Military Training Lands Research Articles

Fires in the face of climate change: Indicators of fire disturbance in heath areas – Inference from military training lands

Global warming significantly affects the frequency and intensity of wildfires in many fire-prone areas of the world and fire disturbance regimes are changing rapidly. Alongside this, controlled burning is often considered or implemented as an alternative method for nature protection. Here, we studied the post-fire secondary succession in dry heath habitat located in military training grounds to recognise the impact of fire on the effectiveness and rate of ecosystem recovery. We focus particularly on identifying indicator species for a given successional phase of Central European dry heath habitats and assessing their value for dating the last fire disturbance. The research involved 60 vegetation patches (plots of 25 m2), which were assigned to four post-fire age classes, namely: 1–5 years (Class A), 6–10 years (Class B), 11–15 years (Class C), and >15 years (Class D). In each study plot, species diversity and coverage of lichens, bryophytes and vascular plants were examined in addition to the physicochemical properties of the soil substrate. Cryptogams and vascular plants clearly differ in terms of the secondary succession pattern; specific sets of cryptogams correspond well to particular post-fire classes and are therefore good determinants of the post-fire succession stage. Spontaneous succession of plant vegetation eventually leads to complete recovery of the heath in a relatively short time. Nevertheless, great vegetation dynamics in the first years after a fire disturbance may result in seemingly different directions of succession. Post-fire classes did not differ noticeably in terms of soil properties, it follows that the effects of fire on soil conditions are negligible; though, a significant upward trend was observed for exchangeable form of K throughout the succession process. Our results indicate that sporadic fires reduce the undesirable overgrowth of heathlands or psamophilous grasslands and generally have a little negative side-effect on the ecosystem. The revealed succession patterns and defined sets of species characteristic for subsequent post-fire age classes are applicable to dating fire disturbances, regardless of whether the fire was planned or spontaneous.

Metal accumulation capacity in indigenous Alaska vegetation growing on military training lands

Permafrost thawing could increase soil contaminant mobilization in the environment. Our objective was to quantify metal accumulation capacities for plant species and functional groups common to Alaskan military training ranges where elevated soil metal concentrations were likely to occur. Plant species across multiple military training range sites were collected. Metal content in shoots and roots was compared to soil metal concentrations to calculate bioconcentration and translocation factors. On average, grasses accumulated greater concentrations of Cr, Cu, Ni, Pb, Sb, and Zn relative to forbs or shrubs, and bioconcentrated greater concentrations of Ni and Pb. Shrubs bioconcentrated greater concentrations of Sb. Translocation to shoots was greatest among the forbs. Three native plants were identified as candidate species for use in metal phytostabilization applications. Elymus macrourus, a grass, bioconcentrated substantial concentrations of Cu, Pb, and Zn in roots with low translocation to shoots. Elaeagnus commutata, a shrub, bioconcentrated the greatest amounts of Sb, Ni, and Cr, with a low translocation factor. Solidago decumbens bioconcentrated the greatest amount of Sb among the forbs and translocated the least amount of metals. A combination of forb, shrub, and grass will likely enhance phytostabilization of heavy metals in interior Alaska soils through increased functional group diversity.

Soil and vegetation responses to amendment with pulverized classified paper waste

The United States Army produces a significant amount of classified paper waste that is pulverized to a fine consistency unsuitable for recycling. However, cheap, high quality organic materials such as classified paper waste are useful as soil amendments. The objective of this research was to evaluate the utilization of pulverized classified paper waste as a soil amendment to improve soil health and increase establishment of desirable native grasses on degraded Army training lands. Paper was applied at rates of 9 to 72 Mg ha−1 to two soil types at Fort Polk, LA: an alfisol (very fine sandy loam - Fine, smectitic, thermic Chromic Vertic Hapludalfs) and an ultisol (loamy fine sandy - Loamy, siliceous, semiactive, thermic Arenic Paleudults). These are common soil orders found on military training lands nationwide and represent fertile (alfisol) and unfertile (ulitsol) soils. Vegetation and soils were monitored over 2 growing seasons. No increase in heavy metals were observed in soils. Extensive analysis showed very low levels of regulated contaminants in the paper, but most were below detection limits. The ultisol site showed improved soil physical and chemical properties, while desirable vegetation benefitted from nutrient immobilization at the alfisol site. Based on the results of this study, applying pulverized paper waste to soil at a rate of 35.9 Mg ha−1 is recommended. Application of paper waste to soils had no adverse environmental effects, improved soil physiochemical properties, and facilitated establishment of desirable native vegetation.

Ecotoxicity of 2,4-dinitrotoluene to cold tolerant plant species in a sub-Arctic soil

Decades of live-fire training exercises have left millions of acres of military training lands contaminated with various munitions constituents such as dinitrotoluene. Those that pose a threat to higher organisms due to their toxicity and mobility in the soil are of particular concern. Plants aid in the biodegradation and phytoextraction of contaminants, and site-specific ecotoxicity determinations are critical to inform effective remediation strategy. These ecotoxicity determinations are lacking in cold-adapted plants and would be very informative for contaminated training lands in cold regions. Therefore, we conducted a phytotoxicity study to determine the median effective concentration (EC50) of 2,4-dinitrotoluene (2,4-DNT) to four native Alaskan plant species in a sub-Arctic soil at two different temperatures. Plant species investigated were white spruce (Picea glauca), field locoweed (Oxytropis campestris), bluejoint grass (Calamagrostis canadensis), and Jacob’s ladder (Polemonium pulcherrimum). Seedling emergence, fresh plant mass, and dry plant mass were used to model plant response to 2,4-DNT contamination. White spruce was most tolerant to 2,4-DNT contamination (EC50 = 130.8 mg kg−1) and field locoweed was least tolerant (EC50 = 0.38 mg kg−1). In general, Arctic plant species were more vulnerable to 2,4-DNT when compared to plant types native to temperate or tropical regions.

Soil elemental analysis in a high conservation tropical forest in Singapore

To understand the distribution of soil elemental concentrations and their potential sources of trace metal contamination in the high-conservation Nee Soon freshwater swamp forest in Singapore, we analyzed samples from 227 surface and 35 subsurface (auger profiles) locations. Our assessment involved distribution maps, principle component analysis, cluster analysis, and correlation analysis of element concentrations determined from a mixed acid digestion and measurement on an ICP-MS. We found a distinct zonation in the distribution of several elements (Ba, Cr, Cu, Fe, Mn, Pb, Sr, Ti, V, and Zn) between the upper and lower catchment that gives an erroneous notion of widespread contamination in the lower catchment. We believe this zonation is natural, likely related to differences in the underlying geology. However, Cu, Pb, and Sb concentrations were greatly enriched by anthropogenic activities on military training lands in the lower catchment, firing ranges in particular. Barium, Sr, and Zn also appear to be enriched in the lower part of the catchment, possibly from anthropogenic activities including military activity and roads. Although soils in the catchment are not highly contaminated, isolated areas with high concentrations of Cu, Pb and Sb may warrant management attention given the sensitive nature of the urban forest, which includes the last remaining fresh water swamp forest in Singapore.

Water Quality & natural resource management on military training lands in Central Texas: Improved decision support via Bayesian Networks

The conservation and management of military training lands has long evolved around the unique criteria for maintaining a viable fighting force. In lieu of this primary mission, landscapes have often experienced accelerated degradation and loss of structural and functional capabilities for providing desired ecosystem services (including the basic training mission). In an effort to aid military land managers as well as anyone who makes and implements decisions for natural resource management; we support an innovative approach towards the integration of evidence and the application of diagnosis and prognosis for the decision-making process through the use of Bayesian Networks. Illustrated below is an example for utilizing Bayesian Networks in the decision support process. We utilized data and experience from ongoing efforts at the Fort Hood Military Installation to build the initial network; then integrate expert input from authors and engineers in propagating the node relationships. Through this approach, we demonstrate how military land managers can integrate varying streams of evidence, including empirical, model generated or expert opinion, into a network for decision support. The example below is developed based upon land management issues within the U.S. Army, but the process can be adapted and implemented across most all ecosystems under some form of land management.

A dynamic simulation/optimization model for scheduling restoration of degraded military training lands

Intensive use of military vehicles on Department of Defense training installations causes deterioration in ground surface quality. Degraded lands restrict the scheduled training activities and jeopardize personnel and equipment safety. We present a simulation-optimization approach and develop a discrete dynamic optimization model to determine an optimum land restoration for a given training schedule and availability of financial resources to minimize the adverse effects of training on military lands. The model considers weather forecasts, scheduled maneuver exercises, and unique qualities and importance of the maneuver areas. An application of this approach to Fort Riley, Kansas, shows that: i) starting with natural conditions, the total amount of training damages would increase almost linearly and exceed a quarter of the training area and 228 gullies would be formed (mostly in the intensive training areas) if no restoration is carried out over 10 years; ii) assuming an initial state that resembles the present conditions, sustaining the landscape requires an annual restoration budget of $957 thousand; iii) targeting a uniform distribution of maneuver damages would increase the total damages and adversely affect the overall landscape quality, therefore a selective restoration strategy may be preferred; and iv) a proactive restoration strategy would be optimal where land degradations are repaired before they turn into more severe damages that are more expensive to repair and may pose a higher training risk. The last finding can be used as a rule-of-thumb for land restoration efforts in other installations with similar characteristics.

Fugitive Dust Emissions from Off-Road Vehicle Maneuvers on Military Training Lands

<abstract> <bold><sc>Abstract.</sc></bold> Off-road vehicle training can contribute to air quality degradation because of increased wind erosion as a result of soil disruption during high wind events. However, limited information exists regarding the impacts of off-road vehicle maneuvering on wind erosion potential of soils. This study was conducted to determine the effects of soil texture and intensity of training with off-road vehicles on fugitive dust emission potential due to wind erosion at military training installations. Multi-pass military vehicle trafficking experiments involving wheeled and tracked vehicles were conducted at three military training facilities (Fort Riley, Kansas; Fort Benning, Georgia; and Yakima Training Center, Washington) with different vegetative conditions and soil textures. The top 6 cm of soil was collected with minimum disturbance into trays and tested in a laboratory wind tunnel for dust emission potential. In wind tunnel testing, the amount of emitted dust was measured using a Grimm aerosol spectrometer. The dust emission potential due to wind erosion was significantly influenced by soil texture, vehicle type, and number of passes. For the light wheeled vehicle, total dust emissions (<20 μm) increased by 357% and 868% for 10 and 50 passes, respectively, from the undisturbed soil condition. For the tracked vehicle, an average increase in total dust emissions (<20μm) of 569% was observed between undisturbed soil and one pass, with no significant increase in emission potential beyond one pass. For the heavy wheeled vehicle, evaluated only at Yakima, emissions (<20 μm) increased by 2,108% and 5,276% for 10 and 20 passes, respectively, from the undisturbed soil condition. Soil texture also played an important role in dust emission potential. For all treatment effects with the light wheeled vehicle, there was a 1,396% increase in emissions (<20 μm) on loamy sand soil over silty clay loam soil.

Monitoring vegetation change and dynamics on U.S. Army training lands using satellite image time series analysis

Given the significant land holdings of the U.S. Department of Defense, and the importance of those lands to support a variety of inherently damaging activities, application of sound natural resource conservation principles and proactive monitoring practices are necessary to manage military training lands in a sustainable manner. This study explores a method for, and the utility of, analyzing vegetation condition and trends as sustainability indicators for use by military commanders and land managers, at both the national and local levels, in identifying when and where vegetation-related environmental impacts might exist. The BFAST time series decomposition method was applied to a ten-year MODIS NDVI time series dataset for the Fort Riley military installation and Konza Prairie Biological Station (KPBS) in northeastern Kansas. Imagery selected for time-series analysis were 16-day MODIS NDVI (MOD13Q1 Collection 5) composites capable of characterizing vegetation change induced by human activities and climate variability. Three indicators related to gradual interannual or abrupt intraannual vegetation change for each pixel were calculated from the trend component resulting from the BFAST decomposition. Assessment of gradual interannual NDVI trends showed the majority of Fort Riley experienced browning between 2001 and 2010. This result is supported by validation using high spatial resolution imagery. The observed versus expected frequency of linear trends detected at Fort Riley and KPBS were significantly different and suggest a causal link between military training activities and/or land management practices. While both sites were similar with regards to overall disturbance frequency and the relative spatial extents of monotonic or interrupted trends, vegetation trajectories after disturbance were significantly different. This suggests that the type and magnitude of disturbances characteristic of each location result in distinct post-disturbance vegetation responses. Using a remotely-sensed vegetation index time series with BFAST and the indicators outlined here provides a consistent and relatively rapid assessment of military training lands with applicability outside of grassland biomes. Characterizing overall trends and disturbance responses of vegetation can promote sustainable use of military lands and assist land managers in targeting specific areas for various rehabilitation activities.

Modeling and Prediction of Land Condition for Fort Riley Military Installation

<abstract><title><italic>Abstract.</italic></title> In the U.S., the Department of Defense manages more than 5500 military installations that occupy approximately 12 million ha of land. These lands are used for various military training programs. Training activities inevitably degrade the land condition, and the degraded land condition, in turn, limits the land’s military training carrying capacity. To sustain the military training land carrying capacity and the environment, land managers must monitor and predict changes to the land condition under various military training schemes. The objective of this study is to develop prediction models for land condition based on military training intensity and on independent variables that play a significant role in driving land condition changes at Fort Riley, Kansas. It is assumed that land condition can be quantified using soil erosion as a surrogate measure, which is mainly determined by a ground and vegetation cover factor, in which the larger the factor, the poorer the land condition. In addition to military training intensity, the independent variables used in these prediction models of land condition included distance from the location to roads, terrain slope (which affects military training access), ground cover, landscape fragmentation (an indirect measure of military training induced disturbance), and spatial variability of canopy cover and military training induced disturbance (as reflected in Landsat Thematic Mapper [TM] images). Various regression models were developed, and predictions made by linear and nonlinear models were compared with and without TM images, with and without stepwise regression procedures, and with and without historical land condition variables. Results showed that the absolute Pearson product moment correlation coefficients of ground cover with the cover factor were larger than 0.63; the correlation was greatest and significant at a risk level of 5%. Ground cover was thus involved in all the stepwise regression and nonlinear models. Although military training intensity was significantly correlated with the cover factor, training intensity was excluded from the best models mainly because both ground cover and landscape fragmentation that existed in the models also reflected the military training induced disturbance. Compared to models in which all the variables were involved, the stepwise regression models reduced the number of the independent variables from 11 or 15 to 3 or 6 (depending on analysis year) with no significant loss of accuracy. In most cases, adding the near and middle infrared TM images, which revealed the spatial variability of military training induced disturbance, improved the prediction of land condition. Based on the correlation coefficient and root mean square error (RMSE) between the predicted and observed values of the cover factor, the nonlinear models that used significant independent variables led to more accurate predictions than the linear regression models. This suggests that the combination of stepwise regression and nonlinear models could increase the accuracy of prediction. Moreover, adding the historical land condition variables, such as historical cover factor and ground cover, into the models could greatly decrease prediction errors.

‘Recovery’, a New Western Wheatgrass Cultivar with Improved Seedling Establishment on Rangelands

‘Recovery’ western wheatgrass [Pascopyrum smithii (Rydb.) Barkworth &amp; D. R. Dewy] (Reg. No. CV‐32, PI 660509) was released in December 2009 by the USDA‐ARS, the Engineer Research and Development Center of the U.S. Army Corps of Engineers, and the USDA‐NRCS. Recovery was developed for reseeding rangelands following severe disturbance, frequent fires, and soil erosion, and it was selected with emphasis on improved and faster seedling establishment. Recovery was evaluated as TC3, TC‐Rich, Army WWG, SERDP WWG, and NRCS‐9076517 and was developed as a synthetic cultivar using two cycles of recurrent selection for plant vigor, seed yield, and rate of seedling emergence from a deep planting depth. In field evaluations, Recovery had an increased frequency of seedlings during the establishment year, when averaged across eight locations, than ‘Arriba’, ‘Barton’, ‘Flintlock’, ‘Rodan’, and ‘Rosana’ western wheatgrasses. Recovery continued to have superior stand until 4–6 yr after planting, when due to their rhizomatous nature, all the western wheatgrasses had similar stand frequencies. Recovery western wheatgrass provides land managers with a new western wheatgrass cultivar possessing rapid establishment for use in areas that are frequently disturbed, such as military training lands. The use of Recovery will help reduce soil erosion and weed invasion following such disturbances.

Federal Land Management, Carbon Sequestration, and Climate Change in the Southeastern U.S.: A Case Study with Fort Benning

Land use activities can have a major impact on the temporal trends and spatial patterns of regional land-atmosphere exchange of carbon. Federal lands generally have substantially different land management strategies from surrounding areas, and the carbon consequences have rarely been quantified and assessed. Using the Fort Benning Installation as a case study, we used the General Ensemble biogeochemical Modeling System (GEMS) to simulate and compare ecosystem carbon sequestration between the U.S. Army's Fort Benning and surrounding areas from 1992 to 2050. Our results indicate that the military installation sequestered more carbon than surrounding areas from 1992 to 2007 (76.7 vs 18.5 g C m(-2) yr(-1)), and is projected to continue sequestering more carbon from 2008 to 2050 (75.7 vs 25.6 g C m(-2) yr(-1)), mostly because of the proactive management approaches adopted on military training lands. Our results suggest that federal lands might play a positive and important role in sequestering and conserving atmospheric carbon because some anthropogenic disturbances (e.g., urbanization, forest harvesting, and agriculture) can be minimized or prevented on federal lands.

Influence of Abrams M1A1 Main Battle Tank Disturbance on Tallgrass Prairie Plant Community Structure

The Department of Defense's Range and Training Land Assessment program provides information and recommendations to range managers regarding the condition of training lands. This information is used to assist in scheduling training areas and in monitoring the effectiveness of rehabilitation projects. Fort Riley Military Installation is a major training reservation located in the Flint Hills of northeastern Kansas, within the tallgrass prairie ecosystem. A randomized complete block design composed of three treatments (M1A1 Abrams tank traffic during wet and dry soil conditions, and a nontrafficked control) with three replications was established in each of two soil types, a silty clay loam and a silt loam soil, on Fort Riley in 2003. Disturbance was created by driving the tank for five circuits in a figure-eight pattern during either during wet or dry soil conditions. Two additional experimental treatments were added during the study: five additional tank passes on one-half of each figure eight in 2004 and burning in 2006. Two areas, a curve and straightaway, within each traffic intensity (and later, burn treatment) subplot were designated for sampling. Aboveground biomass, species composition, and ground cover were measured during each growing season. Recovery of grass and total aboveground biomass in silty clay loam soil was delayed for curve areas and following disturbance in wet soil conditions, respectively. Species composition and ground cover continued to exhibit significant disturbance effects in 2007, with greatest damage observed for repeated traffic under wet soil conditions. Fire effects on vegetation were variable and generally greater for undisturbed control plots than for disturbed areas. The tallgrass prairie typically is considered to be among the most resilient of military training lands, but our research suggests that resiliency is dependent upon soil type and training conditions, and may require longer periods of recovery than previously thought.

Response of soil microbial and invertebrate communities to tracked vehicle disturbance in tallgrass prairie

Soil biota drive fundamental ecosystem processes such as decomposition, nutrient cycling, and maintenance of soil structure. They are especially active in grassland ecosystems such as the tallgrass prairie, where much of the net primary productivity is allocated belowground and ultimately processed by heterotrophic soil organisms. Because both soil microbes and soil fauna display perturbation responses that integrate the physical, chemical, and biological changes to their environment, the structure of belowground microbial and faunal communities is used widely as an indication of the ecological status of soils. To investigate the effects of military training on tallgrass prairie soil communities, a replicated small-plot study of tracked vehicle disturbance effects was initiated at Fort Riley, Kansas in 2003. This article reports subsequent rates of recovery for soil microbial and invertebrate communities over a range of disturbances encompassing different soil types (silty clay loam and silt loam soils), environmental conditions (wet vs. dry traffic events), traffic intensities (single vs. repeated traffic), and track areas (curve vs. straightaway). Microbial biomass in wet silty clay loam soil treatments and on curve areas in silt loam soil was suppressed for 1–2 years following disturbance but increased to levels greater than undisturbed plots in all treatments by the fourth year. Nematode abundance, family richness, trophic composition, and community structure also displayed maximum disturbance for wet treatments and curve areas. Trophic composition and community structure continued to exhibit disturbance effects throughout the 4-year study period, even after recovery of nematode abundance. Earthworm abundance displayed the most severe reductions (78% across soil types, treatments and areas) immediately following tank traffic but, like microbial biomass, subsequently increased to levels greater than undisturbed plots. Nematode community structure provided a reliable and comprehensive assessment of the status of the soil food web and was an effective bioindicator of ecosystem recovery following traffic disturbance. In addition, given the dominant role of earthworms in ecosystem processes and their extreme sensitivity to tracked vehicle disturbance, it is recommended that this group be included in monitoring protocols for military training land managers.

Biodiversity and the Heterogeneous Disturbance Regime on Military Training Lands

Abstract Disproportionately large numbers of threatened and endangered species and unusually high biodiversity occur on active and former military training areas. Although this may seem paradoxical given the apparently destructive nature of military training, an evaluation of the nature and extent of the disturbances is enlightening. Military training frequently produces heterogeneous landscapes. Large portions of military training areas remain virtually untouched, favoring disturbance‐averse species; other portions are heavily disturbed, favoring disturbance‐dependent species. The rich habitat mosaics include the two extremes as well as the continua of disturbance and succession between them, thus providing suitable habitat for a very large number of species with widely varying habitat requirements. To explain the phenomenon, a heterogeneous disturbance hypothesis is proposed which suggests that biodiversity is maximized where multiple kinds, frequencies, severities, periodicities, sizes, shapes, and/or durations of disturbance occur concomitantly on a landscape in a spatially and temporally distributed fashion. The enhanced biodiversity occurring on active and former military training areas illustrates the need for restoration ecologists to restore or maintain an appropriate heterogeneous disturbance regime when attempting to restore ecosystem function and biodiversity.

A unique, environmentally sustainable and cost– effective programme to re-vegetate military training lands utilising composted wastewater biosolids at a large Canadian military training centre

The Greater Moncton Sewerage Commission has developed, in concert with National Defence Canada, an environmentally sustainable and cost effective biosolids management and land reclamation programme at the Canadian Forces Base (CFB) Gagetown, New Brunswick, Canada (the second largest land based Military Training Facility in the British Commonwealth). The use of composted biosolids to revegetate military training lands is thought to be a unique application for the beneficial use of biosolids. Results and practical experience gained from this approach to successfully re-vegetate initial sections of extremely large and vast tracts of these lands are described. The paper also overviews the Commission's modern 115000 m3 x d(-1) advanced, chemically assisted primary wastewater treatment facility and associated alkaline (lime) sludge stabilisation process. Planning strategies, security aspects, special and unique challenges in operating adjacent to an active military training facility, costs, spreading techniques, monitoring, next steps and conclusions are also presented.

Relationships between military land use and storm-based indices of hydrologic variability

Abstract This paper examines the influence of military land use parameters on dimensionless indices related to storm flow, baseflow, and precipitation for five watersheds with areas ranging from 0.76 to 25.01 km2 within the Fort Benning Military Installation in southeastern US. Average magnitude and variability of these indices are grouped into four key hydrologic regimes—magnitude, frequency, duration, and rate of change. Correlation and regression analyses were performed to determine the relationship among the watershed physical characteristics and indices. A number of significant relationships were found. The correlation results show that the increase in road density increased the variability in the peak discharges and the slopes of the rising limb. The increase in the military training land increased the variability in the time base. The number of roads crossing streams is positively correlated with the response lag. Stepwise multiple correlations showed that the storm-based magnitude and variability in peak discharge, baseflow index, and the bankfull discharge have been significantly affected by military management related watershed characteristics. The relationship among the watershed physical characteristics and the storm-based hydrologic indices indicated that the greatest impact of land management is found with statistically significant predictive models for indices of time base, response lag, and time of rise. Military training land, road density, and the number of roads crossing streams were the three management variables that impacted storm responses.

Initial effects of light armored vehicle use on grassland vegetation at Fort Lewis, Washington

Sustainable use of military training lands requires understanding and prediction of the effects of military vehicles on vegetation. We examined the initial impacts of an 8-wheeled, light armored vehicle (LAV) on grassland vegetation at Fort Lewis, Washington. The LAV drove replicate spiral paths at two starting velocities, 10.3 and 5.1 m s −1. The disturbed width (width of ground impacted by the tires) increased as turning radius decreased, but was unaffected by vehicle velocity. An inverse-exponential model predicted disturbed width ( r 2 = 0.68 ) at all turning radii for both velocities combined. In low-velocity spirals, and for straight tracking (turning radius>40 m) and moderate turns (radius 20–40 m) in high-velocity spirals, all vegetation damage was imprint (plants flattened by wheels). During sharp (radius <20 m), high-velocity turns, most or all of the disturbed width was scraped free of surface vegetation and soil, which was piled to the outside of each tire track. Total plant cover (all species) was not affected by track curvature in low-velocity spirals, but decreased in the order straight tracking>moderate turns>sharp turns in high-velocity spirals. In low-velocity spirals, post-tracking cover of several plant growth forms (non-native species, perennial species, sod-forming grasses) was similar to pre-tracking cover, but in high-velocity spirals, post-tracking cover of these growth forms decreased in the order straight⩾moderate=sharp. Cover of native species and forbs decreased more in high- than in low-velocity spirals, but was unaffected by curvature. Pre- and post-tracking cover of annual species, bunchgrasses, and shrubs was ⩽3%. The most severe vegetation damage caused by operation of wheeled LAVs on grasslands is associated with sharp, high-velocity turns.

A Procedure to Extrapolate Vegetation Cover Estimates Over Large Arid and Semi‐arid Regions Using Multiple Spatial Resolution Imagery

Typically, land degradation on arid and semi‐arid military training and testing lands in the desert Southwestern United States is associated with a decrease in total vegetative cover. Long‐term field surveys have been established by the military to measure and monitor total vegetative cover over time. However, field methods are not cost effective due to the large area of training lands, nearly 3 million acres in the California deserts alone, that must be sampled. Measurements recorded at individual transects must still be spatially extrapolated to produce a complete census of the installation. Remote sensing has been used to spatially extrapolate such field measurements over larger areas, but in the past, imagery has lacked sufficient spatial resolution to accurately estimate total vegetative cover. In this study, nested, high resolution imagery was collected at different spatial resolutions for study sites at the Marine Corps Air Ground Combat Center in the south‐central Mojave Desert of southern California. Vegetation cover estimates derived from these multiple resolution images were examined as a possible surrogate for sampling total vegetative cover in the field. Results indicate that a high correlation exits between field measurements of cover and estimates of cover derived from imagery. However, similar to field measurements, if the intent is to estimate total vegetative cover across large geographic areas, high resolution imagery is also costly in terms of collection, processing, and interpretation because a single image generally covers a small geographic area. Therefore, a protocol to scale detailed observations of total cover from high resolution imagery to lower resolution imagery that covers a larger geographic area was developed and tested. The results of this study indicate that a relatively high correlation exists between vegetation cover estimates derived from high resolution imagery and image brightness derived from a nested, lower resolution image. This protocol now allows military land managers to sample site‐specific areas with high resolution imagery and extrapolate absolute estimates of vegetation cover across training and testing lands with more cost effective, lower resolution imagery that provides complete coverage of an installation.

Use of military training doctrine to predict patterns of maneuver disturbance on the landscape. II. Validation

Landscape disturbance from military training maneuvers can cause significant on-site deterioration that may impair ecosystem functioning, reduce training realism, and jeopardize the safety of soldiers and equipment. Excessive runoff and eroded sediments from within the boundaries of training areas may also affect downstream landowners. Repair of on-site and off-site damage can be very costly. Several attempts have been made to predict the spatial distribution of training-induced surface disturbance within landscapes. Techniques have used the current or historic distribution of surface disturbance to predict the future spatial distribution of disturbance. This study evaluated a new methodology to predict the spatial distribution of disturbance based on a variety of maneuver obstacles considered by military planners in the preparation of battle plans as well as applied doctrinal tactics used during cross-country maneuvers. The field validation study was conducted at Grafenwoehr Training Area, the largest US Army training area in Germany. There was a generally favorable agreement between the spatial distribution of predicted and observed high versus low maneuver disturbance, but the relationship was statistically significant only for those areas predicted to have low levels of disturbance. While the results are promising and suggest that further research may enhance the methodology, the allocation of funding for land rehabilitation on military training lands based on a priori prediction of the spatial distribution of surface disturbance is not yet practical.