藏北那曲地区草地退化时空特征分析

利用藏北那曲地区的2000-2011年MODIS-NDVI数据,选用草地植被覆盖度作为草地退化的遥感监测指标,分析了过去10年该区草地退化的时空变化特征,为西藏自治区草原三化遥感监测提供重要参考依据.结果表明:以2000-2002年的3年滑动平均值做“基准”,得出2002-2010年那曲地区草地共退化628.7万hm2,且以轻度退化为主.那曲地区草地退化的面积表现出先增加后减少再增加的一个变化趋势,2002-2005年是那曲地区草地退化的主要阶段.那曲地区草地空间变化主要分布在尼玛县、安多县、班戈县和申扎县.     

藏北高寒牧区草地及牛羊越冬情况调查研究

通过对藏北高寒牧区草地和牛羊越冬情况进行调查与测定分析,结果显示:随着藏北海拔高度的差异,草地生境不同,生态环境持续恶化,草地退化严重,退化面积占草地总面积的50.8%.牧草生产季节不平衡,区域差异明显,生产波动性较大,天然草地产草量300～750 kg.鼠虫害较为严重,分别达到45～60只/ hm2和20～30条/m2.适宜于藏北种植的人工种植牧草量高质优,营养价值较高,产草量比天然未退化草地、退化草地分别提高10～15倍和50倍以上.冷季牛羊体重损失达20%～25%,不同饲养方式生产效果差异较大.     

高寒牧区草地退化的人文因素研究——以甘南牧区玛曲县为例

利用草地退化遥感数据、草地退化普查资料以及社会经济统计资料,从定性与定量角度全面系统地分析了高寒牧区玛曲县草地退化的人文因素。定性分析结果表明,玛曲县草地退化与人口、经济发展、过度放牧、制度低效和牧民经营行为等因素密切相关,这些因素深刻影响着玛曲县的草地退化。定量分析结果表明,影响玛曲县草地退化的因素可归纳为人口经济发展因子、载畜因子和牧业结构调整因子,各因子对草地退化的影响大小不同,其中,人口经济发展因子和载畜因子与草地退化呈正相关,牧业结构调整因子与草地退化呈负相关。     

藏北退化草地群落生物量与土壤养分的关系

草地退化会呈现出地上群落与土壤的同步退化,相对于地上植被的退化,土壤退化呈现一定的滞后性,为分析藏北高寒草地退化过程中的群落地上生物量与土壤养分关系,选取那曲地区不同退化程度高寒草地,对土壤养分和地上生物量进行研究。结果表明,随着退化程度的加剧,藏北地区退化草地群落地上生物量和土壤养分(除全钾外)总体上表现为降低趋势,而且步调基本一致。土壤全氮、全钾含量与土壤有机质呈显著正相关(P0.05),土壤pH与有机质含量呈显著负相关(P0.05)。草地地上生物量与土壤有机质含量呈显著正相关(P0.05),与全氮、全磷、全钾含量的相关性不显著(P0.05)。     

基于NDVI的藏北地区草地退化时空分布特征分析

本文以藏北地区为研究区域,基于归一化植被指数(NDVI)反演草地植被盖度,以植被盖度作为判断草地退化的标准,综合计算藏北地区2000-2010年逐年草地退化指数(grassland degradation index),定量揭示藏北地区草地退化的时空分布规律.结果表明,截至2010年,藏北地区草地退化现状仍然较为严重,退化草地的面积占全区面积的58.2%.其中,重度退化和极重度退化草地面积的比例分别为19.0%和6.5%,区域草地退化指数为1.97,接近中等退化水平.分区结果显示,藏北地区中部,东部,北部草地退化情况较为严重,均处于中等退化等级,西部地区的退化情况最轻,处于轻度退化等级.分析2000-2010年藏北地区全区及各个分区的草地退化趋势表明,只有北部地区有减缓趋势;2000-2010年间与1981-1985年间对比结果显示,重度退化及极重度退化草地面积比例上升幅度较大.2000-2010年间藏北地区平均草地退化指数为1.84,草地退化等级在轻度退化到中度退化之间波动.     

甘南草地生态系统生态位适宜度及其空间差异分析

运用生态位适宜度理论,在前人研究的基础上,构建了草地生态系统适宜度与进化动量测算数学模型。选取人口密度、人均GDP、第一产业人均GDP、农民年均纯收入、中度以上退化草地比例、平均产草量、鼠害发生面积所占比例、单位面积草地牧业产值、载畜量9项指标,测度了甘南草地生态系统生态位适宜度和进化动量。结果表明：甘南州各市、县草地生态位适宜度空间差异较大,根据适宜度可分为五级,并对其空间差异进行了分析。     

西藏典型草地地上生物量季节变化特征

采用高寒草甸、高寒草原、高寒沼泽化草甸和温性草原4种西藏高原典型草地类型地上生物量定点观测数据,分析其地上生物量季节动态变化特征和生长规律。结果表明,高寒沼泽化草甸地上生物量最高,其中围网草地年均地上生物量达384.45 g·m-2,比无围网草地地上生物量高73%,且是温性草原类草地生物量的6倍,是高寒草甸和高寒草原类草地的12~14倍,与自由放牧相比,围栏禁牧措施可以明显提高草原地上生物量,是改良退化草地最有效的措施之一;温性草原草地生产力大于高寒草甸和高寒草原,城市附近山地草地生物量明显大于远离城市的地区,表明城市化进程降低了天然草地放牧强度,是恢复退化草地生产力的有效途径之一;属半干旱气候类型的西藏高原中部,降水是制约草地植被生长的主要因子;草地地上生物量的绝对增长速率和相对增长速率季节动态均在生物量达到高峰期前为正增长,之后为负增长。区域水热条件差异及其季节性变化导致了不同草地类型或同一类型不同区域的草地最快生长期出现的时间存在一定差别。     

天祝高寒草地退化原因分析与治理策略

天祝高寒草地是甘肃省重要的牧区之一。借鉴国内外相关研究进展,综合认为脆弱的生态环境是天祝高寒草地退化的内因,人类不合理的利用和干扰是高寒草地退化的主要驱动力,气候变暖、变干加速了高寒草地的退化。并认为家畜粪便的流失、植物的化感作用和自毒作用也是导致天祝高寒草地退化的原因。提出了天祝高寒草地的整体治理策略,即以草定畜、提高出栏率,轻度和中度退化草地进行草地改良、围栏,重度退化草地进行栽培草地建植,同时结合草地鼠害综合治理、加强人才建设与加快科技成果推广和转化。     

高寒地区退化草地改良试验研究

高寒草地是我国重要的草地资源，素有“高原肉库”之美称，但由于近年来草地利用不合理，家畜载为量过大，草地出现不程度退化，为改善草地植物生存条件，对退化草地进行了改良试验研究，结果表明，３种改良措施可改善草地生境，增加土壤速效养分，施肥改良效果最佳，增加牧草在草群中所占比重，禾本科，豆科和莎草科牧划分别对对照区增加９．０２％～１０．１７％，１８．４０％～２７．７６％和－６．５７％～１．８７％，可食３９     

海北州天然草地退化沙化成因与对策

基于海北州天然草地退化沙化的事实,简要分析了退化沙化的表现和危害,重点阐述了区域天然草地退化沙化的多层次原因,提出了相应的应对策略和建议。分析表明：海北州天然草地退化沙化的直接原因为超载过牧和生物链遭到破坏,间接原因为牧业人口数量的增加和畜牧技术的应用,内在原因为高寒气候特点和复杂地形造成区域草地生态系统的脆弱性。提出3项对策建议：推行计划生育,增加教育投资,控制并逐步减少牧业人口;大力推行现代高效畜牧业发展模式,发展栽培草地,实施“以草定畜”;树立“不再破坏就是保护”的意识,开展天然草地的有限治理。     

西藏那曲地区牦牛资源调查分析与对策

利用1958-2009年间西藏那曲地区牦牛的统计资料,分析了那曲地区牦牛数量变化的特征和规律.结果表明,那曲地区牦牛数量占畜群比例的19%～29%,牦牛数量占畜群比例总体呈下降趋势;畜种群结构的调整已经达到"发展牦牛(含黄牛)、适度发展山羊、减少绵羊、控制马"的总体原则,为那曲地区畜牧业的良性发展奠定了基础.     

新疆昌吉州草地生产力年际动态分析

通过对新疆昌吉州草地生产力2006~2010年5年监测结果显示:各草地类型植被不同程度退化。植物种类减少,草群结构单一,优势种出现频率很低,一年生和短命植物比例增加,中山带毒害草(醉马草)大量出现;草层高度不同程度下降。除山地草甸外,高寒草甸、草甸草原、典型草原和荒漠草层高度下降明显,下降幅度都超过了10%;植被覆盖度降低。除荒漠外高寒草甸、山地草甸、草甸草原、荒漠草原和低地草甸下降明显,下降幅度都超过了10%;草地生产力不同程度下降,在2009~2010年草地生产力有所上升。     

西藏那曲地区草地资源保护与可持续发展建议

西藏那曲地区在长期的传统畜牧业经营方式下,对草地资源缺乏有效的保护和科学管理,片面追求牲畜头数,因此,该地区出现了严重的超载过牧现象,导致草地资源退化加剧,草地畜牧业生产难以可持续发展。对那曲地区草地资源保护及草地资源保护中存在的问题进行了探讨,并对该地区天然草地资源保护与可持续发展提出了建议,以期为该地区加强草地管理、发展生态畜牧业、实现草地畜牧业和草地生态环境和谐发展提供参考。     

加入WTO对西藏草地畜牧业的影响及其对策

本文从畜牧业现状、存在的问题、地理条件、资源特点、经济结构特征等方面,分析我国加入WTO对西藏草地畜牧业发展的影响;利用WTO规则,提出西藏畜牧业在世界经济一体化的形势下,应以国内外市场需要为出发点,进一步优化农牧业产业结构调整,加快与国际市场接轨,积极参与国际分工,进入世界农产品的大循环,实现优势互补.     

草原的生态系统服务:IV.降低服务功能的主要因素和关爱草原的重要意义

草原/草地生态系统服务的价值大小取决于草地的自然资本大小和生态系统功能。影响草原生态系统服务功能的最主要因素是,1.改变草地生态系统的用途,2.草地破碎化,3.火,4.草原退化;对它们影响草原生态系统服务功能的原因和机制进行了论述。草原分布广泛,约占地球陆地面积的40%,有40个国家的草地面积占国土面积的50%以上。世界上有17%,即9.38亿人生活在各类草地上并以草地为生,尽管已经证实草原对全世界和全国人民极其重要,但草原提供的生态系统服务———生态服务和产品服务仍没有得到应有的认识和足够的重视。由于生态系统服务的影响深远,健康的草原及其生态系统服务惠及全国和全世界人民;相反,破坏、损失草原自然资本殃及全国和全世界人民。因此,关爱草原,使草原走可持续发展的道路,是全人类共同的责任和义务。     

Effects of Livestock Grazing Management on Grassland Birds in a Northern Mixed-Grass Prairie Ecosystem

Grassland birds have undergone substantial population declines throughout much of their historic ranges in North America. Most of the remaining grassland bird habitat is restricted to rangelands managed for livestock production, so grazing management has strong implications for grassland bird conservation efforts. We conducted 1 830 point-count surveys at 305 sites during 2016–2017 to evaluate the relative effects of three livestock grazing systems on the abundance and community composition of grassland birds in a northern mixed-grass prairie ecosystem of eastern Montana, United States. Our objectives were to 1) evaluate effects of grazing management on abundance and community composition of grassland obligate birds, focusing specifically on grazing systems, stocking rates, and interactions with rangeland productivity; 2) evaluate the importance of local vegetation characteristics for grassland birds within grazing systems; and 3) assess the effectiveness of rest-rotation grazing to create patch-heterogeneity in rangeland vegetation through the alteration of structural components and the response of grassland birds to these treatments. Overall, we found inconsistent responses in abundances of grassland birds relative to livestock grazing systems and no discernable differences among grazing systems relative to community composition. However, local abundances were often driven by interactions between grazing system and rangeland production potential, suggesting the effects of livestock grazing management were generally mediated by rangeland productivity. In addition, associations between avian abundance and grazing management parameters (e.g., stocking rate) were species specific. Ubiquitous guidelines for livestock grazing systems may be inappropriate for grassland bird conservation efforts in the northern mixed-grass prairie, and high stocking rates may negatively impact populations of dense-grass obligate grassland birds in this region.     

高寒草场荒漠化及其控制技术

对高寒干旱区草场荒漠化特征和引发机理的总结，查明了荒漠化草场奶穹的主要原因是气候巨变、不合理农垦、过牧及鼠害等。通过建立牧业生态户，对严重退化草场围封，进行人工补植优良牧草，灭除不可食毒、杂草，消灭鼠害，暖棚养畜；并将木本植物引入草场，设置灌木、半灌木绿篱，探求时空立体型牧场等多项试验措施。经4年治理，提出一套以牧业生态户为单元，防止高寒草场荒漠化，解决青藏高原雪灾问题的畜牧业可持续发展的路子和模式。     

Effect of Plateau Zokor (Myospalax fontanierii) Disturbance on Plant Community Structure and Soil Properties in the Eastern Qinghai-Tibet Plateau,China

Plateau zokor (Myospalax fontanierii) is a native subterranean rodent in alpine rangeland on Qinghai-Tibet Plateau (QTP) in China, and its foraging, digging, and mounds building cause the unique disturbance pattern to alpine rangeland ecosystem. Over the past decades, the zokors have been regarded as major pests who result in the degradation of the rangeland ecosystem in the QTP and have been simply eliminated by rodenticides or traps. Understanding the function of zokors and evaluating the zokors’ impacts on alpine rangeland systems should be the solid scientific basis for zokor control. In this study, we considered the average nearest neighbor indices of zokor mounds to represent the disturbance intensity of zokor to alpine rangeland and surveyed the plant species richness, diversity indices, biomass, and soil physicochemical properties in intermound areas under different zokor disturbance intensities in alpine rangeland in Tianzhu Tibet Autonomous County, located in eastern QTP. Our results indicated that 1) the plant species diversity indices were positively correlated with zokor disturbance intensity and aboveground and belowground biomasses were not significantly different under the different disturbance intensities; 2) the importance value of the forb functional group increased as the disturbance intensities increased, and the sedge functional group showed the opposite trend. The proportions of aboveground and belowground biomasses of forbs increased as the disturbance level increased; 3) there were no changes in the dominant plant species among the different disturbance intensities, but new plant species (Polygonum viviparum and Equisetum arvense) occurred in the plots with high disturbance intensities; 4) a significant positive correlation was observed between soil moisture in the 0-20 cm layer and disturbance intensity, while soil temperature exhibited a significantly negative relationship with the disturbance intensity; however, no differences in soil chemical properties were observed; and 5) redundancy analysis identified that mound building changed soil physical properties, especially soil moisture, in intermound areas, which influenced the plant community structure. In conclusion, the plateau zokor in our study area increased plant species diversity and did not decrease plant biomass, which is beneficial for alpine rangeland systems. We suggest that rangeland managers should consider the multiple functions of zokors to an alpine rangeland ecosystem instead of simply eliminating them.     

西藏草地畜牧业发展战略的调整

本文分析并提出西藏草地畜牧业发展战略调整应:从传统的纯牧区逐步向半农半牧区和农区过渡,形成牧区繁育,农区、半农半牧区育肥,城镇加工的分布格局;开发东部林芝地区草地载畜潜力,稳定、提高中部拉萨市、山南地区草地畜牧业的生产经营水平,保护西部那曲与阿里地区草地,划定禁牧区,建设西部自然保护区;建植人工草地,实施退耕还草、农田种草,实现以草定畜;在青藏铁路沿线,选择低海拔城镇,建设牦牛肉、肥羔肉小包装、分割肉加工基地,以此带动东部、中部绿色牦牛肉、肥羔肉生产和季节草地畜牧业的发展;建设西部绒山羊基地和"一江两河"流域奶牛业;努力扩大边境畜产品贸易,提高畜产品商品率.     

Behavioral and Ecological Implications of Bunched,Rotational Cattle Grazing in East African Savanna Ecosystem

Rangelands and the wildlife and livestock they support are critical to human livelihoods, but rangeland ecosystems increasingly suffer from overgrazing and degradation. Planned grazing, a strategy that commonly involves time-controlled rotations of high-density (bunched) groups of cattle across a pasture, is marketed as a method to enhance rangeland health and lessen livestock impacts. However, the behavioral mechanisms underlying any potential rangeland improvements resulting from rotational, high-density planned grazing have rarely been examined. To investigate these mechanisms, we compared planned grazing with conventional continuous grazing management in a savanna ecosystem in Kenya. We surveyed cattle grazing behavior, measured changes in vegetation characteristics through surveys conducted before and after cattle grazing, and measured native ungulate abundance following grazing using camera traps. Stocking rates were held constant across treatments, resulting in a commensurate decline in total foliar hits per pin (a proxy for vegetative biomass) across treatments. Planned grazing management altered cattle behavior and reduced grazing selectivity by restricting movements, causing cattle to walk more slowly while grazing and to take more bites per step. Vegetation survey results supported this finding: cattle in the planned grazing treatment ate significantly more Pennisetum grasses (typically avoided because of their unpalatability), creating the opportunity for regrowth of more palatable species after seasonal rains. We also documented significantly higher zebra presence in planned grazing plots after cattle grazing, likely due to increased relative abundance of more palatable grass species. This investigation of grazing behavior, and specifically decreased grazing selectivity as a mechanism underpinning the benefits of planned grazing, shows that when conducted at appropriate stocking densities, planned grazing has the potential to help mitigate rangeland degradation and improve rangeland sustainability for both livestock and wildlife in pastoral African savanna ecosystems.