Precipitation is a critically important ecological factor impacting on plant community characteristics and driving the species composition in semi-arid sandy land. However, there is still much that is not known about the response of plant community characteristics to precipitation changes. This study conducted controlled experiments in the 2018 during the growing season using field rain-generation and rain-reduction devices in the Horqin Sandy Land. In order to explore the relationship between community characteristics and precipitation changes. Treatments comprised: the drought commence in May or in June and lasted for 45 days, 30% or 60% reduction in natural precipitation, and 30% or 60% increase in natural precipitation. It was found that: 1) The rainfall reduction of 60% caused sandy land herb communities to move towards a less complex structure, with species richness index and diversity index showing a significant decline of 8.57% and 4.80%, respectively, and advantage index showing a non-significant decline trend of 1.36%, and an associated reduction in plant productivity. 2) Drought of 45 consecutive days from May had no significant effect on the composition, species diversity or community productivity of sandy land herb species. 3) Drought of 45 consecutive days from June affected multiple sandy land herb species, resulting in a decrease in species density. However, the effect on plant species diversity and community productivity was not significant. In summary, the plant communities in semi-arid sandy land have some resistance to short-term extreme drought events, but show a greater response to long-term drought events. 4) The increase of 30% and 60% precipitation treatments tended to increase community height, community coverage, and above ground biomass, but not significantly so relative to CK. These results help to build a theoretical basis for the understanding of mechanisms of plant community response to precipitation changes.

在半干旱地区,降水是制约草本植物群落结构与物种组成最主要的生态因子,而植物群落特征对降水变化的响应研究仍有很多不确定性。针对此现象,于2018年生长季在科尔沁沙地运用野外增减雨装置开展控制试验,通过自然对照、减少30%降水量、减少60%降水量、5月起连续干旱45 d、6月起连续干旱45 d、增加30%降水量、增加60%降水量7种试验处理,以期揭示草本植物群落特征及其物种组成对降水变化的响应,从而为植物生长对降水变化的适应机制研究提供理论依据。研究结果表明:1) 减少60%降水量将造成沙地草本群落向单一结构发展,使物种丰富度指数、优势度指数和多样性指数显著减少,其减少率依次为8.57%、1.36%和4.80%,同时降低植物生产力。2) 5月起连续干旱45 d对沙地草本植物物种组成、物种多样性和群落生产力无显著影响。3) 6月起连续干旱45 d影响沙地草本植物多个物种重要值,导致物种密度减少,但对植物物种多样性和群落生产力影响不显著。半干旱沙地植物群落对长期干旱事件响应较大,对短期极端干旱事件具有一定的抵抗力。

在全球气候变化背景下, 未来我国北方半干旱地区的降水格局将呈现出季节与年际间降水波动增强和极端降水事件增加的趋势。水分是半干旱草原的主要限制因子, 降水格局变化导致的土壤水分状况的改变必然对生态系统的结构和功能产生显著的影响。该研究选取内蒙古多伦和锡林浩特两个典型半干旱草原群落, 通过分析2006-2013年的降水和多层次土壤(0-10 cm, 10 cm, 20 cm, 30 cm和50 cm)含水量连续观测数据, 研究降水格局变化对土壤水分状况及其垂直分布的影响, 特别是土壤水分对降水事件的脉冲响应过程。结果表明: 两个站点的土壤含水量均呈现显著的季节及年际间波动, 其中土壤表层 0-10 cm水分波动更剧烈。锡林浩特50 cm处土壤含水量波动较大, 主要由于春季融雪的影响。年际间多伦和锡林浩特生长季土壤表层0-10 cm土壤含水量与降水量存在显著的正相关关系, 下层(10-50 cm)土壤含水量与降水量相关性不显著。研究发现小至2 mm的降水事件就能够引起两个站点表层0-10 cm土壤含水量的升高, 即该地区有效降水为日降水量> 2 mm。表层0-10 cm土壤含水量对独立降水事件的脉冲响应可通过指数方程很好地拟合。降水事件的大小决定了降水后表层0-10 cm土壤含水量的最大增量和持续时间, 同时这个脉冲响应过程还受到降水前土壤含水量的影响, 但该过程中并未发现植被因子(叶面积指数)的显著影响。降水后水分下渗深度及该深度的土壤含水量增量主要由降水事件的大小主导, 同时受到降水前土壤含水量的影响。在多伦和锡林浩特, 平均每增加1 mm降水, 下渗深度分别增加1.06和0.79 cm。由此作者认为, 在内蒙古半干旱草原, 降水事件大小和降水前土壤干湿状况是影响土壤水分对降水响应的主要因素, 而植被因子的影响较小。

荒漠生态系统是中国西北地区的代表性生态系统，具有不同于其他生态系统的独特结构和功能。开展荒漠生态系统服务价值评估，对干旱区的生态恢复与重建以及区域环境保护具有重要意义，有助于促进干旱区的可持续发展。把荒漠生态系统服务划分为防风固沙、土壤保育、固碳释氧、水资源调控、生物多样性保育、旅游文化等6类。在此基础上回顾与评述了相关研究，简要概括了已有研究中存在的主要问题，最后建议加强荒漠生态系统提供的独特服务的价值评估和针对特定地区开展小区域的荒漠生态系统服务价值评估等方面的研究，以及科学选取与调整价格参数。

<FONT face=Verdana>Investigation of spatial distribution of aboveground biomass of grassland in desert and desertified regions is essential to evaluate carbon storage in northern China. Furthermore, it is important to understand potential development of husbandry, status of biodiversity, and ecosystem stability in regional scale. In this paper, spatial characteristics of grassland aboveground biomass were studied based on data from 144 sites in desert and desertified regions of northern China. In addition, we analyzed the relationships of aboveground biomass with environmental parameters such as precipitation and temperature. The results show that spatial distribution of grassland aboveground biomass is highly heterogeneous in desert and desertified regions of northern China. Aboveground biomass ranges from 5.5~371.2 g·m-2, with an average of 83.3 g·m-2. Aboveground biomass is significantly negatively correlated with latitude (P&lt;0.05) and is positively correlated with longitude (P&lt;0.001). This means that aboveground biomass decreased with latitude increasing but increased with longitude increasing. Correlation analysis shows that aboveground biomass is significantly correlated with annual precipitation, but is weakly correlated with annual mean temperature and altitude. This implies that rainfall drives the spatial distribution pattern of aboveground biomass in desert and desertified regions of northern China.</FONT>

北方典型荒漠及荒漠化地区草地地上生物量的空间分布特征对揭示中国陆地生态系统的碳储量具有重要意义,同时对于了解区域尺度上畜牧业发展潜力、生物多样性现状、以及生态系统稳定性具有一定的作用。利用北方典型荒漠及荒漠化地区144个草地样点的植被地上生物量数据,分析地上生物量的空间分布特征及其与多年平均降水量、多年平均温度、海拔高度等环境因素的相关关系。结果表明,北方典型荒漠及荒漠化地区草地单位面积地上生物量的空间分布高度异质,在5.5~371.2 g·m-2之间波动,平均地上生物量为83.3 g·m-2。北方典型荒漠及荒漠化地区草地地上生物量在经向和纬向上的分布均有明显的规律性。相关分析显示,植被地上生物量与纬度之间呈显著的负相关关系(P&lt;0.05),与经度之间呈显著正相关关系(P&lt;0.001)。草地地上生物量与年降水量之间存在显著的正相关关系(P&lt;0.001),但和海拔高度、年平均温度之间无显著相关性,这意味着水分条件是导致北方典型荒漠及荒漠化地区草地地上生物量空间分异的重要因素。

Biological stoichiometry theory considers the balance of multiple chemical elements in living systems, whereas metabolic scaling theory considers how size affects metabolic properties from cells to ecosystems. We review recent developments integrating biological stoichiometry and metabolic scaling theories in the context of plant ecology and global change. Although vascular plants exhibit wide variation in foliar carbon:nitrogen:phosphorus ratios, they exhibit a higher degree of 'stoichiometric homeostasis' than previously appreciated. Thus, terrestrial carbon:nitrogen:phosphorus stoichiometry will reflect the effects of adjustment to local growth conditions as well as species' replacements. Plant stoichiometry exhibits size scaling, as foliar nutrient concentration decreases with increasing plant size, especially for phosphorus. Thus, small plants have lower nitrogen:phosphorus ratios. Furthermore, foliar nutrient concentration is reflected in other tissues (root, reproductive, support), permitting the development of empirical models of production that scale from tissue to whole-plant levels. Plant stoichiometry exhibits large-scale macroecological patterns, including stronger latitudinal trends and environmental correlations for phosphorus concentration (relative to nitrogen) and a positive correlation between nutrient concentrations and geographic range size. Given this emerging knowledge of how plant nutrients respond to environmental variables and are connected to size, the effects of global change factors (such as carbon dioxide, temperature, nitrogen deposition) can be better understood.

Although projections of precipitation change indicate increases in variability, most studies of impacts of climate change on ecosystems focused on effects of changes in amount of precipitation, overlooking precipitation variability effects, especially at the interannual scale. Here, we present results from a 6-y field experiment, where we applied sequences of wet and dry years, increasing interannual precipitation coefficient of variation while maintaining a precipitation amount constant. Increased precipitation variability significantly reduced ecosystem primary production. Dominant plant-functional types showed opposite responses: perennial-grass productivity decreased by 81%, whereas shrub productivity increased by 67%. This pattern was explained by different nonlinear responses to precipitation. Grass productivity presented a saturating response to precipitation where dry years had a larger negative effect than the positive effects of wet years. In contrast, shrubs showed an increasing response to precipitation that resulted in an increase in average productivity with increasing precipitation variability. In addition, the effects of precipitation variation increased through time. We argue that the differential responses of grasses and shrubs to precipitation variability and the amplification of this phenomenon through time result from contrasting root distributions of grasses and shrubs and competitive interactions among plant types, confirmed by structural equation analysis. Under drought conditions, grasses reduce their abundance and their ability to absorb water that then is transferred to deep soil layers that are exclusively explored by shrubs. Our work addresses an understudied dimension of climate change that might lead to widespread shrub encroachment reducing the provisioning of ecosystem services to society.

Human-driven environmental changes may simultaneously affect the biodiversity, productivity, and stability of Earth's ecosystems, but there is no consensus on the causal relationships linking these variables. Data from 12 multiyear experiments that manipulate important anthropogenic drivers, including plant diversity, nitrogen, carbon dioxide, fire, herbivory, and water, show that each driver influences ecosystem productivity. However, the stability of ecosystem productivity is only changed by those drivers that alter biodiversity, with a given decrease in plant species numbers leading to a quantitatively similar decrease in ecosystem stability regardless of which driver caused the biodiversity loss. These results suggest that changes in biodiversity caused by drivers of environmental change may be a major factor determining how global environmental changes affect ecosystem stability. Copyright © 2015, American Association for the Advancement of Science.

Plant diversity is the basis for ecosystem structure and function， and climate change has had a profound impact on it， even a serious threat. The decrease or loss of plant diversity necessarily affects the stability of ecosystem structure and function， lead to serious ecological， economic and social consequences. Studies have shown that the response of plant diversity to climate change is controlled by the dynamic balance of temperature and water. This research systematically introduced the effects of climate warming and precipitation pattern change on plant diversity. In this report， the impacts of climate change on plant diversity in different ecosystems， community types and scales （global， regional and local scale） are analyzed and the main factors that influence the difference were summarized. We also propose research hotspots and directions for future plant diversity research in different environmental conditions.

植物多样性是生态系统结构和功能的基础，气候变化已对其产生了深刻的影响，甚至于严重威胁。植物多样性的减少或丧失必然会影响生态系统结构和功能的稳定性，导致严重的生态、经济和社会后果。植物多样性对气候变化的响应受控于气温和水分的动态平衡。本文系统总结了气候变暖和降水格局变化对植物多样性的影响，分析了气候变化对不同生态系统、群落类型、尺度范围（全球尺度、区域尺度、局地尺度）内植物多样性的影响，并归纳了差异的主要影响因素。最后对未来的研究方向做了展望。

Global climate change is one of the most pressing conservation challenges; in particular, changes in precipitation regimes have already substantially influenced terrestrial ecosystems. However, the mechanisms influencing precipitation changes on individual plants and the plant communities in desert grasslands have yet to be fully elucidated. We therefore examine the influence of increased precipitation on plant community compositions in the Gurbantunggut Desert, Xinjiang, northwestern China, from 2005 to 2009. We found that growth of all plant species and the community productivities increased markedly with enhanced water input. Cover of ephemeral synusia also significantly increased due to increased precipitation, implying that the role of the ephemeral community for stabilization of sand dunes was strengthened by increased precipitation. The response of plant community compositions to increased precipitation was primarily reflected as changes in plant density, while increased precipitation did not affect plant species richness and the diversity index. Dominant species drove the response of plant density to increasing precipitation during the five-year study period. However, the relative responses of rare species were stronger than those of the dominant species, thereby potentially driving species turnover with long-term increased precipitation. This finding improved our understanding of how increased precipitation drives the changes in plant community composition in desert grasslands and will help to better predict changes in the community composition of ephemerals under future global climate change scenarios.© 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

To show the impact of vegetation changes over Loess Plateau on the environment three experiments with the real,the improved and the degradation vegetation over the Loess Plateau respectively,have been desighed and run,using the new nonhy drostatic atmospheric mesoscale model MM5 of National Center of Atmospheric Research(NCAR),a precipitation process of Loess Plateau from 26 to 30 June in 2003 is simulated.The impact of vegetation changes over loess Plateau on precipitation with a control experiment and two sensitivity numerical experiments.The results show that the improved vegetation can increase precipitation moisture,reduce runoff and diural change of air temperature,but vice versa for the degradation vegetation.The test comprehensively reveals the physical mechanism of the interaction between land surface and temperature,humidity in atmospheric boundary layer of heterogeneous ground surface.

使用美国NCAR新版MM5非静力平衡模式,模拟了黄土高原2003年6月26~30日的一次降水过程。该试验是通过改变黄土高原局部地区植被覆盖情况,对比分析植被改变区域内各气象要素的变化情况。结果表明:植被改善能使雨量增加,径流量减小,湿度增大,温度日较差减小,使气候变的温和。植被退化却使雨量减少,径流加大,易使水土流失,对水土保持不利。试验较全面地揭示了非均匀地表大气边界层内的温、湿场与陆面相互作用的机理。

This study used daily temperature and precipitation data from 699 weather stations in China from 1951 to 2018 to study the spatiotemporal evolution characteristics of temperature and precipitation in China， by using Mann-Kendall test， wavelet analysis， and RClimDex extreme temperature index methods. The results show that： In terms of time， the temperature in China presents an obvious increasing trend； the increase in precipitation is lagging and slow； the temperature and precipitation have multi-period changes； and there is a correlation on a large time scale. With the number of freezing days ID0 expressed by the highest temperature and abnormal warmth compared with the number of frost days FD0 and the number of warm night days TN90p expressed in the lowest temperature， the number of continuous days TX90p has a smaller change. The longest continuous precipitation days CWD and the longest drought duration CDD show a downward trend. Climate change is mainly characterized by warming and humidification. Spatially， the average temperature and precipitation both show a decreasing trend in the latitude direction. The contours move northward as a whole， which is largely affected by the topography， showing complementary spatial distribution characteristics. The number of warm days TX90p and the number of summer days SU25 are positive across the country. The number of freezing days ID0 and the number of frost days FD0 decrease in most areas. The longest continuous dry days CDD and the longest continuous humid days CWD have a certain degree of opposite spatial variation， and there is an increasing trend in extreme precipitation events. Studying the temporal and spatial evolution characteristics of temperature and precipitation is an important part of understanding and coping with the impact of climate change on the region.

利用1951—2018年中国699个气象站逐日的气温、降水数据，采用Mann-Kendall检验、小波分析、RClimDex极端气温指数方法，研究中国气温和降水时空演变特征。结果表明：在时间上，中国气温呈现明显的增加趋势，降水增加滞后且缓慢，气温和降水存在多周期变化特征，在大时间尺度上存在关联关系，以最高气温表达的冰冻日数ID0和暖昼日数TX90p较之以最低气温表达的霜冻日数FD0和暖夜日数TN90p变化幅度小，最长持续湿润日数和最长持续干旱日数呈下降趋势，气候变化以暖湿化为主要特征；在空间上，平均气温和降水量都表现出纬度方向上的降低趋势，等值线整体向北移动，很大程度上受地形影响，表现出相辅相成的空间分布特征，暖昼日数TX90p和夏季日数SU25在全国范围内均为正值，冰冻日数ID0和霜冻日数FD0存在大部分区域的减小，最长持续干旱日数与最长持续湿润日数在空间上的变化存在一定程度的相反趋势，极端降水事件存在增加趋势。研究气温和降水的时空演变特征是了解和应对气候变化对区域影响的重要内容。

基于中国693个地面观测站1961 -2016年的逐日降水资料, 全面分析了全国和各分区极端降水事件、 连续性极端降水事件及其起止时间的时空分布和变化特征。结果表明, 近56年, 全国极端降水事件明显增多, 极端降水量和极端降水日数呈增加趋势的站点占总站数的68%, 且主要集中在东南沿海和西部地区。华东地区是全国极端降水量增长幅度最大的地区, 增速达18.2 mm·(10a)^-1, 西北地区的极端降水日数增速最快, 每10年增加0.37天。全国平均的连续性极端降水事件表现为不显著的增加趋势, 其中仅西北地区的连续性极端降水量和降水频次的增加趋势达到0.01显著性水平, 华北和西南地区的连续性极端降水事件表现为不显著的下降趋势。全国平均的极端降水事件的开始时间和结束时间分别呈现出明显的提前和推迟趋势, 西北、 青藏和东北地区极端降水事件的开始时间显著提前, 西北地区的结束时间显著推迟, 受其影响, 西北地区的极端降水事件持续期增长幅度最大达到10.4 d·(10a)^-1。

Global warming and a changing precipitation regime could have a profound impact on ecosystem carbon fluxes, especially in arid and semiarid grasslands where water is limited. A field experiment manipulating temperature and precipitation has been conducted in a temperate steppe in northern China since 2005. A paired, nested experimental design was used, with increased precipitation as the primary factor and warming simulated by infrared radiators as the secondary factor. The results for the first 2 yr showed that gross ecosystem productivity (GEP) was higher than ecosystem respiration, leading to net C sink (measured by net ecosystem CO(2) exchange, NEE) over the growing season in the study site. The interannual variation of NEE resulted from the difference in mean annual precipitation. Experimental warming reduced GEP and NEE, whereas increased precipitation stimulated ecosystem C and water fluxes in both years. Increased precipitation also alleviated the negative effect of experimental warming on NEE. The results demonstrate that water availability plays a dominant role in regulating ecosystem C and water fluxes and their responses to climatic change in the temperate steppe of northern China.

物种多样性对生态系统功能的影响是生态学领域的核心问题之一。本研究利用内蒙古荒漠草原80个野外植被、土壤调查样地资料,结合气候数据,探讨物种多样性、生产力与气候因子和土壤养分的关系,为进一步认识多样性-生产力关系提供参考。结果表明,1)物种多样性、生物量与年平均降水量均呈线性正相关,与年平均温度均呈线性负相关,与干燥指数均呈线性正相关。2)物种丰富度与土壤全磷含量呈线性负相关(R²=0.072, P&#x0003C;0.05),与速效氮含量呈线性正相关(R²=0.183, P&#x0003C;0.01),Shannon-Wiener指数与速效氮也呈线性正相关(R²=0.061, P&#x0003C;0.05);生物量与土壤全氮、速效氮和有机碳含量都呈线性正相关,相关系数分别为0.150,0.177,0.089(P&#x0003C;0.01)。3)群落生物量与物种多样性呈线性正相关关系。4)干燥指数是影响多样性和生物量的主要环境因子。

可下载PDF全文。

With global warming， precipitation patterns and distribution patterns are changing all over the world. Among them， the precipitation changes in arid areas are particularly noticeable. Under the global warming， precipitation and water content in the atmosphere have increased in Northwestern China. However， this "warm and wet" is an improvement of the humid degree in arid areas， which does not change the basic climate characteristics of drought and less rain. The precipitation pattern in Northwestern China is fundamentally different from that in Eastern China， and the increase of precipitation is mainly due to the increase of extreme and short-term convective precipitation. In addition， the increase of precipitation mainly occurs in inland river basin， and the arid areas in the basin could not solve the ecosystem problems with abundant water. It is necessary to make clear the difference of drought properties between arid Northwestern China and arid and semi-arid Yellow River basin. The main sources of water resources in Northwestern Hexi Corridor are precipitation and ice and snow resources in mountainous areas. The relationship between precipitation in Northwestern China and snow and ice resources in Qilian and Tianshan mountains should be explored. A scientific and rational understanding of the increase of precipitation in Northwestern China is the premise for the proper allocation and use of water resources in Northwestern China and the scientific development of ecological civilization.

随着全球变暖，全球的降水形式、分布格局都在发生着变化，其中干旱区的降水变化尤为引人瞩目。西北地区干旱少雨，在全球变暖背景下，降水量和大气中的含水量均呈现出增加趋势。通过研究认为这种“暖湿”是一种干旱区湿润程度的改善，并不会改变其干旱少雨的基本气候特征。西北地区降水的形式和性质都和我国东部地区有着根本的差别，降水增加主要是极端和短时对流降水的增加。另外，降水增加主要发生在西北干旱区的内陆河流域，该流域内的干旱地区的农业生态问题并非富水就能解决；西北地区的河西走廊等干旱和极端干旱地区水资源的主要来源是山区降水和冰雪资源；科学理性地认识西北地区降水增加，是正确处理西北地区水资源合理调配和使用、科学开展生态文明建设的前提。

With the combination of field experiment and laboratory analysis, this paper studied the effects of water addition and nitrogen (N) and phosphorus (P) fertilization on the soil properties of typical grassland in Inner Mongolia. Water addition and fertilization showed less effect on the soil organic C and total N contents. Water addition decreased the soil NH₄⁺-N and NO₃^--N contents by 31.1% (<em>P</em>&lt;0.01) and 7.9% (<em>P</em>&lt;0.001), respectively, and N fertilization increased the soil NH₄⁺-N and NO₃^--N contents significantly (<em>P</em>&lt;0.01). Under P fertilization, soil total P and available P contents were 1.7 and 5.9 times of the control, respectively (<em>P</em>&lt;0.01). Soil pH increased significantly with water addition (<em>P</em>&lt;0.01), but decreased in different degree under N and P fertilization. All the results suggested the obvious effect of water&nbsp;addition and N and P fertilization in improving the soil properties in temperate grassland in Inner Mongolia, which would be of importance for the restoration and management of degraded grassland in North China.

To determine biodiversity, 74 plant community plots were surveyed in western Inner Mongolia between 2012 and 2014. These samples were divided into four vegetation types, including temperate steppe, temperate shrub, meadow, and desert. Four biodiversity indices (Patrick index, Simpson index, Shannon-Wiener index and Pielou index) were calculated to show biodiversity differences among the four vegetation types. Climate and soil data were also collected over the course of the survey. Pearson correlation analysis was conducted to reveal the relationship between biodiversity and environmental factors and stepwise regression analysis was used to determine dominant environmental factors. Results indicated that: (1) In western Inner Mongolia, biodiversity indices were different among the four vegetation types. Temperate steppe and meadow had similar values for biodiversity indices, and were also the highest amongst all vegetation types, while the lowest biodiversity was found in the desert. (2) Pearson correlation analysis showed that the Patrick index, Shannon-Wiener index, and Simpson index were all negatively and linearly correlated with mean annual temperature and potential evapotranspiration. (3) Among all chemical properties of the soil, pH, organic carbon and total nitrogen all influenced biodiversity indices. (4) Stepwise regression analysis showed that potential evapotranspiration and soil organic carbon were the most influential factors affecting the Patrick index and Shannon-Wiener index. The only dominant factor for the Simpson index was soil organic carbon while soil total nitrogen was most important factor for the Pielou index.

为深入认识干旱半干旱地区生物多样性的形成机制, 本文基于2012-2015年对内蒙古西部的温带草原、温带灌丛、草甸和荒漠4种植被型调查获取的74个样地数据, 对比了不同植被型的物种多样性差异, 分析了不同环境因子对内蒙古西部自然植被物种多样性的影响。结果表明: (1)综合Simpson指数、Patrick丰富度指数、Shannon-Wiener指数和Pielou均匀度指数分析, 内蒙古西部温带草原和草甸的物种多样性相近, 在4种植被型中最高, 荒漠的物种多样性最低。(2) Pearson相关分析结果表明, 气候因子中, 年均温、年降水量、潜在蒸散量和最冷月均温对群落物种多样性均具有显著影响, 其中Patrick丰富度指数、Shannon-Wiener指数、Simpson指数均与年均温、潜在蒸散量呈显著的负相关关系, 前两者还与年降水量呈显著的正相关关系, 各气候因子对Pielou均匀度指数的影响均不显著。(3)土壤化学性质中的土壤pH值、有机碳和全氮含量均对物种多样性有显著影响。(4)多元回归分析发现, 潜在蒸散量和土壤有机碳含量是影响Patrick丰富度指数和Shannon-Wiener指数的主导因子, 而Simpson指数的主导因子仅为土壤有机碳含量, Pielou均匀度指数的主导因子为土壤全氮含量。

Changes in global precipitation patterns affect soil physical and chemical properties and soil microbial community characteristics of grassland ecosystem. It is of great significance to understand the response of ecosystem characteristics to global change,to explore the relationship between soil physical and chemical factors and soil microbial community characteristics and precipitation changes in grassland. The study selected the alpine grassland ecosystem of Qinghai Lake Bird Island as the research object,a control group (NCK，100% precipitation) and two treated groups (NJ,50% precipitation; NZ，150% precipitation) were set up. The response characteristics of soil microbial communities to precipitation patterns were analyzed by high-throughput sequencing technology. The result of research showed thatthe abundance of bacterial and fungal communities increased,but the diversity of fungal communities decreased under the treatment of NJ. Similarly,the diversity of fungal community and the richness bacterial community increased under NZ,but the diversity of bacterial community decreased. The abundance of bacterial which increased under both NZ and NJ,but the overall relative abundance of fungal communities tended to decrease under NZ. There were significant differences in soil temperature,humidity,biomass,soil nitrate nitrogen (NO₃^--N),ammonium nitrogen (NH₄⁺-N) and total carbon content under NZ and NJ;Soil environmental factors had significant effects on the composition and diversity of soil microbial communities. It is concluded that the physical and chemical properties of soil and microbial communities respond significantly to changes in precipitation. Compared to bacteria,fungi is more sensitive to precipitation.

为探究高寒草地生态系统特征对降水变化的响应，本研究以青海湖鸟岛高寒草地生态系统为研究对象，通过设置减少50%降水（NJ）、增加50%降水（NZ）试验处理和对照（NCK）3组不同降水条件，探究土壤理化因子及微生物群落对不同降水梯度的响应特征。研究结果表明：NJ，NZ处理均增加了细菌群落的丰富度降低了其多样性；NJ处理增加真菌群落的丰富度降低了其多样性，NZ处理增加了真菌群落的多样性降低了其丰富度；NJ处理增加了细菌和真菌群落的相对丰度，NZ处理降低了真菌群落相对丰度增加了细菌群落相对丰度；NZ，NJ处理下土壤温湿度及生物量变化差异显著，土壤硝态氮（NO₃^--N）、铵态氮（NH₄⁺-N）及全碳含量变化显著；土壤环境因子对土壤微生物群落组成与多样性具有显著影响。综上，土壤理化性质及微生物群落对降水变化的响应明显，真菌对降水处理的响应比细菌更为敏感。

Changing precipitation regimes can profoundly affect plant growth in terrestrial ecosystems, especially in arid and semi-arid regions. However, how changing precipitation, especially extreme precipitation events, alters plant diversity and community composition is still poorly understood. A 3-year field manipulative experiment with seven precipitation treatments, including - 60%, - 40%, - 20%, 0% (as a control), + 20%, + 40%, and + 60% of ambient growing-season precipitation, was conducted in a semi-arid steppe in the Mongolian Plateau. Results showed total plant community cover and forb cover were enhanced with increased precipitation and reduced under decreased precipitation, whereas grass cover was suppressed under the - 60% treatment only. Plant community and grass species richness were reduced by the - 60% treatment only. Moreover, our results demonstrated that total plant community cover was more sensitive to decreased than increased precipitation under normal and extreme precipitation change, and species richness was more sensitive to decreased than increased precipitation under extreme precipitation change. The community composition and low field water holding capacity may drive this asymmetric response. Accumulated changes in community cover may eventually lead to changes in species richness. However, compared to control, Shannon-Weiner index (H) did not respond to any precipitation treatment, and Pielou's evenness index (E) was reduced under the + 60% treatment across the 3 year, but not in each year. Thus, the findings suggest that plant biodiversity in the semi-arid steppe may have a strong resistance to precipitation pattern changes through adjusting its composition in a short term.