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1.
Armstrong G 《Heredity》2011,107(6):558-564
Species with different regenerative responses to fire are hypothesised to coexist by utilising the different temporal and spatial niche opportunities created by the stochasticity of the fire regime. This is strongly supported by observations of instability of species'' presence and abundance at the local scale while these are stable at the community scale. However, observations of species coexistence in fire-prone communities are limited to several decades only. To improve the robustness of this hypothesis, coalescent analysis, using chloroplast microsatellites, was undertaken on three sympatric species of Triodia from different functional groups in the fire-prone Kimberley region of Western Australia. The results inferred that T. bitextura, an obligate resprouter, Triodia sp., an obligate seeder, and T. epactia, a facultative resprouter, had mean Tmrca values of 65k, 40k and 111k generations, respectively. Using a mutation rate of 3.2 × 10−5 and a generation time of 5 years gave Tmrca values of 436k, 203k and 556 k years, respectively. These results provide evidence for the coexistence of these species to the same fire regime dating back to the late Pleistocene. It also demonstrates the long-term resilience of an obligate seeder, Triodia sp., in a frequently burnt environment at the community scale. 相似文献
2.
Wildfire is an important ecological disturbance factor in most Mediterranean ecosystems. In the Mediterranean Basin, most shrub species can regenerate after fire by resprouting or seeding. Here, we hypothesize that post-fire regenerative syndromes may potentially co-vary with traits directly related to functional properties involved in resource use. Thus, seeders with a shorter life span and smaller size would have lower water-use efficiency (WUE) than re-sprouting species and would take up nutrients such as nitrogen from more superficial parts of the soil. To test this hypothesis, we compared leaf 13 C and 15 N signatures from 29 co-existing species with different post-fire regeneration strategies. We also considered life form as an additional explanatory variable of the differences between post-fire regenerative groups. Our data support the hypothesis that seeder species (which mostly evolved in the Quaternary under a Mediterranean climate) have lower WUE and less stomatal control than non-seeders (many of which evolved under different climatic conditions in the Tertiary) and consequently greater consumption of water per unit biomass. This would be related to their smaller life forms, which tend to have lower WUE and shorter life and leaf lifespan. Differences in 15 N also support the hypothesis that resprouters have deeper root systems than non-resprouters. The study supports the hypothesis of an overlap between plant functional traits and plant attributes describing post-disturbance resilience. 相似文献
3.
Verdú M Pausas JG Segarra-Moragues JG Ojeda F 《Evolution; international journal of organic evolution》2007,61(9):2195-2204
Mediterranean-type ecosystems are among the most remarkable plant biodiversity \"hot spots\" on the earth, and fire has traditionally been invoked as one of the evolutionary forces explaining this exceptional diversity. In these ecosystems, adult plants of some species are able to survive after fire (resprouters), whereas in other species fire kills the adults and populations are only maintained by an effective post-fire recruitment (seeders). Seeders tend to have shorter generation times than resprouters, particularly under short fire return intervals, thus potentially increasing their molecular evolutionary rates and, ultimately, their diversification. We explored whether seeder lineages actually have higher rates of molecular evolution and diversification than resprouters. Molecular evolutionary rates in different DNA regions were compared in 45 phylogenetically paired congeneric taxa from fire-prone Mediterranean-type ecosystems with contrasting seeder and resprouter life histories. Differential diversification was analyzed with both topological and chronological approaches in five genera (Banksia, Daviesia, Lachnaea, Leucadendron, and Thamnochortus) from two fire-prone regions (Australia and South Africa). We found that seeders had neither higher molecular rates nor higher diversification than resprouters. Such lack of differences in molecular rates between seeders and resprouters-which did not agree with theoretical predictions-may occur if (1) the timing of the switch from seeding to resprouting (or vice versa) occurs near the branch tip, so that most of the branch length evolves under the opposite life-history form; (2) resprouters suffer more somatic mutations and therefore counterbalancing the replication-induced mutations of seeders; and (3) the rate of mutations is not related to shorter generation times because plants do not undergo determinate germ-line replication. The absence of differential diversification is to be expected if seeders and resprouters do not differ from each other in their molecular evolutionary rate, which is the fuel for speciation. Although other factors such as the formation of isolated populations may trigger diversification, we can conclude that fire acting as a throttle for diversification is by no means the rule in fire-prone ecosystems. 相似文献
4.
Leaf and shoot water content and leaf dry matter content of Mediterranean woody species with different post-fire regenerative strategies 总被引：1，自引：0，他引：1
BACKGROUND AND AIMS: Post-fire regeneration is a key process in Mediterranean shrubland dynamics, strongly determining the functional properties of the community. In this study, a test is carried out to determine whether there is co-variation between species regenerative types and functional attributes related to water use. METHODS: An analysis was made of the seasonal variations in leaf relative water content (RWC), leaf dry matter content (LDMC), leaf moisture (LM) and live fine fuel moisture (LFFM) in 30 woody species of a coastal shrubland, with different post-fire regenerative strategies (seeding, resprouting or both). KEY RESULTS: RWC results suggest that the studied resprouters have more efficient mechanisms to reduce water losses and maintain water supply between seasons. In contrast, seeders are more drought tolerant. LDMC is higher in resprouters over the course of the year, suggesting a more efficient conservation of nutrients. The weight of the phylogenetic constraint to understand differences between regenerative strategies tends to be important for LDMC, while it is not the case for variables such as RWC. CONCLUSIONS: Groups of species with different post-fire regenerative strategies (seeders and resprouters) have different functional traits related to water use. In addition to the role of phylogenetical constraints, these differences are also likely to be related to the respective life history characteristics. Therefore, the presence and abundance of species with different post-fire regenerative responses influence the functional properties of the communities. 相似文献
5.
The ancient Gondwanan family Proteaceae has its greatest speciation in fire‐prone environments of Australia. Fire response is either by seedling recruitment from parent plants that succumb to fire (obligate seeders), or survival and resprouting from protected buds (resprouters). Starch is the main source of energy for resprouting and in roots is restricted to parenchyma tissue. This study compared the size and distribution of storage parenchyma and the magnitude of starch reserves in roots of several proteaceous species from different genera in relation to their fire response and taxonomy. Cross‐sections (2 μm) of roots of 51 resprouter and 42 seeder species from 12 genera were stained for starch. Areas of cortex and ray parenchyma along with starch grain density were measured using image analysis software (Assess 2.0) and comparable samples of root tissue were assayed chemically for starch. Starch, where present, predominated in ray and cortex tissue with a greater percentage in resprouters (13.4 ± 1.03) than seeders (1.8 ± 0.26); these results correlated significantly with the chemical assay for starch (r = 0.93, P < 0.0001). Resprouters also had more storage parenchyma (56.9 ± 1.72%) than seeders (41.9 ± 1.91%) mostly due to broader rays (17.5 ± 1.22%) compared with seeders (8.2 ± 0.16%). Percentage of cortex tissue was similar for seeders and resprouters (39.4 ± 2.24 and 33.7 ± 2.04 respectively). Anatomical preferences for storage site were consistent within genera and broad suprageneric groupings. This study shows that histological analysis of root starch is a reliable predictor of resprouting capacity in Proteaceae and that patterns of storage tissue within genera, together with the persistence of parenchyma devoid of starch in seeders, are consistent with response to fire and suggests homoplastic evolution of this response within the family. 相似文献
6.
Nyasha Magadzire Helen M. de Klerk Karen J. Esler Jasper A. Slingsby 《Diversity & distributions》2019,25(7):1012-1023
7.
LYNDSEY M. VIVIAN GEOFFREY J. CARY ROSS A. BRADSTOCK A. MALCOLM GILL 《Austral ecology》2008,33(1):55-67
Abstract Plant responses to fire are variable between and within species and are influenced by numerous factors including fire severity. This study investigated the effects of fire severity on the regeneration and recruitment of forest eucalypts in the Cotter River Catchment, Australian Capital Territory (ACT). This study also examined the potential for the obligate seeder Eucalyptus delegatensis R.T. Baker (Myrtaceae) to expand into adjacent stands dominated by the facultative resprouter Eucalyptus fastigata H. Deane & Maiden (Myrtaceae) by seed shed and seedling establishment beyond the pre‐fire boundary. Sites were located in areas of either higher or lower fire severity, and transects were placed across the boundary of stands of E. delegatensis and E. fastigata. Species distributions, tree survival and seedling densities and heights were recorded, and the location of each boundary was determined as the region of maximum change in species composition along the transects. Eucalyptus delegatensis was the only eucalypt killed by higher severity fire. However, E. delegatensis seedling density was greater at higher severity sites than lower severity sites. Eucalyptus fastigata seedling density was low across all sites, with other eucalypts producing few, if any, seedlings. There was no evidence that E. delegatensis had increased its range into downslope stands dominated by E. fastigata. Patterns of vegetative recovery and seedling recruitment may be related to a number of factors, including differences in allocation patterns between seeders and sprouters, and the effects of overstory and understory competition. It is unclear what processes impede E. delegatensis seedling establishment beyond the stand boundary, but may involve an inability of E. delegatensis to shed seed sufficiently far downslope; unsuitable conditions for germination beyond the boundary; or, competition from a retained or resprouting overstory, despite the potential for increased dispersal distance soon after fire. 相似文献
8.
José Gabriel Segarra‐Moragues Fernando Ojeda 《Evolution; international journal of organic evolution》2010,64(12):3511-3524
Understanding the processes of biological diversification is a central topic in evolutionary biology. The South African Cape fynbos, one of the major plant biodiversity hotspots out of the tropics, has prompted several hypotheses about the causes of generation and maintenance of biodiversity. Fire has been traditionally invoked as a key element to explain high levels of biodiversity in highly speciose fynbos taxa, such as the genus Erica. In this study, we have implemented a microevolutionary approach to elucidate how plant‐response to fire may contribute to explain high levels of diversification in Erica. By using microsatellite markers, we investigated the genetic background of seeder (fire‐sensitive) and resprouter (fire‐resistant) populations of the fynbos species Erica coccinea. We found higher within‐population genetic diversity and higher among‐population differentiation in seeder populations and interpreted these higher levels of genetic diversification as a consequence of the comparatively shorter generation times and faster population turnover in the seeder form of this species. Considering that genetic divergence among populations may be seen as the initial step to speciation, the parallelism between these results and the pattern of biodiversity at the genus level offers stimulating insights into understanding causes of speciation of the genus Erica in the Cape fynbos. 相似文献
9.
Ana Carolina Santacruz‐García Sandra Bravo Florencia del Corro Fernando Ojeda 《Austral ecology》2019,44(8):1416-1429
Recent changes to fire regimes in many regions of the world have led to renewed interest in plant flammability experiments to understand and predict the consequences of such changes. These experiments require the development of practical and standardised flammability testing protocols. The research aims were (i) to compare plant flammability assessments carried out using two different approaches, namely functional trait analysis and testing with a shoot‐level device; and (ii) to evaluate the effect of disturbances and seasonal variability on flammability. The study area was located in the Western Chaco region, Argentina, and 11 species were selected based on their representativeness in forests. We studied six functional traits related to flammability, growth habit and foliar persistence, in forests without disturbances over the three last decades as well as in disturbed forests. The seasonal variation of these functional traits was evaluated over two consecutive years. Functional trait flammability index (FI) and shoot‐level measurements followed standard protocols. Sixty per cent of the species measured presented a high to very high FI. The results of both assessment methods were significantly correlated. Both methods identified the same species as having medium flammability, but differed in regards to the most flammable species. Senegalia gilliesii was identified as the most flammable species when using functional trait analysis, whereas shoot‐level assessments found Larrea divaricata and Schinus johnstonii to be the most flammable. There were no disturbance effects on the FI but there was seasonal variation. Our results validate the use of functional traits as a predictive method of flammability testing and represent the first global effort comparing flammability obtained through functional trait analysis with empirical measurements. The significant correlation between both methods allows the selection of the one that is more appropriate for the size of the area to be evaluated and for the availability of technical resources. Abstract in Spanish is available with online material. 相似文献
10.
群落特征可能取决于物种在功能实体功能特征的独特组合（FE）中的分布。了解这些分布是保护生物多样性和维持生态系统功能的基础。鼎湖山南亚热带常绿阔叶林群落物种丰富,根据物种的多度来区分常见种（每hm2超过一个个体）和偶见种（每hm2少于一个个体）。基于功能实体,分别计算功能实体数量、功能冗余度、功能脆弱度和功能过度冗余度来描述每个样方中常见种和偶见种的功能多样性。采用Wilcoxon检验检测常见种和偶见种功能性状的差异,通过线性回归分析常见种和偶见种的功能多样性与物种数量的关系,采用冗余分析（RDA）影响常见种和偶见种的功能多样性的环境因子。研究结果表明：（1）鼎湖山南亚热带常绿阔叶林群落中功能性状在常见种和偶见种间差异显著。（2）群落中数量较低的偶见种保持着较高比例的功能实体数量。功能实体数量、功能冗余度与常见种和偶见种数量显著正相关,功能过度冗余度与偶见种数量显著正相关,功能脆弱度与常见种和偶见种的物种数量呈显著负相关。（3）海拔是影响常见种功能多样性最关键的地形因子,凹凸度是影响偶见种功能多样性最关键的地形因子。土壤含水量是影响常见种功能多样性最关键的土壤因子,速效钾是影响偶见种功能多样性最关键的环境因子。研究结果表明,尽管物种丰富的热带森林具有较高的功能冗余,但其提供的保险效应不能抵消生态系统的功能脆弱性。减少具有独特功能实体和偶见种的损失是避免热带森林生态系统功能损失的有效和必要的方法。 相似文献
11.
Weiwei Zhao William K. Cornwell Marinda van Pomeren Richard S. P. van Logtestijn Johannes H. C. Cornelissen 《Ecology and evolution》2016,6(22):8223-8234
Fire affects and is affected by plants. Vegetation varies in flammability, that is, its general ability to burn, at different levels of ecological organization. To scale from individual plant traits to community flammability states, understanding trait effects on species flammability variation and their interaction is important. Plant traits are the cumulative result of evolution and they show, to differing extents, phylogenetic conservatism. We asked whether phylogenetic distance between species predicts species mixture effects on litterbed flammability. We conducted controlled laboratory burns for 34 phylogenetically wide‐ranging species and 34 random two‐species mixtures from them. Generally, phylogenetic distance did not predict species mixture effects on flammability. Across the plant phylogeny, most species were flammable except those in the non‐Pinus Pinaceae, which shed small needles producing dense, poorly ventilated litterbeds above the packing threshold and therefore nonflammable. Consistently, either positive or negative dominance effects on flammability of certain flammable or those non‐flammable species were found in mixtures involving the non‐Pinus Pinaceae. We demonstrate litter particle size is key to explaining species nonadditivity in fuelbed flammability. The potential of certain species to influence fire disproportionately to their abundance might increase the positive feedback effects of plant flammability on community flammability state if flammable species are favored by fire. 相似文献
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13.
城市自生草本植物的物种多样性和功能多样性直接影响城市生态系统的功能和稳定性,但目前相关研究依然很缺乏。以深圳市为例,基于建成区600个1hm2样地的现场调查数据,分析自生草本植物的群落结构、物种多样性、群落功能特征及功能多样性。结果显示：（1）调查共记录自生草本植物61科178属273种,其中多年生草本占54.6%,乡土植物占65.6%。（2）占明显优势的功能特征有中小型叶（91.85%）、草质叶（42.59%）、纸质叶（32.96%）、叶片无毛或近无毛（56.67%）、中等密度绒毛（40.37%）、叶面较粗糙（52.59%）、花期4—6个月（50.78%）、果期4—6个月（49.22%）、干果（86.03%）。（3）群落类型间功能丰富度FDp、功能离散度Rao二次熵差异极显著（P<0.01）、功能均匀度FEve差异显著（P<0.05）。（4）公园绿地的物种多样性指数明显高于其他三类绿地;不同绿地类型间的功能丰富度和功能离散度在滞尘、降噪、降温增湿及生物多样性保护方面都有极显著差异（P<0.01）,功能均匀度只在滞尘及生物多样性保护方面差异极显著（P<0.01）。（5）各功能多样性指数均与Margalef指数、Simpson指数及Shannon-Wiener指数呈极显著正相关关系（P<0.01）。研究结论和方法为维护城市生态系统稳定性、建设生态宜居城市、促进城市可持续发展提供理论依据。 相似文献
14.
John T. Hunter 《Journal of Biogeography》2003,30(4):497-510
Aim To investigate if the current theories associated with recruitment strategies are sufficient to explain differences in the proportions of obligate seeders and resprouters on inselbergs and in the matrix. Location The New England Batholith of eastern Australia. Methods The importance of life form and regenerative response of flora species are compared for twenty‐four archipelagos of inselbergs habitat islands and for their adjacent matrix. Forward stepwise multiple linear regression is used to correlate measured and modelled variables with differences in the proportional abundance of obligate seeders on inselbergs at three levels of sampling. Results A total of 216 inselbergs were surveyed and information on 826 vascular plant species was collated. Herbs were the most common life form both on and off inselbergs. There were generally more shrubs on inselbergs than in the matrix. Resprouters were more common everywhere. However, obligate seeders were proportionately more common on inselbergs. The degree of insularity of outcrop floras accounted for 23–37% of the variance in the proportional abundance of obligate seeders at three sampling scales. Main conclusions A model is proposed whereby the mechanisms that influence the abundances of obligate seeders and resprouters are different on inselbergs and in the matrix. Inselberg environments are harsh, arid, have limited safe recruitment sites and below ground resources, but are not light limited. In such habitats, obligate seeders with persistence life‐history traits are favoured. Within the matrix in eastern Australia frequent biomass removal disturbances occur (such as fire) and resprouting is advantageous. High turnover obligate seeders with no persistence life‐history traits can be favoured in the matrix with a reduced disturbance regime and where competition for light still occurs. Some of these matrix obligate seeders occur on inselbergs due to their infrequent disturbance regimes. 相似文献
15.
Sonia Llorente-Culebras;Carlos P. Carmona;William D. Carvalho;André Menegotto;Rafael Molina-Venegas;Richard J. Ladle;Ana M. C. Santos; 《Global Change Biology》2024,30(6):e17375
Islands are biodiversity hotspots that host unique assemblages. However, a substantial proportion of island species are threatened and their long-term survival is uncertain. Identifying and preserving vulnerable species has become a priority, but it is also essential to combine this information with other facets of biodiversity like functional diversity, to understand how future extinctions might affect ecosystem stability and functioning. Focusing on mammals, we (i) assessed how much functional space would be lost if threatened species go extinct, (ii) determined the minimum number of extinctions that would cause a significant functional loss, (iii) identified the characteristics (e.g., biotic, climatic, geographic, or orographic) of the islands most vulnerable to future changes in the functional space, and (iv) quantified how much of that potential functional loss would be offset by introduced species. Using trait information for 1474 mammal species occurring in 318 islands worldwide, we built trait probability density functions to quantify changes in functional richness and functional redundancy in each island if the mammals categorized by IUCN as threatened disappeared. We found that the extinction of threatened mammals would reduce the functional space in 63% of the assessed islands, although these extinctions in general would cause a reduction of less than 15% of their overall functional space. Also, on most islands, the extinction of just a few species would be sufficient to cause a significant loss of functional diversity. The potential functional loss would be higher on small, isolated, and/or species-rich islands, and, in general, the functional space lost would not be offset by introduced species. Our results show that the preservation of native species and their ecological roles remains crucial for maintaining the current functioning of island ecosystems. Therefore, conservation measures considering functional diversity are imperative to safeguard the unique functional roles of threatened mammal species on islands. 相似文献
16.
By Martin A. Smith William A. Loneragan Carl D. Grant John M. Koch 《Ecological Management & Restoration》2000,1(1):50-60
Summary Germinable seed stores of 5- and 8-year-old rehabilitated bauxite mine pits in south-west Western Australia were assessed before and after burning. These seed stores were compared to those of adjacent unmined Jarrah ( Eucalyptus marginata ) forest, to identify at what age fire can be reintroduced, in order to measure restoration success and reduce fire hazard. Soils were sampled in early summer (before fire) and late autumn (after fire). Before fire, the mean topsoil seed bank of 5-year-old sites was 2121 seeds per m2 while 8-year-old sites had a mean of 1520 seeds per m2 . Only the 5-year-old sites were significantly different from the forest mean of 1478 seeds per m2 for the same season. After summer burns (and possibly due to seasonal effects) topsoil seed banks of rehabilitated areas (sampled in autumn) decreased by an average of 53 per cent. Topsoil seed banks of 5–8-year-old sites were resistant to lower intensity burns, with 362 seeds per m2 of native species surviving mild burns and 108 seeds per m2 of native species surviving after an intense summer fire. The topsoil seed reserve of 5–8-year-old rehabilitated areas had a high proportion of annual weed species while the forest sites had high levels of subshrubs and native annuals. Low-intensity burns did not alter the composition of life-forms in the soil seed bank, while intense burns favoured annual weed and shrub species. The results indicate that it is not appropriate to introduce fire to rehabilitated areas before 8 years, due to limited fuel reduction benefits and possible adverse effects on obligate seeding species. The large proportion of weed species in the soil seed bank of young rehabilitated areas is a concern, and remains a major consideration for future disturbance of these areas. 相似文献
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18.
Nathan G. Swenson Brian J. Enquist Jason Pither Andrew J. Kerkhoff Brad Boyle Michael D. Weiser James J. Elser William F. Fagan Jimena Forero‐Montaña Nikolaos Fyllas Nathan J. B. Kraft Jeffrey K. Lake Angela T. Moles Sandra Patiño Oliver L. Phillips Charles A. Price Peter B. Reich Carlos A. Quesada James C. Stegen Renato Valencia Ian J. Wright S. Joseph Wright Sandy Andelman Peter M. Jørgensen Thomas E. Lacher Jr Abel Monteagudo M. Percy Núñez‐Vargas Rodolfo Vasquez‐Martínez Kristen M. Nolting 《Global Ecology and Biogeography》2012,21(8):798-808
Aim In recent years evidence has accumulated that plant species are differentially sorted from regional assemblages into local assemblages along local‐scale environmental gradients on the basis of their function and abiotic filtering. The favourability hypothesis in biogeography proposes that in climatically difficult regions abiotic filtering should produce a regional assemblage that is less functionally diverse than that expected given the species richness and the global pool of traits. Thus it seems likely that differential filtering of plant traits along local‐scale gradients may scale up to explain the distribution, diversity and filtering of plant traits in regional‐scale assemblages across continents. The present work aims to address this prediction. Location North and South America. Methods We combine a dataset comprising over 5.5 million georeferenced plant occurrence records with several large plant functional trait databases in order to: (1) quantify how several critical traits associated with plant performance and ecology vary across environmental gradients; and (2) provide the first test of whether the woody plants found within 1° and 5° map grid cells are more or less functionally diverse than expected, given their species richness, across broad gradients. Results The results show that, for many of the traits studied, the overall distribution of functional traits in tropical regions often exceeds the expectations of random sampling given the species richness. Conversely, temperate regions often had narrower functional trait distributions than their smaller species pools would suggest. Main conclusion The results show that the overall distribution of function does increase towards the equator, but the functional diversity within regional‐scale tropical assemblages is higher than that expected given their species richness. These results are consistent with the hypothesis that abiotic filtering constrains the overall distribution of function in temperate assemblages, but tropical assemblages are not as tightly constrained. 相似文献
19.
蚂蚁群落与栖境关系研究进展及新趋势 总被引：1，自引：0，他引：1
生物群落与栖境的关系是生态学研究的核心之一,蚂蚁群落由于在陆地生态系统中的生物量、分布以及具备的生态功能的重要性,是研究这种关系的理想对象。在查阅大量文献的基础上,简述了蚂蚁物种多样性与栖境关系研究现状。介绍了蚂蚁功能群划分以及在不同尺度上与栖境关系的应用研究,评述了功能群应用的限制。阐明了功能特征的定义以及基于形态特征和营养级方面的蚂蚁群落功能特征与栖境的研究,并对功能特征的研究趋势进行了展望。 相似文献
20.
Simon Thorn Claus Bässler Markus Bernhardt‐Römermann Marc Cadotte Christoph Heibl Hanno Schäfer Sebastian Seibold Jörg Müller 《Ecology letters》2016,19(2):163-170
The species–energy hypothesis predicts that more productive areas support higher species richness. Conversely, when resources are reduced, species richness is reduced. Empirical tests of whether extinctions are predominantly caused by environmental constraints or competitive exclusion are lacking. We experimentally reduced dead wood to c. 15% of the initial amount after a major windstorm and examined changes in assembly mechanisms by combining trait‐based and evolutionary species dissimilarities of eight taxonomic groups, differing in their dependence on dead wood (saproxylic/non‐saproxylic). Species richness and assembly mechanisms of non‐saproxylic taxa remained largely unaffected by removal of dead wood. By contrast, extinctions of saproxylic species were caused by reversing the predominant assembly mechanisms (e.g. increasing importance of competitive exclusion for communities assembled through environmental filtering or vice versa). We found no evidence for an intensification of the predominant assembly mechanism (e.g. competitive exclusion becoming stronger in a competitively structured community). 相似文献