Indicators Of Rangeland Condition Research Articles

Modelling Soil Carbon Content in South Patagonia and Evaluating Changes According to Climate, Vegetation, Desertification and Grazing

In Southern Patagonia, a long-term monitoring network has been established to assess bio-indicators as an early warning of environmental changes due to climate change and human activities. Soil organic carbon (SOC) content in rangelands provides a range of important ecosystem services and supports the capacity of the land to sustain plant and animal productivity. The objectives in this study were to model SOC (30 cm) stocks at a regional scale using climatic, topographic and vegetation variables, and to establish a baseline that can be used as an indicator of rangeland condition. For modelling, we used a stepwise multiple regression to identify variables that explain SOC variation at the landscape scale. With the SOC model, we obtained a SOC map for the entire Santa Cruz province, where the variables derived from the multiple linear regression models were integrated into a geographic information system (GIS). SOC stock to 30 cm ranged from 1.38 to 32.63 kg C m−2. The fitted model explained 76.4% of SOC variation using as independent variables isothermality, precipitation seasonality and vegetation cover expressed as a normalized difference vegetation index. The SOC map discriminated in three categories (low, medium, high) determined patterns among environmental and land use variables. For example, SOC decreased with desertification due to erosion processes. The understanding and mapping of SOC in Patagonia contributes as a bridge across main issues such as climate change, desertification and biodiversity conservation.

Community-based knowledge towards rangeland condition, climate change, and adaptation strategies: the case of Afar pastoralists

IntroductionPastoral communities have a comprehensive knowledge of their environments. This knowledge was acquired through extensive observation of the local environment and continuous herding practices. Pastoralists’ wisdom about their local environment and adaptation strategies to climate change is essential for sustainable development. Thus, appreciation of pastoralists’ knowledge about their environment is also important for the integration of indigenous knowledge with the proper application of scientific approach to fit with the prevailing ecological potential of pastoral areas.MethodsData were collected using focus group discussions, key informant interviews, and in-depth interviews. The in-depth interviews were conducted using a semi-structured questionnaire that was administered to 100 household heads with the age of above 50 years old. Respondents were randomly drawn from selected Pastoralists Associations (PAs) of two study districts. Data were analyzed using descriptive statistics as well as the logit model. The logit model was used to analyze the different coping strategies of pastoralists to overcome the failure of rain during different seasons. This was done by complementing pastoralists’ indigenous knowledge of time-series-based analysis across four seasons (Kerma, Gillal, Hagay, and Sugum) vs. the existing meteorological records. Forty years (from 1971 to 2011) of existing metrological data were used to compare the empirical evidence with pastoralists’ perceptions.ResultsRespondents mentioned that livestock number was the best indicator for evaluating rangeland condition in Afar region. The existing empirical evidence based on metrological data did not show any significant decline in precipitation for the last four decades between 1971 and 2011 as opposed to the perception of pastoralists where 80% of them reported a decline in precipitation. A one unit increase in labor force suggested about 16.1% decrease in the choice of livestock selling as coping strategy in Afar pastoral areas of North-East of Ethiopia. The non-intervened pastoral households had more preference (3.78%) to practice herd splitting than those pastoral households in the intervened district. Similarly, the non-intervened pastoral households had 4.43% more preference to use crop residue for livestock feeding than pastoral HHs in the intervened areas.ConclusionsCommunities’ perceptions showed that livestock number was the best indicator of rangeland condition in the study area. Afar pastoralists’ observations with regard to temperature and precipitation trends over the last four decades greatly corresponded with the existing metrological-based empirical evidence. However, pastoralists’ perception in terms of reduced precipitation was not confirmed by the meteorological-based data records for the short rainy season (SRS). Afar pastoralists’ experience showed that the short rainy season was the best indicator for the occurrence of droughts as compared to other seasons in Afar. Our results suggest that most coping strategies are labor force demanding, and the situation worsens during the long rainy season (LRS). We suggest that differences in intervention between the study areas should not be overlooked as a policy tool in tackling the impact of climate change.

The effects of land management (grazing intensity) vs. the effects of topography, soil properties, vegetation type, and climate on soil carbon concentration in Southern Patagonia

Grazing is an economically important activity in Southern Patagonia’s steppe and woodland ecosystems. In the past, emphasis has been on maximizing the provisioning capacity of these ecosystems with little concern for the longer term conservation of the ecosystem services related to climate regulation, like carbon sequestration. This is changing rapidly as livestock producers in the region work to develop a certification scheme for sustainable land management for Patagonians rangelands. This study is a scientific contribution towards this broader social objective in which we test whether soil C concentration in topsoil (10 cm depth) can be used as an indicator of rangeland condition. Data on climate, soil chemistry, topography, ecosystem type and stocking rates were obtained from the PEBANPA network of permanent plots database for 145 sites across Southern Patagonia. These variables were used as independent variables in a partial least squares regression in which top soil C was the dependent variable. The effects of land use (stocking rate) on top soil C were barely detectable at the regional scale in Patagonia. Top soil C was however strongly associated with other independent variables, notably soil chemistry and climate variables and also vegetation type. Thus, changes in land use management may not have a significant impact on soil carbon sequestration in these types of ecosystems. This may be because many factors interact to determine top soil C such that the footprint of overgrazing on top soil C is drowned out at the regional scale by other variables. This highlights the need for further work to develop indicators for sustainable land management in the region.

Do pasture user groups lead to improved rangeland condition in the Mongolian Gobi Desert?

Pasture user groups have become an important tool by which development agencies have sought to improve rangeland condition and resolve inter-herder conflict. However the ability of these groups to improve rangeland condition in the Gobi Desert is rarely examined. In this paper, three and twelve year old pasture user group areas were compared with non-group areas. Herders and local officials in both group and non-group areas were interviewed to compare activities and institutions that may contribute to degradation through overgrazing. Soil and vegetation based indicators of rangeland condition were also assessed. There were some differences in indicators of rangeland condition between pasture user group and non-group areas, but little evidence of institutions or activities specific to the group that could explain this difference. Herders did not seek to manage grazing pressures for natural resource management aims, nor did they enforce or sanction the external spatial boundaries of pasture user groups. These results suggest that the ability of pasture user group to improve rangeland condition in the Mongolian Gobi Desert may have been overstated.

Comparison of Laboratory and Field Remote Sensing Methods to Measure Forage Quality

Recent research in range ecology has emphasized the importance of forage quality as a key indicator of rangeland condition. However, we lack tools to evaluate forage quality at scales appropriate for management. Using canopy reflectance data to measure forage quality has been conducted at both laboratory and field levels separately, but little work has been conducted to evaluate these methods simultaneously. The objective of this study is to find a reliable way of assessing grassland quality through measuring forage chemistry with reflectance. We studied a mixed grass ecosystem in Grasslands National Park of Canada and surrounding pastures, located in southern Saskatchewan. Spectral reflectance was collected at both in-situ field level and in the laboratory. Vegetation samples were collected at each site, sorted into the green grass portion, and then sent to a chemical company for measuring forage quality variables, including protein, lignin, ash, moisture at 135 °C, Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), Total Digestible, Digestible Energy, Net Energy for Lactation, Net Energy for Maintenance, and Net Energy for Gain. Reflectance data were processed with the first derivative transformation and continuum removal method. Correlation analysis was conducted on spectral and forage quality variables. A regression model was further built to investigate the possibility of using canopy spectral measurements to predict the grassland quality. Results indicated that field level prediction of protein of mixed grass species was possible (r2 = 0.63). However, the relationship between canopy reflectance and the other forage quality variables was not strong.

Coded T-mark continuums: a graphical method for reporting rangeland monitoring data

In this paper we describe a new method of graphically presenting rangeland monitoring data as coded time-mark continuums. This method aims to provide people with an interest in rangelands (stakeholders) with succinct information, which they need to assess rangeland condition and change. This new method graphs data for indicators of rangeland condition as time or T-marks along gradients or continuums. The ends of these continuums are reference points, which are values for indicators defining highly functional to very dysfunctional rangeland systems. The T-marks for an indicator along its continuum are also coded as to how changes relate to combinations of recent seasonal conditions and longer-term management effects. Codes are based on a two-way matrix combining ‘seasonal quality’ (e.g. rainfall in a specified period relative to the long-term record) and expected responses from land management (i.e. increase, decrease or no change relative to that predicted from seasonal quality). Monitoring data available in the Australian Collaborative Rangeland Information System were used to illustrate the use of coded T-mark continuums. We show succinctly how one indicator changed in two different rangeland regions and how multiple indicators changed within one region.

The woody weed encroachment puzzle: gathering pieces

AbstractIncreases in woody plant densities in savanna grazing lands worldwide have resulted in a decline in the grazing capacity of these rangelands. At present, the actual cause of the problem is unknown although a vast body of literature deals with various aspects relevant to the issue.It is generally assumed, however, that the changes in the tree:grass ratio are a response to changes in soil‐water development brought about by rangeland utilization. These utilization patterns differ from those under which the savanna system evolved. While changes in physiognomy are very prominent, these are generally preceded by changes in grass species assemblage.The development of species composition has been used as an indicator of rangeland condition for many years; the increase or decrease of individual species is considered in this context. Thus far, however, the shift from perennial to annual grasses has not been evaluated for its effect on soil moisture development, and subsequent implications for woody plant establishment and growth.The review presented here consolidates the existing information in order to provide a basis for understanding the woody weed encroachment problem. Copyright © 2008 John Wiley & Sons, Ltd.

Gradients in vegetation cover, structure and species richness of Nama‐Karoo shrublands in relation to distance from livestock watering points

Summary Gradients of animal impact known as piospheres tend to develop around artificial watering points, particularly in arid zones. Such grazing gradients represent a potential opportunity for differentiating the long‐term effects of livestock activity from other environmental patterns. In this study, the impact of watering point provision on the plant cover, species richness and community structure of Karoo shrublands, South Africa, was investigated in the context of the evolutionary history and current grazing management practices of the region. The impacts of watering point provision were investigated by sampling plant cover and composition along transects placed at set distances, ranging from 10 m to 2200 m, from 11 watering points. Karoo vegetation cover and structure are relatively resilient to livestock grazing. Karoo plant diversity, as measured by species richness, evenness and dominance, was not as resilient. Twice as many species decreased as increased near watering points. The majority of species that decreased were regarded as being highly palatable to livestock. Heavy grazing, leading to death or repeated reproductive failure, is the most likely mechanism leading to the decline of such species. The highly disturbed area immediately adjacent to watering points was dominated by forbs and contained a large proportion of alien species. Adjacent to this was a zone dominated by widespread shrub species of medium to low palatability. Areas most distant from watering points contained a greater proportion of species known to be highly palatable to livestock. The ability of dominant Karoo shrubs to tolerate heavy grazing may have allowed rangeland managers to maintain stocking rates above that which can be tolerated by the majority of species but which are supported by a minority of grazing‐tolerant species. Synthesis and applications. Highly palatable species are more abundant in areas distant from water points. Larger paddocks therefore provide a refuge for sensitive species that might otherwise be lost from the rangeland as a whole. Species that tend to occur away from watering points represent potentially useful indicators of grazing pressure. The use of these species as indicators of rangeland condition among landowners should be promoted.

The Accuracy of Ground-Cover Measurements

Ground cover is a key indicator of rangeland condition and influences rangeland management decisions, yet there have been few advances in ground-cover measurement methods. The advent of digital photography and automated image processing promise a revolution in the way ground cover is measured. To assess the potential for automation we compared conventional and automated methods for measuring ground cover against known artificial populations. The known populations were created from 20 nadir images of a Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) vegetation type acquired with a 5-megapixel Olympus E20 digital single lens reflex camera mounted on an aluminum camera frame at 2 m above ground level. The images were converted to color, 2-dimensional images that no longer represented real-world conditions but had known cover values and conserved a simplified form of the pattern and spatial context of the plant community. These images were then printed at 1:1 scale to a 1 × 1-m poster. Posters were evaluated for color cover under laboratory conditions using the conventional techniques of steel-point frame, laser-point frame, line-point intercept, ocular estimation, and line intercept. Photographs of the posters were measured for color cover using standard and custom-created algorithms within the VegMeasure image analysis framework, and using the Digital Grid Overlay method. Results indicate that conventional techniques had significantly greater correlation (≥ 92% agreement of measured to known) than measurements from the algorithms used in the VegMeasure analysis (70%). The critical factor influencing accuracy of point-sampling methods was the area of the contact point for the given method. These findings provide an important measure of relative accuracy among methods for land managers and for researchers seeking to improve rangeland monitoring methods. La cobertura basal es un indicador clave de la condición del pastizal e influye en las decisiones de manejo del pastizal; sin embargo, ha habido pocos avances en los métodos de medición de la cobertura basal. El advenimiento de la fotografía digital y el procesamiento automático de imágenes promete un revolución en la forma en la que la cobertura basal es medida. Pare evaluar el potencial de automatización, comparamos métodos convencionales y automatizados para medir la cobertura basal, la comparación se realizó en poblaciones artificiales de cobertura conocida. Las poblaciones artificiales fueron creadas a partir de 20 imágenes de baja altura de un tipo de vegetación de “Wyoming big sagebrush” (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) tomadas con una cámara digital Olympus E20 de 5 megapixeles con lente reflex simple montada en un marco de aluminio a dos metros de altura del nivel del suelo. Las imágenes se convirtieron a color y en imágenes de dos dimensiones que ya no representaban el mundo real, pero tenían valores conocidos de cobertura y conservaron una forma simplificada del patrón y contexto espacial de la comunidad vegetal. Posteriormente estas imágenes fueron impresas en una escala de 1:1 en un poster de 1 × 1 m. Los posters fueron evaluados bajo condiciones de laboratorio para determinar la cobertura por clase de color, para ello se usaron las siguientes técnicas convencionales: marco de puntos de acero, marco de puntos láser, línea de intercepción de puntos, estimación ocular, y la línea de intercepción. Así mismo, la cobertura por clase de color de los posters se midió usando algoritmos estándar y especiales dentro del protocolo de análisis de imágenes VegMeasure y usando el método de la capa de malla digital. Los resultados indican que las técnicas convencionales tuvieron una correlación significativamente mayor (≥ 92% de concordancia de lo medido con lo conocido) que las mediciones de cobertura derivadas de los algoritmos usados en el análisis de VegMeasure (70%). El factor critico que influenció la exactitud de los métodos de muestreo de puntos fue el área de contacto del punto. Estos hallazgos proveen una medida importante de la exactitud relativa entre los métodos evaluados la cual es de utilidad para los manejadores de pastizales e investigadores que buscan mejorar los métodos de monitoreo de los pastizales.

The Accuracy of Ground-Cover Measurements

Ground cover is a key indicator of rangeland condition and influences rangeland management decisions, yet there have been few advances in ground-cover measurement methods. The advent of digital photography and automated image processing promise a revolution in the way ground cover is measured. To assess the potential for automation we compared conventional and automated methods for measuring ground cover against known artificial populations. The known populations were created from 20 nadir images of a Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle Young) vegetation type acquired with a 5-megapixel Olympus E20 digital single lens reflex camera mounted on an aluminum camera frame at 2 m above ground level. The images were converted to color, 2-dimensional images that no longer represented real-world conditions but had known cover values and conserved a simplified form of the pattern and spatial context of the plant community. These images were then printed at 1:1 scale to a 1 X 1-m poster. Posters were evaluated for color cover under laboratory conditions using the conventional techniques of steel-point frame, laser-point frame, line-point intercept, ocular estimation, and line intercept. Photographs of the posters were measured for color cover using standard and custom-created algorithms within the VegMeasure image analysis framework, and using the Digital Grid Overlay method. Results indicate that conventional techniques had significantly greater correlation (92% agreement of measured to known) than measurements from the algorithms used in the VegMeasure analysis (70%). The critical factor influencing accuracy of point-sampling methods was the area of the contact point for the given method. These findings provide an important measure of relative accuracy among methods for land managers and for researchers seeking to improve rangeland monitoring methods.

Livestock grazing effects on ant communities in the eastern Mojave Desert, USA

Abstract The effects of livestock grazing on composition and structure of ant communities were examined in the eastern Mojave Desert, USA for the purpose of evaluating ant communities as potential indicators of rangeland condition. Metrics for ant communities, vegetation, and other ground-cover elements were evaluated as a function of distance from livestock water tanks, which represents a gradient in level of livestock activity in desert settings. Data were collected at six isolated water tanks used by cattle during early summer, with seven plots (90 m × 90 m; 100 pitfall traps) per tank. Thirty-eight species of ants were recorded, with an average of 14 ant species per plot. Ant species richness did not differ as a function of distance from the water tank. Also, overall species composition, as measured by a similarity index for species presence/absence for paired-comparisons of plots, did not show differences attributable to the gradient in grazing impact. In contrast, the relative abundance of several taxa and functional groups was significantly related to distance from the water tank. The predominant pattern was for the greatest abundance to occur at the water tank, with little difference in ant abundance among plots away from the water tank. This pattern was shown by the abundant ants species, Conomyrma bicolor and Pheidole tucsonica, and the groups Conomyrma spp., Pheidole spp., homopteran tenders, and plant foragers. However, two species, Aphaenogaster megommata and Monomorium wheelerorum showed the greatest relative abundance at a distance away from the water tank. A number of ant metrics were significantly related to ground-cover metrics (R2 > 0.5). Organic debris was the variable most frequently related significantly to ant abundance metrics, always in a positive direction, followed by cover for perennial grasses, annual forbs, and shrubs, and bare patch size. Ant community metrics in the study region appear to have little potential to serve as indicators of rangeland condition because differences were evident primarily in severely degraded localized conditions rather than in intermediate widespread conditions.

Desertification and biopedturbation in the northern Chihuahuan Desert

We examined the relationship between biopedturbation (animal caused soil disturbance) and several vegetation and soil-based indicators of rangeland condition to evaluate the effects of desertification on animal soil disturbance. The area, volume, and abundance of various biopedturbation types were assessed at 117 sites in south-central New Mexico where vegetative cover and composition had been measured previously. There were significant relationships between biopedturbation and selected rangeland condition indicators. Increasing percentages of grass cover were positively associated with increasing total area of biopedturbation. Increasing percentages of shrub cover and mean bare patch size were negatively associated with total biopedturbation area. Biopedturbation area and volume were related to indicators of rangeland condition and percent shrub cover best predicts the area of soil disturbed by animals. This relationship, however, cannot reliably predict total biopedturbation area or the area of soil disturbance types.

Participatory selection process for indicators of rangeland condition in the Kalahari

To develop indicator–based management tools that can facilitate sustainable natural resource management by non–specialists, meaningful participation of stakeholders is essential. A participatory framework is proposed for the identification, evaluation and selection of rangeland condition indicators. This framework is applied to the assessment of rangeland degradation processes and sustainable natural resource management with pastoralists in the southern Kalahari, Botswana. Farmer knowledge focused on vegetation and livestock, with soil, wild animal and socio–economic indicators playing a lesser role. Most were indicators of current rangeland condition; however ‘early warning’ indicators were also identified by some key informants. This demonstrates that some local knowledge is process–based. Such knowledge could be used to improve indicator–based management tools and extension advice on the livelihood adaptations necessary to prevent or reduce ecological change, capable of threatening livelihood sustainability. There is evidence that social background influences indicator use. Communal farmers rely most heavily on vegetation and livestock indicators, whilst syndicate and land–owning pastoralists cite wild animal and soil–based indicators most frequently. These factors must be considered if indicator–based management tools are to meet the requirements of a diverse community.

Ant communities and livestock grazing in the Great Basin, U.S.A.

The objectives of this study were to determine if metrics for ant species assemblages can be used as indicators of rangeland condition, and to determine the influence of vegetation and ground cover variables, factors often influenced by livestock grazing, on ant communities. The study was conducted in two areas in the Great Basin: a sagebrush-steppe in southeastern Idaho (n=30 sites), and a salt-desert shrub in western Utah (n=27 sites). Sites were selected based on known rangeland condition (i.e. good, fair, poor) associated with livestock grazing. Ant communities differed considerably between the two study areas. Collectively, more ant species occurred at the Idaho sites (30) than at the Utah sites (21), relatively few species (eight) occurred in both areas, species richness was significantly greater at the Idaho sites (mean=12·0 species) than the Utah sites (mean=6·9 species), and Formica spp. were diverse (total of 15 species) at the Idaho sites but rare (one species) at the Utah sites. In Idaho, all species collectively, generalists, and Formica spp. were significantly less abundant on sites in poor condition than that on sites in good or fair condition, whereas in Utah, seed harvesters and Pheidole spp. were significantly more abundant on sites in poor condition than that on sites in good or fair condition. In Idaho, species richness was significantly lower on sites in poor condition. In Idaho, species richness and relative abundances of several ant groups were significantly related to bare patch size and parameters for cover or species richness of several vegetation groups. In contrast to the comparisons involving sites in poor condition, no differences in ant communities in either Idaho or Utah were evident between sites in good and fair condition. Thus, the ant communities responded only to large changes in rangeland condition and to large differences in climatic/edaphic conditions between the two areas. Hence, ant community metrics appear to have limited utility as indicators of rangeland condition in the Great Basin.

Changes in ant species composition and community organisation along grazing gradients in semi-arid rangelands of the Northern Territory.

The impact of cattle grazing on ant diversity, species composition and community organisation was investigated in the Victoria River District of the Northern Territory, using distance from water as a surrogate of grazing intensity. Two gradients were sampled, one on red earth at Kidman Springs (5 plots), the other on black cracking clay at Mount Sanford (6 plots). Sites were sampled in April (both sites) and October (Kidman Springs only)1998. The two sites supported distinctly different ant communities, with 70 species at Kidman Springs and 36 at Mount Sanford. Species richness and total abundance did not change significantly with distance from water, although species richness was always greatest at the most distant plot. However, multivariate analysis showed that ant species composition changed markedly. Despite large changes in species composition, the abundance of only six of the 24 most common species (two at Kidman Springs and four at Mount Sanford) were significantly correlated with grazing intensity. The abundance of Bassian taxa was promoted by grazing, whereas the species richness of Torresian taxa and the abundance and species richness of Widespread taxa were suppressed. Ant functional group analysis showed community organisation was resilient, with slight changes being primarily driven by Hot Climate Specialists and dependent on the season. However, the relative richness of five functional groups correlated significantly with grazing intensity, all negatively. Ant variables suppressed by grazing were positively associated with patch cover variables and litter, and negatively correlated with annual grass and bare ground, and may serve as indicators of rangeland condition. Key words: biodiversity, cattle grazing, indicators, piosphere, rangeland management, semi-arid, tropical savannas