Rangeland Monitoring Research Articles

Monitoring Drought in the West

Although drought is difficult to define and measure, several indices are presently available to assist in rangeland monitoring and management. Several drought indices are noted with documentation where recent information may be easily found. Temporal and spatial considerations may be helpful in management applications. Research is continuing in the development of understandable, and usable, graphical presentations of drought.

Rangeland Monitoring: Water Quality and Riparian Systems

Ecological concepts serve as a foundation for developing a monitoring program to evaluate water quality and associated riparian systems. Ecological concepts used for developing a monitoring plan must be supported by scientific literature and related to streamflow dynamics and channel interactions. These interactions help determine natural or background habitat quality within and along river longitudinal and environmental gradients from mountains through basins in the western United States. In addition stream size, position in the watershed, and flow are related to sediment sorting, channel bank strength, and channel configuration. These relationships determine channel substrate habitat for aquatic organisms and population diversity. These habitat features may be modified by a channel's ability to store and transport sediment and associated pollutants within a watershed's drainage pattern. Sediment supply, delivery, and timing are altered by differences in snowmelt along elevation gradients, runoff from convective storms, water development history, and stream channel succession. Potential impairment of reference or background aquatic habitat in the western United States is generally sediment related and should be greater in basin river segments and during base flow conditions. Impairment sources can be shown to originate in the steep and first order tributaries of foothill and basin watersheds, and not from valley slopes where supply must cross established riparian zones. Water column, substrate disturbance, and channel bank disturbances may alter amount of sediment and bacteria pollution measured in basins and during base flow conditions.

Rangeland Monitoring and Wildlife Populations

The capability of agricultural producers to monitor the condition and trend of the rangelands on which they operate should not be limited to plant communities. The purpose of this article is to underscore the importance of monitoring wildlife populations and their critical habitats. Agricultural producers should be aware of the many wildlife species that inhabit public and private rangelands. Wildlife species should be part of their range monitoring program. Agricultural producers and their employees are present on specific rangelands more often than the state and federal employees that are mandated to manage the variety of resources on those rangelands. This presence, along with the observations and development of good note taking skills and documentation, will lead to a better understanding of the condition and trend of wildlife populations on various habitats. Such knowledge will benefit the resource as well as the agricultural operation. The objective of this monitoring program is to communicate with the various entities (state, federal, special interest) what you have learned and to help better understand the complexity associated with wildlife species and their habitats. This will improve the chances of making better management decisions on rangelands and integrated agricultural operations.

Rangeland Monitoring and Fire: Wildfires and Prescribed Burning, Nutrient Cycling, and Plant Succession

Prescribed fires are used to manipulate and manage rangelands, but effective monitoring techniques are needed to ensure that management goals and objectives are being met. The application of an effective fire program on rangelands is not a simple task. Overgrazing by livestock since the early development of the livestock industry has altered the vegetative complex on most rangelands with an increase in woody plants. Because of its relatively low cost, prescribed fire, both cool and warm season, are sustainable practices if proper grazing management is part of the management scheme. Grazing management and prescribed fire have often been treated as separate issues by rangeland managers; however, development and application of an effective prescribed burning program requires an understanding of the relationship between fire and grazing. Ranchers need fuel (grass) to burn and they also need income from livestock, which requires forage (grass, a major part of forage). In the short-term, fire reduces carrying capacity for livestock but, in the long-term, fire increases grass production, resulting in increased carrying capacity. Therefore, some monitoring technique is needed that will allow the manager to budget grass for both fuel and forage. The Grazing Manager (TGM) is a software program that projects both forage production (expressed as animal unit days) and, animal demand (expressed as animal unit days) for each forage year. TGM has been successfully used on the Texas A&M University Research Station at Sonora as a tool to integrate prescribed fire and grazing management.

History of Rangeland Monitoring in the U.S.A.

Monitoring of rangelands in the western USA formally began in the U.S. Forest Service in the 1930s. Other federal land management and advisory agencies did not usually monitor their clients' public or private rangelands until after World War II. The initial focus was on the portion of vegetation that was livestock forage. Attention to soils generally came after World War II. The National Environmental Policy Act (NEPA) of 1969 changed the formerly independent role of the action agencies and gave the interested public means of input to and oversight on the actions of the managerial agencies. NEPA also gave the interested public leverage through the courts if a decision was not of their liking. The result has been near grid, lock on proactive management on public rangelands and diversion of a large portion of operating funds to planning. Availability of monitoring data for some locales is largely due to the foresight and persistence of particularly dedicated individuals. Lack of consistent and comparable monitoring procedures within and between the federal management, advisory, and regulatory agencies has made it impossible to conclude reliably what the overall condition and trends in conditions of our public rangelands are. There are currently many competing proposals before Congress to fund efforts at rangeland monitoring standardization. Many additional federal agencies and nongovernmental organizations are getting involved in this debate. By carefully reviewing the history of development of rangeland monitoring, it is possible to identify fatal flaws in previous approaches and suggest actions to avoid previous pitfalls during the forthcoming development of more defendable monitoring approaches at both local and national scales.

Rangeland Monitoring Using Remote Sensing

Monitoring vast landscapes has, from the beginning of rangeland management, depended on people's judgements. This is no longer tenable, but a more effective method has yet to be devised. The problem is how to do an economical inventory that will detect ecologically important change over extensive land areas with acceptable error rates. The error risk is a function of adequate sample numbers and distribution for each indicator monitored. Of all of the indicators identified for monitoring, ground cover and its inverse, bare ground, may be the most discussed. Ground-cover measurements address soil stability and watershed function which are first-priority ecological concerns; are well adapted to remote sensing frameworks thus allowing extensive, unbiased, economical sampling; and, the measurements, especially when done by computer image analysis, have the potential to reduce or avoid the human-judgement factor. Data collection through remote sensing appears the most logical approach to acquiring appropriately distributed information over large areas in short time periods and on random sites far removed from easy ground access. The value of satellite and high-altitude sensors for landscape-level evaluations, such as plant community distribution, is well established but these tools are inadequate for inventory and measurement of details needed for valid conclusions about range condition. New advances in low-altitude remote sensing may give us the ability to accurately measure bare ground and perhaps other indicators. Combining information from high and low-altitude sensors appears to offer an optimal path for developing a practical system for cost-effective, data-based, rangeland monitoring and management.

The Struggle for a Uniform Monitoring System

Development of rangeland inventory and monitoring was initiated as early as in 1908. The early efforts were simple methods to establish rangeland stocking rates. With advancing scientific methodologies and the recognition for moitoring needs, the evaluation of range conditions and management planning increase well after WWII by a number of US federal agencies. By 1970s the environmental protection measures were first emphasized in the USA and were applied also to rangeland utilization. Since then the approaches and methodologies for evaluation of rangelands have changed periodically by accommodating the tenets of federal administrations. The methodologies applied have been geared either to support the environmental preservation or to support economic exploitation. There is still no system, however, for national or regional reporting on range conditions and trends. Local monitoring and management systems often lack scientific and objective basis. Local surveys, however, are important for evaluating existing conditions and should not be based on national reporting requirements. The ecological site concept has been adopted as the toxonomic unit for rangeland classification. It is important that monitoring methods are not biased, based on sufficient sample sizes, and not based on "estimations". The forage allocation based on one-time inventories are seriously flawed and the methods for evaluating stocking rates must be reevaluated. The same applies to the evaluating the rangeland "health." A unified national reporting system must be developed on scientific and objective basis.

Theoretical Underpinnings of Rangeland Monitoring

Monitoring of rangelands has evolved from traditional focus on plant communities and their successional status, taken from a few selected subsamples, to much broader perspectives. Rangelands, being complex biosocial systems, offer a near infinite array of possibilities for choice of variables and how to collect and interpret the data. Past monitoring approaches have inadequately considered objectives, critical definitions, and appropriate sequencing of steps taken. While management objectives should ideally have primacy in choice of variables used in inventory and monitoring, there are some countervailing advantages in employing some commonalities in monitoring protocols among tracts of rangelands. Inventories should come before monitoring. Assessment should follow collection of an adequately long time series of data which is the essence of monitoring. Trends involve judging whether the monitoring data show increases, decreases, or stable trajectories. Assessment involves an always at least partially subjective judgement of condition in relation to appropriate standards and objectives. We are no longer limited to just plant community data collected annually in a few conveniently and subjectively chosen quadrats. Geomatics (remote sensing, GIS, and GPS)opens the possibility of frequent, synoptic (everywhere, instantaneously) landscape coverage via satellite imagery. Indisputable evidence of cause(s) requires concurrent data on these influences along with similar trends from similar circumstances (replications) and controls [reference areas lacking the putative cause(s)]. Three alternatives that could replace plant succession as the underlying, dominant theory of rangeland monitoring are: risk assessment, sustainability, and desertification. Risk assessment is well proven where biophysical indicators can be employed. Politically neutral incorporation of socioeconomic considerations have yet to be demonstrated, however. Sustainability is such a broad and diffuse concept that anyone can read into it whatever he or she wishes. Desertification is the preferred macroconcept to guide us into the future, because its use can more objectively encompass both biophysical and socioeconomic features, at any scale in time and space.

Monitoring for Success

The use of data gained from monitoring vegetation and soil parameters to enhance the ecological and economic efficacy of range livestock enterprises is not a new concept. I have been involved in several applications of rangeland monitoring to enhance the quality of rangeland environments and to preserve range livestock production as a proper and economically effective means of using such environments.

Presence/absence of a keystone species as an indicator of rangeland health

We examined the relationship between a Chihuahuan Desert grassland keystone species (banner tailed kangaroo rat, Dipodomys spectabilis) and several vegetation and soil indicators of rangeland health in order to define a threshold indicator value for irreversible change in ecosystem structure and function. The abundance of occupied and/or abandoned D. spectabilis burrow-mounds was assessed at 117 sites in south-central New Mexico where previous studies had reported vegetation cover and composition. The most robust indicator for presence/absence of D. spectabilis was shrub cover. D. spectabilis did not occur at sites with shrub cover >20%. It was concluded that a threshold value of 20% shrub cover could be applied to assessment and monitoring of Chihuahuan Desert rangelands because higher shrub cover results in the local extinction of this keystone species. The combination of data on the presence/absence of a keystone species with vegetation and soil indicators provides a method for identifying thresholds of degradation that may be irreversible.

Application of Soil Quality to Monitoring and Management

Recent interest in soil quality and rangeland health, and the large areas set aside under the USDA Conservation Reserve Program, have contributed to a gradual convergence of assessment, monitoring, and management approaches in croplands and rangelands. The objective of this paper is to describe a basis for integrating soils and soil quality into rangeland monitoring, and through monitoring, into management. Previous attempts to integrate soil indicators into rangeland monitoring programs have often failed due to a lack of understanding of how to apply those indicators to ecosystem function and management. We discuss four guidelines that we have used to select and interpret soil and soil quality indicators in rangelands and illustrate them using a recently developed rangeland monitoring system. The guidelines include (i) identifying a suite of indicators that are consistently correlated with the functional status of one or more critical ecosystem processes, including those related to soil stability, soil water infiltration, and the capacity of the ecosystem to recover following disturbance; (ii) basing indicator selection on inherent soil and site characteristics and on site‐ or project‐specific resource concerns, such as erosion or species invasion; (iii) using spatial variability in developing and interpreting indicators to make them more representative of ecological processes; and (iv) interpreting indicators in the context of an understanding of dynamic, nonlinear ecological processes defined by thresholds. The approach defined by these guidelines may serve as a paradigm for applying the soil quality concept in other ecosystems, including forests and ecosystems managed for annual and perennial crop production.

Application of Soil Quality to Monitoring and Management

Recent interest in soil quality and rangeland health, and the large areas set aside under the USDA Conservation Reserve Program, have contributed to a gradual convergence of assessment, monitoring, and management approaches in croplands and rangelands. The objective of this paper is to describe a basis for integrating soils and soil quality into rangeland monitoring, and through monitoring, into management. Previous attempts to integrate soil indicators into rangeland monitoring programs have often failed due to a lack of understanding of how to apply those indicators to ecosystem function and management. We discuss four guidelines that we have used to select and interpret soil and soil quality indicators in rangelands and illustrate them using a recently developed rangeland monitoring system. The guidelines include (i) identifying a suite of indicators that are consistently correlated with the functional status of one or more critical ecosystem processes, including those related to soil stability, soil water infiltration, and the capacity of the ecosystem to recover following disturbance; (ii) basing indicator selection on inherent soil and site characteristics and on site- or project-specific resource concerns, such as erosion or species invasion; (iii) using spatial variability in developing and interpreting indicators to make them more representative of ecological processes; and (iv) interpreting indicators in the context of an understanding of dynamic, nonlinear ecological processes defined by thresholds. The approach defined by these guidelines may serve as a paradigm for applying the soil quality concept in other ecosystems, including forests and ecosystems managed for annual and perennial crop production.

The Statistical Power Of Rangeland Monitoring Data: A range consultant shares his thoughts on when numbers are really justified — and when they aren’t

The Statistical Power Of Rangeland Monitoring Data: A range consultant shares his thoughts on when numbers are really justified — and when they aren’t

A Proposed Method for Determining Shrub Utilization Using (LA/LS) Imagery

Utilization of plant above ground biomass has continued to be a critical yet difficult assessment in rangeland monitoring. Shrub size and woody structure further compound the measurement of shrub biomass utilization. This study was designed to determine the potential utility of low altitude/large scale (LA/LS) imagery in assessing shrub utilization. A near monoculture of Ceriotoides lanata (Pursh) J.T. Howell (winterfat) located in the western desert shrubland of Utah was used to evaluate this technique. Four, 3.1 by 3.1 m plots were identified and the shrubs within the plots were defoliated by hand-picking at about 10% intervals with imagery of the plots obtained between pickings. Imagery was obtained using a radio controlled airplane (drone) fitted with a 35 mm camera. Images were evaluated using image processing software and the resulting reflectance data correlated with defoliation percentages (weight basis) for each plot. Reflectance data from images correlated highly with defoliation percentages (r2 > 0.9). This technique of using LA/LS imagery shows promise for a quick and accurate tool in assessing utilization of shrubs. DOI:10.2458/azu_jrm_v54i4_quilter

A proposed method for determining shrub utilization using (LA/LS) imagery

Utilization of plant above ground biomass has continued to be a critical yet difficult assessment in rangeland monitoring. Shrub size and woody structure further compound the measurement of shrub biomass utilization. This study was designed to determine the potential utility of low altitude/large scale (LA/LS) imagery in assessing shrub utilization. A near monoculture of Ceriotoides lanata (Pursh) J.T. Howell (winterfat) located in the western desert shrubland of Utah was used to evaluate this technique. Four, 3.1 by 3.1 m plots were identified and the shrubs within the plots were defoliated by hand-picking at about 10% intervals with imagery of the plots obtained between pickings. Imagery was obtained using a radio controlled airplane (drone) fitted with a 35 mm camera. Images were evaluated using image processing software and the resulting reflectance data correlated with defoliation percentages (weight basis) for each plot. Reflectance data from images correlated highly with defoliation percentages (r2 > 0.9). This technique of using LA/LS imagery shows promise for a quick and accurate tool in assessing utilization of shrubs.

Bryophytes and the morphospecies concept: a comparison of novice and expert sorting

THE exclusion of bryophytes (mosses, liverworts and hornworts) from the majority of impact assessment and monitoring studies is probably due to key characters being microscopic and difficult to work with given limited resources. Coarse morphological groups have been used in rangeland monitoring where a level of identification accessible to amateurs successfully separated different soil crust groups (Eldridge and Rosentreter 1999). However, there has been only one study of the feasibility of using a morphospecies approach for bryophytes. Oliver and Beattie (1993) included mosses in their study of the comparison of the results of "biodiversity technicians" and expert taxonomists. They found that novices split and lump many moss species. The bryoflora they investigated was species-rich with 86 species found in 220 specimens. In this study, I investigate a different environment with a level of species richness that is more typical of many dry sclerophyll forests (Pharo and Beattie 1997). Novices collected the specimens as well as sorted, which is a realistic replication of the task facing biologists when undertaking biodiversity surveys or establishing monitoring studies. Here I compare the efforts of 65 novices (second-year biogeography students) and myself in sampling an area of sub-alpine Tasmania. I was interested quantifying the abilities of this group rather than a smaller, more experienced group because a range of interests and abilities were represented. The results are informative as to the feasibility of including bryophytes in monitoring projects where the focus of the project may be on other groups and the field officer has little experience with bryophytes.

Technical note: Use of digital surface model for hardwood rangeland monitoring

We built digital surface models (DSM) that contain 3D surface morphological information of the entire landscape using digital photogrammetry and aerial photographs. Changes in landscape components such as crown closure and tree height in hardwood rangeland were estimated using DSM. In comparison with manual interpretation results, errors of crown closure and tree hieght estimation using DSM were less than 0.7% and 1.5 m, respectively. This technique can be used for rangeland management, monitoring and ecological studies.

In situ narrow‐band reflectance characteristics of cover components in sagebrush‐steppe

To capitalize on the planned deployment of satellite‐bourne narrow‐band multispectral radiometers (e.g., Hyperspectral Imager) in rangeland monitoring, a study was undertaken to evaluate the in situ, spectral uniqueness of 16 important sagebrush steppe cover components in southeastern Idaho during peak plant growth in June of 1995. Five major plant species from the study area were also sampled multi‐temporally in 1996, during peak green (June), mid‐sensecence (late July), and late‐senescence (late August). In situ, simulated TM data were also used to evaluate the broad‐band NDVI of these same components. Balsamroot, flixweed, cheatgrass, bluebunch wheatgrass, horsebrush, and three‐tip sagebrush differed in many portions of their June 1995 narrow‐band spectral response curves. NDVI values decreased through the forb, grass, and shrub components, respectively. Rates of change in reflectance (and NDVI) over time among the five major plants tended to mirror their phenologies, with forbs changing the most, followed by grasses, and finally, shrubs. Maturing cheatgrass (an annual) was also distinct from bluebunch wheatgrass (a perennial) because of the former's rapid senescence that resulted in greater red reflectance by late July. Soil components were less spectrally distinct from one another, as well as from litter and standing dead shrub. Wet and dry soils were separable, in part because the latter had a more variable narrow‐band response curve. The size of the IFOV examined did not affect sagebrush spectral response, but inversely affected the response of balsamroot. Narrow‐band imagery, due to the increased differences among spectral response curves, appears to have significant potential for distinguishing among components in sagebrush steppe rangelands. These differences may be further accentuated if multi‐temporal data are collected to capitalize on phenological variations among cover components.

Soil Depth Assessment of Sagebrush Grazing Treatments Using Electromagnetic Induction

Depth to a root restricting layer affects both soil moisture and nutrient availability, resources strongly correlated to plant cover and production. We evaluated the potential of 2 electromagnetic induction meters (EM38 and EM31) for non-destructively assessing soil depth to bedrock in 2 long-term seasonal sagebrush steppe sheep grazing treatments with different vegetational compositions. Apparent conductivity readings, measured with the EM38 and EM31 in both the horizontal (H) and vertical (V) dipole orientations, were positively related to soil depth. Apparent conductivity measured with the EM31H (r2 = 0.78) and EM38V (r2 = 0.75) were the best predictors of depth. Soil depth distributions were similar between grazing treatments based on Kolmogorov-Smirnov (K-S) tests of the EM38H apparent conductivity (P = 0.47) and EM38V apparent conductivity (P = 0.56). In constrast, K-S tests for the EM31H apparent conductivity (P = 0.09) and EM31V apparent conductivity (P < 0.01) indicated the fall-grazed treatment had a larger area in which soil depth exceeded 150 cm. Because less than 2% of each grazing treatment was predicted to have soils deeper than 150 cm, however, overall site differences between the 2 treatments appeared to be minor. Therefore, the vegetational differences between the treatments have probably resulted more from differences in the seasonality of grazing rather than ecological site characteristics as reflected in soil depth. Maps of soil depth indicated both treatments consisted of intermittent shallow and deep soils, created by several parallel basalt pressure ridges. Results suggest electromagnetic induction can effectively assess the spatial variability of soil depth and could aid in selecting sites for rangeland monitoring or manipulation.

Isotopes, Wool, and Rangeland Monitoring: Let the Sheep Do the Sampling

/ Stable carbon isotope analyses of wool staples provided insight into the vegetation consumed by sheep at a temporal resolution not previously studied. Contemporary Australian and historic South African samples dating back to 1916 were analyzed for their stable carbon isotope ratio, a proxy for the proportion of C3 and C4 plant species consumed by animals. Sheep sample vegetation continuously throughout a year, and as their wool grows it integrates and stores information about their diet. In subtropical and tropical rangelands the majority of grass species are C4. Since sheep prefer to graze, and their wool is an isotopic record of their diet, we now have the potential to develop a high resolution index to the availability of grass from a sheep's perspective. Isotopic analyses of wool suggest a new direction for monitoring grazing and for the reconstruction of past vegetation changes, which will make a significant contribution to traditional rangeland ecology and management. It is recommended that isotopic and other analyses of wool be further developed for use in rangeland monitoring programs to provide valuable feedback for land managers.KEY WORDS: Carbon isotope ratios; Vegetation change; Rangelands; Monitoring; Wool