内蒙古典型草原区3种不同草地利用模式下植物功能群及其多样性的变化

以呼伦贝尔草原辉河国家级自然保护区草原群落为研究对象, 选取3块生境条件基本相同的样地(250 m × 250 m) ——放牧场、割草场及公共草场, 每块样地设置3条样带, 每条样带上设置8个样方(1 m × 1 m), 研究了不同草地利用模式下草原群落的物种组成、生物多样性及群落的功能群特征。结果表明: 在放牧场、割草场和公共草场3种不同利用模式下, 植物功能群结构及其多样性发生了变化。灌木、半灌木的累积优势度在各利用模式间差异显著( p< 0.05), 在割草场中最高; 多年生禾草的累积优势度在各利用模式间差异显著(p< 0.05); 一、二年生草本的累积优势度在各利用模式间差异显著(p< 0.05)。旱生植物功能群在公共草场中所占比例最高, 为50%; 中旱生植物在割草场中的百分比最低, 为19%, 且在各利用模式间差异显著(p< 0.05); 各利用模式下, 灌木、半灌木功能群生物量均较低; 随着割草场、公共草场及放牧场3种草地利用模式下利用强度的增加, 多年生禾草和多年生杂类草两大功能群的生物量递减, 而一、二年生草本功能群生物量递增。草地利用强度的增加, 使得草地植物群落结构简单、脆弱。丰富度指数和多样性指数在放牧场最低, 在割草场最高; 均匀度变化并不明显。割草场利用模式有助于改善草原的健康状况, 而放牧场及公共草场利用模式均存在不同程度的过度放牧现象, 尤其是公共草场利用模式由于所有权不明确而缺乏有效的管理, 导致草原退化明显。     

锡林河流域羊草草原植物种群和功能群的长期变异性及其对群落稳定性的影响

 分析了内蒙古锡林河流域羊草(Leymus chinensis)草原群落植物种群、功能群和群落生物量的长期变异性,以及植物功能群间的补偿作用对群落稳定性的影响,结果表明：从种群水平到功能群和群落水平,地上生物量的年度间变异性逐渐降低,而稳定性则逐渐增加。植物功能群组成对群落稳定性具有更强烈的影响,在植物生活型功能群组成中多年生根茎禾草与多年生丛生禾草和多年生杂类草功能群,在生物量的年度变化上具有补偿作用,在生态类群组成中,旱生植物与中旱生植物也具有补偿作用。植物种群多度的长期变异性可能依赖于物种对环境波动的敏感性和种间相互作用对环境波动的放大效应,生物多样性使物种对环境波动响应的多样性增加,并通过不同响应类型(功能群)间的补偿作用使群落稳定性增加。     

锡林河流域羊草草原植物种群和功能群的长期变异性及其对群落 …

分析了内蒙古锡林河流域羊草（Ｌｅｙｍｕｓ ｃｈｉｎｅｎｓｉｓ）草原群落植物种群、功能群和群落生物量的长期变异性,以及植物功能群间的补偿作用对群落稳定性的影响。结果表明：从种群水平到功能群落水平,地上生物量的年度间变异性逐渐降低,而稳定性则逐渐增加。植物功能群组成对群落稳定性具有更强烈的影响,在植物生活型功能群组成中多年生根茎禾草与多年生丛生禾草和多年生杂类草功能群,在生物量的年度变化上具有补偿作用     

去除干扰对内蒙古典型草原植物叶片功能属性的影响

以内蒙古典型草原为研究对象,选取放牧和割草、去除放牧、去除放牧和割草样地进行群落调查和叶片属性测量,比较分析各样地土壤性质、群落生产力及主要物种的比叶面积(SLA,Specific Leaf Area)、叶片干物质含量(LDMC,Leaf Dry Matter Content)、叶片氮含量(LNC,Leaf Nitrogen Concentration)在个体、功能群和群落水平对去除干扰的响应。结果表明,1)去除干扰处理在短期对土壤特性和群落生产力的影响不显著;2)多数物种在放牧和割草样地SLA较低,说明典型草原多数物种的SLA表现为放牧逃避;3)不同功能群植物叶片属性对去除干扰的响应不一致,去除放牧后,多年生杂类草的SLA和LDMC不受影响,但LNC变小;多年生禾草的SLA增加,而LDMC和LNC无显著变化。一年生植物在去除放牧和割草后,LNC显著增加。去除割草后,多年生禾草SLA减小,而多年生杂类草SLA、LNC增加,LDMC减小;4)在群落水平,放牧和割草样地由于较占优势的多年生禾草SLA较低,群落比叶面积最低,在去除放牧和割草样地,群落叶片氮含量显著增加;5)在内蒙古典型草原,LDMC能够很好地将多年生禾草和多年生杂类草区分,SLA在个体、功能群和群落水平均比LDMC敏感。     

内蒙古高原针茅草原植物多样性与植物功能群组成对群落初级生产力稳定性的影响

内蒙古高原4类地带性草原群落,贝加尔针茅（Stipa baicalensis Roshew.）群落、大针茅（S.grandis P.Smirn.）群落、克氏针茅（S.krylovii Roshev.）群落和小针茅（S.klemenzii Roshev.）群落初级生产力连续12年的定位研究结果表明,在气修波动下群落生产力及其稳定性与群落多样性特征的变化是一致的,从贝加尔针茅群落到小针茅群落。植物多样性显下降,群东中起重要作用的植物功能群的数量逐渐减少,群落初级生产力及其稳定性也逐渐降低。生活型功能群组成中,多年生丛生禾草、多年生根茎禾草与苔草和多年生杂类草功能群多样性与群落初级生产力稳定性极显地呈正相关。生态类群组成中,旱生植物和中旱生植物功能群多样性也与群落初级生产力稳定性极显地呈正相关,生态位互补效应（niche complementary effect）可能是高植物多样性群落具有高生产力的机制,而植物多样性对群落初级生产力稳定性的影响可能是通过不同功能群间的补偿作用来实现的。     

Plant functional groups mediate effects of climate and soil factors on species richness and community biomass in grasslands of Mongolian Plateau

植物功能群在调控气候和土壤因子对蒙古高原草原群落物种丰富度和生物量影响中的作用 植物功能群组成主要受环境因素驱动,同时植物功能群组成也是影响草地生物多样性和生产力的主要因素之一。因此,理解植物功能群在调控环境因素对生态系统功能和生物多样性影响中可能发挥的作用至关重要。通过对蒙古高原草原65个样点的植物生物量和物种丰富度的调查,将157种多年生草本植物分为两种植物功能群(即禾草和杂类草)。通过随机森林模型和普通最小二乘回归,确定与植物功能群物种丰富度和地上生物量显著相关的环境因素(即干燥度、土壤总氮和pH),并利用结构方程模型探讨筛选出的环境因素与群落物种丰富度和生物量间的关系,以及植物功能群在驱动这种关系中发挥的作用。干燥度与禾草、杂类草以及整个群落的地上生物量和物种丰富度均呈显著的单峰关系。所有的物种丰富度和生物量指标均与土壤总氮和pH值显著相关。禾草在维持蒙古高原草原生态系统群落生物量中起着关键作用,并受气候因素的直接影响。而杂类草物种丰富度决定了群落总丰富度,并受到土壤因素直接的调控。因此,群落组成在调控环境因素对群落生物量和植物多样性的影响中起着关键作用。     

煤矿复垦地不同恢复阶段植物群落功能群结构与生物多样性变化

选取黄土高原区黑岱沟露天煤矿不同复垦阶段(1995～2010年)样地4块,以原地貌样地为对照,以时空替代的方法,对煤矿复垦地的植物群落的功能群结构及生物多样性进行研究.结果表明:(1)随着复垦时间的延长,植物群落功能群组成以多年生禾草和多年生杂类草为主,其累积优势度均呈现增加的趋势,而一、二年生草本的累积优势度减小;复垦初期,群落功能群单一、组成种类贫乏,多为一、二年生植物;复垦后期,羊草及冰草逐步出现,复垦地最终形成以克氏针茅、本氏针茅、赖草及糙隐子草为主的植物群落.(2)复垦过程中,中生植物及中旱生植物所占比例逐步增加,而旱生植物比例逐步减少;多年生禾草及多年生杂类草生物量随着复垦时间的增加而递增,而一、二年生草本植物生物量递减;群落总生物量呈先急剧增加、又急剧减少、后缓慢增加的规律.(3)群落的Shan-non-Wiener多样性指数(H)、Patrick丰富度指数(Pa)及Pielou均匀度指数(JP)随着复垦时间延长而增加.     

内蒙古高原针茅草原群落β多样性研究

用比较样地法调查了内蒙古高原 4类地带性针茅 (Stipa)草原群落的 β多样性特征 .结果表明 ,Whit tacker指数 βws与尺度有关 ,随取样面积的增加 ,βws逐渐降低 .取样面积相同时 ,4类群落的 βws比较接近 .各群落的Cody指数最初也随样方面积的扩大而增大 ,当样方面积扩大到一定尺度时 ,贝加尔针茅群落和大针茅群落为 >0 .5m2 ,克氏针茅群落和小针茅群落为 >2m2 ,Cody指数趋于稳定 .同一尺度下 ,贝加尔针茅群落的Cody指数最高 ,小针茅群落的Cody指数最低 .多数情况下 ,群落内样本间的间隔距离 ,对Cody指数有较大的影响 ;从贝加尔针茅群落到小针茅群落 ,植物生活型和生态类群功能群组成中 ,多年生丛生禾草与根茎禾草、多年生杂类草和中旱生植物的多样性显著降低 ,旱生植物多样性先增加 ,尔后到小针茅群落显著降低 .群落的植物种类组成表现出明显生态替代现象 ,不同群落间的Cody指数逐渐降低 ;贝加尔针茅群落与大针茅群落的Morisita Horn指数最高 ,达 0 .72 .克氏针茅群落与小针茅群落的相似系数最低 ,为 0 .42 .     

内蒙古典型草原不同功能群生产力对凋落物添加的响应

通过连续5年对退化草地进行凋落物添加处理, 分析不同处理强度植物群落动态, 探讨凋落物对草地地上和不同功能群生产力的影响。结果表明: 凋落物添加对草地地上生产力有显著的促进作用, 草地地上生产力随着凋落物添加强度的增加而变化不大。处理效应主要表现在处理后第一年, 重度处理与对照有极显著差异(p < 0.05), 以后几年差异不显著(p > 0.05), 年度间差异极显著(p < 0.001)。凋落物添加对植物群落各功能群生产力无显著影响。年度间不同处理各功能群相对生物量随年际变化的主成分分析(PCA)结果说明: 草地生产力主要是由多年生丛生型禾草与多年生杂类草在生态系统中的竞争补偿作用决定的, 随着凋落物添加强度的增加, 二者的竞争作用减弱, 相关性下降, 多年生丛生型禾草占更大优势, 预示着多年生杂类草与一二年生草本、灌木、多年生根茎型禾草的竞争补偿作用增大。     

不同干扰方式对内蒙古典型草原植物种组成和功能群特征的影响

研究休牧、补播和自由放牧3种人为干扰方式对内蒙古典型草原群落植物种组成、功能群组成、群落物种多样性和地上生物量的影响.结果表明: 3种干扰方式对植物功能群结构及其多样性有显著影响,休牧方式下群落植物种数量、地上生物量、多样性指数和丰富度指数最大,分别为22种、171.32 g·m^-2、1.46和5.7,灌木半灌木和多年生禾草的重要值、物种所占比例、地上生物量、多样性指数、丰富度指数和均匀度指数显著高于其他干扰方式,多年生杂类草的重要值、物种所占比例、地上生物量、多样性指数和均匀度指数显著低于其他干扰方式,中生植物、C3和C4植物的地上生物量最大,分别为22.22、143.35和27.97 g·m^-2.补播方式下,中旱生植物地上生物量最大,为13.60 g·m^-2,旱生植物物种所占比例最小(48.5%),C4植物物种所占比例最大(28.8%).自由放牧方式下,一、二年生草本植物物种所占比例最大,达12.3%,中生植物和C4植物所占比例最小,分别为17.0%和20.9%.春季休牧措施有利于退化草原的恢复.     

The Influence of Plant Diversity and Functional Composition on Ecosystem Stability of Four StipaCommunities in the Inner Mongolia Plateau

The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa communities in the Inner Mongolia Plateau. The research work was based on a 12-year study (from 1984 to 1995) of species abundance, diversity, and primary productivity of four Stipa communities, i.e. S. baicalensis Roshev., S. grandis P. Smirn., S. krylovii Roshev., and S. klemenzii Roshev. respectively. The Shnnon-Wiener index was used as a measurement of plant diversity, while functional composition was used to differentiate the functional groups that were included in the communities. The plant species of four Stipa communities were classified into functional groups based on the differences in life forms and ecological groups, which influence their performance in resource requirements, seasonality of growth, tolerance to water stress, and life history. Plant species were classified into five functional groups based on their differences in life form, shrubs and half shrubs, perennial bunch grasses, perennial rhizome grasses, forbs, annuals and biennials. Based on their differences in water requirement these species were classified into four functional groups: xerads, intermediate xerads, intermediate mesophytes, and mesophytes. The results showed: 1) Plant species diversity stabilized ecosystem processes. Shannon-Wiener index were 2.4014, 2.1720, 1.6248, 0.3543 from S. baicalensis community to S. grandis, S. krylovii and S. klemenzii community, respectively. The dynamics of the aboveground net primary productivity (ANPP) for a 12-year's period showed a reverse pattern, the coefficients of variation of the four communities were 21.94%, 20.63%, 29.21% and 39.72% respectively. 2) The life form functional group component of diversity was a greater determinant of the ecosystem processes than the species component of diversity. The effects of perennial bunch grasses, perennial rhizome grasses and forbs on community stability were highly significant. 3) The ecological group component of diversity was also a great determinant of the ecosystem processes. The effects of xerads, intermediate xerads, and mesophytes on community stability were also very strong.     

Grazing effect on grasslands escalated by abnormal precipitations in Inner Mongolia

Grazing effects on arid and semi‐arid grasslands can be constrained by aridity. Plant functional groups (PFGs) are the most basic component of community structure (CS) and biodiversity & ecosystem function (BEF). They have been suggested as identity‐dependent in quantifying the response to grazing intensity and drought severity. Here, we examine how the relationships among PFGs, CS, BEF, and grazing intensity are driven by climatic drought. We conducted a manipulative experiment with three grazing intensities in 2012 (nondrought year) and 2013 (drought year). We classified 62 herbaceous plants into four functional groups based on their life forms. We used the relative species abundance of PFGs to quantify the effects of grazing and drought, and to explore the mechanisms for the pathway correlations using structural equation models (SEM) among PFGs, CS, and BEF directly or indirectly. Grazers consistently favored the perennial forbs (e.g., palatable or nutritious plants), decreasing the plants’ relative abundance by 23%–38%. Drought decreased the relative abundance of ephemeral plants by 42 ± 13%; and increased perennial forbs by 20 ± 7% and graminoids by 80 ± 31%. SEM confirmed that annuals and biennials had negative correlations with the other three PFGs, with perennial bunchgrasses facilitated by perennial rhizome grass. Moreover, the contributions of grazing to community structure (i.e., canopy height) were 1.6–6.1 times those from drought, whereas drought effect on community species richness was 3.6 times of the grazing treatment. Lastly, the interactive effects of grazing and drought on BEF were greater than either alone; particularly, drought escalated grazing damage on primary production. Synthesis. The responses of PFGs, CS, and BEF to grazing and drought were identity‐dependent, suggesting that grazing and drought regulation of plant functional groups might be a way to shape ecosystem structure and function in grasslands.     

Does the intensive grazing and aridity change the relations between the dominant shrub Artemisia kopetdaghensis and plants under its canopies?

The interspecific plant interactions along grazing and aridity stress gradients represent a major research issue in plant ecology. However, the combined effects of these two factors on plant–plant interactions have been poorly studied in the northeast of Iran. To fill this knowledge gap, 144 plots were established in 12 study sites with different grazing intensities (high vs. low) and climatic characteristics (arid vs. semiarid) in northeastern Iran. A dominant shrub, Artemisia kopetdaghensis, was selected as the model species. Further, we studied changes in plant life strategies along the combined grazing and aridity stress gradients. In this study, we used relative interaction indices calculated for species richness, Shannon diversity, and species cover to determine plant–plant interactions using linear mixed‐effect models (LMM). The indicator species analysis was used to identify the indicator species for the undercanopy of shrub and for the adjacent open areas. The combined effects of grazing and aridity affected the plant–plant interactions and plant life strategies (CSR) of indicator species. A. kopetdaghensis showed the highest facilitation effect under high stress conditions (high grazing, high aridity), which turned into competition under the low stress conditions (low grazing, low aridity). In the arid region, the canopy of the shrub protected ruderals, annual forbs, and grasses in both high and low grazing intensities. In the semiarid region and high grazing intensity (low aridity/high grazing), the shrubs protected mostly perennial forbs with C‐strategy. Our findings highlight the importance of context‐dependent shrub management to restore the vegetation damaged by the intensive grazing.     

Linking nitrogen partitioning and species abundance to invasion resistance in the Great Basin

Resource partitioning has been suggested as an important mechanism of invasion resistance. The relative importance of resource partitioning for invasion resistance, however, may depend on how species abundance is distributed in the plant community. This study had two objectives. First, we quantified the degree to which one resource, nitrogen (N), is partitioned by time, depth and chemical form among coexisting species from different functional groups by injecting ¹⁵N into soils around the study species three times during the growing season, at two soil depths and as two chemical forms. A watering treatment also was applied to evaluate the impact of soil water content on N partitioning. Second, we examined the degree to which native functional groups contributed to invasion resistance by seeding a non-native annual grass into plots where bunchgrasses, perennial forbs or annual forbs had been removed. Bunchgrasses and forbs differed in timing, depth and chemical form of N capture, and these patterns of N partitioning were not affected by soil water content. However, when we incorporated abundance (biomass) with these relative measures of N capture to determine N sequestration by the community there was no evidence suggesting that functional groups partitioned different soil N pools. Instead, dominant bunchgrasses acquired the most N from all soil N pools. Consistent with these findings we also found that bunchgrasses were the only functional group that inhibited annual grass establishment. At natural levels of species abundance, N partitioning may facilitate coexistence but may not necessarily contribute to N sequestration and invasion resistance by the plant community. This suggests that a general mechanism of invasion resistance may not be expected across systems. Instead, the key mechanism of invasion resistance within a system may depend on trait variation among coexisting species and on how species abundance is distributed in the system.     

Responses of grassland ecosystems to precipitation and land use along the Northeast China Transect

Abstracts. The Northeast China Transect (NECT) has been used to study how water availability influences the composition of plant functional types, soil organic matter, net primary production, trace gas flux, and land‐use patterns. We discuss relations of plant species number, soil C and N and above‐ground biomass with a precipitation gradient and interactions with land‐use practices (grassland fencing, mowing and grazing), on the basis of data from the west part of NECT. The results indicate: 1. The above‐ground biomass of grassland communities has a linear relationship with precipitation under three land‐use practices, while plant species number, soil C, and total soil N have linear relationships with precipitation under fencing and mowing; under grazing the relationships are non‐linear. 2. Plant species number, soil C and total soil N have strong linear relationships with above‐ground biomass under both fencing and mowing, while they seem to have nonlinear relationships under grazing. 3. Land‐use practices along the precipitation gradient result not only in changes in grassland communities but also in qualitative changes of their structure and function. 4. Grasslands are more vulnerable to changes in climate under mowing than under fencing, and are more capable to store C in soil and plants. 5. At a given precipitation level, number of plant species, above‐ground biomass, and soil C are higher under low to medium intensity of human activities (mowing and grazing). A better understanding of how different intensities of human activities will affect the structure and function of grassland will require further research.     

克氏针茅草原植物叶片性状对放牧强度的响应

放牧干扰是影响草地植物性状的方式之一,植物叶片性状能够客观反映植物对生长环境的适应性.本文以呼伦贝尔克氏针茅草原不同放牧强度的样地为研究区,探讨叶片性状间的相互关系及在不同放牧梯度上和不同生活型功能群之间的变化规律.结果表明:克氏针茅草原植物的主要叶片性状在不同生活型植物之间差异均不显著,但是各个性状之间的相关性较强.在放牧梯度上,重度放牧样地上叶片磷含量和氮磷比值与中度放牧区和轻度放牧区有显著差异;在生活型功能群分类中,放牧对多年生杂草的叶片磷含量和氮磷比值有显著影响,表明多年生杂草对放牧较为敏感,重度放牧改变了植物养分利用策略.合理放牧可以改善克氏针茅草原植物养分性状并有利于遏制草原的退化.     

放牧方式对中蒙典型草原植物功能群特征的影响

基于中蒙典型草原不同放牧方式,研究了不同放牧方式下中蒙典型草原植物功能群特征。结果显示,内蒙古定居放牧样地多年生草本比例显著低于其它放牧样地,比例为57.576%;而旱生植物比例显著高于其它放牧样地,比例为69.697%。蒙古四季游牧样地功能群多样性指数和优势度指数均高于内蒙古放牧样地,均匀度指数与多样性指数相反。功能群多样性指数与优势度指数间呈显著正相关（r＞0.855,P＜0.05）;均匀度与多样性指数、优势度指数间均呈负相关。多年生和一年生草本植物、旱生和中旱生植物的生态位宽度均较大,从而导致多年生与一年生植物间、旱生与中旱生植物间生态位重叠值相应较大。说明,不合理的放牧导致草原植被群落退化,降低草原生态经济价值。     

Vole mound effects and disturbance rate in a mediterranean plant community under different grazing and irrigation regimes

A factorial field experiment was used to assess the influence of soil-disturber mammals in the structure of a 9-year-old Mediterranean annual plant community subjected to different sheep grazing and irrigation regimes. We estimated the disturbance rate (mound building activity) by Mediterranean voles, their effects on vegetation and the mechanisms of these effects during a period of vole outbreak. The effects on vegetation were analysed at the levels of species, functional groups and plant community. Disturbance rate was high and voles can disturb the entire soil surface once every four or five years. The availability of certain trophic resources (perennial plants) appeared to drive vole expansion in the experimental plots and it was independent of the irrigation and grazing treatments. Mound building activities largely affected vegetation but conserved plot differences. Total vegetation cover, absolute cover of all functional groups, mean vegetation height and species richness were less on mounds than on undisturbed ground. These effects did not change the relative abundance of annuals, perennials, grasses and forbs. Only the relative abundance of small-seeded species decreased on mounds. As the proportion of these seeds was similar in both types of patches, we suggest that small-seeded species had more difficulties for germinating or emerging when they are buried during mound formation. Irrigation and sheep grazing promoted large changes in the vegetation parameters but these effects were, in general, similar on mounds and undisturbed ground. Our results show that the availability of germinable seeds may be the major limitation for mound revegetation, probably due to the scarcity of seeds existing at the depths from which soils are excavated. Our results also suggested a resource limitation on mounds. The results provide additional evidence that soil disturbances by small herbivore mammals exert relevant ecological effects on abandoned Mediterranean croplands. We discuss the ecological implications of vole mound-building activities for plant succession, plant species conservation and forage resource availability for livestock. This revised version was published online in June 2006 with corrections to the Cover Date.