a map of
the installation (Figure B1). The sampling grid resulted in 136 sample points; however, access to one area was denied, resulting
in a total of 135 points. A regular sampling interval was chosen over a random sampling interval in order to include all
parts of the base with a similar sampling effort. At each of the 135 points, three 100-meter long transects,
spaced 50 meters apart, were sampled with three end points on a
3 by 3 grid centered at each transect. The field researcher sampled the end points of which were the nine subpoints
described above. Grid points, and start and end points for each transect, were identified in the field using a handheld global
positioning system (GPS) receiver (Garmin Etrex
The web site itself may have changed. You can check the current page or check for previous versions at the Internet Archive. Yahoo! is not affiliated with the authors of this page or responsible for its content. PWTB 200-1-37 Method to Estimate Vegetative Cover on Army Training Lands PUBLIC WORKS TECHNICAL BULLETIN 200-1-37 25 OCTOBER 2005 METHOD TO ESTIMATE VEGETATIVE COVER ON ARMY TRAINING LANDS Public Works Technical Bulletins are published by the U.S. Army Corps of Engineers, 441 G
Street, NW, Washington, DC 20314-1000. They are intended to provide information on specific
topics in areas of Facilities Engineering and Public Works. They are not intended to
establish new DA policy. 2 DEPARTMENT OF THE ARMY U.S. Army Corps of Engineers 441 G Street, NW Washington, DC 20314-1000 CEMP-CE Public Works Technical Bulletin 25 October 2005 No. 200-1-37 Facilities Engineering Environmental METHOD TO ESTIMATE VEGETATIVE COVER ON ARMY TRAINING LANDS 1. Purpose. This Public Works Technical Bulletin (PWTB)
describes a method for estimating percent ground cover and environmental damage caused by off-road vehicle traffic at U.S.
Army installations. 2. Applicability. This PWTB applies to all continental U.S.
(CONUS) and outside CONUS (OCONUS) Army training and testing
facilities. 3. References. a. Army Regulation (AR) 200-1, Environmental Protection and Enhancement, 21 February 1997. b. See additional references in Appendix E. 4. Discussion. a. The U.S. Army manages over 12 million acres of land in
order to support mission readiness through military training and testing activities (Houston et al. 2001). The training lands at
most Army installations are in use constantly for ground training and tracked vehicle maneuvers that result in damage to
ecosystem structure and function (Dale et al. 2002). The loss of Army training lands to severe soil erosion due to mission
impacts has resulted in increasing investments in land monitoring and rehabilitation (Vachta and Hutchinson 1990;
Althoff et al. 2004). PWTB 200-1-37
25 October 2005
b. Models that predict the effects of training on land are based on a narrow timeframe and often do not calculate
cumulative effects over long time periods. Temporal variations due to military training are extreme and difficult to predict.
The cumulative effects of damages caused by military training
can affect ecosystem health and the potential for successful rehabilitation. Removal of vegetation can increase the
amplitude of soil moisture oscillations, for example, which will impact revegetation and recovery over time (Milton 1995).
Ecological sustainability is related to a broad time frame (Smyth and Dumanski 1995), so predictions based only on current
conditions are unreliable. In addition, field tests on Army installations have shown collection of field data to be labor-
and time-intensive, and, often, excessive amounts of data are
collected for sites that require only minimal recovery effort (Vachta and Hutchinson 1990). c. Assessing the sustainability of training lands is further complicated because of heavy land use by vehicles that results
in excessive loss of vegetative cover (Foster et al. 2004). The evaluation of ground cover is a necessary component of land
management models, since it is a primary indicator of a stable
and sustainable soil base that is needed for protection from soil erosion (OBrien et al. 2003). Visual cover estimates are
often used as a rapid method for erosion control projects. Percent plant cover can also be determined using the point-
intercept method (Stocking 1994; Vachta and Riggins 1990) with frequent sampling during defined times of the growing season
(Herrick and Whitford 1995). These methods to obtain estimates of vegetative cover are labor-intensive, which may decrease the
ability of land managers to take repeated samples during the
same year (Althoff et al. 2004). d. A simpler method would decrease time and labor
requirements of data collection to estimate vegetative cover on Army training and testing lands. Analysis of digital images can
be a useful technique (Fransen et al. 1998; Althoff et al. 2004) because the images can be randomly and quickly acquired along
transects or grids. Digital imagery processing software can be
used to determine the relative amount of pixels within the image that represent percent cover. A database of images can be kept
to provide a temporal record of vegetative cover of a sampling site. e. This report summarizes efforts to develop an effective method to estimate ground cover on Army installations using
digital imagery. A cost-effective method to estimate vegetative 2 PWTB 200-1-37
25 October 2005 APPENDIX A INTRODUCTION The U.S. Army manages over 12 million acres of land (Houston et al. 2001), most of which is in constant use by military trainers
to meet mission requirements (Fang et al. 2002; Milchunas et al.
2000). These large expanses of land are used to conduct deployment, tactical positioning, camouflage, and offensive and
defensive maneuver operations. Environmental impacts on ecosystems from military training are similar to consequences
from military actions during wartime (Austin and Bruch 2000; Whitecotten et al. 2000; Dudley et al. 2002). Plant populations
may be greatly reduced or altered due to vehicle operations that can result in the clearing of vegetation and severe soil
compaction. Soil conditions are changed due to the removal of
vegetation, the erosion of topsoil and the mixing and compaction of soil horizons. These changes can result in erosion, water
pollution, and loss of habitat for species (Jansen 1997). Degradation of soils in military training areas can result in
significant reductions in plant diversity (Dale et al. 2002) with negative impacts to ecosystems. Installation land managers must inventory and monitor vegetative
cover in order to estimate erosion potential and ecological health of training lands. The Universal Soil Loss Equation
(USLE) provides a rough estimate of erosion (Tiwari et al. 2000) and is used by land managers to determine erosion potential of
selected areas of concern. The USLE includes a cover management factor, C, or the ratio of soil loss from an area with specified
vegetative cover. The Army Training and Testing Area Carrying Capacity (ATTACC) program is a software model used to determine
land rehabilitation and maintenance costs associated with land-
based military training. ATTACC is part of the Army's Integrated Training Area Management (ITAM) Program, mandated for
all Department of Defense (DOD) installations. The ATTACC model uses the C factor from the USLE to calculate current land
condition as a means to estimate the erosion status of soils (U.S. Army Environmental Center 1999). The Army currently uses
vegetative cover surveys to monitor land condition; however,
methodologies for determining vegetative cover are not universal and vary among installations. These methods can be so labor-
intensive and time consuming that repeated estimates per plot during the year become unrealistic (Althoff et al. 2004).
Quantitative, accurate, and inexpensive techniques that do not require extensive technical skills are needed to estimate ground
cover and vegetative damage on training lands. A-1 PWTB 200-1-37
25 October 2005
Two methods commonly used to assess plant growth are estimates of cover and biomass production. Biomass estimates are more
exact measures of how much growth has occurred within an area; however, the methods require the destructive harvest of plants
and are prone to large yearly variations dependent on
precipitation amounts. Cover estimates are often used to describe vegetative conditions because they do not involve
clipping of plants, and are, therefore, less destructive than biomass production techniques. Plant density and frequency may
also be used as additional growth measurements, with frequency representing plant community structure and plant density
representing the number of plants per unit area (Stocking 1994). Cover is an important ecological characteristic and is generally
calculated as the percentage of ground surface covered by
vegetation. Cover can be expressed in absolute terms (square meters/hectares) but is most often expressed simply as a
percentage. Researchers use several types of cover to classify erosion potential, but the most common examples are foliar,
canopy, ground, and basal covers. Foliar cover is the area covered by the aerial portions of plants, canopy cover is the
area covered by the outer perimeter of foliage, ground cover is
the percentage of ground covered by plants, litter, rocks and gravel at a site, and, basal cover is the area of ground covered
by the basal (new growth) portion of the plants (NARSC 1996). The cover types that are most relevant to erosion potential are
ground cover and basal cover, since these estimates reflect the amount of plant materials situated directly on the soil surface. Visual plant cover estimates are often used because they are more rapid (Sykes et al. 1983). Visual methods estimate the
percent of ground cover of different classes of vegetation
within an area or quadrant. The percent cover in each vegetation class is then summed together to obtain a total
estimate of plant cover. Aerial photography and Geographic Information System (GIS) vegetative layers are useful for
overall resource surveys, but they are not detailed enough in their resolution to provide accurate estimates of cover. The
simplest, most practical and least costly techniques for direct
measure of vegetative cover are vertical photography and the use of a quadrant sighting frame (Stocking 1994). An analysis of
digital photographs randomly taken to document vegetative cover is described and the results are compared with two other common
methods, visual ground cover estimates and basal cover estimates using the point-intercept method. A-2 PWTB 200-1-37
25 October 2005
The digital photography method described is less labor intensive than the point-intercept method, while providing a temporal
record of ground cover conditions. Estimation of basal cover by this method produced the best results, especially in the early
and late phases of the growing season when plant growth is more
distinct from background colors. The method also allows for the standardization of ground cover estimates between sites,
something that cannot be accomplished when using gross visual estimates. A-3 PWTB 200-1-37
25 October 2005 APPENDIX B PROJECT DETAILS AND DATA COLLECTION For the purpose of testing the efficacy of using digital photography for ground cover estimations, photographs from two
installations were obtained for analysis. Photographic
documentation of vegetative conditions was obtained from Fort Hood, TX, and Fort Benning, GA. The analyses of the digital
images determined the number of pixels that fall within certain color classes that represent vegetation, litter, or bare ground.
Since data collection and analyses from each installation varied slightly, sampling procedures will be discussed separately. Fort Hood, Texas Fort Hood data were collected at regular intervals spaced 2,000
meters apart, based on a sampling grid laid out over a map of
the installation (Figure B1). The sampling grid resulted in 136 sample points; however, access to one area was denied, resulting
in a total of 135 points. A regular sampling interval was chosen over a random sampling interval in order to include all
parts of the base with a similar sampling effort. At each of the 135 points, three 100-meter long transects,
spaced 50 meters apart, were sampled with three end points on a
3 by 3 grid centered at each transect. The field researcher sampled the end points of which were the nine subpoints
described above. Grid points, and start and end points for each transect, were identified in the field using a handheld global
positioning system (GPS) receiver (Garmin Etrex
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