Patterns of species turnover are central to the geography of biodiversity and resulting challenges for conservation, but at broad scales remain relatively little understood. Here, we take a first spatially-explicitly and global perspective to link the spatial turnover of species and environments. We compare how major groups of vertebrate ectotherms (amphibians) and endotherms (birds) respond to spatial environmental gradients. We find that high levels of species turnover occur regardless of environmental turnover rates, but environmental turnover provides a lower bound for species turnover. This lower bound increases more steeply with environmental turnover in tropical realms. While bird and amphibian turnover rates are correlated, the rate of amphibian turnover is four times steeper than bird rates. This is the same factor by which average geographic ranges of birds are larger than those of amphibians. Narrow-ranged birds exhibit rapid rates of species turnover similar to those for amphibians, while wide-ranged birds largely drive the aggregate patterns of avian turnover. We confirm a strong influence of the environment on species turnover that is mediated by range sizes and regional history. In contrast to geographic patterns of species richness, we find that the turnover in one group (amphibians) is a much better predictor for the turnover in another (birds) than is environment. This result confirms the role of amphibian sensitivity to environmental conditions for patterns of turnover and supports their value as a surrogate group. This spatially-explicit analysis of environmental turnover provides understanding for conservation planning in changing environments.

<p>Beta diversity is an important component of biological diversity, measuring compositional change in species assemblages across temporal and spatial scales. Beta diversity concerns not only a number of ecological and evolutionary issues, but can also guide the selection of protected areas and help to optimize conservation networks. It has thus become a hot topic in biodiversity research in recent years. Researchers have used various measures and analytical methods to investigate patterns of beta diversity and its underlying mechanisms for various taxa and in different regions. Here, we reviewed literature from the past decade pertaining to the following aspects of beta diversity: metrics, temporal and spatial patterns, determinants and applications in biodiversity conservation. Whittaker introduced the term beta diversity in 1960, but defined it vaguely. As the concept of beta diversity evolved, a high variety of measures were developed to quantify the concept. The comparison of results from different studies may be hindered by the variety of measures used to quantify beta diversity. Presently, the most popular methods for measuring beta diversity are similarity/ dissimilarity coefficients such as Jaccard index and S&oslash;rensen index. In the last few years, several methods to quantify beta diversity have emerged, some of which are worth noting. Beta diversity depends on temporal scale, spatial scale and taxonomic scale, and decreases with increasing analytical grain size. There is no consensus among scientists that beta diversity decreases with latitude, i.e. that it is higher in tropics and lower near the poles. Beta diversity is high within mountain ranges and at the interface of biogeographic realms; thus, larger/more reserves are needed in these regions to cover the entire gradient of species turnover. Studies on beta diversity across temporal scales have shown that climatic change has resulted in shifts in species composition through time, and that the migration of species between different continents/regions has led to biotic homogenization. Based on a thorough review of beta diversity literature, we think the following questions might be the focus of future research: (1) the influence of evolutionary history and biological characteristics of different taxonomic groups on their beta diversity; (2) the influence of temporal/spatial scales on beta diversity and its determinants; and (3) the effect of anthropogenic activities on beta diversity.</p>

Beta多样性度量时空尺度上物种组成的变化, 是生物多样性的重要组成部分, 与许多生态学和进化生物学问题密切相关, 并且其信息可用于保护区选址和布局规划, 因此在最近10年间成为生物多样性研究的热点问题之一。多年来, 学者们利用各种度量方式和分析方法, 在不同地理区域, 对许多生物类群beta多样性的时空格局和形成机制进行了大量研究。本文主要从beta多样性的度量方法、时空格局、形成机制及其在生物多样性保护中的应用等几个方面, 总结了最近10多年来相关研究的进展。Whittaker(1960)最初提出beta多样性概念时就缺乏严格的定义, 随着概念的不断演化, 度量方法也同样呈现出多样化, 而度量手段的多样化非常不利于不同研究之间的比较。目前应用最普遍的度量方法是采用相似性指数, 如Jaccard和S&oslash;rensen指数。最近几年, 新的度量方法还在不断出现, 其中一些方法非常值得注意。Beta多样性具有时空尺度和分类尺度依赖性, 一般随分析粒度(grain)的增加而降低。虽然有些研究表明beta多样性随纬度增加而降低, 但学者们并没有达成共识。山区和生物地理区的交界处beta多样性都比较高, 因而需要在这些地区增加保护区的面积或者数量以囊括物种变化梯度。对时间尺度上beta多样性的研究表明, 气候变化确实导致了物种组成在时间上的变化, 并且物种在不同大陆和地区间的迁移导致了生物同质化。扩散过程和生态位过程共同决定了beta多样性, 只是这两个过程的相对重要性依尺度、地理区域和物种类群的不同而有所差异。综上所述, 我们认为未来beta多样性研究的热点问题是：(1)不同生物类群的进化历史和生物学特征对beta多样性的影响; (2)不同的时空尺度对beta多样性及其维持机制的影响; (3)人类活动对beta多样性的影响。

The role of deterministic and stochastic processes in community assembly is a key question in community ecology. We evaluated the effect of an abiotic filter (hydroperiod) on the partitioned diversity of three taxonomic groups (birds, vegetation, macroinvertebrates) from prairie pothole wetlands in Alberta, Canada, which naturally vary in water permanence. We observed that alpha and gamma diversity were higher in permanent than temporary wetlands (16-25% and 34-47% respectively, depending on the taxon). This suggests an influence of deterministic constraints on the number of species a wetland can support. Taxa which cannot persist in shallow, temporary wetlands are excluded by the deterministic constraints that a shortened hydroperiod imposes. In contrast, we observed that beta diversity was significantly higher (2-12%) in temporary wetlands than permanent ones, and temporary wetlands supported more unique combinations of community composition than permanent wetlands, despite having a smaller regional species pool. This observation contradicts prior mesocosm studies that found beta diversity mirrored the pattern in gamma diversity along an environmental filtering gradient. We conclude that deterministic processes are more influential in more stable permanent wetlands, whereas stochastic processes play a more important role in assembly in dynamic temporary wetlands that must disassemble and re-establish annually. Considering three distinct taxonomic groups differing in their relative mobility, our large-scale field study demonstrates that both stochastic and deterministic processes act together to influence the assembly of multiple communities and that the relative importance of the two processes varies consistently along a gradient of environmental filtering.

The classical environmental control model assumes that species distribution is determined by the spatial variation of underlying habitat conditions. This niche-based model has recently been challenged by the neutral theory of biodiversity which assumes that ecological drift is a key process regulating species coexistence. Understanding the mechanisms that maintain biodiversity in communities critically depends on our ability to decompose the variation of diversity into the contributions of different processes affecting it. Here we investigated the effects of pure habitat, pure spatial, and spatially structured habitat processes on the distributions of species richness and species composition in a recently established 24-ha stem-mapping plot in the subtropical evergreen broad-leaved forest of Gutianshan National Nature Reserve in East China. We used the new spatial analysis method of principal coordinates of neighbor matrices (PCNM) to disentangle the contributions of these processes. The results showed that (1) habitat and space jointly explained approximately 53% of the variation in richness and approximately 65% of the variation in species composition, depending on the scale (sampling unit size); (2) tree diversity (richness and composition) in the Gutianshan forest was dominantly controlled by spatially structured habitat (24%) and habitat-independent spatial component (29%); the spatially independent habitat contributed a negligible effect (6%); (3) distributions of richness and species composition were strongly affected by altitude and terrain convexity, while the effects of slope and aspect were weak; (4) the spatial distribution of diversity in the forest was dominated by broad-scaled spatial variation; (5) environmental control on the one hand and unexplained spatial variation on the other (unmeasured environmental variables and neutral processes) corresponded to spatial structures with different scales in the Gutianshan forest plot; and (6) five habitat types were recognized; a few species were statistically significant indicators of three of these habitats, whereas two habitats had no significant indicator species. The results suggest that the diversity of the forest is equally governed by environmental control (30%) and neutral processes (29%). In the fine-scale analysis (10 x 10 m cells), neutral processes dominated (43%) over environmental control (20%).

探索植物器官中氮(N)、磷(P)含量沿环境梯度的分异规律, 有助于揭示陆地生态系统物质循环和植物养分适应策略的过程和机制。该文采用分层随机抽样法, 在中国南方12个省市区布设462个灌丛样点, 对其中193种优势木本植物叶N、P含量进行调查取样。结果表明: 1)南方灌丛优势木本植物叶的N、P含量几何均值分别为16.57 mg&#x000b7;g^-1和1.02 mg&#x000b7;g^-1; 其中, 落叶木本植物(17.91 mg&#x000b7;g^-1、1.14 mg&#x000b7;g^-1)显著高于常绿木本植物(15.19 mg&#x000b7;g^-1、0.89 mg&#x000b7;g^-1); 叶P含量较N含量具有更大的变异性和环境依赖性。2)随年平均气温(MAT)的升高, 常绿木本植物叶N、P含量降低, 落叶木本植物叶N、P含量呈逐渐增加的趋势; 随年降水量(MAP)的增加, 常绿木本植物叶N含量降低, 落叶木本植物叶N含量增加, 两者P含量下降。3)土壤N含量的增加对两者叶的N含量无显著影响; 但随土壤P含量的增加, 常绿和落叶木本植物叶P含量均显著增加。4)广义线性回归显示, 植物生活型分别可解释叶N、P变异的7.6%和14.4%, MAP和土壤P含量分别解释了0.8%和16.4%的叶P变异。结果表明, 中国南方灌丛中优势植物叶的N含量主要受不同生活型植物生长需求所决定, 而P含量则受气候、土壤和植物生活型共同决定。

Elevation is involved in determining plant diversity in montane ecosystems. This study examined whether the distribution of plants in the Yatsugatake Mountains, central Japan, substantiated hypotheses associated with an elevational diversity gradient. Species richness of trees, shrubs, herbs, ferns, and bryophytes was investigated in study plots established at 200-m elevational intervals from 1,800 to 2,800 m. The changes in plant diversity (alpha and beta diversities, plant functional types, and elevational ranges) with elevation were analyzed in relation to climatic factors and elevational diversity gradient hypotheses, that is, mass effect, mid-domain effect, and Rapoport's elevational rule. In addition, the elevational patterns of dominance of plant functional types were also analyzed. A comparison of alpha and beta diversities revealed that different plant groups responded variably to elevation; the alpha diversity of trees and ferns decreased, that of herbs increased, whereas the alpha diversity of shrubs and bryophytes showed a U-shaped relationship and a hump-shaped pattern. The beta diversity of shrubs, herbs, and bryophytes increased above the subalpine-alpine ecotone. In accordance with these changes, the dominance of evergreen shrubs and graminoids increased above this ecotone, whereas that of evergreen trees and liverworts decreased. None of the plant groups showed a wide elevational range at higher elevations. These elevational patterns of plant groups were explained by climatic factors, and not by elevational diversity gradient hypotheses. Of note, the changes in the dominance of plant groups with elevation can be attributed to plant-plant interactions via competition for light and the changes in physical habitat. These interactions could alter the elevational diversity gradient shaped by climatic factors.© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Although eastern Asia (EAS) and eastern North America (ENA) have similar climates, plant species richness in EAS greatly exceeds that in ENA. The degree to which this diversity difference reflects the ages of the floras or their rates of evolutionary diversification has not been quantified. Measures of species diversity that do not incorporate the ages of lineages disregard the evolutionary distinctiveness of species. In contrast, phylogenetic diversity integrates both the number of species and their history of evolutionary diversification. Here we compared species diversity and phylogenetic diversity in a large number of flowering plant (angiosperm) floras distributed across EAS and ENA, two regions with similar contemporary environments and broadly shared floristic history. After accounting for climate and sample area, we found both species diversity and phylogenetic diversity to be significantly higher in EAS than in ENA. When we controlled the number of species statistically, we found that phylogenetic diversity remained substantially higher in EAS than in ENA, although it tended to converge at high latitude. This pattern held independently for herbs, shrubs, and trees. The anomaly in species and phylogenetic diversity likely resulted from differences in regional processes, related in part to high climatic and topographic heterogeneity, and a strong monsoon climate, in EAS. The broad connection between tropical and temperate floras in southern Asia also might have played a role in creating the phylogenetic diversity anomaly.

We examined variability in hierarchical beta diversity across ecosystems, geographical gradients, and organism groups using multivariate spatial mixed modeling analysis of two independent data sets. The larger data set comprised reported ratios of regional species richness (RSR) to local species richness (LSR) and the second data set consisted of RSR:LSR ratios derived from nested species-area relationships. There was a negative, albeit relatively weak, relationship between beta diversity and latitude. We found only relatively subtle differences in beta diversity among the realms, yet beta diversity was lower in marine systems than in terrestrial or freshwater realms. Beta diversity varied significantly among organisms' major characteristics such as body mass, trophic position, and dispersal type in the larger data set. Organisms that disperse via seeds had highest beta diversity, and passively dispersed organisms showed the lowest beta diversity. Furthermore, autotrophs had lower beta diversity than organisms higher up the food web; omnivores and carnivores had consistently higher beta diversity. This is evidence that beta diversity is simultaneously controlled by extrinsic factors related to geography and environment, and by intrinsic factors related to organism characteristics.

Environmental heterogeneity is regarded as one of the most important factors governing species richness gradients. An increase in available niche space, provision of refuges and opportunities for isolation and divergent adaptation are thought to enhance species coexistence, persistence and diversification. However, the extent and generality of positive heterogeneity-richness relationships are still debated. Apart from widespread evidence supporting positive relationships, negative and hump-shaped relationships have also been reported. In a meta-analysis of 1148 data points from 192 studies worldwide, we examine the strength and direction of the relationship between spatial environmental heterogeneity and species richness of terrestrial plants and animals. We find that separate effects of heterogeneity in land cover, vegetation, climate, soil and topography are significantly positive, with vegetation and topographic heterogeneity showing particularly strong associations with species richness. The use of equal-area study units, spatial grain and spatial extent emerge as key factors influencing the strength of heterogeneity-richness relationships, highlighting the pervasive influence of spatial scale in heterogeneity-richness studies. We provide the first quantitative support for the generality of positive heterogeneity-richness relationships across heterogeneity components, habitat types, taxa and spatial scales from landscape to global extents, and identify specific needs for future comparative heterogeneity-richness research.© 2014 John Wiley & Sons Ltd/CNRS.

Vegetation maps are important sources of information for biodiversity conservation, ecological studies, vegetation management and restoration, and national strategic decision making. The current Vegetation Map of China (1:1000000) was generated by a team of more than 250 scientists in an effort that lasted over 20 years starting in the 1980s. However, the vegetation distribution of China has experienced drastic changes during the rapid development of China in the last three decades, and it urgently needs to be updated to better represent the distribution of current vegetation types. Here, we describe the process of updating the Vegetation Map of China (1:1000000) generated in the 1980s using a "crowdsourcing-change detection-classification-expert knowledge" vegetation mapping strategy. A total of 203,024 field samples were collected, and 50 taxonomists were involved in the updating process. The resulting updated map has 12 vegetation type groups, 55 vegetation types/subtypes, and 866 vegetation formation/sub-formation types. The overall accuracy and kappa coefficient of the updated map are 64.8% and 0.52 at the vegetation type group level, 61% and 0.55 at the vegetation type/subtype level and 40% and 0.38 at the vegetation formation/sub-formation level. When compared to the original map, the updated map showed that 3.3 million km of vegetated areas of China have changed their vegetation type group during the past three decades due to anthropogenic activities and climatic change. We expect this updated map to benefit the understanding and management of China's terrestrial ecosystems.Copyright © 2020 Science China Press. Published by Elsevier B.V. All rights reserved.

Geographic, climatic, and soil factors are major drivers of plant beta diversity, but their importance for dryland plant communities is poorly known. This study aims to: i) characterize patterns of beta diversity in global drylands, ii) detect common environmental drivers of beta diversity, and iii) test for thresholds in environmental conditions driving potential shifts in plant species composition.224 sites in diverse dryland plant communities from 22 geographical regions in six continents.Beta diversity was quantified with four complementary measures: the percentage of singletons (species occurring at only one site), Whittake's beta diversity (β(W)), a directional beta diversity metric based on the correlation in species occurrences among spatially contiguous sites (β(R)), and a multivariate abundance-based metric (β(MV)). We used linear modelling to quantify the relationships between these metrics of beta diversity and geographic, climatic, and soil variables.Soil fertility and variability in temperature and rainfall, and to a lesser extent latitude, were the most important environmental predictors of beta diversity. Metrics related to species identity (percentage of singletons and β(W)) were most sensitive to soil fertility, whereas those metrics related to environmental gradients and abundance ((β(R)) and β(MV)) were more associated with climate variability. Interactions among soil variables, climatic factors, and plant cover were not important determinants of beta diversity. Sites receiving less than 178 mm of annual rainfall differed sharply in species composition from more mesic sites (> 200 mm).Soil fertility and variability in temperature and rainfall are the most important environmental predictors of variation in plant beta diversity in global drylands. Our results suggest that those sites annually receiving ~ 178 mm of rainfall will be especially sensitive to future climate changes. These findings may help to define appropriate conservation strategies for mitigating effects of climate change on dryland vegetation.

The change rules of different slope on the structure characteristics and species diversity of the Main shrub community in arid valleys of the Bailongjiang River were studied with Quadrat survey method. Aim to understand the vegetation characteristic and Species diversity changes from different elevation gradient of arid valleys in bailongjiang river, It will provides the theory basis for vegetation restoration in this region.Results show that: (1)species are different in the same slope of different altitude gradient, as well as in the different slope of same altitude gradient. with the increase of altitude,the species of different slope show that increased after decreased first, The main vegetation types are also different in the same slope of different altitude gradient; (2)With the increase of altitude gradient, &alpha;-diversity of shrub community and &alpha;-diversity of herb community in different slope all showed that a trend from rise to decline. Correlation analysis was carried out on the &alpha;-diversity index, contribution rate of species diversity for the species diversity is the largest,it is showed that the richness index(D₁, D₂)&gt; ecological dominance index(SN)&gt; interspecific opportunity index(H)&gt; evenness index of community(R); (3)With the change of altitude gradient, &beta;-diversity Whittaker index of the main shrub community have less change in different slope, the maximum appeared at an altitude of 1 250-1 650 m,Routledge and Cody &beta;-diversity index between an altitude of 1 450-1 650 m reache maximum, but generally presents the waveform changes. &beta;-diversity of herb community have larger change, At an altitude of 1 050-1 250 m, &beta;-diversity of herb community in the sunny slope reaches maximum. At an altitude of 1 250-1 450 m,&beta;-diversity index of herb community in the semi-shady slope and semi-sunny slope reaches maximum, &beta;-diversity index of herb community in the semi-shady slope and semi-sunny slope were higher than sunny slope. Species diversity &alpha; and diversity &beta; are different that in Different slope directions and different altitudinal gradients in dry valleys of Bai Long River and different slope directions have a certain correlation with the change of altitudinal gradient, species diversity &alpha; and diversity &beta; indicating that elevation and slope directions are one of the main factors affecting biodiversity.

采用样方调查法，研究了白龙江干旱河谷不同坡向主要灌丛群落沿着海拔梯度的结构特征、物种多样性的变化规律，旨在了解白龙江干旱河谷不同海拔梯度植被特征和物种多样性变化，为白龙江干旱河谷区域不同海拔植被恢复提供理论依据。研究结果表明：（1）不同海拔梯度同一坡向物种数不同，同一海拔不同坡向物种数也不同，随着海拔的升高不同坡向物种数表现为先增加后减少的趋势，同一海拔梯度内不同坡向主要植被类型也不同。（2）主要灌木群落&alpha;多样性在不同坡向随着海拔梯度的升高，表现出先升高后减小的趋势。不同坡向草本群落&alpha;多样性随着海拔的升高，也表现出先升高后减小的趋势。对主要灌丛&alpha;多样性指数进行相关性分析得物种丰富度指数对物种多样性贡献率最大，表现为丰富度指数（D₁、D₂）&gt; 生态优势度指数（SN）&gt; 种间机遇指数（H）&gt; 群落均匀度指数（R）。（3）不同坡向主要灌丛群落&beta;多样性Whittaker指数沿着不同海拔梯度变化不大，最大值出现在海拔1250~1650m；Routledge和Cody&beta;多样性指数在海拔1450~1650m出现最大值，但是大体呈现出波形变化。草本&beta;多样性随着海拔的升高变化较大，阳坡植物的&beta;多样性指数在海拔1050~1250m达到最大，阴坡和半阴半阳坡在海拔区间1250~1450m达到最大，半阴半阳坡的&beta;多样性指数均大于阳坡。白龙江干旱河谷不同坡向、不同海拔梯度物种&alpha;多样性和&beta;多样性都不同，且不同坡向随着海拔梯度的变化物种&alpha;多样性和&beta;多样性呈一定的相关性，说明海拔和坡向是影响生物多样性主要因子之一。

为了探究不同施氮量对长期定植芒属植物后酸性红壤中固定的土壤有机碳矿化过程的影响,本研究以长期定植芒草的根际红壤为试验材料,采用控制变量法开展土壤有机碳矿化培养试验。结果表明:施氮极显著降低了土壤有机碳矿化量,随着施氮量的升高而降低,呈现极显著的负激发效应(P-1</sup>,42.59 mg&#183;kg^-1和33.14 mg&#183;kg^-1。本研究发现,高水平施氮会降低土壤pH值、可溶性有机碳,从而抑制红壤有机碳矿化过程,进一步稳定芒属植物种植对酸性红壤有机碳的积累效应。

<p>In the typical dry valleys of the Three Parallel Rivers region, northwest Yunnan Province, we investigated vegetation using six sampling transects, each comprised of ten standard plots, along altitudinal gradients on the eastern and the western aspects of Nu River, Langcang River, and Jinsha River. With these data, we compared the elevation-related distribution of plant species richness and species turnover rates along the six transects, and explained the patterns using geography and vegetation variables. The dry-warm vegetation zone was dominated by shrubs and herbs and located below the altitude of 3,000 m a.s.l. At higher elevations, shrub and herbs were replaced with a forest zone. The spatial distribution of plant species richness increased with elevation and latitude, especially for herb and shrub species, and was also related to river, vegetation zones, and longitude. The species richness of shrubs also increased significantly across the region, from west to east. Species richness of herbs and shrubs in the Nu River were higher than those in the Lancang River and the Jinsha River, whereas the difference of species richness among three rivers was not significant for trees. Herb species richness in the forest zone was less than that in the shrub and herb zones. Species turnover rate of different zones presented inconsistent altitudinal gradient patterns, but all peak values appeared in the ecotones between shrub communities, in the lower altitudes of the transect, and forest communities, in the higher altitudes. The forest-shrub ecotone is located at an altitude range of 1,900-2,100 m in the Nu River valley, at an altitude range of 2,300-2,400 m in the Lancang River valley and at an altitude range of 2,700-2,900 m in the Jinsha River valley. The mean species turnover rates between shrub & herb section and forest section within each transect were less than the mean turnover rates of the same vegetation section between different transects within the same basin, and also less than the mean turnover rates for same vegetation section in all six transects. Spatial isolation could explain 34.2% of the variation in species turnover rate among the 12 vegetation sections of the six altitudinal transects, while vegetation differences explained less than 0.5% of the variation. These results show the primary role of environment difference in determining the species richness between vegetation types, whereas geographical isolation between the rivers as a dominant factor in the assembly (e.g. species composition) of plant communities.</p>

在滇西北三江并流地区典型干旱河谷段, 在怒江、澜沧江和金沙江的东、西坡共设置了6条海拔梯度样带, 通过标准样地的植物群落调查, 分析各条样带植物的物种丰富度、物种更替率的海拔梯度格局, 并比较了地理和植被变量对分布格局的解释。干旱河谷植被带位于海拔3,000 m以下, 以灌丛和灌草丛为主, 其在各河谷的分布上限自西向东依次升高。植物物种丰富度的分布主要与海拔、流域、经纬度和植被带有关, 沿纬度和海拔梯度升高而显著增加的格局主要表现在草本层和灌木层, 灌木物种丰富度还呈现自西向东显著增加的趋势。怒江的灌木和草本种物种丰富度显著高于金沙江和澜沧江, 三条江的乔木种丰富度差异则不显著。森林带的样方草本物种丰富度显著低于灌草丛带样方, 并且还拥有后者没有的乔木种。不同样带的植物物种更替速率呈现了不一致的海拔梯度格局, 但均在样带海拔下部的灌草丛群落与海拔上部森林群落之间的交错带出现峰值。森林-灌草丛植被交错带在怒江样带处于海拔1,900-2,100 m处, 在澜沧江河谷位于海拔2,300-2,400 m, 在金沙江河谷位于海拔2,700-2,900 m。所有海拔样带的森林段或灌草丛段相对于同一样带不同植被段之间的物种更替程度为最小, 不仅小于同一流域不同样带相同植被段之间物种更替率的均值, 更小于所有样带相同植被段之间的更替率均值。在三条河流6条海拔样带的12个植被带段之间的物种更替变化中, 空间隔离因素可以解释34.2%, 而植被类型差异仅能解释不到0.5%。本研究结果显示了环境差异对不同植被类型物种丰富度的首要影响, 和各河流之间的空间隔离对植物群落构建和物种构成的主要作用。

The typical natural secondary shrub community was chosen in Lin’an of Zhejiang Pro-vince to discover its possibility of restoration to arbor forest with three kinds of forest management models being taken, <i>i.e</i>., no care as control, closed forest management and target tree tending. Over four years growth, compared with control, closed forest management significantly increased average DBH and height by 130% and 50%, respectively, while 260% and 110% for target tree tending. In target tree tending plots, larger trees had been emerging with 4.5-8.5 cm diameter class and 4.5-8.5 m height class and formed a new storey of 4 m compared with control. The species biodiversity indexes at shrub layer were significantly increased in closed management plots, and did not decrease in target tree tending plots. Closed forest management did not change the tree species composition, following its previous succession direction. However, target tree tending increased the importance value of target species with the high potential succession direction of mixed coniferous-broadleaved forest. The results revealed that the secondary shrub community with target tree tending achieved more desired goals on DBH and height growth of dominant trees and species composition improvement compared with closed management. If the secondary shrub community could be managed when the operational conditions existed, target tree tending model should be selected to accelerate the restoration of shrub toward arbor forest.

在浙江省临安市选择典型天然次生灌丛,分别进行封禁和目标树抚育,探讨灌丛恢复为乔木林的可能性.结果表明: 4年后,与未管护(对照)相比,封禁和目标树抚育后群落平均胸径分别提高1.3和2.6倍,平均高度分别提高0.5和1.1倍;目标树抚育林木出现了对照林分没有的4.5～8.5 cm径阶和4.5～8.5 m树高阶,形成了4 m高的新林层;灌木层物种丰富度和多样性指数没有因抚育而下降;封禁管理维持了群落的树种组成,遵循原有的演替方向;目标树抚育显著改变了群落的树种组成,提高了目的树种的重要值,近期有可能恢复成为针阔混交林群落.与封禁相比,目标树抚育在优势林木胸径和高度生长、树种组成改善等方面更能达到预想的目标.在有条件经营的情况下,可以选择目标树抚育模式对天然次生灌丛进行管理,从而达到加快群落恢复演替形成乔木林的目的.

Although much research has focused on biodiversity in mountain regions, elevational patterns of community similarity (i.e. species turnover) and the underlying processes are still rarely discussed. In this study, based on field investigations of 28 forest communities in the western Qinling Mountains, we evaluated the combined effects of habitat divergence and geographical distance on patterns of similarity in species composition using Mantel tests and multiple regressions on distance matrices (MRM). We also compared the rates of similarity decay of different life forms with geographical distance using permutation tests. Results indicated that, for all three life forms, community similarity decreased significantly with elevational, geographical, and habitat distances. Geographical distance and habitat heterogeneity together explained 41.1%, 59.0% and 47.4% of variance in species composition of trees, shrubs and herbs, respectively, with geographical distance uniformly explaining more variance than habitat heterogeneity. Woody plants showed a faster decay in similarity with geographical distance than herbaceous species. These results suggest that, at the scale of our study, dispersal limitations and habitat filtering influence species composition together, and highlighted that dispersal limitation may play a more important role in structuring the forest communities of the western Qinling Mountains.

群落间物种组成的相似性递减格局与生境过滤、空间过程密切相关, 探索其成因涉及到群落构建机制等生态学核心问题。本研究以秦岭西部森林群落为研究对象, 运用Mantel检验和基于距离矩阵的多元回归方法, 探究了不同生态因子对群落相似性变异的贡献, 并通过置换检验比较不同生活型之间相似性的空间递减率差异。结果显示: (1) 3种生活型物种组成相似性与地理距离、海拔距离、局地生境异质性差异均呈显著递减趋势; (2)地理距离与生境差异作为主导因子, 分别共同解释乔木、灌木和草本群落相似性变异的41.1%、59.0%和47.4%, 且地理距离的单独解释率均大于生境过滤的单独解释率; (3)不同生活型相似性在空间上的递减率大小关系为: 乔木 &#x0003E; 灌木 &#x0003E; 草本, 表明物种因扩散能力的不同而对空间阻隔效应的响应存在差异。本研究初步确定扩散限制与生境过滤共同主导了秦岭西部森林群落的构建过程, 且扩散限制所起作用更为显著。