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1.
张勇  刘朔孺  于海燕  刘东晓  王备新 《生态学报》2012,32(14):4309-4317
溪流底栖动物群落结构受不同空间尺度环境因子的共同作用。基于2010年钱塘江中游流域60个样点的大型底栖无脊椎动物和环境变量数据,寻找与研究流域底栖动物群落结构变化密切相关的关键环境变量,解析流域尺度和河段尺度的环境因子对底栖动物群落的相对影响。PCA分析表明该区域的主要环境梯度是流域内的土地利用类型及其引起的溪流物理生境退化程度和水体营养状态。CCA分析发现影响底栖动物群落的流域尺度的关键环境变量是纬度、海拔、样点所在流域大小、森林用地百分比,河段尺度是总氮、总磷、钙浓度、二氧化硅浓度和平均底质得分。偏CCA分析得到两种尺度环境因子对底栖动物变异的总解释量为26.4%,流域尺度和河段尺度变量分别为总解释量的50%和31%;方差分解结果表明研究区域大型底栖无脊椎动物受到两种尺度环境因子的综合影响,且流域尺度环境因子较河段尺度环境因子更为重要,体现了其在溪流生态系统保护、恢复、监测和评价中的重要参考价值。  相似文献   

2.
Gao F  Yin HB  Hu WP  Deng JC  Gao JF 《应用生态学报》2010,21(8):2132-2139
采用野外采样调查的方法,结合聚类(Cluster)、多维排序尺度(MDS)、典范对应分析(CCA),以及Shannon多样性指数、Pielou种类均匀度指数、Margalef种类丰度指数等手段,研究了巢湖流域春季大型底栖动物的种群结构特征、多样性及其与环境因子的相关性.调查共采集到大型底栖动物23种,其中环节动物门6种,占26.1%,节肢动物门8种,占34.8%,软体动物门9种,占39.1%;流域内大型底栖动物的优势种为环节动物门的霍甫水丝蚓(Limno-drilus hoffmeisteri)和苏氏尾鳃蚓(Branchiura sowerbyi),以及软体动物门的铜锈环棱螺(Bel-lamya aeruginosa),且其在流域内的分布具有显著的空间差异性.出入湖河流上游区域(群落Ⅰ)生物多样性相对较好;出入湖河流下游区域(群落Ⅱ)生物多样性最差;巢湖湖体及出入湖河流河口(群落Ⅲ)生物多样性处于两者之间.巢湖流域大型底栖动物空间分布受各种环境因素影响,其中Chl a与NO-3为主要影响因素.  相似文献   

3.
基于11个反映水生昆虫生活史、对外界抵抗力和生理特征的生物学性状,应用目前国际上通用的fourth-corner统计方法,系统研究了浙江省钱塘江中游流域水生昆虫功能多样性对土地利用变化的响应.结果表明: 部分生物学性状对土地利用变化敏感,且其随人类干扰强度的变化所发生的改变与预期吻合,其最大个体长度逐渐下降,呼吸方式从以鳃呼吸为主转变为以表皮呼吸为主,掘穴者数量显著增加.参照点的功能多样性指数(Rao值)显著高于干扰点(P<0.001).说明人类活动引起的土地利用变化导致溪流水质和栖境质量下降,引起群落的变异和对生物性状组成的筛选,最终导致水生昆虫群落功能多样性改变.生物性状及功能多样性是未来评价生态健康的潜在指标.  相似文献   

4.
雅鲁藏布江流域底栖动物多样性及生态评价   总被引:4,自引:0,他引:4  
雅鲁藏布江起源于喜马拉雅山,是世界上海拔最高的河流之一,是流经我国西藏境内重要的国际河流,其河流生态系统具有特殊地貌及生态条件。研究该流域底栖动物多样性分布特征及其影响因子,是科学评价该区域河流生态系统健康状况,实现资源可持续开发利用的基础。2009年10月—2010年6月期间,以底栖动物作为指示物种,对雅江流域干支流及堰塞湖的14个采样断面进行河流生态评价。采用Alpha及Beta生物多样性指数分别指示局部采样河段及全区域的底栖动物多样性。对采样断面底栖动物组成分析发现:14个采样断面共采集到底栖动物110种,隶属57科102属。雅江干流底栖动物种类数最高为29,平均为19。支流年楚河种类数为17。支流拉萨河,尼洋河,帕龙藏布的最高种类数分别为25,33,36;平均种类数分别为21,21,22,生物多样性普遍高于干流。整个流域中底栖动物平均种类数相差不大,但种类组成和密度相差较大。调查区域的Beta多样性指数β高于低海拔地区的相似的山区河流,说明雅江流域内底栖动物群落差异性高于正常海拔地区。对14个采样断面的物种组成进行除趋势对应分析表明:影响雅江流域底栖动物多样性的主要因素为河型,河床阻力结构,堤岸结构,水流流速。保持稳定的阶梯-深潭结构和自然堤岸结构,以及适宜的流速有利于保护雅江河流生态。  相似文献   

5.
永定河流域大型底栖动物群落分布格局及其影响因子   总被引:1,自引:0,他引:1  
人类干扰造成了全球河流生态系统的普遍退化。流域尺度的水生生物分布特征及其影响因素研究对于河流生态系统的保护与恢复具有重要意义。本研究以永定河流域大型底栖动物群落为研究对象,分别于2017年春季(3月)、夏季(7月)、秋季(11月)开展全流域尺度的大型底栖动物调查。研究表明: 永定河流域以摇蚊科为主,优势类群包括直突摇蚊属、摇蚊属、雕翅摇蚊属以及多足摇蚊属。聚类分析表明,大型底栖动物群落结构存在显著的空间差异性,按照群落相似性可分为2组: 组1主要包含桑干河和东洋河水系,以直突摇蚊为主要优势种;组2主要包含洋河、妫水河以及永定河干流部分河段,以雕翅摇蚊为主要优势种。单因素方差分析表明,组2生物量、Shannon指数、Margalef指数、Pielou均匀度指数以及物种丰富度均显著高于组1,指示了该区域内更好的生态状况。大型底栖动物的季节差异显著,夏季的密度、生物量和各多样性指数均显著低于春季和秋季。典范对应分析显示,影响永定河大型底栖动物空间分布的环境因子主要包括水温、铵氮、pH、溶解氧和总磷。从水文因子的角度,流量和流速与主要生物参数存在显著相关性。组2中流速和流量与大型底栖动物密度和EPT%存在显著的正相关关系,表明急流生境有利于EPT(蜉蝣目、襀翅目、毛翅目)敏感类群的生存;但流量和流速与多样性指数呈负相关关系,表明过高流量和流速的生境条件不利于大型底栖动物多样性的维持。总之,水环境因子、水文因子都显示出了对大型底栖动物群落结构和多样性特征的影响,表明永定河流域生态系统受到多类型人为活动的影响。减少水质污染、适度恢复部分河段的流量是永定河流域生态系统修复的重要环节。  相似文献   

6.
大型底栖动物是河流生态系统较好的指示类群,越来越广泛地应用于河流生态状况评价.识别大型底栖动物空间分布的影响因素可以分为宏观尺度因子、中观尺度因子和微观尺度因子.前人的研究较多集中于中观尺度.本研究基于10 m河段微生境因子与大型底栖动物调查,采用地统计学方法,在微观尺度上分析了大型底栖动物空间分布特征及其与微生境的关系.结果表明:不同生境类型中底栖动物指标存在差异性,激流、深潭和急流的Shannon指数平均值分别为2、1.9、1.78;大型底栖动物密度、生物量、丰富度指数及Shannon指数具有空间自相关性,存在一定的扩散效应;微生境因子与大型底栖动物指标及物种的空间关系存在差异性,其中,水深和流速与大型底栖动物关系的拟合度较弱,底质组成与大型底栖动物的拟合关系相对较好,底栖动物密度与粒径<4 mm底质体积百分比呈现正空间自相关,生物量、丰富度指数、Shannon指数与粒径>32 mm底质体积百分比呈现正空间自相关.本研究结果可为底栖动物扩散机制研究、调查样方设置、物理生境修复等提供参考.  相似文献   

7.
和克俭  刘虹  丁佼  黄晓霞  刘琦  张琦 《生态学报》2021,41(23):9525-9535
研究土地利用对大型底栖动物群落的影响,对流域土地利用规划修编和河流生态修复等有重要意义。以红河上游的把边江流域为研究区,调查大型底栖动物群落现状,计算37个样点上游集水区土地利用组分、配置、多样性和水文距离4个方面20个土地利用指标,分析不同土地利用方式对大型底栖动物群落的影响。本次调查共鉴定出25个大型底栖动物分类单元,其中水生昆虫最多,占分类单元总数的72%;摄食功能群以捕食者(PR)、刮食者(SC)和直接收集者(GC)为主。把边江流域城镇用地和林地对大型底栖动物群落的影响占主导地位,而耕地对大型底栖动物群落的影响较小。影响把边江流域大型底栖动物群落的关键土地利用指标为城镇用地面积比(3PLA)、城镇用地最大斑块指数(3LPI)、城镇用地聚合指数(3AI)、城镇用地水流长度(3FLOW)、林地最大斑块指数(1LPI)和林地形状指数(1LSI)。土地利用组分、配置和水文距离是影响把边江流域大型底栖动物群落的主要方面,而土地利用多样性对大型底栖动物群落的影响较小。大型底栖动物物种密度和物种多样性与3PLA、3LPI、3AI、3FLOW和1LSI呈负相关,与1LPI呈正相关。1LPI与浮游目(如小蜉科、扁蜉科)为代表的清洁物种呈现较明显的正相关关系。城镇用地指标与SC和SH(撕食者)密度具有显著的负相关关系,与GC密度有较弱的正相关关系,而与其他功能群没有明显的相关关系。SC和SH对水质和环境条件敏感,而GC对人类干扰耐受性较强。1LPI与SC和FC(滤食收集者密度)正相关,而与PR和GC密度负相关。SC和FC对生境的完整性要求较高,而GC和PR对人为干扰和较为破碎的生境更为适应。一方面,随着城镇用地的规模、边界复杂性和聚集程度增加,研究区大型底栖动物密度和多样性降低;另一方面,随着林地完整性降低,大型底栖动物物种均匀度降低。土地利用与大型底栖动物物种多样性和功能群多样性的关系不完全一致,1LSI和3FLOW与物种多样性负相关,而与功能群多样性呈正相关关系,土地利用对物种-功能群-群落不同尺度上的影响差异还需要更深入的研究。  相似文献   

8.
渔山岛岩石相潮间带大型底栖动物物种多样性   总被引:1,自引:0,他引:1  
为系统研究渔山岛潮间带大型底栖动物群落结构与生物多样性,作者于2009年3月至2010年1月在该岛潮间带布设5条断面进行了4个季节的取样,调查大型底栖动物种类组成、生物量和丰度,并分析了多样性状况.结果显示:共鉴定出大型底栖动物100种;Shannon-Wiener多样性指数(H')、Pielou均匀度指数(J)、Ma...  相似文献   

9.
以厦门湾为研究区域,收集2014—2015年大型底栖动物的调查数据,计算了大型底栖动物的分类学多样性指数,分析了分类学多样性指数与传统生物多样性指数的相关性和依从性,并从多个角度探讨大型底栖动物的分类充分性。结果表明,厦门湾大型底栖动物分类多样性指数(Δ)介于6.04—83.71之间,平均值为68.26,站位分布不均匀;分类差异性指数(Δ~*)介于74.27—99.54之间,平均值为84.23;平均分类差异指数(Δ~+)、分类差异变异指数(Λ~+)的理论平均值分别为86.82、345.0,个别站位落在95%置信区间外,表明局部区域环境受到了一定程度扰动。Δ、Δ~*与Margalef指数、Pielou均匀度指数、Shannon-Wiener指数、Simpson指数呈显著相关,而Δ~+、Λ~+与传统多样性指数间无显著相关;分类学多样性指数可作为传统生物多样性指数的补充。种级、属级和科级的同一多样性指数间呈显著线性相关,拟合度较高(多数R2﹥0.9);根据三个分类水平站位的nMDS二维排序图、2-STAGE的相似性和聚类图,种级、属级和科级的群落结构一致性强,属级较种级丢失的信息约8%、科级为20%,因此在条件有限的情况下,大型底栖动物的监测与评价可根据实际的条件和需求适当将生物鉴定放宽至属水平。  相似文献   

10.
拉萨河流域大型底栖动物群落结构及其与环境因子的关系   总被引:5,自引:0,他引:5  
陈丽  王东波  君珊 《生态学报》2019,39(3):757-769
2017年8月对拉萨河流域23个采样点的底栖动物群落和环境因子特征进行了调查,采集到大型底栖动物41属(种),其中水生昆虫35属(种),占85.4%;软体动物2属(种),占4.9%;环节动物3属(种),占7.3%;线形动物1属(种),占2.4%。各点位平均物种数为8种,优势种组成差别较大,优势种主要有四节蜉属(Baetis spp.)、大蚊属(Tipula sp.)、纹石蛾属(Hydopsychesp.)、短石蛾属(Brachycentrus sp.)、水丝蚓属(Limnodrilus sp.)、摇蚊属(Chironomus sp.)等,各采样点底栖动物平均密度为362只/m2。运用生物多样性指数分析底栖动物的群落结构,Marglef丰富度指数、香农威纳指数和均匀度指数平均值分别为1.18、1.32和0.49,生物多样性指数水平较低。采用均匀度指数法和底栖动物BI指数法进行了水质评价,两种评价结果显示分别有30.3%和56.5%的采样点水质为中污染至重污染状态。典范对应分析结果表明:影响拉萨河流域底栖动物群落的主要环境因子是海拔、化学需氧量、硫化物、p H值、总磷和总氮。  相似文献   

11.
The ecoregion is currently widely used as the basic geospatial unit in freshwater biodiversity conservation. The popularly used delineation is usually based on the assumption that attributes of aquatic ecosystems are influenced by landscape-scale environmental variables. However, few ecoregion delineations attempt to establish the local validity of this assumption prior to delineation, and few studies check the correspondence of the derived ecoregion boundaries with the distributions of attributes of aquatic biota. In this study, we established an approach to overcome these shortcomings. The notable features of the approach are: (1) the delineation variables were filtered through a series of analytical steps to select those that best represented the aquatic community traits, and which avoided redundancy in the data; (2) the method was quantitative and repeatable; and (3) the derived ecoregion boundaries were checked for consistency with the spatial attributes of aquatic biota. The approach was applied in the Taizi River Basin, northeast China. The procedure proposed here filtered out altitude and annual precipitation as the best variables to include in the freshwater ecoregion delineation. Then, using the quantitative ISODATA classification method, the basin was classified into three ecoregions. A test of accuracy indicated that freshwater ecoregions matched well with the spatial distribution pattern of macroinvertebrate community attributes. Statistical analysis showed that natural geographical attributes and river attributes were different in the three ecoregions, and indices representing macroinvertebrate community attributes are significantly different as a whole among the three ecoregions. The case study proved this approach effective on ecoregion delineation.  相似文献   

12.
13.
1. Although many studies have focussed on the effects of catchment land use on lotic systems, the importance of broad (catchment) and fine (segment/reach) scale effects on stream assemblages remain poorly understood. 2. Nine biological metrics for macrophytes (498 sites), benthic macroinvertebrates (491) and fish (478) of lowland and mountain streams in four ecoregions of France and Germany were related to catchment and riparian buffer land use using partial Redundancy Analysis and Boosted Regression Trees (BRTs). 3. Lotic fauna was better correlated (mean max., r = 0.450) than flora (r = 0.277) to both scales of land use: the strongest correlations were noted for mountain streams. BRTs revealed strong non‐linear relationships between mountain assemblage metrics and land use. Correlations increased with increasing buffer lengths, suggesting the importance of near‐stream land use on biotic assemblages. 4. Several metrics changed markedly between 10–20% (mountain ecoregions) and 40–45% (lowland) of arable land use, irrespective of the buffer size. At mountain sites with >10% catchment arable land use, metric values differed between sites with <30% and sites with >30% forest in the near‐stream riparian area. 5. These findings support the role of riparian land use in catchment management; however, differences between mountain and lowland ecoregions support the need for ecoregion‐specific management.  相似文献   

14.
Plants are connected to habitats by functional traits which are filtered by environmental gradients. Since tree species composition in the forest canopy can influence ecosystem processes by changing resource availability, litter accumulation, and soil nutrient content, we hypothesised that non-native invasive trees can establish new environmental filters on the understorey communities. In the hardwood floodplain forests in Northern Italy, the invasive trees Robinia pseudoacacia L. and Prunus serotina Ehrh. are the dominant canopy species. We used trait data assembled from databases and iterative RLQ analysis to identify a parsimonious set of functional traits responding to environmental variables (soil, light availability, disturbance, and stand structure) and the dominant native and invasive canopy species. Then, RLQ and fourth-corner analysis was conducted to investigate the joint structure between macro-environmental variables and species traits and functional groups were identified. The trait composition of the herb-layer was significantly related to the main environmental gradients and the presence of the invaders in the canopy showed significant relationships with several traits. In particular, the presence of P. serotina may mitigate or even erase the effect of disturbances, maintaining a stable forest microclimate and thus favouring ‘true’ forest species, while R. pseudoacacia may slow down forest succession and regeneration by establishing new stable associations with a graminoid-dominated understorey. The impact of the two invasive trees on herb layer composition appears to differ, indicating that different management and control strategies may be needed.  相似文献   

15.

Land-use practices in Mongolia can lead to environmental degradation and consequently affect the structure and function of biological communities. The main aim of this study was to determine land-use effects on freshwater macroinvertebrate communities based on their response to grazing and mining, using a trait-based approach (TBA). The functional structure of macroinvertebrate communities was examined using 86 categories of 16 traits. A total of 13 physical and chemical variables were significantly different among the levels of land-use intensity. Significant declines in functional diversity were observed with increased land-use intensity. The community weighted mean of 19 trait categories for 11 traits varied significantly among different levels of land-use intensity. Traits were significantly explained by environmental variables across a land-use intensity gradient. Water temperature, gravel, nitrate, silt, and cobble were the main predictor variables and explained 28% of the total variance of the trait variation. The functional structure of the macroinvertebrate community was strongly related to environmental conditions. The TBA is an important method in assessing disturbance responses in freshwater communities of steppe and taiga regions, such as in Mongolia and other countries in Central Asia and will be useful in finding best management practices for conserving aquatic ecosystems.

  相似文献   

16.
The relationships between functional traits and environmental gradients are useful to identify different community assembly processes. In this work, we used an approach based on functional traits to analyse if changes in hydroperiod and tree covers of ponds are relevant for local amphibian community assembly processes. Ephemeral ponds with low vegetation cover are expected to impose constraints on different species with particular trait combinations and, therefore, to exhibit communities with lower functional diversity than more stable ponds with greater tree cover. Sampling was conducted in 39 temporary ponds located along vegetation and hydroperiod gradients in the most arid portion of the Chaco ecoregion. Seven functional traits were measured in each species present in the regional pool. Associations between these traits and environmental gradients were detected using multivariate ordination techniques and permutation test (RLQ and fourth‐corner analyses respectively). Functional diversity indices were then calculated and related to variations in the environmental gradients. The results obtained allowed us to identify different sets of traits associated with hydroperiod and tree cover, suggesting that these environmental variables are relevant for structuring amphibian communities according to interspecific variations in functional traits from both, larval and adult stages. Contrary to our expectations, communities associated with more stable ponds and with greater tree cover exhibited lower functional diversity than expected by chance (and were the ponds with highest species richness). This result indicates that the reduction in relative importance of environmental restrictions imposed by a very short hydroperiod and the lack of tree cover, favours different species of the regional pool that are similar in several functional traits. Accordingly, communities associated with stable ponds with high tree cover exhibited high functional redundancy.  相似文献   

17.
The relationship between functional traits and environmental factors contribute to understanding community structure and predicting which species will be able to elude environmental filters in different habitats. We selected 10 functional traits related to morphology, demography and regeneration niche in 54 subtropical premontane tree species to describe their main axes of functional differentiation. We derived species traits, environmental variables and species abundance data from 20 1-ha permanent plots established in a seasonal subtropical premontane forest in northwestern Argentina. We analyzed the relationship between species functional traits and environmental factors through RLQ and fourth-corner analyzes. We found an axis of structural differentiation that segregates understory from canopy species, and an axis of functional differentiation that segregates species that maximize resource acquisition from those that promote resource conservation. Environmental and forest use gradients operate hierarchically over subtropical premontane tree species influencing the distribution of demographic and morphological traits. The interaction between climatic and topographic factors influences the distribution of species functional traits at the regional scale. In addition, the history of forest use seems to operate at the landscape scale and explains the distribution of species traits reflecting a trade-off between resource acquisition and resource conservation strategies in secondary forests across different successional stages. Our results support the idea that functional traits may be used to analyze community structure and dynamics through niche differentiation and environmental filtering processes.  相似文献   

18.

Questions

Rhododendron ponticum subsp. baeticum is an invasive shrub of growing concern in continental Europe, but little is known about its impact on native plant communities. Here we ask: do environmental conditions differ between forest stands invaded by it and uninvaded stands? Do these differences correlate with R. ponticum's cover? Are these differences associated with differences in taxonomic and functional diversity of vascular plant species of the herb layer? Can these vegetation changes be explained by the sorting of certain life-history traits by R. ponticum-induced environmental changes?

Location

Several forests invaded by R. ponticum in the French Atlantic domain.

Methods

We recorded vegetation composition and a number of environmental variables in 400-m2 plots that were established in 64 paired forest stands (32 invaded vs 32 uninvaded). We compiled traits from existing databases. We computed several metrics of taxonomic and functional diversity. We compared environmental variables and diversity metrics between invaded and uninvaded stands. We used correlation and regression analyses to relate them with R. ponticum's cover. We ran RLQ and fourth-corner analyses to explore the relationships between R. ponticum invasion, environmental variables, species traits, and vegetation composition.

Results

Independent of its abundance, R. ponticum invasion was associated with lower light arrival at the forest floor and increased litter thickness. Concomitantly, species richness and diversity and trait diversity were reduced. The major driver of species assemblages was soil pH, which strongly interacted with the invasion gradient. R. ponticum did not sort species according to traits associated with shade tolerance and thick-litter tolerance. However, tree and shrub saplings were more abundant in invaded than uninvaded stands, at the expense of graminoid and fern species.

Conclusions

As R. ponticum becomes the dominant shrub, it exerts new selection forces on life-history traits of extant species, mostly via reduced light availability, increased litter thickness, and physical competition, thereby reducing taxonomic and functional diversity of the herb layer, without impeding tree and shrub self-regeneration, at least in the short term.  相似文献   

19.
The development of biomonitoring tools is increasingly appealing in light of the increasing degradation of aquatic ecosystems. In this context, we investigated the responses of stream fish communities to the gradient of environmental degradation in different basins using a variety of indices based on functional diversity, functional composition, and taxonomic diversity. We used datasets from three Brazilian ecoregions. In order to describe the gradient of environmental degradation we scored streams based on local and landscape variables. The functional structure of the assemblages was described in relation to seven functional traits related to habitat use, swimming capacity, and maneuverability. We described assemblages in each ecoregion separately in relation to 20 potential indicators, grouped in four families: indices of functional diversity based on presence/absence (FDp/a); indices of functional diversity weighted by abundance (FDabund); indices of functional composition (mT); and, indices based on taxonomic diversity (TDiv). The relationship between the indicators and the gradient of environmental degradation were evaluated using linear regression. We found a significant interaction effect (ANOVA, p = 0.006) between group of indices and ecoregions for the performance of indicators, suggesting a context-dependent response. The indices, on an individual basis, had variable performance and consistency among ecoregions. Four mT indicators demonstrated the highest average performance and consistency. Taxonomic diversity indicators consistently had the lowest average performance, while FDp/a and FDabund indicators had low average performance and variable inter-regional consistency. The differential inter-regional performance of indicators was due to the differences in the lengths of the gradients of environmental degradation. Our results indicate that functional traits have greater predictive power compared to taxonomic indicators for fish responses to a gradient of environmental degradation. Although indicators of functional composition are the most promising, we emphasize that caution is needed when generalizing functional diversity indicators across ecoregions because most of them are context-dependent.  相似文献   

20.
The survival and success of alien plant species is determined by species traits (i.e., invasiveness) and the characteristics of the habitats in the region of introduction (i.e., invasibility). However, little is known about species traits as related to habitat characteristics. We assessed the characteristics of successful invaders and the interaction of environmental factors and life-history traits for alien plant species. The vascular plants were recorded from 52 agricultural landscapes in Finland. We compared the traits of native and alien plant species with Fisher’s exact test and used a three table ordination analysis, RLQ analysis, to relate species traits to environmental conditions. Species were clustered according to their position on the RLQ axes, and the clusters were tested for phylogenetic independence. The successful alien plant species were associated with life form and preferences for moisture and nitrogen, but the trait composition varied according to the habitat type. Two RLQ axes explained 80.5% of the variation, and the species traits were significantly associated with environmental variables. The clustering showed that the occurrence of alien plant species in agricultural habitats was driven by invasion history, traits related to dispersal (dispersal type, seed mass) and habitat preferences, as well as environmental features, such as geographical location, temperature and the quality and disturbance regime of the habitats. All clusters were phylogenetically non-independent. Thus, the clusters of alien species comprised species of diverse taxonomic affinities, although, they shared the traits explaining their occurrence in particular habitats. This information is useful for understanding the link between species traits and the environmental conditions of the habitats, and complexity of the invasion process.  相似文献   

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