Analysis of the Species Dominance & Dominant on the Karst Mountain Grassland Plant Community

[Objective] The aim was to study the species,quantity and community traits of dominant plant in karst mountain grassland plant community so as to provide support for the vegetation restoration in karst mountain grassland.[Method] Standard plot sites investigation method was used study the quantity traits of different plant communities of different altitudes and slopes.[Result] The IV SDR4 were the highest in the all plot sites of plant community on the kasrt mountain grassland,but the IV SDR4 were showed a trend of decreasing with the increasing of the altitude.The dominant quantity was increasing with the altitude upward,so the altitude was the mostly factor for plant community construction.[Conclusion] Altitude was the main factor to influence the community structure of plant.

Survey Techniques of Grassland Plant Resources

Based on years of practice and survey methods of grassland resources at home and abroad, the technical problems that may occur in the survey process are analyzed, the preparatory work before survey, specific content of field survey and sample processing and analysis and specimen preparation are elaborated. Moreover, the announcements of major technical methods are also described in details.

History,Current Status and Trends of the Investigation for Grassland Plant Resources at Home and Abroad

The existing main problems in the investigation for grassland plant resources are found out by systematically analyzing the history, current status and de- velopment trends of the investigation for grassland plant resources at home and abroad. The paper cxploratively points out that the investigation for grassland plant resources should focus on integrated muhidisciplinary research in the future, ultimately realizing highly efficient utilization and sharing of information in grassland plant resources.

Effects of grazing on carbon and nitrogen in plants and soils in a semiarid desert grassland,China

Grazing can modulate the feedback between vegetation and soil nutrient dynamics（carbon and nitrogen）,altering the cycles of these elements in grassland ecosystems.For clarifying the impact of grazing on the C and N in plants and soils in the desert grassland of Ningxia,China,we examined the plant biomass,SOC（soil organic carbon）,total soil N and stable isotope signatures of plants and soils from both the grazed and ungrazed sites.Significantly lower aboveground biomass,root biomass,litter biomass and vegetation coverage were found in the grazed site compared to the ungrazed site,with decreases of 42.0%,16.2%,59.4% and 30.0%,respectively.The effects of grazing on plant carbon,nitrogen,？15N and ？13C values were uniform among species.The levels of plant carbon and nitrogen in grasses were greater than those in the forbs（except for the carbon of Cynanchum komarovii and Euphorbia esula）.Root 15 N and 13 C values increased with grazing,while the responses of root carbon and nitrogen to grazing showed no consistent patterns.Root 15 N and 13 C were increased by 79.0% and 22.4% in the grazed site compared to the ungrazed site,respectively.The values of SOC and total N were significantly lower in the grazed than in the ungrazed sites for all sampling depths（0–10 and 10–20 cm）,and values of SOC and total N at the surface（0–10 cm） were lower than those in the deeper soils（10–20 cm）.Soil ？15N values were not affected by grazing at any sampling depth,whereas soil ？13C values were significantly affected by grazing and increased by 19.3% and 8.6% in the soils at 0–10 and 10–20 cm,respectively.The soil ？13C values（–8.3‰ to –6.7‰） were higher than those for roots（–20.2‰ to –15.6‰） and plant tissues（–27.9‰ to –13.3‰）.Our study suggests that grazing could greatly affect soil organic carbon and nitrogen in contrast to ungrazed grassland and that grazing appears to exert a negative effect on soil carbon and nitrogen in desert grassland.

Effects of Nitrogen Application on Plant Growth and Soil Inorganic Nitrogen Content in Alpine Grasslands

In order to further determine the nitrogen demand of plants in alpine grassland ecosystem,different nitrogen levels( 0,1,2,4,8,16,24,32 g/m2)were designed through field control to study the responses of different plant functional groups( grass,sedge and weed) to different nitrogen application levels in the aboveground biomass and soil inorganic nitrogen( nitrate nitrogen and ammonium nitrogen).The results showed that with the increase of nitrogen application rate,the aboveground biomass of different functional groups increased linearly,and the soil inorganic nitrogen content increased with the increase of nitrogen application rate,among which treatments N16,N24 and N32 increased significantly in soil nitrate nitrogen content( P < 0.05).The results showed that the optimal nitrogen content in alpine grasslands was 8 g/m^2,which could not only promote plant growth,but also effectively control soil nitrate nitrogen content.

Effects of converting natural grasslands into planted grasslands on ecosystem respiration： a case study in Inner Mongolia, China

With increasingly intensifying degradation of natural grasslands and rapidly increasing demand of high quality forages, natural grasslands in China have been converted into planted grasslands at an unprecedented rate and the magnitude of the conversion in Inner Mongolia is among the national highest where the areal extent of planted grasslands ranks the second in China. Such land-use changes（i.e., converting natural grasslands into planted grasslands） can significantly affect carbon stocks and carbon emissions in grassland ecosystems. In this study, we analyzed the effects of converting natural grasslands into planted grasslands（including Medicago sativa, Elymus cylindricus, and M. sativa＋E. cylindricus） on ecosystem respiration（F（eco）） in Inner Mongolia of China. Diurnal F（eco） and its components（i.e., total soil respiration（F（ts））, soil heterotrophic respiration（F（sh）） and vegetation autotrophic respiration（F（va））） were measured in 2012（27 July to 5 August） and 2013（18 July to 25 July） in the natural and planted grasslands. Meteorological data, aboveground vegetation data and soil data were simultaneously collected to analyze the relationships between respiration fluxes and environmental factors in those grasslands. In 2012, the daily mean F（eco） in the M. sativa grassland was higher than that in the natural grassland, and the daily mean F（va） was higher in all planted grasslands（i.e., M. sativa, E. cylindricus, and M. sativa＋E. cylindricus） than in the natural grassland. In contrast, the daily mean F（ts） and F（sh） were lower in all planted grasslands than in the natural grassland. In 2013, the daily mean F（eco）, F（ts） and F（va） in all planted grasslands were higher than those in the natural grassland, and the daily mean F（sh） in the M. sativa＋E. cylindricus grassland was higher than that in the natural grassland. The two-year experimental results suggested that the conversion of natural grasslands into planted grasslands can generally increase the F（eco） and the increase in F（eco） is more pronounced when the plantation becomes more mature. The results also indicated that F（sh） contributed more to F（eco） in the natural grassland whereas F（va） contributed more to F（eco） in the planted grasslands. The regression analyses show that climate factors（air temperature and relative humidity） and soil properties（soil organic matter, soil temperature, and soil moisture） strongly affected respiration fluxes in all grasslands. However, our observation period was admittedly too short. To fully understand the effects of such land-use changes（i.e., converting natural grasslands into planted grasslands） on respiration fluxes, longer-term observations are badly needed.

Effects of Grassland Caterpillars on Plant Community Structure of Alpine Kobresia Meadows and Soil Properties

[Objective] To investigate the relationship between the grassland caterpillar with different grades and the structure of alpine Kobresia meadow or soil feature. [Method] A total of 10 plots （20.00 m × 20.00 m） were chosen. In each plot, five smaller plots （5.00 m × 5.00 m） were randomly selected and six sample plots （0.25 m × 0.25 m） were then selected in each smaller plot. The biomass, vegetation height, grasslayer thickness, bare land area, soil moisture and total vegetation cover degree were determined. Data were analyzed statistically by Excel 2003 and SPSS 13.0 software. [ Result] There was a significant difference （P 〈 0.05） between the grassland caterpillars at different hazard grades and the structure of alpine Kobresia meadow or soil properties. [ Conclusion] With the increase of grassland caterpillar density, the plant community structure of alpine Kobresia meadows changes from sedge family-dominant community to the forbs-dominant community.

Winter Foraging Plants of Domestic Sheep in Hulunbeir Grassland

Winter food constitution and favorite level of domestic sheep were studied with the microhistological analysis technique of feces in Hulunbeir Grassland. some problems were inquired into, such as the quality state of local herbage resource, improvement of pasture, rational use of herbage, etc. The results showed that the staple food of domestic sheep in winter was Gramineae, which made up 73.3 percent of the total foraging species. Fabaceae was second, 11.6 per cent. Composite took third place, 7.4 per cent. The proportion of other species were very small.

Soil and Vegetation Seasonal Changes in the Grazing Andean Mountain Grasslands

Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna(Vicugna vicugna) and alpaca(Lama pacos). The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined: total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. Thegood soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.

Long-term effects of mowing on plasticity and allometry of Leymus chinensis in a temperate semi-arid grassland,China

Mowing is an important land management practice for natural semi-arid regions. A growing body of empirical evidence shows that different mowing regimes affect the functioning of grassland ecosystems. However, the responses of plant functional traits to long-term mowing and their allometric scaling under long-term mowing are poorly understood. For a better understanding of the effects of mowing on grassland ecosystems, we analyzed the allometric traits of leaves and stems of Leymus chinensis （Trin.） Tzvel., a dominant grass species in eastern Eurasian temperate grassland, at different mowing intensities （no clipping, clipping once every two years, once a year and twice a year）. Experiments were conducted on plots established over a decade ago in a typical steppe of Xilinhot, Inner Mongolia, China. Results showed that most of the functional traits of L. chinensis decreased with the increased mowing intensity. The responses of leaves and stems to long-term mowing were asymmetric, in which leaf traits were more stable than stem traits. Also significant allometric relationships were found among most of the plant functional traits under the four mowing treatments. Sensitive traits of L. chinensis （e.g. leaf length and stem length） were primary indicators associated with aboveground biomass decline under high mowing intensity. In conclusion, the allometric growth of different functional traits of L. chinensis varies with different long-term mowing practices, which is likely to be a strategy used by the plant to adapt to the mowing disturbances.

Phytodiversity and medicinal plant distribution in pasturelands of North Western Himalaya in relation to environmental gradients

This study aimed at elucidating phytodiversity of pasturelands of North-western Kashmir Himalayan biotic province in relation to various environmental gradients, with added focus on assessing distribution of important threatened medicinal plant taxa across surveyed pasturelands. A total of 16 sites that spanned across a broad altitudinal gradient(2502-4120 m) were selected. Phytosociological data like density, cover, frequency and abundance of vascular flora were collected and processed using gradient analysis. Soil moisture, nitrogen, organic carbon, acidity and electrical conductivity, altitude, degree of slope and human disturbance were recorded from each site. Analysis of species composition showed a total of 293 species of vascular plants, belonging to 192 genera and 64 families recorded from surveyed sites. Rank abundance exhibited that majority of species are locally rare and patchily distributed, with over 60% of species recording frequencies between 0%-20% and none showing frequencies more than 80%. Species richness showed significant variations and ranged from 20(Parihasmaidan) to 114(Nagbarren) for macro and 3.53±2.11(Thajwas) to 8.76± 1.01(Marsar) for micro-scale of measurement. The ShannonWiener(H') and Simpson's diversity(Ds) indices also varied greatly and were recorded highest(H'= 2.76 & Ds= 0.36) for Marsar and lowest(0.87 & 0.62) for Parihasmaidan. The diversity attributes suggested that pasturelands with lower species richness and diversity on macro-scale were not always species poor and less diverse on micro-measurement scale. The life form groupings highlighted the hemicryptophytic character of vegetation and species with highest importance value index were Sibbaldia cuneata(5.71), Rumex nepalensis(2.89), Juniperus wallichiana(2.88), Cynodon dactylon(2.83), Poa annua(2.49) and Sambucus wightiana(2.41). The results of canonical correspondence analysis showed that effect of altitude and anthropogenic disturbance was overriding and among various environmental factors, species distribution was mainly correlated with altitude along first canonical axis, while to second axis anthropogenic disturbances were important. Using generalized additive model, these variables also appeared as significant predictors for distribution of various threatened taxa. The findings of this study may thus help in evolving an appropriate strategy and an ecological management tool for long term conservation and management of these mountain ecosystems.

黄河源区高寒退化草地空间分布特征

为了解黄河源地区“黑土滩”退化草地的空间分布规律和分布的关键地形特征,利用2019年黄河源区玛沁县、河南县、泽库县遥感影像解译数据,结合实地调查,分析高寒“黑土滩”型退化草地空间分布特征。结果表明:黄河源区“黑土滩”型退化草地海拔为3500~4000m,且在海拔3700~3800m时退化最严重;从坡向分析来看,“黑土滩”型退化草地主要发生于阳坡、半阳坡,从坡度分析来看,“黑土滩”型退化草地主要发生于缓坡地和滩地。聚类分析发现研究区草地类型为阳坡极度退化草地、半阳坡重度退化草地、阳坡-滩地轻度退化草地、半阳坡轻度退化草地、湿地轻度退化草地、阴坡未退化草地等6类。随着退化程度的加剧,植被盖度、地上生物量减少;同一土层的全氮、全磷、碱解氮、速效磷、有机质含量在湿地轻度退化草地和阴坡轻度退化草地中最高,阳坡极度退化草地最低,且差异显著(P<0.05);丰富度指数、多样性指数、均匀度指数以及土壤速效钾含量在重度、轻度退化草地较高,湿地轻度退化草地显著最低。阳坡极度退化草地全钾含量、鼠害破坏率和鼠洞数最高,湿地轻度退化草地全钾含量最低,与阳坡极度退化草地差异显著(P<0.05);湿地轻度退化草地和阴坡轻度退化草地均无鼠类活动。

Response of Grassland Vegetation to Air Temperature and Precipitation in Minqin Desert Region

[ Objective] This paper aims to analyze response characteristics of desert grassland vegetation to climate change. [ Method] The responses of grassland vegetation in desert region to air temperature/precipitation changes were analyzed by phenological observations since 1974, observation data conceming vegetation samples and meteorological data during the same period. The changing trend significance was denoted by linear trend line and its regression significance. The interrelation between the two variables was indicated by correlation coefficients. Data were analyzed by the software SPSS 13.0. [Result] （1） The rising rate of annual average temperature in the Minqin desert area since 1961 was greater than both the global level and Ghina＇s level over the past century. （2） Desert plants＇ response to temperature changes were mainly displayed as the advance of spring phenology, the delay of autumn phenology and the extension of growing duration. Plants＇ main response to precipitation changes was that vegetation coverage and pure coverage were decreasing along with precipitation reducing. （3） Both the vegetation coverage and pure coverage mainly had a positive correlation with the annual precipitation. Plant density mostly had a positive correlation with the precipitation in September. （4） The impact of rising temperature on plant phenology in spring was greater than that in autumn. [ Conclusion] The effects of temperature changes on desert grassland plants were the advance of spring phenology, the delay of autumn phenology, the extension of growing season and longer plant growing period than that in other reports. The responses of desert grassland vegetation to precipitation changes were that both vegetation coverage and pure coverage were decreasing along with precipitation reducing, and plant density fluctuated along with precipitation change.

西藏高寒草原湿润度梯度下植物群落特征空间格局及其驱动因子

西藏高原是中国高寒生态系统类型和生物多样性均聚集的区域之一,其中以高寒典型草原和高寒草甸草原为主生态系统类型,但其系统活力、组织力和恢复力均较弱,容易受到全球气候变化的影响,表现出极强的脆弱性。目前青藏高原草地生态系统植物群落分布状况与其变化规律以及对各种环境因子的反应研究多集中于站点尺度或样带尺度,但研究结果尚有较大的不确定性。研究于西藏地区沿着不同的湿润度梯度选择14处高寒草原区样地,通过植物群落调查、土壤理化性质分析,探索草本植被群落空间格局对气候因子响应特征及其主要驱动因子,其结果为青藏高原天然草地保护和可持续利用提供基础科学数据支撑。结果表明:(1)研究区内依据湿润度分区可分为干旱区、微干区、微润区和湿润区4类;研究区1971—2021年的气候数据分析发现,北部的干旱程度在逐渐减轻,而南部在1991—2010阶段干旱化趋势逐渐加强,整个研究区的湿润度指数均在下降;(2)植物群落调查发现不同植物功能群的变化各有差异,莎草科地上生物量随湿润度增加而增加,杂类草地上生物量呈现单峰趋势,而其他植物功能群无明显规律;湿润度较高的微润区间植物群落的Shannon-Wiener指数、Simpson指数、丰富度指数、均匀度指数均高于其他湿润度区间;(3)土壤理化性质分析发现高湿润度区域的土壤含水量、全氮、硝态氮、铵态氮、速效磷含量均为最高;对各环境因子与植物群落特征指标进行相关性、主成分分析后构建结构方程模型,发现直接影响西藏高寒草原植物群落特征变化因子为湿润度,土壤含水量和土壤pH,且都表现为显著的负效应(P<0.05),同时湿润度对土壤含水量和土壤全量养分产生了显著的正向影响(P<0.05),进而影响着西藏高原高寒草原不同植物功能群的分布、多样性、地上生物量。

放牧、氮添加对荒漠草原植物和土壤碳氮的影响

为了探究放牧和氮添加对内蒙古荒漠草原植物—土壤碳、氮循环的影响,在禁牧(UG,0只羊单位·hm^(-2))和重度放牧(HG,1.74只羊单位·hm-2)样地进行氮添加处理,各处理水平为:对照(CK,0 g·m^(-2)·a^(-1))、低氮(LN,5 g·m^(-2)·a^(-1))、中氮(MN,10 g·m^(-2)·a^(-1))和高氮(HN,20 g·m^(-2)·a^(-1))。通过对短花针茅(Stipa breviflora)叶片和土壤全碳(Total carbon, TC)、全氮(Total nitrogen, TN)、稳定碳同位素(Stable carbon isotopes, δ13C)、稳定氮同位素(Stable nitrogen isotopes, δ15N)及土壤有机碳(Soil organic carbon, SOC)、速效氮(Available nitrogen, AN)的测定分析,结果表明:放牧显著增加土壤TC、TN和AN含量(P<0.05);放牧使短花针茅叶片δ13C,δ15N值显著减小(P<0.05);氮添加使短花针茅叶片δ15N值显著减小(P<0.05)。放牧和氮添加在一定程度上均加速了短花针茅和土壤的养分循环,同时氮添加对短花针茅的氮吸收及分馏效应有一定影响,对退化草地恢复起重要作用。

基于深度学习方法荒漠草原典型植物花朵计数

草原植物花朵计数可以帮助我们了解草原植物的生长状况、繁殖能力、群落结构等信息,通过人工计数方法获取草原上不同物种花朵丰度是一个费时费力的过程。本研究基于深度学习目标检测方法,在鄂尔多斯荒漠草原上10个样地和50个样方上开展检测模型训练、评估和应用。从YOLOv7的3个模型整体表现来看,YOLOv7-E6E的F1-sorce和mAP@0.5均可达到0.7以上,具有较高的识别精度。从YOLOv7的3个模型在5种花朵检测的表现来看,YOLOv7-X、YOLOv7-E6E模型在北芸香、蒙古韭、细叶韭的检测上mAP@0.5高于0.8,而3个模型中仅有YOLOv7-E6E在蒺藜、兔唇花的mAP@0.5超过0.6。从模型在50个样方的花朵计数应用来看,YOLOv7-E6E模型花朵计数的总体正确率为0.91,能满足这5种草原开花植物检测和计数的需要。综上所述,通过深度学习花朵快速计数可以提高样方尺度花期植物调查效率,但为满足大规模物种调查和计数的任务需求,仍需扩大样本量和不断改进模型结构,以提高模型植物花朵检测的整体性能。

祁连山国家公园不同类型草地植被及土壤特征研究

为掌握祁连山国家公园内不同草地类型植被及土壤特性的差异,对祁连山国家公园青海片区门源县的高寒荒漠、高寒草甸、高寒湿地和温性草原的植被特性、土壤理化性质和土壤微生物进行研究。结果表明:高寒草甸、高寒湿地以莎草科和禾本科植物为主,高寒荒漠以景天科植物为主;高寒草甸的植被盖度和地上生物量最高,分别为98.83%和348.67 g/m^(2);高寒湿地和高寒草甸的土壤含水量分别为92.05%和57.99%,显著高于温性草原与高寒荒漠(P<0.05);而高寒湿地和高寒草甸的土壤孔隙度分别为74.35%和70.01%,显著高于温性草原和高寒荒漠(P<0.05);不同草地类型土壤的速效氮、全氮和有机质含量均呈现高寒草甸>高寒湿地>温性草原>高寒荒漠的趋势。相关性分析表明,植被盖度与土壤容重极显著负相关(P<0.01),与土壤全氮、速效氮显著正相关(P<0.01)。在土壤含水量更高的高寒湿地中放线菌门(Actinobacteria)相对丰度较低,且由于透气性差、土壤含氧量低,导致高寒湿地中好氧微生物丰度少,群落结构脆弱。在土壤含水量较低、土壤透气性好的高寒荒漠中酸杆菌门(Acidobacteria)、被孢霉门(Mortierellomycota)等好氧微生物相对丰度较高。在植被丰富、地上生物量高的温性草原、高寒草甸中担子菌门(Basidiomycota)丰度较高。该研究结果揭示了不同草地类型的植被、土壤和微生物间的相互关系,为祁连山国家公园草地生态系统的可持续利用及科学管理提供了基础数据。

高寒草地四种植物叶片化学计量学特征及其对坡度的响应

本研究以高寒草甸和高寒灌丛共有物种黑褐苔草(Carex atrofusca Schkuhr Riedgr.)、黄花棘豆(Oxytropis ochrocephala Bunge.)、冷地早熟禾(Poa crymophila Keng.)、乳白香青(Anaphalis lactea Maxim.)为研究对象,比较分析四种植物叶片碳(Carbon, C)、氮(Nitrogen, N)、磷(Phosphorus, P)含量差异及其随坡度变化的变化趋势。结果表明:高寒草甸植物叶片C,N含量、C/N比值种间差异显著,高寒灌丛植物叶片N,P含量,C/N,C/P,N/P比值种间差异显著;高寒灌丛乳白香青叶片C/N,C/P比值和黄花棘豆叶片C/P,N/P比值显著高于高寒草甸;随着坡度增大,两种草地类型所有植物叶片C含量和N/P比值均无显著变化趋势;高寒草甸黑褐苔草和黄花棘豆叶片N含量显著减少,C/N比值显著增大;高寒灌丛乳白香青叶片P含量显著减少,C/P比值显著增大。两种草地类型植物叶片化学计量特征对坡度的响应差异说明了植物适应环境策略的多样化。

锡林郭勒草原不同植物群落特征与土壤养分特性研究

为了揭示不同草原亚型的植被特点和土壤养分特征,探明物种多样性与土壤养分之间的相互关系,本研究以内蒙古锡林郭勒草原为研究区,通过野外采样、室内化验、冗余分析等方法对草甸草原、典型草原和荒漠草原三种草原亚型的植物群落特征、土壤养分特性及其相互关系进行分析。结果表明,(1)植物群落的生物量(W)、丰富度指数(M)、多样性指数(H′)和优势度指数(D)均表现为草甸草原>典型草原>荒漠草原,均匀度指数(J)在荒漠草原数值最高。(2)土壤钾含量在典型草原中最高,其他土壤养分含量均在草甸草原中最高;速效氮、速效钾、有机质和全氮含量在不同草原亚型中差异显著(P<0.05),全磷和全钾含量差异不显著。(3)草甸草原中对植物群落特征影响最大的是速效氮含量,作用最小的是全磷含量;典型草原中对植物群落特征影响较大的是速效氮、速效磷含量,作用较小的是速效钾含量;荒漠草原中全磷含量对植物群落特征影响较大,全钾含量对植物群落特征的作用较小。综上,在草甸草原和典型草原的植被保护中,应注重氮元素的投入,而对荒漠草原,应注重磷元素的控制。

牦牛和藏羊放牧对青藏高原高寒草地植物群落氮库的影响

放牧是青藏高原高寒草地最主要的利用方式,牦牛和藏羊是青藏高原最常见的放牧家畜,家畜通过采食植物地上部分会使地上生物量减少,进而对植物群落氮库产生影响。本研究依托青海省高寒草地-家畜系统适应性管理技术平台的放牧试验样地,探讨不同家畜类型放牧对高寒草地植物群落氮库的影响。研究结果表明:未放牧处理下高寒草地地上生物量为180.0 g·m^(-2),藏羊单独放牧显著降低了植物群落地上生物量。对未放牧处理下不同功能群氮素含量的研究发现:豆科植物(26.4 mg·g^(-1))>杂类草(17.0 mg·g^(-1))>禾草(12.9 mg·g^(-1))≈莎草(11.8 mg·g^(-1))。放牧显著增加了禾草和莎草氮含量,对杂类草氮含量影响较小。放牧对群落水平植物地上部分氮含量的影响变化小于对各功能群的变化影响,因为植物群落具有稳定性。当高寒草地植物群落处于放牧压力下,会从土壤中获取更多的氮以维持生长,放牧会进一步加剧青藏高原高寒草地植物生长的氮限制。