在河北省承德鱼儿山牧场研究不同放牧强度对草地土壤理化性质的影响，研究结果表明：随放牧强度增加，土壤表层0～10cm容重增大，土壤变得紧实，渗透性降低；土壤全磷和速效磷含量降低，而全氮和速效钾含量增加。

近几年，黄河源区高寒草原退化沙化明显。研究了黄河源区紫花针茅高寒草原在不同退化程度下植物群落、生物量和土壤的特征，结果表明，随着高寒草原退化程度加大，植被盖度、草地质量指数和优良牧草地上生物量比例逐渐下降，草地间的相似性指数减小，植物群落多样性指数和均匀度指数呈单峰式曲线变化规律。随着退化加剧，禾草地上生物量减少显著，杂草类植物地上生物量先增加后减少，而莎草科植物地上生物量的变化不受草地退化程度的影响。高寒草原土壤表层０～２０ｃｍ 的植物根系随土壤深度的增加而减少，随草地退化程度的加剧呈倒“Ｖ”型变化。高寒草原物种多样性与生物量之间呈“Ｖ”型变化规律，随着退化程度增加，物种丰富度与生产力的关系由显著正相关转变为负相关。随着高寒草原的退化程度加剧，土壤湿度、土壤有机质、速效磷、硝态氮、速效钾的含量和土壤紧实度都减小。随着高寒草原植被的退化演替，土壤退化越来越严重，贫瘠化不断加剧，到重度退化阶段，旱生沙生植物出现，呈现沙化初始景观。

Grazing is significant factor impacting the ecological processes of grassland ecosystems.This study was conducted to investigate the effects of natural grazing intensity on plant community and soil nutrients in alpine meadow.Using comparative experiments,research was initiated under different grazing intensities to provide a theoretical basis for defining the reasonable stocking rate of alpine meadow.Our results showed that: Both above-ground biomass and species richness of plant community were the highest in fencing than that in light and moderate grazing,and the least in heavy grazing treatment;Shannon-Wiener diversity index was not significantly different among fencing,light and moderate grazing;the above-ground biomass and cover of palatable herbages(grasses and sedges) was reduced with grazing intensity increasing,while the forbs in heavy grazing treatment had higher above-ground biomass than that in fencing,light and moderate grazing;over three growing stages,soil moisture decreased with grazing intensity enhancing in May,but increased in July and September;the soil bulk density in moderate grazing was significantly lower than that in other three grazing treatment( P <0.05);the pH value was the highest(pH 7.31) in heavy grazing and was not significantly different among fencing,light and moderate grazing treatment;soil organic carbon was reduced with increasing grazing intensity in plant growing stages;soil total nitrogen was not significant different among light,moderate and heavy grazing treatment.However,soil ammonium-N and nitrate-N increased along the increasing of grazing intensities over the whole plant growing stages;soil available phosphorus shared the same trend as total phosphorus that they had the highest value under moderate grazing.Our result suggested that the moderate grazing was effective way to protect biodiversity and improve grassland productivity,while fencing is beneficial for recovering of the degraded alpine meadow.

放牧作为最主要的生物干扰因子之一,影响着草地生态系统植被和土壤的生态进程。在自然放牧条件下,通过不同放牧强度的比较试验,对高寒草甸土壤营养成分及地上群落特征进行分析,为制定合理的放牧强度提供理论依据。结果表明:随着放牧强度加大,地上总生物量、物种丰富度在封育样地最高,在重牧样地最低,而封育、轻牧、中牧样地香浓-威纳多样性指数并没有显著的差异;禾草和莎草的地上生物量和总盖度在中牧条件下最高。与轻牧、中牧和封育样地相比,重牧样地的杂草有较高的地上生物量和总盖度;5月份土壤含水量随放牧强度增加而减少,7月份、9月份则相反;封育、轻牧、重牧样地的土壤容重显著低于中牧样地( P P <0.05);土壤的全氮含量在各放牧样地里并没有显著变化,而土壤氨态氮、硝态氮则在植物整个生长季节随着放牧强度的加大而增加;在整个生长季节里全磷含量最大值都出现在中牧样地里,速效磷含量表现出了和全磷一致的结果。因此,适度放牧是保护生物多样性,维持土壤养分以及提高草地生产力的有效途径;当高寒草甸由于退化导致生物量锐减,生物多样性丧失等严重后果时,围栏可以作为有效的恢复手段。

青藏高原由于受地理位置和气候条件的影响,大气、水源、土壤、草原、生物等保持着原生的洁净状态,是发展生态畜牧业的理想之地,高寒草地也是当地牧民赖以生存和世代经营的基础.结合放牧对青藏高原高寒草地的影响,从放牧生态系统的“结构—需求—供给”角度分析青藏高原高寒草地的可持续利用,探索青藏高原高寒草地放牧生态系统可持续发展的对策.

Human activity has adversely affected global carbon(C) and nitrogen(N), and contributed to an alteration of climate that will generate discernible feedbacks to all organisms and ecosystems on earth. The purpose of this study was to provide the basis of degrading mechanisms in alpine meadow research and understanding global C reserves and quantifying the pools and changing of soil carbon under grazing intensity. The combined methods of field survey and experiment analysis were applied to detect the influence of biomass and soil carbon characteristics under different grazing intensity: enclosure (EN), light grazing (LG), moderate grazing (MG), heavy grazing(HG) and control (CK)on an alpine meadow. The experiment plots were located in the Yushu Longbao alpine meadow. The results showed that aboveground biomass and underground biomass of grassland were maximum in EN treatment. With the grazing intensity increasing, the aboveground biomass and underground biomass decreased. The soil moisture in EN and LG treatments were significantly higher( P ＜0.05) than the other treatments which influenced by grazing disturbance. In the soil profile, the soil moisture decreased with soil depth increase in all treatments. Trampling of grazed not only influenced soil moisture but also impacted soil bulk density, the soil bulk density increased with the grazing intensity increasing. The soil organic carbon(SOC) and total nitrogen were also influenced by grazing, the total nitrogen decreased in the following order: LG＞EN＞MG＞CK＞HG whereas the SOC decreased in the following order LG＞EN＞MG＞HG＞CK. Optium trampling of grazing increased soil bulk density, however, but the effects on meadow vegetation and soil structure of high grazing intensity were not benefical for sustainable development of grassland ecosystem.

为了揭示高寒草甸生态系统在放牧扰动下的植被和土壤特征变化,通过野外样地调查和室内分析法研究和探讨围栏封育(EN)、轻度放牧(LG)、中度放牧(MG)、重度放牧(HG)、对照区(CK)几种不同放牧强度对草地生物量和土壤碳特征的影响,为高寒草甸的退化研究提供依据。结果表明,封育区地上生物量和地下生物量最高,随着放牧强度的增加,草地地上生物量和地下生物量均呈减少趋势;放牧干扰对高寒草甸土壤湿度也产生影响,其中封育区和轻牧区土壤湿度显著高于其他处理( P ＜0.05);在土壤剖面上,随着土层深度的增加土壤湿度呈明显降低趋势;放牧的践踏作用不仅影响土壤湿度,而且随着放牧强度的增加土壤容重增加;土壤全氮和土壤有机碳也对放牧有一定的响应,土壤全氮表现为LG＞EN＞MG＞CK＞HG,土壤有机碳从高到底为LG＞EN＞MG＞HG＞CK。草地受到放牧干扰时,适度的践踏干扰将提高草地生产力和碳固存,但是高强度的放牧对草地植被和土壤结构的干扰作用不利于草地生态系统的可持续发展。

Changes in the growth and nutrition content of cereals (spring wheat, oats and rye) under simulated rotational grazing utilization (SG) were studied in the Yellow River irrigation area. The results showed that under SG the forage yields of oats were 38.8% and 9.9% more than that of rye and spring wheat respectively. The total above-ground yields (grain and straw) of spring wheat and rye when used as grain production (GP, traditional utilization method) were 37.5% and 35.0% higher than when they were used as SG, while there was no significant difference in rye yields across the two utilizations. Crude protein yields of the three small grain crops were significantly higher under SG than GP. Crude fat contents of spring wheat and rye were higher under SG than GP, but crude fat yields of oats were lower under SG. Compared with GP, crude fiber contents of the three small grain crops under SG decreased by 42.9%, 53.0% and 21.9% respectively. Grazing resulted in an increase of water soluble carbohydrate contents and lower NDF, ADF and crude fiber contents when compared with GP. On the whole, the three small grain crops have higher feed evaluation scores when they were used as SG and the score of rye was highest.

优质饲草生产是区域草地农业系统稳定的关键,引黄灌区存在季节性饲草亏缺。小麦、燕麦和黑麦等小谷物在引黄灌区有悠久的种植历史,具有生长快、耐刈割和再生能力强的特点,春季直到初夏可以放牧或刈割鲜草,也可调制干草冷季饲用,是潜在的饲草作物。在景泰引黄灌区模拟家畜轮牧小麦、燕麦和黑麦3种小谷物,比较其饲用价值,以期为利用现有作物资源发展动物生产、改革和完善农业系统提供科学依据。结果表明,在景泰引黄灌区模拟家畜轮牧春小麦、燕麦和黑麦3种小谷物,燕麦产草量分别比黑麦和春小麦高38.8%和9.9%,当用作籽实生产时春小麦和燕麦地上部分总生物量分别高于模拟放牧37.5%和35.0%,黑麦差异不显著。轮牧利用的3种小谷物粗蛋白产量显著高于籽实生产。春小麦和黑麦的粗脂肪含量在模拟轮牧下明显高于用于籽实生产,但轮牧下燕麦粗脂肪产量低于籽实生产。轮牧利用后小谷物的粗纤维含量分别下降42.9%,53.0%和21.9%。轮牧后小谷物可溶性碳水化合物含量逐渐增加,而籽实生产的春小麦和黑麦可溶性碳水化合物含量先增加后下降。轮牧下3种小谷物NDF、ADF和纤维素含量低于其用于籽实生产。定量评价,小谷物轮牧利用比籽实生产更具饲用价值,而燕麦的饲用价值高于其他两种作物。

Grazing is the basic measure of land management both at home and abroad,and the grazing land covers more than a half of the global terrestrial sphere. Restrained by the traditional agrarian culture,there are many misunderstandings of grazing management system in China and it was regarded as a main cause for ecological deterioration,poverty and cultural retardation in pastoral areas so prohibition of grazing was a popular phenomenon. Actually,the current problems of China’s grassland are not originated in grazing itself,but the misconception and deficiencies in grazing management,which breaks up the relationships among human beings,grassland and livestock. Historical evidences have witnessed the great contribution made by grazing to mankind. With technological and social development grazing has experienced three stages: the primary nomadic,the transformation grazing and the modern grazing,and some Western countries have completed the modern transformation of grazing system in the 1930s. The core of modernization of grazing model is the rotational grazing based on a system unit of inhabitants,grassland and livestock. The rotational grazing is an open agricultural technical system with various sub-models to adapt to various agricultural systems and to meet the requirements of ecology and production,so it is significant progress of grassland grazing management. To secure the dual ecological and the economic benefits of grassland ecosystem,China’s animal husbandry should accelerate its modern transformation in terms of grazing and grassland management. It is the necessary approach to modernize its animal husbandry as well as to build up an essence in its modern agriculture.

放牧是国内外普遍运用的土地管理的基本手段,至今全球陆地大约半数以上处于放牧管理之下。但受传统农耕文化的影响,我国当前对放牧管理系统存在很多误解,尤其是把草原的生态恶化、牧区贫困、文化落后都归罪于草原放牧,导致禁牧盛行。从放牧的基本内涵看,当前我国草原所面临的问题,不在放牧本身,而是对放牧认识的不足和放牧管理的缺陷,割裂了人居-草地-畜群之间的联系。从历史角度看,放牧做出了巨大贡献。而随着社会和科技的进步,放牧历经原始游牧期、放牧转型期与放牧现代化时期三阶段。西方发达国家在20世纪30年代就实现了放牧的现代化转型。畜牧业现代化的核心是以人居-草地-畜群放牧系统单元为内核的划区轮牧。划区轮牧是一种开放的农业技术体系,具有多种方式,适应于不同的农业系统,可兼顾生态与生产的需求,是草地放牧管理的重大进步。为了实现草原生态系统的生态和经济双重效应,我国畜牧业应该尽快实现草原管理和放牧的现代化转型。这是我国草地畜牧业现代化的必经之路,也是现代农业的必要内涵。

Alpine grassland is widely distributed in Northern Tibet. Stipa purpurea alpine grassland is one of the most important and representative meadow types in this area. In recent years, due to global warming and human activities such as overgrazing or excessive reclamation, the alpine grassland in Northern Tibet has undergone an accelerated and large-scale degradation. The grassland′s productivity and biological diversity have decreased significantly and locally, this has also become a great obstacle to sustainable social, economic and ecological development. To investigate community characteristics and α diversity of Stipa purpurea alpine grassland under different grazing intensity in Northern Tibet is critical not only to the understanding of local degradation mechanisms, but also to the establishment of rational grassland management procedures, as required for continued healthy and sustainable development of alpine grassland.In our study, based on a grazing experiment in Northern Tibet grassland ecosystem, the community characteristics of Stipa purpurea alpine grassland under different grazing intensity were investigated. The research was conducted at the grazing experimental site of Anduo County, Naqu, Tibet Autonomous Region, at an average elevation over 4,500 m above sea level. The experiment included four different stocking rates: no grazing (0 head/hm2, CK), light grazing (2.395 head/hm2, LG), moderate grazing (3.593 head/hm2, MG) and heavy grazing (5.988 head/hm2, HG). Based on the method of community investigation, community structure characteristics, such as species height, coverage and density were recorded. Aboveground biomass within areas of 0.5 m×0.5 m quadrat was also measured during the grass vigorous growth period. The species important value and summed dominance ratio were calculated by combining relative coverage, relative frequency and relative height. The species important value and summed dominance ratio were selected as comprehensive evaluation index of the importance of the species. The species diversity was measured using the Shannon-Wiener index and Pielou evenness index.The results showed that, with increasing grazing intensity, the above-ground biomass and the total coverage of plant communities followed a decreasing trend. Compared with the no grazing and light grazing treatments, the above-ground biomass and total coverage in the heavy grazing treatment were significantly lower. The important value of Stipa purpurea and other species was reduced gradually with increasing grazing intensity. Sedges such as Carex moorcroftii and other forbs, which the local livestock was rather avoiding, and also poisonous grasses were observed increased. The Shannon-Wiener index and Pielou evenness index changed according to the same pattern: MG﹥LG﹥HG﹥CK. The species diversity index of alpine grassland in this area reached the highest level under moderate grazing intensity. However, when the grazing intensity continued to increase beyond that level, the indices would decline rapidly.Comprehensive analysis indicated that the grassland had not only the highest diversity index under moderate grazing intensity, but could also resist a certain carrying capacity and prevent grassland degradation. Moderate grazing should be the most reasonable management strategy in Stipa purpurea alpine grassland. However, if grazing intensity continues to increase, the Stipa purpurea grassland type in this area would be transformed into a Carex moorcroftii, Herbarum variorum grassland community, which was clearly found to be of lesser economic and ecological value under the observed conditions.

基于放牧试验，研究了不同放牧强度下藏北地区紫花针茅(Stipa purpurea)高寒草原植物群落特征的变化规律。结果表明，随着放牧强度的增强，植物群落盖度、地上生物量均呈现显著降低的趋势；紫花针茅等禾草类植物的重要值逐渐降低，莎草类中青藏苔草(Carex moorcroftii)、牲畜不喜食的杂类草及有毒有害植物均有增加的趋势；如果持续过度放牧，植物群落表现出由紫花针茅等禾草为建群种的草地型向青藏苔草(Carex moorcroftii)、杂类草(Herbarum variarum)草地型过度的趋势；在中度放牧强度下，紫花针茅高寒草原α物种多样性达到最高水平，而继续增强放牧强度，则造成各项指标的迅速降低。

在藏北高原高寒草地样带上对４０个围栏内草地群落物种多样性和地上生物量进行测定，探讨了生长季降水对高寒草地生物量和物种多样性分布格局的影响以及地上生物量－物种多样性之间的关系模式。结果表明，降水格局显著地影响藏北高原内部高寒草地群落物种丰富度、多样性和均匀度，群落结构特征与初级生产力关系密切；藏北地区高寒草地地上生物量、物种丰富度、Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ指数和Ｐｉｅｌｏｕ均匀度指数随生长季累积降水呈指数增加趋势；在高寒草地群落物种丰富度－生产力关系研究中单峰模式的判别系数 R ２ （０．７５４）略高于线性回归模型（０．７４３）。沿藏北高原样带高寒草地物种丰富度随地上生物量单调递增，单峰模式的单调递减区间并未出现；然而单峰模型预示着在地上生物量高于１２１．１７ｇ／ｍ ２ 的高寒草地群落物种丰富度可能随生物量单调递减，从而使物种丰富度－地上生物量表现为较为标准的单峰模式；Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ多样性指数和Ｐｉｅｌｏｕ均匀度指数与地上生物量也均呈单峰模式，但其单调递减区间窄于单调递增区间，峰值分别对应的草地群落地上生物量为７１．９０和６０．９０ｇ／ｍ ２ 。

The impact of different grazing intensity, including enclosure (EN), light grazing (LG), moderate grazing (MG), heavy grazing (HG), free grazing (FG), on soil moisture was studied by using paired T test method in Longbao on Tibetan Plateau. The results showed that the significant level of impact on soil was increased with the increasing of grazing intensity. The difference of soil moisture between EN and LG, EN and MG were not significant in all soil layers; with increasing of depth, differences between HG and LG, HG and MG were decreased; the impacts of FG and HG treatments were the most significant. The order of treatment impact from soil surface to 50 cm was LG>GU, MG>GU, HG>FG, EN>FG and EN>HG, LG>HG. The FG and HG enhanced evapotranspiration, reduced soil moisture, and accelerated the wetland degeneration. Proper grazing management was critical to reduce evapotranspiration and degeneration.

在青藏高原隆宝滩高寒沼泽湿地进行不同放牧强度试验，应用统计学成对数据的t检验方法，定性研究围栏封育（EN）、轻度放牧（LG）、中度放牧（MG）、重度放牧（HG）、自由放牧（GU）5种放牧处理对不同深度土壤湿度的影响差异。结果表明：随着牧压强度的增加，影响湿地土壤水分含量的显著性也增强。EN和LG、MG处理对土壤水分含量的影响各个层次都不显著；HG对LG和MG的差异随深度的增加而减弱； GU和HG处理的影响最为显著，从土壤表层到50 cm深度，均表现为LG>GU、MG>GU、HG>GU、EN>GU和EN>HG、LG>HG。自由放牧和重度放牧加大土壤水分的蒸散，导致湿地土壤水分含量降低，加速湿地退化。合理有序的放牧活动是减少湿地土壤水分蒸发，减缓湿地退化的有效手段。

The impact of different grazing intensities on biodiversity and productivity of alpine grassland in Qinghai lake region was investigated using comparative sampling plots. The relationship between plant species diversity and productivity was explored through two years continuous grazing trials. Results showed that species richness and diversity index had a single peak change with the increase of grazing intensity. Species diversity was supreme under moderate grazing intensity. Species richness, diversity index and evenness index were minimum under high grazing intensity. Along with the increase of grazing intensity, community productivity decreased ( P P R 2 =0.910, P =0.027; R 2 =0.953, P =0.010). Therefore, grazing intensity is an important factor to affect species diversity and productivity.

通过2年的连续放牧试验,采用比较样地法,调查了不同放牧强度对环青海湖高寒草原生物多样性和生产力的影响,并探讨了植物物种多样性与草地生产力之间的关系,为高寒草原的合理利用提供基础资料。结果表明:物种丰富度和多样性指数随放牧强度的增加基本呈单峰变化,即在中度放牧下多样性最高,重度放牧下群落物种丰富度、多样性指数和均匀度指数均表现为最小;群落生产力随放牧强度的增加而降低( P P R 2 =0.910, P =20.027; R 2 =0.953, P =20.010),结合Simpson多样性指数和Alatalo均匀度指数才能更好地反映维持草地生产力水平的多样性指标。放牧强度是影响群落物种多样性和生产力及其关系的重要因素。

【Objective】To provide scientific basis for grazing and restoration of alpine degraded grassland in Tibet,this study investigated the effects of grazing intensity on vegetation community and soil physical and chemical properties.【Method】The experiment of yak grazing was carried out from June 2010 to August 2012 in beginning alpine meadow in Tibet.Three treatment,heavy grazing,moderate grazing and no grazing as control,were set to researched the effects of different grazing intensities on richness,homogeneous degree,biomass,coverage,density,and height of vegetation community and soil physicochemical properties.【Result】With the increase of grazing intensity,evenness and biomass of vegetation community increased while richness and total coverage decreased.The homogeneous degree index and the biomass of the ground or the underground is increased firstly then decreased.The coverage and height of alpine wormwood and purple flowers.grandis decreased while the density increased.The density and the hardness of soil in alpine meadow ecosystem in-creased along with the grazing intensity.Toal porosity of soil increased in layer of 0-10 cm,while it did not change significantly inlayers of 10-20 cm and 20-30 cm.The highest water content in soil was found in soil layer of 0-10 cm in moderate ( P ＞0.05).With the increase of grazing intensity,Soil organic matter,total nitrogen,available nitrogen,available phosphorus and pH significantly decreased ( P ＜0.05),the available K content in 0-10 cm and 10-20 cm soil decrease after the first increase,and the available phosphorus no significant changes in regularity.【Conclusion】Heavy grazing was the main reason for degradation of alpine meadow and change of soil physical and chemical properties.Fencing was the best way to recover vegetation of alpine meadow in short-term.Moderate grazing was beneficial to the increase of vegetation and improvement of soil physical and chemical properties.

【目的】研究放牧强度对高寒草甸植被群落和土壤理化性质的影响，为西藏高寒草甸科学放牧和退化草地生态系统的恢复提供科学依据。【方法】于2010-06-2012-08在西藏邦杰塘高寒草甸开展牦牛放牧控制试验，设置对照(零放牧)、适度放牧和重度放牧3个处理，研究不同放牧强度对植被群落丰富度、均匀度、生物量、盖度、密度、高度和土壤理化性质的影响。【结果】随放牧强度的增加，植被群落的丰富度和总盖度降低，均匀度指数和地上、地下生物量均先增大后减小；高山嵩草和紫花针茅的盖度和高度随放牧强度的增加而降低，密度增大。高寒草甸生态系统中土壤的体积质量和硬度随放牧强度的增加而增大；0～10 cm土层土壤总孔隙度随放牧强度的增加而增大，10～20和20～30 cm土层总孔隙度变化规律不明显；土壤含水量在0～10 cm土层以适度放牧区最高，但各处理间无显著差异（ P ＞0.05）；随放牧强度的增加，土壤有机质、全氮、速效氮含量以及pH均显著减小( P ＜0.05)，速效钾含量在0～10和10～20 cm土壤中先增加后减少，速效磷变化无明显的规律性。【结论】重度放牧是高寒草甸植被退化、土壤理化性质改变的主要因素。围栏封育可作为高寒草地植被短期恢复的最佳方式。适度放牧有利于植被群落的增多和改善土壤理化性质。

对甘肃省天祝县4个退化梯度高寒草甸的植被特征和土壤养分特征进行了研究。结果表明,随着退化程度的加剧,草地地上生物量、植被高度、盖度、土壤有机碳、全氮、全磷和土壤含水量都显著降低(P0.05),重度退化草地土壤容重显著升高(P0.05)。草地植物群落发生明显退化演替,矮生嵩草(Kobresia humilis)、线叶嵩草(K.capillifolia)和垂穗披碱草(Elymus nutans)的优势种地位被珠芽蓼(Polygonum viviparum)所替代,物种数由未退化样地的19种减少到重度退化样地的7种,退化指示类毒杂草生物量比例逐渐增加,由9.77%上升到62.93%。草地的退化程度会影响草地的植被特征和土壤养分特征,应根据不同退化阶段采取不同的恢复治理策略。

放牧是草地生态系统最重要的管理方式之一,草地土壤-植物-家畜互作对放牧的响应模式始终是放牧生态学研究的前沿和热点。青藏高原的草地主要通过放牧管理,但较少有控制性的放牧试验,尤其鲜有生产性的划区轮牧试验。为此,以甘肃省玛曲县高寒草甸一藏羊划区轮牧(SDSR)系统和连续放牧(SLC)系统为研究对象,2010-2012年对土壤理化性质、草地植被特征、家畜生产力及放牧行为等进行了3年连续监测,分析了高寒草甸放牧系统土壤-草地-家畜的动态特征及其互作关系。主要研究结果如下：1)藏羊暖季平均月增重3.5-4.5kg/头,牧草现存量2.2-3.8t/ha,两者均从10月开始逐渐下降。较低的放牧率下(24羊月/ha),放牧制度(连续放牧和自由放牧)对藏羊个体活体增重、单位草地面积羊群活体增重和牧后牧草留存量没有显著影响(P0.05)。轮牧藏羊个体活体增重和牧后牧草留存量随着放牧率(24、36和48羊月/ha)的增大而降低,单位草地面积羊群活体增重则随放牧率增加。2010、2011、2012年适宜牧压指数分别为27.6、24.4和23.8AUD/tDM,三年平均适宜牧压指数为25.2AUD/tDM (animal unit·day, AUD),当三年和三年平均最大牧草现存量分别为5.01、4.87、4.96和4.95t/ha时,适宜牧压指数分别为1255.1、1078.7、1072.2和1131.8羊单位·天/ha。2)7月到12月,藏羊连续放牧的采食速度、觅食速度和咀嚼(食团)速度随放牧月份延长而降低,每步采食口数呈相反趋势。每食团咀嚼口数和两食团间隔时间随着放牧时间延长而增加提高到一定程度后保持稳定。反刍/采食时间比、采食速度、觅食速度、两食团间隔时间及每食团咀嚼口数均与牧草现存量和日均温正相关,每步采食口数和食团咀嚼速度则负相关。觅食速度、每步采食口数、咀嚼速度、每食团咀嚼口数和两食团间隔时间随日均温的变化幅度随着藏羊初始体重的增加而降低,每步采食口数、每食团咀嚼口数和两食团间隔时间随牧草现存量的变化幅度随着藏羊初始体重的增大而降低,即藏羊体型愈大,其放牧行为对温度或牧草量的敏感性愈弱。3)围封导致0-10cm表层土壤中有机碳(SOC)、全氮(TN)含量显著增加(P0.05),但降低土壤全磷(TP)的含量(P0.05),对10-20、20-30和30-40cm土壤中SOC、TN和TP含量影响不显著(P0.05)；连续放牧和围封处理下同一土层土壤容重和含水量差异不显著(P0.05)。4)与连续放牧相比,围封提高了高寒草甸常见物种的种群密度、植物密度和群落地上与地下生物量(尤其是0-10cm土层,P0.05),但对植物物种多样性影响不显著(P0.05)；增加了平均株高大于40cm物种牧草的生物量(P0.05),降低20-40cm物种的生物量(P0.05),而高度低于20cm物种的变化不显著(P0.05)。说明围封能够改变高寒草甸植物群落结构。5)凋落物累积量随放牧压增加而下降(P0.001)。凋落物分解速率随其碳和木质素含量及木质素/N的增加而降低。分解环境解释了凋落物“原地”分解速率差异的87%,而凋落物自身质量则可解释7%,而N的降解速率则可以分别被分解环境和自身质量解释2%和71%,说明放牧导致凋落物的分解环境和自身质量的差异对凋落物物质和所含元素分解影响不同。

摘　要： 甘南地处青藏高原东北部,畜牧业是本地的主导产业,甘南牦牛是当地重要的特色畜种,大力发展甘南牦牛产业对当地畜牧业经济发展及农牧民增收具有重要作用。在调查甘南牦牛产业化发展的基础上,分析了甘南牦牛产业化发展中存在的问题,并提出了相应对策。

A study has been undertaken to investigate changes in organic carbon and nitrogen storage under different grazing regimes in the alpine meadow ecosystem of the eastern margin of the Qinghai-Tibetan plateau. Organic carbon and nitrogen storage was measured in above-ground biomass, litter, roots and the 0-80 cm soil layer (divided 8 layers, and each layer was 10 cm) at four sites that represent different grazing management regions: non-grazing (NG), grazing rest during the growing stage (RG), traditional grazing (TG) and continuous grazing (CG). The results indicated that organic carbon and nitrogen in the 0-80 cm soil layer, roots, above-ground tissue and litter were significantly higher in NG, RG and TG than in CG. In general, the proportion of organic carbon in the alpine meadow ecosystem was the largest in soils (88.859%-98.242%), followed by roots (1.563%-8.742%), vegetation (0.172%-1.430%) and litter (0.022%-0.969%); similarly, the proportion of nitrogen was the largest in soils (97.331%-99.633%), followed by roots (0.316%-2.071%), vegetation (0.047%-0.442%) and litter (0.003%-0.157%). There were obvious differences in the vertical distributions of soil organic carbon and nitrogen storage under the four grazing regimes, with these differences mainly affecting the 0-40 cm layer and with no significant effect on deeper layers. Organic carbon and nitrogen storage was mainly distributed in the 0-40 cm layer, with grazing tending to move this storage to deeper layers. NG, RG and TG significantly increased storage in the alpine meadow ecosystem, while CG significantly reduced storage and was associated with a loss of carbon and nitrogen. Non-grazing and seasonal rest grazing can thus contribute to achieving carbon and nitrogen sinks on the eastern margin of the Qinghai-Tibetan Plateau and are important grazing management regimes for this and similar areas.

为探讨不同放牧管理模式高寒草甸生态系统有机碳、氮储量特征的变化,对青藏高原东缘禁牧(NG)、全生长季休牧(RG)、传统放牧(TG)和连续放牧(CG)4种放牧管理模式高寒草甸地上植被、地表凋落物、根系和土壤有机碳、氮储量进行测定和分析。结果表明,1)NG、RG和TG较CG显著提高了土壤、根系、植被和凋落物有机碳、氮储量。2)高寒草甸生态系统中,土壤有机碳储量所占比例最大(88.859%~98.242%),其次为根系(1.563%~8.742%),再次为植被(0.172%~1.430%),最小为凋落物(0.022%~0.969%);氮储量所占比例最大的是土壤(97.331%~99.633%),其次为根系(0.316%~2.071%),再次为植被(0.047%~0.442%),凋落物最小(0.003%~0.157%)。3)不同放牧管理模式土壤有机碳、氮储量具有明显的垂直分布特征,随土壤深度的增加土壤有机碳、氮储量明显降低。为期4年不同放牧模式仅对0~40 cm土层土壤有机碳、氮储量有影响。4)土壤有机碳、氮储量主要分布在0~40 cm土层,同时,放牧有使有机碳、氮向深层转移的趋势。5)NG、RG和TG显著提高了高寒草甸生态系统总有机碳、氮储量,而CG显著降低了总有机碳、氮储量,导致有机碳、氮的流失。禁牧和季节性休牧能有效增加青藏高原东缘高寒草甸生态系统有机碳、氮储量,实现碳、氮增汇的目的,是该区和类似区域草地放牧管理的重要模式。

A series of comparative sampling plots were selected to study the effects of different grazing intensities on the biodiversity and productivity of a  Leymus chinensis  meadow steppe in Inner Mongolia. It was shown that with the increase of grazing intensity, α diversity index decreased after an initial increase, and had the highest value in light grazing areas, which supported the ‘medium disturbance theory’, while β diversity index had an increasing trend. Lesser similarity of plant species was observed under different grazing intensities. There was a significant linear relationship between aboveground net primary productivity (ANPP) and Alatalo evenness index ( P

采用比较样地法研究了不同放牧强度对羊草草甸草原群落多样性和生产力的影响。结果表明： α 多样性指数随放牧强度的增加表现为先增加后降低的趋势，其值在轻度放牧区最大，支持了“中度干扰理论”； β 多样性指数随放牧强度的增加而变大；不同放牧强度的草地植物种类相似性变差、草地地上净初级生产力与Alatalo均匀度指数具有显著的线性相关性（ P P >0.05)；不放牧不能持续维持草地的健康状况，但健康的草地状况可以有效地缓冲放牧和气候干扰，并能够维持较高的草地生产力和生物多样性。

采用单因素重复设计探讨锡林郭 勒草甸草原不同草地利用强度下天然牧草的响应。结果表明:不同利用强度对粗蛋白质产生影响主要发生在对照和重度利用;随利用强度增加,粗纤维含量降低,粗 灰分含量上升,粗脂肪呈先增加后降低趋势;含水量以对照和轻度利用处理较高,中度利用和重度利用处理较低。

 Effects of grazing intensity disturbance on nutrition characteristics of dominant species Kobresia pygmaea and Stipa purpurea in Kobresia meadow of the QinghaiTibet plateau were studied. The results showed that there were differences on responses of plant nutrients to different grazing intensity between these two dominant plants. Grazing had the benefit of calcium and phosphorus absorption for the plants. Heavy grazing significantly (P＜0.05) increased calcium and phosphorus absorption of K.pygmaea compared to moderate grazing and control. The changes between the moderate grazing and control were not significant (P＞0.05). The calcium content of S.purpurea followed a trend of heavy grazing>moderate grazing>control, while the phosphorus content increased firstly and then decreased with the increasing grazing intensity. It was also found that grazing reduced significantly (P＜0.05) the forage crude fiber content and increased contents of the forage crude protein and crude fat. Grazing livestocks promoted the compensatory growth of the plants, accelerated grasssoil nitrogen cycles, increased pasture nitrogen uptake and increased the forage crude protein content, so that grazing improved the forage quality in Kobresia meadow of the QinghaiTibet plateau.

以青藏高原高山嵩草草甸优势植物高山嵩草（Kobresia pygmaea）和紫花针茅（Stipa purpurea）为对象，研究不同放牧强度对其营养成分变化的影响。结果表明，不同优势种对放牧响应不同，放牧有利于高山嵩草草甸优势植物钙和磷的吸收，高山嵩草重度放牧下钙与磷含量显著高于适度放牧与对照(零放牧)（P＜0.05），且适度放牧与对照差异不显著（P＞0.05）。紫花针茅钙含量依次为重度放牧＞适度放牧＞对照，磷含量随着放牧强度的增加，出现先升高后下降的变化趋势；放牧家畜的啃食促进了植物的补偿性生长，放牧粗纤维含量显著低于对照（P＜0.05）；同时放牧增加了高山嵩草草甸优势植物粗脂肪和粗蛋白含量。放牧家畜对草地的影响，加速了牧草-土壤氮循环，促进了牧草对土壤氮的吸收，进而增加了牧草的粗蛋白含量，改善了牧草品质。

在小叶章草甸,以本地黄牛为试验动物,连续五年进行重度、中度和轻度放牧试验,以不放牧为对照。观测不同放牧强度对始牧期(5月15日)小叶章种群特征及营养成分的影响,并分析其变化规律。结果表明:随放牧强度增加,小叶章的高度、盖度和干草产量显著降低(P0.05);与对照相比,重牧、中牧和轻牧的小叶章高度四年平均分别降低了22.95%、16.03%和7.54%,盖度分别降低了20.38%、12.25%和5.53%;干草产量分别降低47.35%、44.29%和35.81%;而小叶章密度在重牧区增加了3.02%,中牧和轻牧分别降低30.53%和36.34%。放牧年限对小叶章的株高和干草产量的影响不明显,但盖度和密度随放牧年限增加呈下降趋势。随着放牧年限的增加,小叶章的粗灰分、中性洗涤纤维和酸性洗涤纤维含量呈上升的趋势,粗蛋白和粗脂肪的含量呈下降的趋势。