The role of traditional farming practices in ecosystem conservation: The case of transhumance and vultures

Transhumance is a traditional livestock practice based on the movement of livestock between winter and summer pastures with importance placed on biodiversity conservation. We analyzed the transhumant activity of sheep and cows in the uplands of the Cantabrian Mountains, NW Spain, and its influence on the ecology and management of the griffon vulture, a scavenger with a relevant ecosystem function. For the first time, we provided strong evidence of the close relationship between vultures and transhumance, which was previously only suggested. Vultures occupied roosting sites very close to the summer pastures and often consumed livestock carcasses. There was a strong spatiotemporal adjustment in the use of these mountain areas by transhumant livestock, especially sheep, and vultures. The number of transhumant sheep and cows within 10-12.5 km around the roosts were the best predictors of vulture occurrence and abundance, respectively, in generalized linear mixed models. Our estimates of potentially available food from livestock carcasses for vultures indicated that our study area can maintain important griffon vulture populations through a system based on traditional livestock farming including transhumance. Thus, transhumance is able to influence the top of the ecosystem (scavengers) and could aid in sustainable management of griffon vulture populations. In our study area, transhumant sheep were reduced by 62% in the last 15 years and only 20% of summer pastures are now occupied. The potential impact that the ongoing loss of transhumant activity could have on mountain ecosystem conservation should be assessed and taken into account by the new European Common Agricultural Policy.     

Can tree shelterbelts on agricultural land reduce flood risk?

Abstract. Agricultural practices in the UK have come under increased scrutiny since the heavy and widespread flooding of 2000 and 2001. Although the impact of land use on runoff and flood risk is of growing concern, there are few quantitative data available. A preliminary study was undertaken in the Nant Pontbren catchment, mid-Wales. Experimental tree shelterbelts were established in selected pastures of land used for sheep grazing. Water infiltration rates were up to 60 times higher in areas planted with young trees than in adjacent grazed pastures. This demonstrates that farm trees could represent a key landscape feature, reducing run-off even when only present as a small proportion of the land cover. This is likely to be just one of the environmental and economic benefits of planting trees to re-create a more diverse agricultural landscape.     

Satellite Thermography for Soil Salinity Assessment of Cropped Areas in Uzbekistan

A change of canopy temperature can indicate stress in vegetation. Use of canopy temperature to assess salt stress in specific plant species has been well studied in laboratory and greenhouse experiments, but its potential for use in landscape‐level studies using remote sensing techniques has not yet been explored. Our study investigated the application of satellite thermography to assess soil salinity of cropped areas at the landscape level. The study region was Syrdarya Province, a salt‐affected, irrigated semi‐arid province of Uzbekistan planted mainly to cotton and wheat. We used moderate‐resolution imaging spectroradiometer satellite images as an indicator for canopy temperature and the provincial soil salinity map as a ground truth dataset. Using analysis of variance, we examined relations among the soil salinity map and canopy temperature, normalized difference vegetation index, enhanced vegetation index, and digital elevation model. The results showed significant correlations between soil salinity and canopy temperature, but the strength of the relation varied over the year. The strongest relation was observed for cotton in September. The calculated F values were higher for canopy temperature than for the other indicators investigated. Our results suggest that satellite thermography is a valuable landscape‐level approach for detecting soil salinity in areas under agricultural crops. © 2016 The Authors. Land Degradation & Development Published by John Wiley & Sons Ltd.     

Human-wildlife conflicts influence attitudes but not necessarily behaviors: Factors driving the poaching of bears in China

Human-wildlife conflicts often spur retaliatory killing, which may be a major threat to some wildlife species. Asiatic black bears depredate crops and livestock and also attack humans. We investigated whether human–bear conflicts in Sichuan Province, southwestern China, resulted in increased bear poaching. We conducted semi-structured interviews within 429 15 × 15-km cells across the province, asking villagers about bear occurrence, population trends, attitudes toward bears, human–bear conflicts, responses to bear damage, and bear poaching. Bears raided crops (n = 174 cells), killed livestock (n = 114 cells), and attacked people (n = 49 cells). Fifty percent and 43% of villagers held negative and neutral attitudes toward bears, respectively; attitudes were more negative among people who had previous interactions with bears or lived where bear encounters were more likely. Although killing bears was illegal, villagers in 117 cells (38%) indicated that bear poaching occurred around their villages. However, killing bears was not significantly linked to damage: indeed, killing was more common in areas without human–bear conflicts. Poachers killed bears mainly for trade of their valuable parts (gall bladder and paws, 78.5%). Tibetan people experienced bear damage and also had negative attitudes toward bears, but reported less poaching than Han or Yi people, due to their religious beliefs. Our study indicated that human-wildlife conflicts shaped people’s attitudes toward bears, but strong economic incentives, not attitudes, prompted illegal killing. Whereas mitigation of human–bear conflicts could help foster more positive attitudes toward bears and the nature reserves that protect bears, this strategy will not remove the primary threat against this species.     

Post-fledging dispersal, habitat use, and survival of Sprague’s pipits: Are planted grasslands a good substitute for native?

Loss and degradation of native grasslands on the North American landscape are some of the key factors influencing population declines of grassland songbirds. It is unclear what role anthropogenic grasslands play in the conservation of grassland specialists and whether demographic parameters of grassland songbirds differ between anthropogenic and native grasslands. Furthermore, there has been little research examining the overlap (or lack thereof) between nesting and post-fledging habitat. We initiated a radio-telemetry study from 2004 to 2008 on dispersal, microhabitat use, and survival of juvenile Sprague’s pipits (Anthus spragueii), a threatened grassland-obligate songbird, in native pastures and fields planted with exotic species (planted grasslands). Dispersal distance was greater in planted compared to native grasslands, but appeared to be constrained to natal fields up to 26-d post-fledging. Pipits used microhabitats in planted grasslands with vegetation that was on average 11 cm taller than used locations in native pastures, possibly due to the rapid growth of planted vegetation by the time individuals fledged. Individuals that were reared in planted grasslands had consistently lower daily survival rates compared to those in native pastures. Our observation that young birds rarely left their natal field suggests that conserving nesting habitat in native pastures would be an effective management strategy for this species. However, our results suggest that planted grasslands may act as population sinks given the lower survival of juvenile pipits reared in planted fields in our region. Demographic studies during the post-fledging period are essential to determine the conservation value of anthropogenic grasslands for North American songbirds.     

The effect of blanket bog drainage on habitat condition and on sheep grazing, evidence from a Welsh upland bog

There has been increasing interest in potential benefits to be gained by restoring damaged peatlands, with the majority of funding currently being driven by the recovery of protected habitats. However, few data are available linking vegetation community declines with peatland drainage, and so the potential for recovery remains difficult to predict. Surprisingly, there is a similar paucity of research demonstrating the extent of drainage impacts on grazing conditions for livestock, despite this being a priority amongst land managers. We attempt to address these two knowledge gaps, first by investigating whether ditches in blanket bog habitat have improved or increased grazing for sheep, and second by assessing the impact of ditches on the condition of vegetation communities. At an extensively drained upland blanket bog in Wales, currently undergoing ditch blocking restoration, we collected vegetation and sheep occurrence data across five catchments and over 2 years. We present evidence that drained areas had remained relatively wet and were less preferred by sheep. Furthermore, our results show that while sheep preferred graminoid-rich areas, drainage did not increase the abundance of this species group. Drainage at the site has, however, resulted in some degradation in blanket bog vegetation adjacent to ditches; although at the landscape scale, historic high grazing levels appear to explain much of the current poor ecological condition of the site. We conclude that drain-blocking restoration should not reduce sheep grazing conditions beyond their current relatively poor state, and thus in this respect may not represent a threat to hill farming productivity.     

Land Cover Transition in Northern Tanzania

Land conversion in sub‐Saharan Africa has profound biophysical, ecological, political and social consequences for human well‐being and ecosystem services. Understanding the process of land cover changes and transitions is essential for good ecosystem management policy that would lead to improved agricultural production, human well‐being and ecosystems health. This study aimed to assess land cover transitions in a typical semi‐arid degraded agro‐ecosystems environment within the Pangani river basin in northern Tanzania. Three Landsat images spanning over 30 years were used to detect random and systematic patterns of land cover transition in a landscape dominated by crop and livestock farming. Results revealed that current land cover transition is driven by a systematic process of change dominated by the following: (i) transition from degraded land to sparse bushland (10·8%); (ii) conversion from sparse bushland to dense bushland in lowland areas (6·0%); (iii) conversion from bushland to forest (4·8%); and (iv) conversion from dense bushland to cropland in the highlands (4·5%). Agricultural lands under water harvesting technology adoption show a high degree of persistence (60–80%) between time slices. This suggests that there is a trend in land‐use change towards vegetation improvement in the catchment with a continuous increase in the adoption of water harvesting technologies for crop and livestock farming. This can be interpreted as a sign of agricultural intensification and vegetation regrowth in the catchment. Copyright © 2015 John Wiley & Sons, Ltd.     

The Use of Goats Grazing to Restore Pastures Invaded by Shrubs and Avoid Desertification: A Preliminary Case Study in the Spanish Cantabrian Mountains

Spanish mountains have been affected by the expansion of shrubs and forests since the mid‐20th century. This secondary succession in vegetation has some positive effects, but also drawbacks, such as an increase in fire risk, loss of diversity in land use, a reduction in landscape and cultural value, less water available in river channels and reservoirs, constraints on livestock farming, a reduced number of local species and loss of biodiversity. This paper analyses the potential for grazing domestic goats to help control the spread of several species of shrubs such as the common broom (Cytisus scoparius), red raspberry (Rubus idaeus) and roses (Rosa sp.) that are commonly found in degraded pastures in the Cantabrian Mountains of northern Spain. Using experimental plots, the effects of two levels of stocking density (4·5 and 9 goats ha⁻¹ y⁻¹) are compared with other land management systems used in the region: burning, mechanical clearing and trimming. The combined use of goats with support from burning, clearing and trimming controls the spread of shrubs. The most efficient treatment was found with nine goats ha⁻¹ y⁻¹. Goat grazing also changes the distribution of shrubs, transforming a dense and continuous coverage into separate clumps and thereby enabling livestock to graze more easily. Maintaining a mixed structure of shrubs and pastures is the best treatment due to the low population density of the Cantabrian Mountains, as this enhances the biodiversity, controls fire risk and enriches the landscape; it also allows extensive livestock grazing as a main economic resource. Copyright © 2013 John Wiley & Sons, Ltd.     

Modelling the spatial distribution of human-caused grizzly bear mortalities in the Central Rockies ecosystem of Canada

We examined the spatial patterns of 297 human-caused grizzly bear mortalities from 1971 to 2002 within the Central Rockies ecosystem (CRE) of Canada to explore relationships between mortalities and variables reflecting human development, terrain, and vegetation. Using logistic regression, we modelled the distribution of grizzly bear mortalities based on local landscape attributes as well as examining variation among demographic status, seasons, and mortality type. Grizzly bear mortalities were concentrated in three main regions of the CRE: (1) Lake Louise; (2) Banff town site; and (3) Alberta Provincial lands near the Red Deer River. We found no evidence for environmental differences in mortality locations between sexes or seasons, while sub-adult male and legal harvest mortalities were more dispersed than other mortalities. Models describing the relative risk of mortality were positively associated with human access, water, and edge features, while negatively associated with terrain ruggedness and greenness indices. Model predictions fit well with independent data. Overall, relatively little of the landscape was secure from human-caused mortality for grizzly bears. This would be most directly remedied by controlling human access.     

Declining birds in Australian agricultural landscapes may benefit from aspects of the European agri-environment model

Temperate Australia’s wheat/sheep zone and much of Western Europe have both experienced dramatic declines in native bird populations associated with agricultural landscapes. We compare recent conservation strategies on private land in the context of each region’s historical agricultural development and the ecology of its bird fauna. Specifically, we consider which aspects of the conservation instruments and practices employed in European agricultural landscapes might be used to augment and inform approaches to private-land biodiversity conservation in Australia. Australian biodiversity conservation activities have focussed predominantly on remnant native vegetation and rarely target the agricultural matrix (i.e. land that is primarily used for agricultural production). However, declining species include those that not only primarily inhabit woodland, but also species for which components of the agricultural matrix are important, or even their main, habitat. In contrast, in Europe a range of conservation activities undertaken through agri-environment schemes focus explicitly on the management of the agricultural matrix. Whilst the different approaches to conservation on private land in Australia and Europe reflect the two continents’ different ecologies, land-use histories and political economies of agriculture, there are a number of parallels between bird population declines in the two regions, and an opportunity may exist to incorporate some of the successful aspects of the European agri-environment approach into emerging stewardship schemes in Australia. We suggest that the long-term nature of European agri-environment agreements, the principle of landholder payments more commensurate with reduced production opportunity and management actions specifically targeted at the agricultural matrix, are features of the European scheme that could benefit both woodland- and matrix-inhabiting bird species in Australian agricultural landscapes.     

喀斯特峰丛洼地农业生产活动的景观效应初探

为探讨峰丛洼地农业生产活动对景观的影响,从农业生产活动对峰丛洼地水文、植被及土壤的影响及其对景观格局演变的作用等方面入手,重点分析了农业生产与景观演变的相关性,结果表明:农业生产对峰丛洼地景观格局的影响,主要是由对原始植被的破坏导致表层岩溶水循环途径的阻断及表层岩溶带产流模式的改变造成的,即地下径流转化为地表径流。农业生产活动对喀斯特峰丛洼地景观变化的作用主要是破坏了地表植被系统的稳定性,造成景观破碎,使景观均质性减弱,造成景观的逆向演替乃至出现石漠化。     

A FUZZY RULE BASE APPROACH FOR DEVELOPING A SOIL PROTECTION INDEX MAP: A CASE STUDY in the UPPER AWASH BASIN,ETHIOPIAN HIGHLANDS

Land use practices and vegetation cover distribution are considered to be the most important dynamic factors that influence the land degradation or the soil erosion of a region. In this study, a Soil Protection Index (SPI) is defined as a function of land use practices and intensity of vegetation cover. This index is used to map the relative degree of protection of topsoil from being eroded by external effects such as rainfall and overland flow. A fuzzy rule‐based model integrated within ArcGIS® has been set‐up and tested with the aim to develop SPI maps. The amount of vegetation cover distribution, that is, Normalized Difference Vegetation Index as proxy parameter and Land Use–Land Cover map are chosen as fuzzy input parameters for the SPI as the desired system output. The approach was tested in the Upper Awash basin in Ethiopia. The output SPI map was qualitatively evaluated against the expert‐defined land degradation risk class, and it was found that locations that are mapped with ‘low and very low’ SPI classes at different time periods of the year have a high potential land degradation risk. Furthermore, socio‐economic data (‘population and livestock densities’) and environmental parameters (‘altitude and soil erodibility’) for the region are used to correlate with the SPI map as an indirect method of evaluation. It is found that population and livestock density explained 68 per cent of the spatial distribution pattern of predicted SPI and an adjusted R‐squared value of 0·681 (p < 0·05) was obtained. It was also found that the SPI distribution over the region for two different time periods, that is, January and July 2001, correlated positively (R² = 0·41 and R² = 0·51) with the soil erodibility of the region. The transferability and applicability of the model for different environmental settings or landscapes were tested by mapping the SPI of Italy. This SPI map of Italy was compared with the soil erosion map of Italy produced by the European Soil Bureau. It can be concluded that the SPI map reflects the potential land degradation risk distribution of the case‐study region. Results show that a fuzzy rule‐based model can provide useful preliminary information even without detailed and precise data information for developing appropriate strategies for land degradation assessment vital for sustainable land use management. Copyright © 2012 John Wiley & Sons, Ltd.     

Moderate sheep grazing in semiarid shrubland alters small-scale soil surface structure and patch properties

We investigated whether long-term moderate livestock grazing by sheep (ca. 10 animal unit days/ha) in a semiarid shrubland with a long-term average annual rainfall of 200 mm causes changes in soil surface structure and dimensions of shrub and intershrub patches. We examined grazing-induced changes in landscape patchiness, patch structure, and soil moisture in three grazed and three ungrazed plots of 4 m × 4 m on a south-facing slope and the opposite, more productive north-facing slope. The measurements were done in early spring 2001 and 2002 before grazing started, in two surveys, one using two parallel transects and one using sample quadrats of 20 cm × 30 cm under three shrubs per plot and on an adjacent part of the intershrub matrix. On the north-facing slope, the sheep reduced shrub patch size as they trampled the soil mounds under the shrubs and browsed the shrub canopy. Reduced shrub patch size decreases the area and resources available for plant production. On the south-facing slope, the sheep mainly disrupted the soil crust in the intershrub area. This may increase soil erosion, but also seedling establishment. The contrast in impacts on the two slopes is due to the interaction between environment (productivity, exposure and vegetation) and sheep behavior (herbivory and trampling). On both slopes, the changes due to grazing are significant, though small. Changes in patch size and properties induced by moderate grazing can have positive and negative effects on productivity and diversity, but may also be viewed as early signs of landscape degradation as is often caused by heavy grazing.     

Estimation of animal location from radio telemetry data with temporal dependencies

We evaluate the performance of several estimators of animal location when data arise from radio telemetry studies. We assume that error-prone bearings are taken at regular time intervals from known locations, that observations may be frequent enough to introduce temporal dependencies, and that animals remain within well-defined home ranges. We simulated data to examine several factors including home range shape, dependency between successive locations, sample size and strategy, and bearing error. Simulated data, supplemented by data based on actual paths for Rocky Mountain elk (Cervus elaphus nelsoni), were used to evaluate alternative location estimators: Lenth’s maximum likelihood estimator (MLE) that assumes independence; Pace’s moving average version of the MLE that introduces a post hoc dependence in the data; and three estimators from state-space models that explicitly model animal movement and dependencies. The state-space models differed in the assumed model of animal movement and included a simple normal random walk, a variation of the random walk that includes a centralizing parameter, and a discretetime version of the Ornstein-Uhlenbeck model for movement within an elliptical home range. Estimates were evaluated in terms of location error and estimator precision. The independent MLE had the poorest performance under most scenarios, particularly when actual locations were dependent. The centrally biased random walk estimator generally had smallest location errors and best precision, whether or not data displayed dependencies. Rather than assuming independence or discarding observations to achieve independence, estimation of location would be served better by accounting for potential dependencies. Methods based on simple models of animal movement may vastly improve estimates, and models that recognize an animal’s sense of home territory are preferred.     

Pimpinella saxifraga is maintained in road verges by mosaic management

Road verges have been proposed as refuges for vulnerable grassland species in the modern, changing landscape, but little comparative knowledge exists on how management regimes affect population dynamics of such species. We compared the effects of various management regimes on the population dynamics of Pimpinella saxifraga in road verges and pastures, using elasticities and LTRE analyses with underlying vital rates as model components in three road verges and three pastures in an agricultural landscape in W Norway. Under present management regimes, we observed slightly higher population growth rates in pastures than in road verges. The pasture populations had comparatively lower survival but higher reproduction than the road verge populations, thus demonstrating a management-induced negative correlation. Such negative correlations may reflect species’ adaptability to environment changes, thereby reducing the extinction risk. We generally observed small changes in P. saxifraga demography to management but considerable variation along environmental gradients, underlining the importance of studying multiple populations. The linear form of the road verges enabled a fine-scale mosaic application of different management regimes. Individuals growing in zones receiving survival-lowering management produced seeds that compensated the lack of seeds in zones receiving fertility-lowering management. The observation of ‘mosaic’ management that allows road verge metapopulations to complement each others life-history characteristics exemplifies the unique potential of road verge ecosystems to maintain semi-natural grassland species like P. saxifraga, as well as providing habitats for different species exhibiting various life histories.     

Butterfly distribution and abundance is affected by variation in the Swedish forest-farmland landscape

Remaining patches of semi-natural grasslands are hot spots for biodiversity in modern agricultural landscapes. In Sweden semi-natural pastures cover approximately 500,000 ha. However, power-line corridors, road verges and clear-cuts cover larger areas (in total about 2,000,000 ha), and these open, less intensively managed habitats are potentially important for species associated with taller vegetation and flower resources (e.g. pollinating insects). The aim of the present study was to evaluate the relative importance of semi-natural pastures and the other three open habitats for butterflies in 12 forest-farmland mosaic landscapes in south central Sweden. Species composition differed significantly between habitats in multivariate analyses. Power-line corridors and semi-natural pastures harbored several species that were disproportionally abundant in these habitats (13 and 8 species, respectively), and power-line corridors also harbored several species that were classified as typical in indicator species analyses. There were more butterfly species, higher abundances and a tendency for more individuals of red-listed species in power-line corridors than in the other three habitats. Effects of the surrounding landscape composition seemed to be weaker than that of the local habitat. However, species composition was significantly associated with landscape composition and species with intermediate and low mobility were more abundant in forested landscapes than in landscapes dominated by arable fields. Analyses of flying time and host plants for larvae suggest that early flying species and species associated with dwarf shrubs were more common in power-line corridors than in the other habitats. A landscape perspective, which takes several habitats into account, is needed for conservation of butterfly communities in forest-farmland landscapes. Power-line corridors and road verges offer possibilities for creating habitats that are suitable for pollinating insects through conservation-oriented management.     

Large‐scale Modeling of Soil Erosion with RUSLE for Conservationist Planning of Degraded Cultivated Brazilian Pastures

Pasture degradation is one of the major environmental and economic problems of Brazilian livestock production. Based on the estimates of soil loss in 140,297 km² pasturelands of Goiás State and the Federal District, the effects of land use and management and conservation practices on soil erosion by water were evaluated. Soil loss was estimated with the empirical revised universal soil loss equation model under four scenarios of land use and management of pastures and the implementation of terraces. The effects of converting hilly areas into permanently preserved areas were also evaluated. Well‐managed pastures planted in terraces and highly sloped areas with native vegetation featured a reduction of 709% in the rate of soil erosion by water in comparison with poorly managed pastures without soil conservation practices. The environmental consequences of pasture degradation become particularly important when they are associated with land use in the Amazon and Cerrado biomes because farmers in these regions are forced to open new natural areas. In addition, the high indices of bare soil in degraded pastures contribute significantly to sediment deposition in rivers and dams. The modeling of soil loss is demonstrated to be an important tool for land use planning and supporting public policies focused on the sustainable use of natural resources. The results of these simulations demonstrate the importance of actions to recover degraded pastures, such as the Federal Government's program known as ABC (Low Carbon Agriculture). Copyright © 2015 John Wiley & Sons, Ltd.     

Amphibian distribution in a traditionally managed rural landscape of Eastern Europe: Probing the effect of landscape composition

A massive decline of biodiversity is caused by land-use changes. Efforts must therefore be made to better understand the factors that govern organismal distribution, especially for countries where traditional management is about to be intensified such as in Romania. We here document the spatial distribution of amphibians from a Romanian rural landscape where land-use is still largely traditional. We related the occurrence of nine amphibian species and species richness to measures of composition and configuration of the landscape surrounding 54 ponds at three spatial scales: circular areas of 400, 600 and 800 m radii. Busy roads most severely impacted single species and amphibian richness whereas landscape composition measures, such as cover of urban areas, agricultural areas, pastures, forests and wetlands were of little importance. We suggest that the relative unimportance of landscape compositional measures on amphibians is a consequence of the traditional management of these landscapes that keep the environmental conditions favorable for most species.     

Multi-scale factors affecting bird use of isolated remnant oak trees in agro-ecosystems

With recent emphasis on sustainable agriculture, conservation of native biota within agricultural systems has become a priority. Remnant trees have been hypothesized to increase biological diversity in agro-ecosystems. We investigated how remnant Oregon white oak (Quercus garryana) trees contribute to conserving bird diversity in the agro-ecosystem of the Willamette Valley, Oregon, USA. We compared bird use of isolated oak trees in three landscape contexts - croplands, pastures, and oak savanna reserves - and ranked the relative importance of four factors thought to influence bird use of individual trees: (i) tree architecture; (ii) tree isolation; (iii) tree cover in the surrounding landscape; and (iv) landscape context, defined as the surrounding land use. We evaluated species-specific responses and four community-level responses: (i) total species richness; (ii) richness of oak savanna-associates; (iii) tree forager richness; and (iv) aerial and ground forager richness. We documented 47 species using remnant oaks, including 16 species typically occurring in oak savanna. Surprisingly, landscape context was unimportant in predicting frequency of use of individual trees. Tree architecture, in particular tree size, and tree cover in the surrounding landscape were the best predictors of bird use of remnant trees. Our findings demonstrate that individual remnant trees contribute to landscape-level conservation of bird diversity, acting as keystone habitat structures by providing critical resources for species that could not persist in otherwise treeless agricultural fields. Because remnant trees are rarely retained in contemporary agricultural landscapes in the United States, retention of existing trees and recruitment of replacement trees will contribute to regional conservation goals.     

盐池县天然草场产草量与载畜量调查研究

由于近几年的连续干旱,盐池县天然草场植被呈现一定的退化趋势.从防止草地退化沙化的目的出发,在野外调查的基础上,对天然草场的产草量和载畜量进行了测算,结果表明,盐池县天然草场的合理载畜量为40.85万标准羊单位,实际超载23.39万羊单位,超载率为57.25%.