Resource partitioning of sympatric small mammals in an African forest‐grassland vegetation mosaic

It is often hypothesized that two species competing for the same resource cannot stably coexist unless they partition their resources in space and time. More recently stable isotope analyses have complemented traditional, observation‐based niche research by conceptualizing many of the characteristics of communities, for example, trophic niche width and the partitioning of resources. Here we quantify resource partitioning of sympatric small mammal species in an African ecosystem by analysing stable isotope ratios of hair collected from a South African forest‐grassland vegetation mosaic, and combine this with known spatial and temporal behavioural data to interpret community competition and resource partitioning. We observe niche separation to different degrees across the entire community, with different species displaying either unique isotopic dietary preferences, or partitioning resources in space and/or time. δ¹³C values were more enriched in species that inhabited afromontane grassland compared with those that inhabited afromontane forest, a reflection of the dominant vegetation in each habitat. Contrary to expectations, arboreal rodents occupied higher trophic positions than terrestrial rodents and approaching δ¹⁵N values similar to insectivorous shrews, suggesting that arboreal rodents feed on items such as arthropods enriched in ¹⁵N. While grassland species display phenotypic plasticity in terms of dietary preferences, small mammals that occurred in forests display narrow niche preferences, suggesting these species may be particularly sensitive to habitat modifications. Our results illustrate that the use of stable isotopes can be used in conjunction with spatial and temporal behavioural knowledge to elucidate resource partitioning in small African mammal communities.     

Coevolution in resource-limited competition communities

A coevolutionary model of species packing is developed which allows evolutionary adjustment in both niche position and within-phenotype niche width of from one of three competing species. The environment is specified as a single resource dimension x and availability of resources along x is given by a Gaussian curve with parameters ($\text{x}\text{?}{}_{\mathrm{R}}\text{and}\text{σ}{}_{\mathrm{R}}$). The model predicts that for S species the ratio of optimal niche width (?) to σ_R is roughly independent of σ_R and can be approximated by $\text{1}\text{S}$ when the competitors are completely resource limited. Niche separation ($\text{d}\text{?}\text{w}\text{?}$) increases only moderately with increases in resource diversity σ_R and is greater for two than for three competing species. To the extent that the competitors do not utilize all resources, both optimal niche separation and niche width decrease. Many of the general trends in niche width and niche separation predicted by this coevolutionary model parallel those from optimal foraging theory and limiting similarity models of community structure. The coevolutionary model stands out, however, in the singularly high values predicted for niche separation, making coevolved communities highly invadeable. Hence, the theory suggests, as some empirical evidence indicates, that coevolved competition communities can only exist as such on remote islands or in other habitats which might be free from invasion by outside species. For such communities, resource diversity (σ_R) should have much less effect on species packing than either species number itself or the extent that these competitors are resource limited.     

乌鲁木齐达坂城山区地衣生态位特征的研究

为揭示达坂城山区地衣对生境资源的利用状况及竞争程度,该研究在野外设置30个样方并调查其物种盖度数据,利用生态位宽度、生态位重叠指数及排序分析,探讨达坂城山区地衣的生态位特征及环境影响因子。结果表明:(1)达坂城山区生态位最宽的为丽黄鳞衣(Rusavskia elegans)和内卷野粮衣(Circinaria contorta),对不同环境具有较强的适应性,其他地衣物种生态位宽度较窄,对环境资源利用程度低。(2)物种间生态位重叠值整体偏低,生态位重叠值较高的物种对极少,地衣物种生态位分化程度高,物种间竞争不激烈。(3)生态位较宽的物种与多数物种之间都存在生态位重叠,但重叠值较低; 一些生态位较窄的物种与其他物种之间的生态位重叠值较高; 生态位重叠和生态位宽度之间并无直接的线性关系。(4)地衣物种沿海拔梯度分布具有差异,海拔、光照强度、湿度、风速和人为干扰是本地区地衣群落物种生态位特征差异的主导环境因子。综上所述,达坂城山区地衣物种由于生境资源的竞争占据各自独特的生态位,形成了生态位的分化,群落较为稳定,沿海拔梯度的生境条件差异是物种差异分布的重要原因。该研究可为地衣群落构建研究提供理论依据,并对该地区地衣物种的多样性和生境保护具有重要意义。     

Oribatid mites reveal that competition for resources and trophic structure combine to regulate the assembly of diverse soil animal communities

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ON THE COEXISTENCE AND COEVOLUTION OF ASEXUAL AND SEXUAL COMPETITORS

The coexistence and coevolution of sexual and asexual species under resource competition are explored with three models: a nongenetic ecological model, a model including single locus genetics, and a quantitative-genetic model. The basic assumption underlying all three models is that genetic differences are translated into ecological differences. Hence if sexual species are genetically more variable, they will be ecologically more variable. Under classical competition theory, this increased ecological variability can, in many cases, be an advantage to individual sexual genotypes and to the sexual species as a whole. The purpose of this paper is to determine the conditions when this advantage will outway three disadvantages of sexuality: the costs of males, of segregation, and of the additive component of recombination. All three models reach similar conclusions. Although asexuality confers an advantage, it is much less than a two-fold advantage because minor increases in the overall species niche width of the sexual species will offset the reproductive advantage of the asexual species. This occurs for two reasons. First, an increase in species niche width increases the resource base of the sexual species. Second, to the extent that the increase in niche width is due to increased differences between individuals, a reduction in intraspecific competition will result. This is not to imply that the sexual species will always win. The prime conditions that enable sexual species to stably coexist with or even supplant an asexual sister species are:

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大兴安岭次生林区不同龄级落叶松(Larix gmelinii)生态位特征和竞争关系

生态位能够反映物种在群落中的功能地位,通过生态位可以定量地研究种内、种间、生境三者之间的相互关系。以大兴安岭次生林区优势种群落叶松（Larix gmelinii）为研究对象,运用Levins公式、Pianka指数和Hegyi单木竞争指数模型分析了该优势种的生态位特征、生态位宽度与重叠度以及重叠程度与竞争作用之间的关系。研究结果表明：随落叶松个体的发育其生态位呈先增大后减小的规律性变化;生态位宽度较大的落叶松个体间重叠程度往往也较高,生态位宽度与重叠度呈显著的线性正相关;落叶松个体间的生态位重叠程度与彼此之间的竞争作用无明显相关性、种群内存在互利性生态位重叠现象;生物个体间的竞争作用与研究尺度有关。     

高寒草甸植物群落物种多样性和生产力关系的光竞争研究

通过施肥形成的生产力由低到高的过程中,物种多样性往往降低。总体竞争假说认为对所有资源的竞争作用对多样性的影响随着生产力提高而加剧,导致物种多样性的下降;光竞争假说则认为随着生产力提高,种间竞争从低生产力时的地下竞争转向高生产力时的光竞争,是光竞争导致了物种多样性的下降。为了验证这两种假说,本文通过在甘南玛曲高寒草甸的均匀施肥实验,研究了光竞争对高寒草甸植物群落物种多样性和生产力关系的影响。结果表明：(1)随着施肥梯度的增加,大部分植物的生长速率加快,高度和叶面积增加;(2)随着施肥梯度的增加,植物群落地上总的生物量提高,叶面积指数增加,透光率降低,物种多样性减少;(3)个体大小不对称的光竞争导致了高寒草甸植物群落物种多样性随施肥梯度的增加而减少。     

Competition and species diversity: removal of dominant species increases diversity in Costa Rican butterfly communities

Biological communities are usually dominated by a few species and show characteristically skewed species abundance distributions. Although niche apportionment and resource competition are sometimes implicated in such patterns, few experimental studies have shown direct links between resource limitation, competition with dominant species and their impacts on the overall diversity and composition of large natural communities. Here I report the results of an experiment in which I first studied species diversity and composition in two Costa Rican nectar-feeding butterfly communities numerically dominated by two species of Anartia butterflies. Then I removed Anartia from these communities to study changes in resource availability, species abundance relationships, community diversity and composition as an outcome of the removal of the dominant competitors. In the face of competition with Anartia , nectar was scarce, species abundance distributions were highly skewed, and species diversity was low in both communities. Within two weeks after the removal of Anartia , there were parallel changes in both communities: competition for nectar reduced and the nectar quantity increased substantially, which facilitated increase in community diversity and resulted in significantly less skewed species abundance distributions. Higher nectar quantity also enabled the distribution of body size and proboscis length of constituent species in the communities to expand at both ends. This study thus experimentally showed that resource competition with the dominant species was excluding many species from the communities, lowering their diversity and skewing relative species abundance relationships. These findings are of fundamental importance for competition theory and community ecology because they indicate ways in which diverse communities may be affected by and recover from competition with dominant species.     

Neutral processes and species sorting in benthic microalgal community assembly: effects of tidal resuspension

Benthic microalgae (BMA) provide vital food resources for heterotrophs and stabilize sediments with their extracellular secretions. A central goal in ecology is to understand how processes such as species interactions and dispersal, contribute to observed patterns of species abundance and distribution. Our objectives were to assess the effects of sediment resuspension on microalgal community structure. We tested whether taxa‐abundance distributions could be predicted using neutral community models (NCMs) and also specific hypotheses about passive migration: (i) As migration decreases in sediment patches, BMA α‐diversity will decrease, and (ii) As migration decreases, BMA community dissimilarity (β‐diversity) will increase. Co‐occurrence indices (checkerboard score and variance ratio) were also computed to test for deterministic factors, such as competition and niche differentiation, in shaping communities. Two intertidal sites (mudflat and sand bar) differing in resuspension regime were sampled throughout the tidal cycle. Fluorometry and denaturing gradient gel electrophoresis were utilized to investigate diatom community structure. Observed taxa‐abundances fit those predicted from NCMs reasonably well (R² of 0.68–0.93), although comparisons of observed local communities to artificial randomly assembled communities rejected the null hypothesis that diatom communities were assembled solely by stochastic processes. No co‐occurrence tests indicated a significant role for competitive exclusion or niche partitioning in microalgal community assembly. In general, predictions about relationships between migration and species diversity were supported for local community dynamics. BMA at low tide (lowest migration) exhibited reduced α‐diversity as compared to periods of immersion at both mudflat and sand bar sites. β‐diversity was higher during low tide emersion on the mudflat, but did not differ temporally at the sand bar site. In between‐site metacommunity comparisons, low‐ and high‐resuspension sites exhibited distinct community compositions while the low‐energy mudflats contained higher microalgal biomass and greater α‐diversity. To our knowledge this is the first study to test the relevance of neutral processes in structuring marine microalgal communities. Our results demonstrate a prominent role for stochastic factors in structuring local BMA community assembly, although unidentified nonrandom processes also appear to play some role. High passive migration, in particular, appears to help maintain species diversity and structure communities in both sand and muddy habitats.     

Pollen load diversity and foraging niche overlap in a pollinator community of the rare <Emphasis Type="Italic">Dictamnus albus</Emphasis> L.

Bees collect pollen as an important resource for offspring development while acting as pollen vectors for the plants visited. Foraging preferences of pollinators together with plant species availability shape the web of interactions at the local scale. In this study, we focused on the bee pollinator community of a population of the rare protected perennial herb Dictamnus albus, with the aim to characterise the pollen preferences and the foraging niche overlap among species through time. Bees were sampled during four consecutive years in a natural population of D. albus, throughout the blooming period of the plant species. We performed an analysis of insect pollen loads to investigate the interactions with the study species and the co-flowering plants in the area, and to evaluate the degree of foraging overlap among pollinators. Over the study years, all bee species showed a high fidelity to D. albus (60–80%), even if some taxa preferentially collected pollen from other flowering species. The foraging niche overlap in the pollinator community decreased together with an increased diversity of co-flowering plant species. The results obtained indicate that bees preferentially forage on D. albus in the studied area, but that co-flowering species contribute to complement their diet and likely reduce competition for foraging resources. It appears therefore important to maintain a high diversity of co-flowering plants to preserve the diversity in the studied pollinator community of D. albus.     

太行山中段植物群落优势种生态位研究

运用TWINSPAN把样方分为8个群落类型,用Levins、Shannon-wiener生态位宽度公式和Petraitis生态位特定重叠指数公式测定群落中主要种群生态位宽度和生态位重叠,并分析各种群生态位的生态学意义。在总群落中,披针苔草和草地早熟禾的生态位宽度最大,说明它们对群落环境的适应能力最强,对资源的利用能力也最强;在不同的群落里（群落Ⅰ到群落Ⅷ）,相同种群生态位宽度有极大差别,草地早熟禾在群落Ⅱ中,B1为 2.753,B2为 15.561,在群落Ⅷ中,B1为0,B2为1;总群落中,各种群的生态位宽度明显大于其在其他群落里的生态位宽度。两个种群的生态位重叠值越大,说明它们占据越相似的资源空间,珠芽蓼和火绒草的生态位重叠值高达0.892（群落Ⅰ中）,说明它们利用资源的相似性程度很高;在总群落中,各种群之间生态位重叠值都很低。     

Do biotic interactions shape both sides of the humped‐back model of species richness in plant communities?

A humped-back relationship between species richness and community biomass has frequently been observed in plant communities, at both local and regional scales, although often improperly called a productivity-diversity relationship. Explanations for this relationship have emphasized the role of competitive exclusion, probably because at the time when the relationship was first examined, competition was considered to be the significant biotic filter structuring plant communities. However, over the last 15 years there has been a renewed interest in facilitation and this research has shown a clear link between the role of facilitation in structuring communities and both community biomass and the severity of the environment. Although facilitation may enlarge the realized niche of species and increase community richness in stressful environments, there has only been one previous attempt to revisit the humped-back model of species richness and to include facilitative processes. However, to date, no model has explored whether biotic interactions can potentially shape both sides of the humped-back model for species richness commonly detected in plant communities. Here, we propose a revision of Grime's original model that incorporates a new understanding of the role of facilitative interactions in plant communities. In this revised model, facilitation promotes diversity at medium to high environmental severity levels, by expanding the realized niche of stress-intolerant competitive species into harsh physical conditions. However, when environmental conditions become extremely severe the positive effects of the benefactors wane (as supported by recent research on facilitative interactions in extremely severe environments) and diversity is reduced. Conversely, with decreasing stress along the biomass gradient, facilitation decreases because stress-intolerant species become able to exist away from the canopy of the stress-tolerant species (as proposed by facilitation theory). At the same time competition increases for stress-tolerant species, reducing diversity in the most benign conditions (as proposed by models of competition theory). In this way our inclusion of facilitation into the classic model of plant species diversity and community biomass generates a more powerful and richer predictive framework for understanding the role of plant interactions in changing diversity. We then use our revised model to explain both the observed discrepancies between natural patterns of species richness and community biomass and the results of experimental studies of the impact of biodiversity on the productivity of herbaceous communities. It is clear that explicit consideration of concurrent changes in stress-tolerant and competitive species enhances our capacity to explain and interpret patterns in plant community diversity with respect to environmental severity.     

Beyond ecological opportunity: Prey diversity rather than abundance shapes predator niche variation

1. Ecological opportunity (i.e. the diversity of available resources) has a pivotal role in shaping niche variation and trophic specialisation of animals. However, ecological opportunity can be described with regard to both diversity and abundance of resources. The degree to which these two components contribute to niche variation remains unexplored.
2. To address this, we used an extensive dataset on fish diet and benthic invertebrate diversity and density from 73 sampling events in three Norwegian rivers in order to explore realised trophic niches and the response of dietary niche variation along gradients of resource diversity (potential trophic niches), resource density (as a proxy of resource abundance) and fish density (as a proxy of inter‐ and intra‐specific competition) in a freshwater top predator (the brown trout, Salmo trutta L.).
3. Linear models indicated that individual and population niche variation increased with increasing ecological opportunity in terms of prey diversity. However, no simple cause‐and‐effect associations between niche indices and prey abundance were found. Our multiple regression analyses indicated that the abundance of certain resources (e.g. Chironomidae) can interact with prey diversity to determine individual and population realised trophic niches. Niche variation (within‐individual component and inter‐individual diet variation) decreased with increasing inter‐ and intra‐specific competition.
4. This study extends prevailing trophic ecology theory by identifying diversity, rather than density, of available prey resources as a primary driver of niche variation in fish of temperate riverine systems with no extensive resource limitation. The study also shows that ecological opportunity may mask the direction of the effect (compression or expansion) of competition on niche variation when food resources are diverse.
5. Our study provides novel empirical insight to the driving forces behind niche variation and reveals that diversity, rather than density, of available prey resources may be a primary driver of niche variation in freshwater fish. Our study supports the view that a broader potential trophic niche promotes broader realised trophic niche variation by individuals, which leads to individual niche diversification by opening access to alternatives resources, resulting in a concomitant rise in the realised trophic niche width of the population.

     

Phylogenetic restriction of plant invasion in drought‐stressed environments: Implications for insect‐pollinated plant communities in water‐limited ecosystems

BackgroundPlant–pollinator community diversity has been found to decrease under conditions of drought stress; however, research into the temporal dimensions of this phenomenon remains limited. In this study, we investigated the effect of seasonal drought on the temporal niche dynamics of entomophilous flowering plants in a water‐limited ecosystem. We hypothesized that closely related native and exotic plants would tend to share similar life history and that peak flowering events would therefore coincide with phylogenetic clustering in plant communities based on expected phenological responses of plant functional types to limitations in soil moisture availability.LocationGaliano Island, British Columbia, Canada.MethodsCombining methods from pollinator research and phylogenetic community ecology, we tested the influence of environmental filtering over plant community phenology across gradients of landscape disturbance and soil moisture. Floral resource availability and community structure were quantified by counts of flowering shoots. We constructed a robust phylogeny to analyze spatial and temporal variation in phylogenetic patterns across the landscape, testing the significance of the observed patterns against a randomly generated community phylogeny. Phylogenetic metrics were then regressed against factors of disturbance and soil moisture availability.ResultsCritical seasonal fluctuations in floral resources coincided with significant phylogenetic clustering in plant communities, with decreasing plant diversity observed under conditions of increasing drought stress. Exotic plant species in the Asteraceae became increasingly pervasive across the landscape, occupying a late season temporal niche in drought‐stressed environments.Main conclusionResults suggest that environmental filtering is the dominant assembly process structuring the temporal niche of plant communities in this water‐limited ecosystem. Based on these results, and trends seen elsewhere, the overall diversity of plant–pollinator communities may be expected to decline with the increasing drought stress predicted under future climate scenarios.     

Trophic niche partitioning between two prey and their incidental predators revealed various threats for an endangered species

Documenting trophic niche partitioning and resource use within a community is critical to evaluate underlying mechanisms of coexistence, competition, or predation. Detailed knowledge about foraging is essential as it may influence the vital rates, which, in turn, can affect trophic relationships between species, and population dynamics. The aims of this study were to evaluate resource and trophic niche partitioning in summer/autumn between the endangered Atlantic‐Gaspésie caribou (Rangifer tarandus caribou) population, moose (Alces americanus) and their incidental predators, the black bear (Ursus americanus) and coyote (Canis latrans), and to quantify the extent to which these predators consumed caribou. Bayesian isotopic analysis showed a small overlap in trophic niche for the two sympatric ungulates suggesting a low potential for resource competition. Our results also revealed that caribou occupied a larger isotopic niche area than moose, suggesting a greater diversity of resources used by caribou. Not surprisingly, coyotes consumed mainly deer (Odocoileus virginianus), moose, snowshoe hare (Lepus americanus), and occasionally caribou, while bears consumed mainly vegetation and, to a lesser extent, moose and caribou. As coyotes and bears also feed on plant species, we documented trophic niche overlap between caribou and their predators, as searching for similar resources can force them to use the same habitats and thus increase the encounter rate and, ultimately, mortality risk for caribou. Although the decline in the Gaspésie caribou population is mostly driven by habitat‐mediated predation, we found evidence that the low level of resource competition with moose, added to the shared resources with incidental predators, mainly bears, may contribute to jeopardize the recovery of this endangered caribou population. Highlighting the trophic interaction between species is needed to establish efficient conservation and management strategies to insure the persistence of endangered populations. The comparison of trophic niches of species sharing the same habitat or resources is fundamental to evaluate the mechanisms of coexistence or competition and eventually predict the consequences of ecosystem changes in the community.     

Resource partitioning and interspecific interactions among sympatric rain forest arboreal mammals of the Western Ghats, India

Resource partitioning in a community of diurnal arboreal mammalsconsisting of the lion-tailed macaque Macaca silenus, bonnetmacaque (BM) Macaca radiata, Nilgiri langur Semnopithecus johnii,and the Indian giant squirrel Ratufa indica of the Western Ghats,southern India, was studied. Differences in their diet, verticalstratification, food resource niche breadth, niche overlap,and behavioral interactions were examined. Resource partitioningwas through differential habitat use, resource use, and verticalstratification. Of the four species, the BM was not a residentspecies and made frequent forays into evergreen forest fromthe adjacent deciduous forest during the flowering season ofCullenia exarillata and fruiting season of Ficus microcarpa.The macaques had narrower niches, and the langur and the squirrelhad wider niches. Niche overlap was highest between the twomacaques. Overlap among the study species was particularly pronouncedduring the flowering of C. exarillata. There was significantcorrelation between niche overlap and intolerance among thestudy species. Certain species pairs showed little or no mutualintolerance despite high overlap. Cooperative interactions suchas alarm calls occurred more frequently among the resident species.Interaction matrices revealed an underlying pattern of interspecificdominance hierarchy, with the BM dominating over the other threespecies. Our study suggests that the BM do not coexist withthe other three because of high overlap with its congener andlow occurrence of cooperative interactions.     

雅鲁藏布江中游浮游植物群落优势种时空生态位

为探究雅鲁藏布江中游浮游植物群落分布格局及其优势种时空生态位特征,于2021年7月、10月对该水域进行浮游植物样品的采集和水体理化因子的测定,鉴定浮游植物物种,计算浮游植物优势种生态位宽度、生态位重叠值、生态响应速率及相对资源占有率,运用共现网络模型分析群落的种间关联性,并对浮游植物优势种与环境因子进行Pearson相关性分析。结果表明：该水域共鉴定到浮游植物644种,隶属于8门12纲25目49科152属,其中,优势种22种,优势种中硅藻占90.9%,在群落中占绝对优势;丰水期的肘状针杆藻丰度最大(74.193×10⁴细胞/L)且出现频率最高(0.867),是丰水期绝对优势种;整体上优势种生态位宽度时间(0.833)>空间(0.254),优势种时空生态位宽度主要受空间生态位宽度的影响,空间异质性是影响该水域浮游植物优势种分布的主要因素;优势种时空二维生态位无意义重叠的种对占40.69%,优势种时空二维的生态位重叠以中、低等级为主,优势种间对时空资源需求异质性高,种间潜在竞争关系较弱;该水域枯水期浮游植物群落的网络结构紧密,群落连通性、群落复杂度和物种间生态位...     

草地群落物种多样性维持机制的研究Ⅱ物种实现的生态位

尽管为解释种类丰富的植物群落物种共存和多样性维持机制,生态学家位做了大量的努力并提出了许多假说和模型。但这一问题仍处在争议之中,需要更多的证据支持他们的观点或提出新的看法,使这一生物多样性难题不断地向前推进。以松赖平原物种丰富度较高的羊草－杂类草群落为对象,在土壤C、N、P、K和H2O等5个资源轴上,探讨了物种多样性与实现生态位的关系。结果表明：尽管物种生态位存在一定程度的分化,但多数物种的生态位是高度重叠的,物种生态位的分化在草地群落物种共存和多样性维持中,不是唯一的途径,认为应更加重视的物种在长期协同进化中所形成的生物学特性。     

Effect of habitat degradation on competition,carrying capacity,and species assemblage stability

Changes in species’ trophic niches due to habitat degradation can affect intra‐ and interspecific competition, with implications for biodiversity persistence. Difficulties of measuring species’ interactions in the field limit our comprehension of competition outcomes along disturbance gradients. Thus, information on how habitat degradation can destabilize food webs is scarce, hindering predictions regarding responses of multispecies systems to environmental changes. Seagrass ecosystems are undergoing degradation. We address effects of Posidonia oceanica coverage reduction on the trophic organization of a macroinvertebrate community in the Tyrrhenian Sea (Italy), hypothesizing increased trophic generalism, niche overlap among species and thus competition and decreased community stability due to degraded conditions. Census data, isotopic analysis, and Bayesian mixing models were used to quantify the trophic niches of three abundant invertebrate species, and intra‐ and interspecific isotopic and resource‐use similarity across locations differing in seagrass coverage. This allowed the computation of (1) competition strength, with respect to each other and remaining less abundant species and (2) habitat carrying capacity. To explore effects of the spatial scale on the interactions, we considered both individual locations and the entire study area (“‘meadow scale”). We observed that community stability and habitat carrying capacity decreased as P. oceanica coverage declined, whereas niche width, similarity of resource use and interspecific competition strength between species increased. Competition was stronger, and stability lower, at the meadow scale than at the location scale. Indirect effects of competition and the spatial compartmentalization of species interactions increased stability. Results emphasized the importance of trophic niche modifications for understanding effects of habitat loss on biodiversity persistence. Calculation of competition coefficients based on isotopic distances is a promising tool for describing competitive interactions in real communities, potentially extendible to any subset of ecological niche axes for which specimens’ positions and pairwise distances can be obtained.     

黔中喀斯特次生林主要物种的生态位及种间联结性动态变化

为探讨黔中喀斯特次生林演替规律,基于2013-2019年的定点监测数据,从群落物种组成、生态位宽度、生态位重叠值、种间联结等方面研究了黔中喀斯特次生林生态位和种间联结性的动态变化.结果表明,7年间建群种的重要值占比减小,六月雪(Serissa japonica)、珍珠荚蒾(Viburnum foetidum)等物种优势...