Ecological stoichiometry explains larger-scale facilitation processes by shrubs on species coexistence among understory plants

Plant facilitation (positive plant–plant interactions) strongly influences biodiversity, structure, and dynamics in plant communities, and the topic has received considerable attention among ecologists. Most studies of facilitation processes by shrubs have been conducted at small spatial scales between shrubs and their neighboring species. Yet, we know little about whether facilitation processes by shrubs at a small scale (i.e., a patch scale) also work at a larger scale (i.e., a site scale) in terms of the maintenance of biodiversity. Here, we report that the facilitative effects of shrubs on plant diversity at a larger scale can be explained by changing ecological stoichiometry. The soil fertility showed unimodal shape along shrub cover gradient, suggesting that the facilitative effects of a shrub do not necessarily increase as the shrub develops. The unimodal shape of dependence of plant species richness on shrub cover probably was generated by the unimodal dependence of soil fertility on shrub cover. Soil nutrient enrichment by shrubs shifted low N:P ratios of plant communities with low levels of shrub cover to more balanced N:P ratios at intermediate levels of shrub cover. At the peak N:P ratio along the gradient in shrub cover, the maximum species richness and functional richness were observed, which was consistent with the unimodal relationship predicted by the resource balance hypothesis. Thus, our findings showed that facilitation processes by shrubs at a patch scale also work at a larger scale in terms of the maintenance of biodiversity. Because observed larger-scale facilitation processes are enhanced at some intermediate levels of shrub cover, this study offers practical insight into the need for management practices that allow some intermediate levels of grazing by livestock for optimizing the role of larger-scale facilitation processes in the maintenance of biodiversity and ecosystem functioning in arid and semi-arid rangelands.     

Additive Partitioning of Diversity Reveals No Scale-dependent Impacts of Large Ungulates on the Structure of Tundra Plant Communities

Large herbivores can change ecosystem functioning by impacting plant diversity. However, although such impacts are expected to be scale-dependent in ecosystems with wide-roaming ungulates, scaling issues rarely enter empirical assessments. We here test the hypothesis that the impact of increased reindeer abundance on plant diversity in alpine tundra is scale-dependent. Based on potentially high productivity of the focal habitat units and hence the possibility of positive grazer impacts on plant diversity we predicted higher α and β diversity at the habitat scale where reindeer densities are high. We also explored whether there were differences in diversity patterns at larger scales, including the scale of reindeer management districts. We estimated grazing disturbance as high versus low reindeer density in selected districts (a total extent of 7421 km²) of Northern Norway where reindeer-induced vegetation shifts are debated. We focus on dominance patterns because they can quantify the vegetation state and thus performed additive partitioning of Simpson diversity on multiple scales assessing also species’ contributions to diversity. Contrary to our predictions, we found only weak scale-dependent effects of reindeer grazing on plant diversity. Under high reindeer densities there was evidence for a landscape-scale homogenization of the vegetation, but the predicted α and β diversity increases at the habitat scale were not found. Consistently through all scales considered, four shrub species contributed the most to plant diversity. These results contradict the idea that reindeer at high stocking densities induce shifts in plant species dominance in productive habitats. We conclude that context-dependencies such as spatial scales of management units and habitat types need to be explicitly considered in evaluations of the impacts of large ungulates on plant diversity.     

Effects of Prosopis flexuosa on soil properties and the spatial pattern of understorey species in arid Argentina

Abstract. In arid zones dominant woody plants are capable of causing changes in microclimate and soil properties likely to affect species composition, as well as the establishment and spatial distribution of plant species. In North American and European deserts species richness appears to be higher under the canopy of shrubs and trees, in contrast with Chilean deserts where it seems to be lower. Since Prosopis flexuosa (Fabaceae, Mimosoideae) is the most conspicuous tree in the central Monte desert, Argentina, we analysed the effect of this species on the composition and abundance of the shrub and herbaceous layers and on soil properties. We considered two mesohabitats: ‘under P. flexuosa canopy’ and ‘intercanopy areas’. In addition, we analysed the differences between two microhabitats under canopies: ‘northern part of the canopy’ and ‘southern part of the canopy’. Results indicate that species composition and soil properties are affected by both mesohabitats and microhabitats. We found a higher number of shrubs under canopies, whereas that of grasses and perennial forbs increased in intercanopy areas. Concentrations of organic matter, nitrogen, potassium and phosphorus, factors limiting biological productivity in Monte desert soils, were significantly higher under than outside P. flexuosa canopies. Electrical conductivity and concentrations of Na⁺, Ca⁺⁺, Mg⁺⁺ were higher in the northern than in the southern microhabitats. No differences in species richness, evenness or diversity were found between mesohabitats or between microhabitats. We conclude that P. flexuosa modifies the spatial pattern of plant species in the shrub and herbaceous layers and the chemical conditions of the soil, generating spatial heterogeneity on different scales.     

Habitat engineering under dry conditions: The impact of pikas (Ochotona pallasi) on vegetation and site conditions in southern Mongolian steppes

Question: Does ecosystem engineering by small mammals have a significant influence on vegetation patterns in the arid steppe vegetation of southern Mongolia? Location: Gobi Altay Mountains, southern Mongolia. Methods: We assessed the impact of the small lagomorph Ochotona pallasi on plant community composition, nutrient levels and biomass production in montane desert steppes. Data were derived from vegetation relevés, harvests of above‐ground standing crop and a bioassay, followed by analyses of soil and plant nutrient contents. Results: Although the local climate is arid with <150 mm annual precipitation, clear evidence of allogenic ecosystem engineering was found. Plant communities on burrows differed from those on undisturbed steppe in that they contained more species of annuals and dwarf shrubs, and a greater abundance of the important fodder grass Agropyron cristatum. Standing crop and nutrient concentrations were higher for plants growing on burrow soil. In situ measurements and a pot experiment showed that this effect was related to increased levels of soil nutrients (P, K, N) rather than moisture availability. Conclusions: The study confirms that O. pallasi positively influences soil nutrient levels on its burrows, which leads to increased grassland productivity even under dry conditions. Thus, O. pallasi does not deteriorate site conditions, and the need for presently applied pest control schemes aimed at this species should be reassessed.     

Positive effects of shrubs on herbaceous species richness across several spatial scales: evidence from the semiarid Andean subtropics

Question: What is the effect of shrubs on herbaceous species richness at three spatial scales: quadrat, site, and region? Location: Prepuna, subtropical semi‐arid Andes. Methods: At eight sites, we recorded the presence of herbaceous species in spaces beneath shrubs/small trees and in open areas. At the quadrat scale, the average species number per quadrat was calculated and compared between the two microhabitats (shrubs/open). At the local (site) scale, all quadrats of each site were pooled according to microhabitat, and all sites were then combined for the regional analysis. Results and conclusions: We found greater herbaceous species richness below shrubs at all three spatial scales considered. Several species were found exclusively associated with the shrub undercanopy. This effect seems to depend more on greater inventory diversity at the different scales than on greater differentiation diversity in the herbaceous communities associated with shrubs. Facilitation seems to be responsible for the increase of species richness beneath shrubs, but further experimental study is needed to obtain insight into the underlying mechanisms.     

荒漠灌丛土壤动物分布及其生态功能

在干旱、半干旱荒漠生态系统中,灌丛作为一种重要的植被类型,其独特的形态和生理适应特性能够有效促进退化生态系统结构与功能的恢复。土壤动物是荒漠生态系统中不可或缺的重要组成部分,对促进灌丛"肥岛"演变具有重要的生态作用,有利于灌丛生态功能的发挥及退化生态系统的恢复。近年来,国内外学者对荒漠灌丛微生境土壤动物的研究逐步深入,取得大量的研究成果。在此基础上,首先综述荒漠灌丛微生境土壤动物群落分布和生态功能,总结灌丛与土壤动物分布间作用关系的数学模型,针对荒漠灌丛土壤动物研究中存在的问题提出了未来可能的研究方向和建议。     

乌鲁木齐地区典型灌木群落结构特征及其多样性研究

根据2013年对乌鲁木齐地区典型灌木群落野外50个样地调查的数据,结合双向指示种分析分类方法,从各群落基本特征、物种组成、区系特征、物种多样性等方面对乌鲁木齐地区典型灌木群落结构特征及其多样性进行了分析。结果表明:(1)被调查的50个样地灌木植被群落中共出现了169种植物(其中灌木植物36种,草本植物133种),隶属于118属,31科,其中以藜科、菊科、禾本科等干旱区的表征科居多。灌木物种的植物区系以地中海区、西亚至中亚分布和北温带分布为主。(2)采用TWINSPAN分类方法可将50个样方划分为10个灌木群落类型。乌鲁木齐地区典型灌木群落多样性指数偏低,黑果小檗+宽刺蔷薇+金丝桃叶绣线菊群落的多样性指数最大,群落之间水平差异显著;欧亚圆柏群落、宽刺蔷薇+矮锦鸡儿群落和铃铛刺+喀什菊群落次之;多枝柽柳群落和琵琶柴+喀什霸王群落最低。(3)属于灌丛植被类型的灌木群落,物种多样性指数为草本层灌木层;属于荒漠植被类型的灌木群落,物种多样性空间结构为灌木层草本层。     

Patterns of plant biodiversity in the woodland-steppe ecotone in southeastern Inner Mongolia

Biodiversity patterns of the woodland-steppe ecotone in southeastern Inner Mongolia were investigated. Controlled by climatic factors, the plant species diversity of the woodland-steppe ecotone is moderate as compared with the adjacent woodland and steppe communities. From woodland through woodland-grassland and woodland-steppe to steppe, about 2/3 species were replaced at each boundary; only seven herb species were detected to be distributed in all four vegetation zones. Landscape classification based on landform, climate, and vegetation shows that landform condition is most critical to landscape diversity in the studied area. The most fragmented landform in the woodland zone does not necessarily lead to low plant species diversity. However, similar understory species in different woodland types lead to continuous woodland vegetation and, hence, high species richness. High fragmentation in the woodland-steppe zone and discontinuous distribution of woodlands might be a driving factor for lower species richness. Reconstruction of the Holocene climatic changes and vegetation development demonstrates that the highest plant species diversity occurred in the ecotone from 4500 to 2500 ¹⁴C yr BP at different sites, while the woodland zone extended much farther northwestward. When woodlands retreated from the current ecotone with climatic drying, the fragmentation of woodlands in the current ecotone led to plant species loss.     

Expansion of Rosa rugosa and Hippophaë rhamnoides in coastal grey dunes: Effects at different spatial scales

The study analysed the effects of shrub expansion on vegetation composition and plant species diversity in coastal grey dunes on the North Sea island Spiekeroog, comparing Rosa rugosa and Hippophaë rhamnoides. Species composition was recorded in plots of two spatial scales, 1 and 16 m², considering the full range of shrub cover from less than 10 to almost 100%. Although R. rugosa and H. rhamnoides established and spread in the same grey dune environment, the vegetation of the two shrubland types was much different. While the H. rhamnoides plots were relatively species-rich, characterised by remnant grey dune vegetation with many small, often annual, light-demanding species except in the densest shrubs, the R. rugosa plots were clearly species-poorer due to the loss of many typical grey dune species, including only few shade-tolerant taxa. The total number of species, the number of herbaceous species and of species typical for grasslands decreased with increasing cover of H. rhamnoides and R. rugosa at both spatial scales. For the number of shrubs and shrubland species, hardly any significant effects of shrub cover were observed in R. rugosa, while there were positive effects in H. rhamnoides. Both the Shannon index and evenness decreased with increasing cover of the two shrub species at both spatial scales. Here, the decline in species diversity was more improved in R. rugosa than in H. rhamnoides.     

小叶、中间和柠条三种锦鸡儿的分布式样及其生态适应

确定了小叶锦鸡儿、中间锦鸡儿和柠条锦鸡儿3种植物的分布式样:小叶锦鸡儿为蒙古高原东部-F松辽平原西部-华北山地分布种,中间锦鸡儿为东戈壁-鄂尔多斯高原-黄土高原北部分布种,柠条锦鸡儿为南阿拉善-西鄂尔多斯分布种。小叶锦鸡儿适应分布于蒙古高原典型草原带和森林草原带以及华北山地落叶阔叶林带,在草原带高平原上可形成灌丛化草原的景观,在草原带的沙地上可形成以小叶锦鸡儿为建群种的沙地灌丛植被;中间锦鸡儿适应分布于蒙古高原的荒漠化草原及草原化荒漠带、鄂尔多斯高原的典型草原和荒漠化草原带的沙地及梁地上、黄土高原北部的黄土丘坡上,常形成以中间锦鸡儿为建群种的沙地灌丛植被;柠条锦鸡儿则适应分布于草原化荒漠和典型荒漠带的固定和半固定沙地上。近缘的3种锦鸡儿的地带性分布从东至西或从北向南形成明显的有规律的地理替代分布格局。     

荒漠草原与典型草原NPP、碳积累对不同降雨年份和利用方式的响应

不同草原利用方式正在影响着内蒙古的草原生态系统,而且在未来降水空间格局变化的背景下,它们共同决定了生态系统植被类型、净初级生产力(NPP)和生态系统碳积累。选取内蒙古中部两个重要的草地类型:荒漠草原和典型草原,研究不同草原利用方式(围栏禁牧、划区轮牧、割草、自由放牧)植物群落在降雨量不同的两个生长季节地上(ANPP)、地下净初级生产力(BNPP)的变化,同时也评估了植物群落的碳积累,研究结果表明:1)在降雨量亏缺年份,与围封相比,荒漠草原自由放牧区ANPP、BNPP及碳积累分别下降了57.1%、51.7%和56.0%,而典型草原自由放牧区分别下降了18.4%、25.1%和17.9%。2)在降雨量充足年份,与围封相比,荒漠草原划区轮牧区ANPP、BNPP以及碳积累分别增加了18.2%、9.8%和21.9%,而典型草原各处理下围封禁牧区ANPP仍是最高;3)两种草地类型下,降雨量对自由放牧的调控作用高于其它草地利用方式;4)荒漠草原ANPP在丰雨年是欠雨年的2倍,而典型草原仅增加了79.0%,降雨量对荒漠草原生产力的季节调控作用远高于典型草原。在未来全球气候变暖和降水格局变化的情况下,荒漠草原降雨量是影响荒漠植物群落NPP和碳积累的主导因子。     

Influence of Vegetation on Bat Use of Riparian Areas at Multiple Spatial Scales

ABSTRACT Research on habitat use by bats typically occurs at a single fine spatial scale, despite recent work demonstrating the importance of considering multiple spatial scales when investigating vertebrate habitat selection. We assessed bat use of 118 stream reaches located throughout the Oregon Coast Range, USA, and measured vegetation characteristics at 3 spatial scales surrounding each of these locations. We used an information-theoretic approach to determine vegetation characteristics most closely related to bat activity and a multilevel modeling approach to evaluate variation in bat activity at different spatial scales. Characteristics of vegetation at the finest spatial scale explained more variation in bat activity than did characteristics of vegetation at broader spatial scales, suggesting that fine-scale anthropogenic or natural disturbance events that alter cover of shrubs or trees in riparian areas are likely to influence bat habitat use. The influence of vegetation on activity varied by species of bat and appeared to operate more strongly through constraints imposed by vegetation architecture than through influences on abundance of insect prey. This diversity of responses to vegetation characteristics among bat species suggests that the best strategy for biodiversity conservation over broad spatial scales is maintenance or creation of a diversity of riparian vegetation conditions. We recommend that land managers planning to manipulate riparian vegetation strive to create diversity in shrub coverage, canopy coverage, and open space above the stream channel to promote foraging habitat for all species.     

荒漠草原人工灌丛化对蒸散发及其组分的影响——以盐池县为例

我国西北防沙治沙工程中大量的种植中间锦鸡儿(Caragana intermedia)会导致荒漠草原发生灌丛化现象,研究人工灌丛化对荒漠草原蒸散发的影响,不仅能够揭示半干旱区人为活动对生态系统水循环的影响机理,还可以指导区域生态治理实践。以宁夏盐池县荒漠草原为例,基于植被的生理生态参数和荒漠草原水热条件,采用生物地球化学模型(Biome Bio-Geochemical Cycles,Biome-BGC)和地球呼吸系统模拟模型(Breathing Earth System Simulator,BESS)结合的方法,模拟荒漠草原生态系统人工灌丛引入前后蒸散发及其组分的变化,定量研究荒漠草原人工灌丛化对区域生态水文循环中蒸散发的影响。结果表明,人工灌丛的引入使植被结构及特征发生了变化,叶面积指数(Leaf Area Index,LAI)年最大值由0.20增加为0.67,改变了植被年内与年际变化特征。荒漠草原人工灌丛化后,生态系统年均蒸散发由251.74 mm增加到了281.42 mm;人工灌丛化对生长季的蒸散发增强明显,8月蒸散发峰值时,日均蒸散发由1.27 mm/d增加到1.56 mm/d。灌丛化过程使生态系统蒸腾量平均增加了1.35倍,蒸发量增加了1.06倍,改变了生态系统蒸散发的组分结构,导致蒸发比例降低、蒸腾比例增高。由此可知,荒漠草原在防沙治沙和生态治理中大量种植灌木的现象,加大了区域生态系统的蒸散发,并改变了水分耗散结构,从而对生态系统地气水汽交换有较大影响,研究结论对荒漠草原生态治理及未来的植被重建有一定的借鉴意义。     

Grazing effects on the species‐area relationship: Variation along a climatic gradient in NE Spain

Questions: Does grazing have the same effect on plant species richness at different spatial scales? Does the effect of spatial scale vary under different climatic conditions and vegetation types? Does the slope of the species‐area curve change with grazing intensity similarly under different climatic conditions and vegetation types? Location: Pastures along a climatic gradient in northeastern Spain. Methods: In zones under different regimes of sheep grazing (high‐, low‐pressure, abandonment), plant species richness was measured in different plot sizes (from 0.01 to 100 m2) and the slope of the species‐area curves was calculated. The study was replicated in five different locations along a climatic gradient from lowland semi‐arid rangelands to upland moist grasslands. Results: Species richness tended to increase with grazing intensity at all spatial scales in the moist upland locations. On the contrary, in the most arid locations, richness tended to decrease, or remain unchanged, with grazing due to increased bare soil. Grazing differentially affected the slope (z) of the species‐area curve (power function S=c A^z) in different climatic conditions: z tended to increase with grazing in arid areas and decrease in moist‐upland ones. ß‐diversity followed similar pattern as z. Conclusions: Results confirm that the impact of grazing on plant species richness are spatial‐scale dependent. However, the effects on the species‐area relationship vary under different climatic conditions. This offers a novel insight on the patterns behind the different effects of grazing on diversity in moist vs. arid conditions reported in the literature. It is argued that the effect of spatial scale varies because of the different interaction between grazing and the intrinsic spatial structure of the vegetation. Variations in species‐area curves with grazing along moisture gradients suggest also a different balance of spatial components of diversity (i.e. a‐ and ß‐diversity).     

天山北坡植物土壤生态化学计量特征的垂直地带性

生态化学计量工作专注于植物与土壤的元素比例关系及其环境解释等问题上,还需要分析在连续环境梯度上元素比例关系的变化规律以进一步加深已有的认识。受水热梯度的影响,植被与土壤在天山北坡均存在明显的垂直地带性,这为探讨植物土壤生态化学计量特征的垂直带谱提供了有利条件。在天山中段北坡海拔1000—3840m范围内,按海拔梯度对植物和土壤分别采样,测定其C、N、P含量。结果表明:(1)随海拔的升高,植物C、N、P含量及其计量比变化规律各不相同,C含量随海拔变化保持不变,仅山地针叶林显著低于亚高山灌丛草甸、高山垫状植被和山前灌木(P0.05);N含量、C∶P、N∶P随海拔先升高后降低,山地针叶林和亚高山灌丛草甸显著高于山地荒漠草原、山地草原、高山垫状植被(P0.05);P含量、C∶N则是随海拔先降低后升高,高山垫状植被显著高于其他植被类型,山地荒漠草原、山前灌木和高山草甸显著高于山地草原、针叶林和亚高山灌丛草甸(P0.05)。(2)从生活型角度,乔木、灌木和草本C、N含量、C∶N差异不显著,灌木P含量、C∶P、N∶P显著高于草本(P0.05);乔木和灌木更受P限制,草本更受N限制。(3)随海拔的升高,土壤C、N、P含量、C∶P、N∶P均先升高后降低,其中山地针叶林和亚高山灌丛草甸均显著高于山地荒漠草原和山地草原(P0.05),土壤C∶N表现为一直降低,山地荒漠草原显著高于其他植被类型(P0.05)。(4)植物C、N、P及计量比与土壤相关性分析中,仅植物C∶P与土壤C∶P相关性显著,且植物C、N、P含量与土壤相关系数小于植物C∶P、N∶P与土壤相关系数。在垂直地带性上,土壤主要通过生态化学计量比影响植物的生长。     

The relationship between species richness and productivity in four typical grasslands of northern China

The relationship between plant species richness and primary productivity has long been acentral topic in biodiversity research.In this paper,we examine the relationship between species richness and productivity in four typical grasslands of Northern China at different spatial scales.At the community scale,a positive correlation was found for six of seven communities.A unimodal pattern was found only for one community (Stipa glareosa community),while at a large scale (vegetation type or landscape/region),the relationship was also found significantly positive.Species richness ranged from 4 to 35 species,and community aboveground productiand aboveground productivity were found in alpine meadow,followed by meadow steppe,typical steppe and desert steppe.     

贺兰山不同海拔典型植被带土壤微生物多样性

土壤微生物多样性在海拔梯度的分布格局研究近年来受到和植物动物一样的重视程度,但是干旱风沙区微生物多样性在海拔梯度上的多样性分布规律尚未揭示。本研究以处于干旱风沙区的贺兰山不同海拔的六个典型植被带（荒漠草原带、山地旱生灌丛带、温性针叶林带、针阔混交林带、寒温性针叶林带和亚高山草甸带）土壤为研究对象,利用Biolog微平板法和磷脂脂肪酸甲酯法(FAMEs)系统研究微生物多样性群落特征以及在不同植被带分布规律。结果表明：土壤微生物功能多样性随海拔增加发生变化,且微生物群落结构存在显著差异。Biolog分析显示土壤微生物群落代谢活性依次是：亚高山草甸>寒温性针叶林>针阔混交林>温性针叶林>山地旱生灌丛>荒漠草原,随海拔的升高土壤微生物群落物种丰富度指数（H）和均匀度指数（E）总体上均表现出增大的趋势,差异显著（P＜0.05）;FAMEs分析表明不同海拔的微生物区系发生了一定程度的变化,寒温性针叶林土壤微生物磷酸脂肪酸生物标记的数量和种类均最高,且细菌、真菌特征脂肪酸相对含量也最高;土壤微生物群落结构多样性次序是：寒温性针叶林带>针阔混交林带>温性针叶林带>亚高山草甸>山地旱生灌丛>荒漠草原。本研究结果表明贺兰山海拔梯度的微生物多样性分布规律不同于已有的植物多样性“中部膨胀”研究结果,这说明在高海拔地区有更多的适合该生境的微生物存在,这对维持干旱风沙区的生态系统功能稳定性具有重要意义。     

Community organization and species richness of ants (Hymenoptera/Formicidae) in Mongolia along an ecological gradient from steppe to Gobi desert

Aim Ants (Hymenoptera/Formicidae) have strong influences on ecosystems especially in arid regions. However, little is known about ants of the vast steppe and desert regions of Central Asia. Here we provide the first comprehensive study of ant communities in Mongolia, conducted along a north‐to‐south gradient in climate. We examined ants’ distribution patterns, assessed the impact of climatic parameters on community structure and species diversity and investigated the influence of the corresponding communities of plants. Location Mongolia (Central Asia). Methods We observed 31,956 ants at seed baits at 11 study sites along a transect from steppe to Gobi desert for which we attained meteorological data (mean yearly precipitation: 197 to 84 mm). Extra sampling was conducted at sugar and protein baits and by the inspection of different microhabitats. Vegetation patterns of each plot were recorded. Statistical evaluation comprised ordination and correlation. Results We observed 15 species of ants at seed baits. Three faunal complexes of ants could be distinguished by detrended correspondence analysis (DCA): (1) in steppe baits were dominated by Formica‐ and Myrmica‐species, (2) in semi desert we found mostly species of Tetramorium, Myrmica, Proformica, Plagiolepis, and Leptothorax, and (3) in desert Cataglyphis aenescens and Messor aciculatus dominated, and Lasius was exclusively found there. Another 11 rare ant species were sampled by hand and at sugar baits. Altogether five ant species were new to the Mongolian fauna: Cardiocondyla koshewnikovi, Myrmica koreana, Myrmica pisarskii, Polyergus nigerrimus, and Proformica kaszabi. Assignment of taxa to functional groups showed that in steppe cold climate specialists dominated, in semi desert we found mainly opportunists, and in desert hot climate specialists. Several functional groups know from arid zones in other parts of the world were missing. In desert certain species were highly dominant. First DCA scores of ant‐ and plant‐communities were highly correlated with each other and with climatic parameters. While plant species diversity was positively correlated with increasing northern latitude, ant diversity and ant species richness were not correlated with latitude and responded neither to precipitation, nor to any other climatic parameter. Semi desert was a transition zone between steppe and desert, with high species richness. Ant genus composition of the ecotone overlapped with both other regions. However, beta diversity between pairs of plots within this zone was low, indicating a small‐scale mosaic pattern. Main conclusions The ant communities in the Mongolian steppe and desert zones were strongly influenced by low temperatures and differed in many aspects from the ant fauna in other arid ecosystems, especially in terms of species richness, diversity of feeding guilds, and richness of functional groups.     

Grassland composition,structure, and diversity patterns along major environmental gradients in the Central Tien Shan

What species and traits signal vegetation types along prominent environmental gradients in the Central Tien Shan and what are the corresponding diversity patterns? Vegetation was sampled at 41 sites throughout the Kyrgyz Republic using quadrats stratified throughout a 1,000-m² sample area. Relationships among major environmental gradients, vegetation structure, and species composition were explored with nonmetric multidimensional scaling. Species distributions were examined to characterize phytogeographic patterns. Seven vegetation types ranging from desert grassland to meadow steppe were identified with cluster analysis, ordered primarily along elevation/mean annual temperature gradients. Four arid grassland types were distinguished, ranging mainly from 900 to 1,700 m elevation, and characterized by co-dominance of grasses and forbs with secondary dominance by shrubs. Annual and biennial forbs equaled perennial forbs in total importance. Grasses include C3 and C4 species. Three montane grassland types were recognized and characterized by co-dominance of perennial C3 grasses and forbs. Transition to montane steppe occurred from 1,500 to 1,900 m and is correlated with absence of C4 grasses and dominance of Festuca valesiaca. Highest diversity was found at intermediate elevations, from 1,800 to 2,600 m, in meadow steppe habitats. Forty-six percent of 580 identified species are Middle Asian endemics and remaining species primarily have distributions including Eastern Europe, the Caucasus, and western Siberia. Although grassland degradation from overgrazing has been chronic throughout the region, grasslands are widespread throughout the Kyrgyz Republic and many, particularly mid-elevation meadow steppes, retain high levels of native species diversity.     

Phylogenetic structure and formation mechanism of shrub communities in arid and semiarid areas of the Mongolian Plateau

The mechanisms of species coexistence within a community have always been the focus in ecological research. Community phylogenetic structure reflects the relationship of historical processes, regional environments, and interactions between species, and studying it is imperative to understand the formation and maintenance mechanisms of community composition and biodiversity. We studied the phylogenetic structure of the shrub communities in arid and semiarid areas of the Mongolian Plateau. First, the phylogenetic signals of four plant traits (height, canopy, leaf length, and leaf width) of shrubs and subshrubs were measured to determine the phylogenetic conservation of these traits. Then, the net relatedness index (NRI) of shrub communities was calculated to characterize their phylogenetic structure. Finally, the relationship between the NRI and current climate and paleoclimate (since the Last Glacial Maximum, LGM) factors was analyzed to understand the formation and maintenance mechanisms of these plant communities. We found that desert shrub communities showed a trend toward phylogenetic overdispersion; that is, limiting similarity was predominant in arid and semiarid areas of the Mongolian Plateau despite the phylogenetic structure and formation mechanisms differing across habitats. The typical desert and sandy shrub communities showed a significant phylogenetic overdispersion, while the steppified desert shrub communities showed a weak phylogenetic clustering. It was found that mean winter temperature (i.e., in the driest quarter) was the major factor limiting steppified desert shrub phylogeny distribution. Both cold and drought (despite having opposite consequences) differentiated the typical desert to steppified desert shrub communities. The increase in temperature since the LGM is conducive to the invasion of shrub plants into steppe grassland, and this process may be intensified by global warming.