西藏那曲牧区雪灾损失的多因子灰色关联分析

通过那曲地区牧区雪灾的定性分析,应用灰色系统理论的关联分析方法,以1985年、1995年两次雪灾的平均损失率为参考数列;以气温、降水、稳定的积雪日数、草地退化比例、草场实际载畜量、草地超载比例,冬储草量作为比较数列,对那曲地区雪灾损失进行多因素关联分析。研究结果客观、定量地揭示了雪灾损失与各影响因素之间的相互关系,为那曲地区雪灾的抗灾防灾提供了科学的依据。     

西藏自治区那曲地区草地资源现状与可持续发展

本文简要介绍了西藏自治区那曲地区草地资源基本概况和草地类型、分布等特征,综合分析了影响其可持续发展的三大因子,在现有的基础上提出了该区实现草地可持续发展的途径与对策。     

藏北那曲地区草地和未利用土地动态变化及原因

根据1990年和2000年2期那曲土地利用馒盖分类图,运用GIS的空间分析和数理统计功能,分析那曲地区草地退化和未利用土地的增加情况,并结合气象资料和人口资料分析这些变化的原因。结果表明：10a间,那曲地区未利用地增加;草地减少,突出表现为草地向未利用地转化。草地向林地和耕地转化,导致这种结果的主要原因是由于人类的社会经济活动造成的,人类社会经济活动引起这一地区土地利用变化的强度已经超过自然因子所能达到的强度,起到了绝对的主导作用。     

生物与土壤

S812.32007010239西藏那曲地区草地植被及土壤养分状况调查=Investigation of grassland growth and soil nutrient situation in Naqu prefec-ture of Tibet/万运帆,高清竹…∥草业科学.—2006,23(5).—7~11对西藏那曲地区草地植被状况、土壤水分、养分状况进行了调查分析.结果表明:无论是从牧草生长还是从土壤水分、养分状况来看,那曲地区东西部草地存在显著差异,东部草地明显好于西部草地.东部草地的平均土壤含水量比西部草地高50%,植被覆盖度约是西部草地的2.36倍,单位面积产草量约是西部草地的3倍.那曲地区草地土壤偏碱性,东部草地土…     

国土开发整治

5812.95 2004021671西藏那曲现行草场管理方式与草地退化的关系=Thecur-rent managen、ent Pattem and grassland degradation in Naquprefecture,Tibet,China碗兴唬,杨萍…//草业科学一2003(9)一49一53 通过对那曲地区草场管理方式和草地退化现状的分析,探讨了现行的草场管理方式对载畜量、草场建设、草场保护和草场生态的影响,进一步证明了现行的“牲畜私有,草场公有”的草地畜牧业经营方式是造成草场严重超载、滥牧、抢牧、缺乏建设、缺少管护的后果,从而导致草地严重退化,环境趋于恶化.对此,提出了尽快落实草地承包责任制,科学利用与…     

基于ETM+影像的草地退化评价模型研究——以西藏自治区那曲县为例

在实地调查和样方测定基础上,选用建群种植株高度、草地植被盖度和草地生物量作为草地退化地面评价体系中的单一评价指标,并通过加权综合三个单一评价指标,构建草地退化地面综合评价指标;在分析退化草地光谱特征的基础上,从ETM+影像的波段数据中派生出草地退化的遥感评价指标。通过相关分析的方法,选出最能反映草地退化趋势、最适于用于线性拟合的地面评价指标（地面综合评价指标）和遥感评价指标（TM4/TM5）,采用线性回归技术构建草地退化遥感评价模型,并通过计算确定系数（R2）、均方根差（RMSE）和相对误差对模型精度做出评价。确定主要草地类型的不同退化等级标准,完成草地退化图的编制。通过分析草地退化地面评价指标与遥感评价指标之间的关系,探讨了西藏北部草地退化的遥感评价模型,为科学、快速评价草地退化提供一种新思路。     

西藏那曲地区畜牧业生态系统功能评价

畜牧业生态系统功能评价是进行草地系统保护与管理、防治草地退化的前提，是畜牧业系统优化和持续发展的根本。为此，以西藏自治区那曲地区草地为研究对象，通过设立评价指标，建立多因子评价模式，采用三角分析法对区域内畜牧业生态系统的社会、经济、生态功能进行综合评价。为区域畜牧业未来发展提供依据。     

气候变化及人为干扰对西藏地区草地退化的影响研究

随着草地保护政策的实施,气候及人为干扰对西藏地区草地退化的影响作用发生变化,明确草地退化的影响因素,评价草地保护政策对草地退化恢复的效用,是合理保护西藏地区草地生态平衡的基础.本文以西藏地区为研究区,基于1995-2015年GIMMS-NDVI及统计数据估测草地退化情况,并通过残差分析及回归分析评估了气候变化、人为干扰...     

质变和量变两种维度下新疆山区土地覆盖变化分析

山区是新疆主要的产流区,山区土地覆被变化对新疆经济发展和生态环境安全具有重要意义,但新疆山区的土地利用整体变化情况尚不太清楚。该文基于新疆1∶10万土地覆被类型数据和GIMMS 3 g植被指数数据,综合运用GIS空间分析和月平均、距平和趋势保留预置白处理方法及Mann-Kendall非参数趋势检验方法,提取与分析了新疆三大山区在1990—2010年土地覆盖类型转化和1982—2013年的植被覆盖变化情况,尝试从2个维度分析新疆山区土地覆被变化情况,探讨了植被覆盖的显著变化与土地覆盖类型之间的空间关系。结果表明:1)以土地覆盖类型转化为标志的新疆土地覆被质变情况发生比例很小,99%的土地覆被类型没有发生变化;2)新疆三大山区中均有大于35%的面积植被状态发生了不同方向上的显著变化,阿勒泰山区植被退化30.38%,植被改善4.07%,天山山区植被退化25.27%,植被改善18.26%,昆仑山山区植被退化33.69%,植被改善19.83%;3)发生退化的区域主要分布于人类活动干扰较强的低海拔及山前地区,且主要以草地和稀疏草地为主,阿勒泰山区草地退化面积占到总面积22.18%,天山山区稀疏草地和草地退化面积占到总面积18.88%;昆仑山区植被稀疏草地和草地退化面积占到总面积10.74%。研究结果说明从质变和量变二种角度的分析能够提供对山区土地覆被变化提供更全面的认识,在分析土地覆被变化的生态水文响应时应当给予综合考虑。     

草地退化遥感评价与监测研究进展

草地退化成为中国最主要的生态问题之一,研究其时空特征、影响以及驱动因子对退化草地治理和草地资源持续利用均有指导意义。从草地退化评价与监测研究的技术手段、基础、监测方法分类、常见的遥感分级指标及其局限性等方面的研究现状进行了综述,结果发现,目前草地退化遥感评价与监测工作中存在着草地退化与草地植被长势概念混淆、草地退化程度被"高估"、现有分级指标对某些特定的退化类型不敏感等问题,利用年降水量资料对植被覆盖度、地上生物量等现有分级指标进行校正,针对特定的退化类型,引入草地群落中退化指示植物的综合算术优势度、覆盖度的相对百分数等新的综合性分级指标并对其进行遥感反演是未来发展趋势,具有广阔的应用前景。     

毛乌素地区农业用地方式转换与沙漠化

Introduction and the study area Desertification refers to land degradation phenomenon and process in arid, semi-arid and dry sub-humid areas (the humid index between 0.05 and 0.65) resulting from various factors, including climatic variations and human ac…     

The effects of land-use types and conversions on desertification in Mu Us Sandy Land of China

Based on multi-temporal remotely sensed materials of both 1985 and 2000, we analyzed the effects of land-use types and their conversions on desertification in Mu Us Sandy Land in the agro-pastoral transitional zone of north central China. In this study, the desertified land was classified into five degrees: potential, light, medium, severe and extreme. The results indicate that the extent of desertification expands slightly, while desertification degree is enhanced significantly. About 22.35% of the total land area in the study area is in the desertification course, and the expanded area of both severely and extremely desertified land accounts for 3.67% of the total area of Mu Us Sandy Land. About 9053 km2 of area witnessed changes in land-use types between 1985 and 2000, which accounted for 10.75% of the total. More importantly, the area of conversions among cultivated land, forestland and rangeland added up to 971.6 km2. This research reveals that both improper land-use types and conversions could accelerate the desertification process. Both cultivated land and forestland have more effects on the desertification development than rangeland. Some land-use type conversions, such as rangeland to cultivated land, rangeland to forestland and forestland to cultivated land, are attributed to the acceleration of the desertification development while the opposite can control the desertification development.     

Grazing response in the vegetation communities of the Kamiesberg, South Africa: Adopting a plant functional type approach

Potential grazing impacts associated with the sustained heavy grazing of a communal rangeland are explored through a plant functional type approach. An informative typology is derived that shows grazing responses. An examination of plant functional types within growth forms does not provide any additional insights, whereas looking at traits alone does demonstrate a grazing response with increases in the traits of large basal and erect leafy growth forms and losses in the traits of medium height, simple leaves and few flowers. There is also evidence of a biogeographic shift, with an increase in a succulent-dominated plant functional type at higher altitudes on the heavily grazed communal rangeland. This is attributed to the fact that in adopting the proposed universal language advocated by plant functional type practitioners some of the subtleties of this particular vegetation type are lost. For example growth form height classes are too coarse for the shorter vegetation of the Succulent Karoo. In the resultant ‘fuzzy’ groups, responses are lost. While the method adopted is informative a stronger case is made for a more simple growth form analysis traditionally adopted in rangeland analysis.     

豫北平原的沙质草地及其畜牧业发展

豫北平原的沙质草地分布于黄河多次泛滥改道冲积形成的沙丘、沙地。其主要类型有:①以白茅、达乌里胡枝子为主的草从草地;②刺槐、杨树等林地下层以藜、白茅、茜草等为主的林下草地;③以碱茅、狗牙根等为主的低湿草地。沙质草地的主要特征为种类组成简单,牧草产量低(<2 000 kg·hm^-2)且利用过度。但多种优良栽培牧草在沙地生长良好,可获较高产量。在沙地开发中,应针对各草地类型采取相应措施改造为人工、半人工草地。同时应结合沙地多种林木、果树和经济作物种植,建设农牧林复合经营的系统。畜牧业开发应以产业化为主导,发展适应市场需求的优良畜种,实行适度规模经营。     

Climatic and Topographical Factors Affecting the Vegetative Carbon Stock of Rangelands in Arid and Semiarid Regions of China

Rangeland systems play an important role in ecological stabilization and the terrestrial carbon cycle in arid and semiarid regions. However, little is known about the vegetative carbon dynamics and climatic and topographical factors that affect vegetative carbon stock in these rangelands. Our goal was to assess vegetative carbon stock by examining meteorological data in conjunction with NDVI (normalized difference vegetation index) time series datasets from 2001-2012. An improved CASA (Carnegie Ames Stanford Approach) model was then applied to simulate the spatiotemporal dynamic variation of vegetative carbon stock, and analyze its response to climatic and topographical factors. We estimated the vegetative carbon stock of rangeland in Gansu province, China to be 4.4× 10¹⁴ gC, increasing linearly at an annual rate of 9.8×10¹¹ gC. The mean vegetative carbon density of the whole rangeland was 136.5 gC m^-2. Vegetative carbon density and total carbon varied temporally and spatially and were highly associated with temperature, precipitation and solar radiation. Vegetative carbon density reached the maximal value on elevation at 2500-3500 m, a slope of >30°and easterly aspect. The effect of precipitation, temperature and solar radiation on the vegetative carbon density of five rangeland types (desert and salinized meadow, steppe, alpine meadow, shrub and tussock, and marginal grassland in the forest) depends on the acquired quantity of water and heat for rangeland plants at all spatial scales. The results of this study provide new evidence for explaining spatiotemporal heterogeneity in vegetative carbon dynamics and responses to global change for rangeland vegetative carbon stock, and offer a theoretical and practical basis for grassland agriculture management in arid and semiarid regions.     

Indicators of Great Basin rangeland health

Early-warning indicators of rangeland health can be used to estimate the functional integrity of a site and may allow sustainable management of desert rangelands. The utility of several vegetation canopy-based indicators of rangeland health at 32 Great Basin rangeland locations was investigated. The indicators were originally developed in rangelands of the Chihuahuan Desert. Soil resources are lost through wind and water-driven erosion mainly from areas unprotected by plant canopies (i.e. bare soil). Study sites in Idaho had the smallest bare patches, followed by sites in Oregon. The more arid Great Basin Sagebrush Zone sites in Utah had the largest bare patches. Several vegetational indicators including percent cover by vegetation, percent cover by life-form, percent cover by sagebrush, and percent cover by resilient species were negatively related to mean bare patch size and are potential indicators of Great Basin rangeland condition. Plant community composition and the range of bare patch sizes were different at sites in the three locations in Idaho, Oregon and Utah. Therefore, expected indicator values are location specific and should not be extrapolated to other locations. The condition of study sites were often ranked differently by different indicators. Therefore, the condition of rangeland sites should be evaluated using several indicators.     

Visualization and quantification of significant anthropogenic drivers influencing rangeland degradation trends using Landsat imagery and GIS spatial dependence models: A case study in Northeast Iran

Developing countries must consider the influence of anthropogenic dynamics on changes in rangeland habitats. This study explores happened degradation in 178 rangeland management plans for Northeast Iran in three main steps: (1) conducting a trend analysis of rangeland degradation and anthropogenic dynamics in 1986-2000 and 2000-2015, (2) visualizing the effects of anthropogenic drivers on rangeland degradation using bivariate local spatial autocorrelation (BiLISA), and (3) quantifying spatial dependence between anthropogenic driving forces and rangeland degradation using spatial regression approaches. The results show that 0.77% and 0.56% of rangelands are degraded annually during the first and second periods. The BiLISA results indicate that dry-farming, irrigated farming and construction areas were significant drivers in both periods and grazing intensity was a significant driver in the second period. The spatial lag (SL) model (wi=0.3943, Ei=1.4139) with two drivers of dry-farming and irrigated farming in the first period and the spatial error (SE) model (wi=0.4853, Ei=1.515) with livestock density, dry-farming and irrigated farming in the second period showed robust performance in quantifying the driving forces of rangeland degradation. To conclude, the BiLISA maps and spatial models indicate a serious intensification of the anthropogenic impacts of ongoing conditions on the rangelands of northeast Iran in the future.     

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.     

An optimization approach for sustainable development planning of savanna systems

A savanna system is a natural ecosystem in which the competition between grass and woody vegetation in a semi-arid rangeland should be maintained for its sustainable development. Finding an optimal management plan for obtaining maximum economic profit from raising cattle without loss of sustainability of the savanna system during a planning period is a great challenge for rangeland managers. In this study, we formulate the sustainable development planning of the savanna system as an optimal control model, in which maximization of the stocking rate of cattle during the planning period is chosen as the objective while sustainable development requirements are achieved through the constraints represented by the desired final state of the system. Using Pontryagin's maximum principle, the model is transformed into a two-point boundary-value problem with nonlinear differential equations that is then solved using an iterative approach. An example with a specified desired final state in a savanna system without fire is used to demonstrate the performance of the model and the algorithm. Numerical experiments show that the planning strategy obtained from the optimal control model achieves maximum economic profit from raising cattle during the planning period and simultaneously improves the resilience of the system and maintains sustainable development of the rangeland. The outcomes demonstrate that resilience, sustainable development and economic profit are consistent concepts in optimal management strategy for rangeland management.     

内蒙伊盟牧场利用与沙漠化及其防治

本世纪七十年代以来, 沙漠化问题在世界范围内引起了广泛的注意。沙漠化对社会生产和人类的生活与生产是一个严重的威胁。内蒙古自治区伊克昭盟是一个沙漠化比较严重的地区, 迄一九七七年, 全盟流沙面积达27, 666平方公里, 比解放初扩大1.3倍。伊盟牧业在国民经济中比重很大, 牧区约占全盟面积72%。在沙漠化成因中, 牧场的利用不合理是一个主要的方面。因此, 研究牧场利用与土地沙漠化的关系, 总结牧民合理利用牧场的经验, 并提出防治沙漠化的途径, 对于解决这个地区的沙漠化问题, 是十分重要的。