The effects of human disturbance on the species composition,species diversity and functional diversity of a Miombo woodland in northern Malawi

Anthropogenic disturbances have serious impacts on ecosystems across the world. Understanding the effects of disturbance on woodlands, especially in regions where local people depend on these natural resources, is essential for sustainable natural resource management and biodiversity conservation. In this study, we evaluated the effects of anthropogenic disturbance, specifically selective logging of Brachystegia floribunda, on woodlands by comparing species composition, species diversity and functional diversity of woody plants between disturbed and undisturbed woodlands. We combined species data and functional trait data for leaves, fruits and other traits related to resource and disturbance responses to calculate functional indices (functional richness, evenness and divergence) and community‐weighted means of each trait. Shifts in taxonomic species composition were analysed using nonmetric multi‐dimensional scaling. Species composition differed significantly between disturbed and undisturbed woodlands. Tree density was greater in disturbed woodlands, whereas evenness, functional evenness and functional divergence were greater in undisturbed woodlands. In terms of forest cover, selective logging of B. floribunda appeared to have little impact on Miombo woodlands, but some shifts in functional traits, such as the shift from a deciduous to evergreen phenology, may increase the vulnerability of these ecosystems to environmental change, especially drought.     

Seed arrival, ecological filters, and plant species richness: a meta-analysis

Theoretical models predict that effects of dispersal on local biodiversity are influenced by the size and composition of the species pool, as well as ecological filters that limit local species membership. We tested these predictions by conducting a meta-analysis of 28 studies encompassing 62 experiments examining effects of propagule supply (seed arrival) on plant species richness under contrasting intensities of ecological filters (owing to disturbance and resource availability). Seed arrival increased local species richness in a wide range of communities (forest, grassland, montane, savanna, wetland), resulting in a positive mean effect size across experiments. Mean effect size was 70% higher in disturbed relative to undisturbed communities, suggesting that disturbance increases recruitment opportunities for immigrating species. In contrast, effect size was not significantly influenced by nutrient or water availability. Among seed-addition experiments, effect size was positively correlated with species and functional diversity within the pool of added seeds (species evenness and seed-size diversity), primarily in disturbed communities. Our analysis provides experimental support for the general hypothesis that species pools and local environmental heterogeneity interactively structure plant communities. We highlight empirical gaps that can be addressed by future experiments and discuss implications for community assembly, species coexistence, and the maintenance of biodiversity.     

Effects of intensive human management on the taxonomic and functional diversity of ground beetles in a planted forest landscape

The rapid expansion of planted forests harms native biodiversity. Few studies report the effects of replacing wetlands with planted forests on ground beetles. We analyze how the taxonomic and functional diversity of ground beetles are affected by intensive management of a planted forest landscape in the Lower Delta of the Parana River. We defined six habitat types (n?=?3, N?=?18): young and mature willow (YW, MW), young and mature poplar without cattle (YP, MP), young and mature silvopastoral poplar (YS, MS). Using pitfall traps (N?=?1728), we recorded 35 species (1896 individuals). YW and MS reached the highest taxonomic diversity and richness. YW with more vertical heterogeneity showed higher species richness than MW. Hydrophilic species were more abundant in YW. Zoophagous species were more abundant in MS. YS, MS, and YW reached the highest functional evenness, which implies that a large part of the functional niches was used. Cattle dung and freshwater canals for livestock offer more resources for ground beetles. The planted tree species, stand age, and presence of cattle affects taxonomic and functional diversity of ground beetles. Willow and silvopastoral planted forests are the most suitable habitats for hosting wetland species. So, we recommend using willow species rather than poplar species when planted forests replace fluvial wetlands, increasing irrigation of poplar planted forests through ditches and canals, conserving or restoring different strata of understory to increase vertical heterogeneity, and maintaining the landscape heterogeneity. These management measures are essential to prevent the loss of wetland species and conserve ground beetle’s diversity.

     

茂县土地岭植被恢复过程中物种多样性动态特征

植被恢复是退化生态系统重建的重要途径,植被恢复过程物种多样性的变化反映了植被的恢复程度.通过群落调查和多样性分析,研究了岷江上游土地岭植被恢复过程中群落物种多样性特征.结果表明： 恢复过程中6类不同类型群落分别表现其对于不同环境特征、干扰及更新方式等的响应;森林是较灌丛更适合当地环境状况的植被类型;人工恢复无干扰和轻度干扰群落的多样性相对较高,是较好的恢复模式.重度干扰使得1年生植物与地下芽植物比例增加,其它口食性较好的多年生草本减少.较强的干扰是群落无法更新、长期处于灌丛阶段且多样性较低的重要原因.本地区人工恢复群落在更新进程和多样性维持上优于自然更新群落,种植华山松加速了本地区植被演替进程.建议以适合恢复区域的多种恢复配置方式进行造林,并避免较强干扰,可以加速群落演替进程并保持恢复群落较高的物种丰富度与多样性.     

小兴安岭森林地表鞘翅目成虫对不同干扰梯度的响应

为探讨小兴安岭凉水自然保护区森林生态系统中地表鞘翅目成虫群落对不同人为干扰梯度的响应,于2015年7月、8月和10月分别对轻度干扰[原始阔叶红松林(KY)和谷地云冷杉林(YL)]、中度干扰[阔叶红松择伐林(ZF)和次生白桦林(BH)]及重度干扰[落叶松人工林(RL)和红松人工林(RHS)]的6个林型进行取样调查。结果表明:(1)整个采样周期共捕获地表鞘翅目成虫879只,隶属9科44物种;其中轻度干扰生境共捕获6科29种251只(KY捕获5科21种150只,YL捕获4科20种101只),中度干扰生境捕获6科27种276只(ZF捕获3科20种144只,BH捕获6科23种132只),重度干扰生境捕获6科29种352只(RL捕获4科22种232只,RHS捕获5科17种120只)。(2)7月和8月步甲科和葬甲科占据数量优势,10月步甲科和葬甲科成虫数量明显减少而隐翅虫科数量占优势;不同林型及不同干扰梯度地表鞘翅目成虫物种总数和总个体数于7、8、10月均表现为下降趋势,且群落多样性也呈不同程度下降。(3)林型和月份对地表鞘翅目成虫群落结构具有显著影响,干扰梯度对群落结构无显著影响;6个林型之间地表鞘翅目成虫个体数量具有显著差异,但在物种组成上无显著差异;不同干扰梯度间地表鞘翅目成虫个体数、物种数无显著差异,且随干扰梯度变化没有明显的梯度性规律;相似性系数和聚类分析表明,属于同一干扰梯度的两个林型没有表现出高度的相似性。本研究表明干扰梯度不是决定各林型间地表鞘翅目成虫群落多样性存在差异的主要原因,凉水森林生态系统地表鞘翅目成虫对不同干扰梯度的响应不符合中度干扰假说,林型和时间则是影响地表鞘翅目成虫群落组成的显著因素,本实验为地表生物多样性保护和森林生态系统管理提供数据支撑。     

Plant diversity induces shifts in the functional structure and diversity across trophic levels

Changes to primary producer diversity can cascade up to consumers and affect ecosystem processes. Although the effect of producer diversity on higher trophic groups have been studied, these studies often quantify taxonomy‐based measures of biodiversity, like species richness, which do not necessarily reflect the functioning of these communities. In this study, we assess how plant species richness affects the functional composition and diversity of higher trophic levels and discuss how this might affect ecosystem processes, such as herbivory, predation and decomposition. Based on six different consumer traits, we examined the functional composition of arthropod communities sampled in experimental plots that differed in plant species richness. The two components we focused on were functional variation in the consumer community structure (functional structure) and functional diversity, expressed as functional richness, evenness and divergence. We found a consistent positive effect of plant species richness on the functional richness of herbivores, carnivores, and omnivores, but not decomposers, and contrasting patterns for functional evenness and divergence. Increasing plant species richness shifted the omnivore community to more predatory and less mobile species, and the herbivore community to more specialized and smaller species. This was accompanied by a shift towards more species occurring in the vegetation than in the ground layer. Our study shows that plant species richness strongly affects the functional structure and diversity of aboveground arthropod communities. The observed shifts in body size (herbivores), specialization (herbivores), and feeding mode (omnivores) together with changes in the functional diversity may underlie previously observed increases in herbivory and predation in plant communities of higher diversity.     

Evidence that niche specialization explains species-energy relationships in lake fish communities

1. Interspecific niche differences have long been identified as a major explanation for the occurrence of species-rich communities. However, much fieldwork studying variation in local species richness has focused upon physical habitat attributes or regional factors, such as the size of the regional species pool. 2. We applied indices of functional diversity and niche overlap to data on the species niche to examine the importance of interspecific niche differentiation for species richness in French lake fish communities. We combined this information with environmental data to test generalizations of the physiological tolerance and niche specialization hypotheses for species-energy relationships. 3. We found evidence for a largely non-saturating relationship (relative to random expectation) between species richness and functional evenness (evenness of spacing between species in niche space), while functional richness (volume of niche space occupied) peaked at moderate levels of species richness and niche overlap showed an initial decrease followed by saturation. This suggests that increased niche specialization may have allowed species to coexist in the most species-rich communities. 4. We tested for evidence that increased temperature, local habitat area, local habitat diversity and immigration affected species richness via increased niche specialization. Temperature explained by far the largest amount of variation in species richness, functional diversity and niche overlap. These results, combined with the largely non-saturating species richness-functional evenness relationship, suggest that increased temperature may have permitted increased species richness by allowing increased niche specialization. 5. These results emphasize the importance of niche differences for species coexistence in species-rich communities, and indicate that the conservation of functional diversity may be vital for the maintenance of species diversity in biological communities. Our approach may be applied readily to many types of community, and at any scale, thus providing a flexible means of testing niche-based hypotheses for species richness gradients.     

Effects of functional diversity and functional dominance on complementary light use depend on evenness

Questions

Does functional diversity play a more important role than species richness in complementary resource use? Is the effect of functional diversity on complementarity greater when species evenness is higher? Does functional dominance play an important role in resource use when species evenness is low?

Location

An arable field in Linhai City, Zhejiang Province, China.

Methods

We assembled experimental plant communities with different species richness (one, two, four, eight and 12 species) and evenness (low and high). In each community, we quantified light interception efficiency (LIE ) and light complementarity index (LC ) to reflect light use. We measured four functional traits related to light capture to quantify functional diversity and functional dominance. We then tested effects of observed species richness, functional diversity and functional dominance on LIE , LC and above‐ground biomass in the low and high evenness communities.

Results

Functional diversity was positively related to LIE , LC and above‐ground biomass in the high evenness communities, but not in the low evenness communities. In contrast, functional dominance was positively related to LIE and negatively related to LC in the low evenness communities, but not in the high evenness communities. Moreover, functional dominance had a larger promotion to above‐ground biomass in the low evenness communities. Observed species richness and evenness had a significant interactive effect on LIE and LC . LIE of a species mixture of the low evenness communities was positively correlated with LIE of the monoculture consisting of the species with the highest initial abundance in the species mixture, while LC of a species mixture of the low evenness communities was negatively correlated with it.

Conclusions

Functional diversity and functional dominance play a crucial role in light complementary use of plant communities, and their effects on light complementarity are mediated by species evenness. Thus, interactions of functional traits and evenness may greatly affect ecosystem functioning.

     

Effects of anthropogenic habitat disturbance on local pollinator diversity and species turnover across a precipitation gradient

Anthropogenic habitat disturbance can have profound effects on multiple components of forest biotas including pollinator assemblages. We assessed the effect of small-scale disturbance on local richness, abundance, diversity and evenness of insect pollinator fauna; and how habitat disturbance affected species turnover across the landscape and overall diversity along a precipitation gradient in NW Patagonia (Argentina). We evaluated the effect of disturbance on overall pollinator fauna and then separately for bees (i.e. Apoidea) and non-bee pollinators. Locally, disturbed habitats had significantly higher pollinator species richness and abundances than undisturbed habitats for the whole pollinator assemblage, but not for bees or non-bees separately. However, significant differences in species richness between habitats vanished after accounting for differences in abundance between habitat types. At a local scale Shannon–Weaver diversity and evenness did not vary with disturbance. A β diversity index indicated that, across forest types, species turnover was lower between disturbed habitats than between undisturbed habitats. In addition, rarefaction curves showed that disturbed habitats as a whole accumulated fewer species than undisturbed habitats at equivalent sample sizes. We concluded that small patches of disturbed habitat have a negligible effect on local pollinator diversity; however, habitat disturbance reduced β diversity through a homogenization of the pollinator fauna (in particular of bees) across the landscape.     

山西五鹿山森林群落木本植物功能多样性

通过选取群落中木本植物种子的扩散方式、传粉方式、植株高度和盖度等13个功能性状,计算出群落的6个功能多样性指数:功能性状距离、功能性状平均距离、功能体积、功能均匀度、功能分散指数和Rao二次熵指数,结合群落物种丰富度指数、Shannon-Wiener指数和物种均匀度指数对山西五鹿山森林群落木本植物功能多样性进行研究。结果表明:(1)功能性状距离、功能性状平均距离、功能体积与物种丰富度、Shannon-Wiener指数显著正相关;功能均匀度与Shannon-Wiener指数、物种均匀度指数显著正相关;功能分散指数、Rao二次熵指数与物种均匀度指数、Shannon-Wiener指数显著正相关;(2)功能多样性的差异很大程度上是由于物种差异所引起的;(3)6个功能多样性指数可分为三类:功能性状距离、功能性状平均距离、功能体积为功能丰富度指数;功能均匀度为功能均匀度指数;功能分散指数和Rao二次熵指数为功能离散度指数。该分类结果符合指数的计算方法和生态学意义,以及相互独立的标准。     

Influence of tree species and soil properties on ground beetle (Coleoptera: Carabidae) communities

Although Carabidae is among the best-studied families of beetles in Europe from the faunistic point of view, there is still a lack of available information on the ecological requirements of the particular carabid species. The habitat preferences that determine the distribution of species are largely influenced by habitat structure and microclimate. In addition to other factors, these habitat parameters are influenced by the nature of the vegetation. Therefore, our study investigated the influence of tree species on carabid beetle communities. We conducted the research at 9 stands in the Borová Hora Arboretum (Zvolen, Central Slovakia). Each studied site represents a monoculture of one of nine tree species. At each site, some soil and leaf litter attributes (pH, conductivity, and content of H, C, N and P) were evaluated. Ground beetles were collected by pitfall trapping during the vegetation periods in 2008–2011. In total, 3012 individuals of 29 species were obtained. Significant differences in the total dynamic activity and species richness of the carabid beetle communities among the compared forest stands were revealed. The results of the research confirmed statistically significant relationships among 1) the soil conductivity and both the richness and Shannon diversity of the ground beetle communities, 2) the litter and soil N content and richness, the Shannon diversity and the species composition of the ground beetle communities. The Shannon diversity and richness were negatively related to the soil conductivity and positively related with the N content. Our research showed that dominant tree species indirectly influence diversity and composition of carabid communities via the soil properties.     

A functional trait-based approach to understand community assembly and diversity–productivity relationships over 7 years in experimental grasslands

Several multi-year biodiversity experiments have shown positive species richness–productivity relationships which strengthen over time, but the mechanisms which control productivity are not well understood. We used experimental grasslands (Jena Experiment) with mixtures containing different numbers of species (4, 8, 16 and 60) and plant functional groups (1–4; grasses, legumes, small herbs, tall herbs) to explore patterns of variation in functional trait composition as well as climatic variables as predictors for community biomass production across several years (from 2003 to 2009). Over this time span, high community mean trait values shifted from the dominance of trait values associated with fast growth to trait values suggesting a conservation of growth-related resources and successful reproduction. Increasing between-community convergence in means of several productivity-related traits indicated that environmental filtering and exclusion of competitively weaker species played a role during community assembly. A general trend for increasing functional trait diversity within and convergence among communities suggested niche differentiation through limiting similarity in the longer term and that similar mechanisms operated in communities sown with different diversity. Community biomass production was primarily explained by a few key mean traits (tall growth, large seed mass and leaf nitrogen concentration) and to a smaller extent by functional diversity in nitrogen acquisition strategies, functional richness in multiple traits and functional evenness in light-acquisition traits. Increasing species richness, presence of an exceptionally productive legume species (Onobrychis viciifolia) and climatic variables explained an additional proportion of variation in community biomass. In general, community biomass production decreased through time, but communities with higher functional richness in multiple traits had high productivities over several years. Our results suggest that assembly processes within communities with an artificially maintained species composition maximize functional diversity through niche differentiation and exclusion of weaker competitors, thereby maintaining their potential for high productivity.     

Negative relationships between species richness and evenness render common diversity indices inadequate for assessing long-term trends in butterfly diversity

Species richness and evenness, the two principle components of species diversity, are frequently used to describe variation in species assemblages in space and time. Compound indices, including variations of both the Shannon–Wiener index and Simpson’s index, are assumed to intelligibly integrate species richness and evenness into all-encompassing measures. However, the efficacy of compound indices is disputed by the possibility of inverse relationships between species richness and evenness. Past studies have assessed relationships between various diversity measures across survey locations for a variety of taxa, often finding species richness and evenness to be inversely related. Butterflies are one of the most intensively monitored taxa worldwide, but have been largely neglected in such studies. Long-term butterfly monitoring programs provide a unique opportunity for analyzing how trends in species diversity relate to habitat and environmental conditions. However, analyzing trends in butterfly diversity first requires an assessment of the applicability of common diversity measures to butterfly assemblages. To accomplish this, we quantified relationships between butterfly diversity measures estimated from 10 years of butterfly population data collected in the North Saskatchewan River Valley in Edmonton, Alberta, Canada. Species richness and evenness were inversely related within the butterfly assemblage. We conclude that species evenness may be used in conjunction with richness to deepen our understandings of assemblage organization, but combining these two components within compound indices does not produce measures that consistently align with our intuitive sense of species diversity.     

Abundance,not diversity,of host beetle communities determines abundance and diversity of parasitoids in deadwood

Most parasites and parasitoids are adapted to overcome defense mechanisms of their specific hosts and hence colonize a narrow range of host species. Accordingly, an increase in host functional or phylogenetic dissimilarity is expected to increase the species diversity of parasitoids. However, the local diversity of parasitoids may be driven by the accessibility and detectability of hosts, both increasing with increasing host abundance. Yet, the relative importance of these two mechanisms remains unclear. We parallelly reared communities of saproxylic beetle as potential hosts and associated parasitoid Hymenoptera from experimentally felled trees. The dissimilarity of beetle communities was inferred from distances in seven functional traits and from their evolutionary ancestry. We tested the effect of host abundance, species richness, functional, and phylogenetic dissimilarities on the abundance, species richness, and Shannon diversity of parasitoids. Our results showed an increase of abundance, species richness, and Shannon diversity of parasitoids with increasing beetle abundance. Additionally, abundance of parasitoids increased with increasing species richness of beetles. However, functional and phylogenetic dissimilarity showed no effect on the diversity of parasitoids. Our results suggest that the local diversity of parasitoids, of ephemeral and hidden resources like saproxylic beetles, is highest when resources are abundant and thereby detectable and accessible. Hence, in some cases, resources do not need to be diverse to promote parasitoid diversity.     

Diversity and community biomass depend on dispersal and disturbance in microalgal communities

The evidence for species diversity effects on ecosystem functions is mainly based on studies not explicitly addressing local or regional processes regulating coexistence or the importance of community structure in terms of species evenness. In experimental communities of marine benthic microalgae, we altered the successional stages and thus the strength of local species interactions by manipulating rates of dispersal and disturbance. The treatments altered realized species richness, evenness and community biomass. For species richness, dispersal mattered only at high disturbance rates; when opening new space, dispersal led to maximized richness at intermediate dispersal rates. Evenness, in contrast, decreased with dispersal at low or no disturbance, i.e. at late successional stages. Community biomass showed a non-linear hump-shaped response to increasing dispersal at all disturbance levels. We found a positive correlation between richness and biomass at early succession, and a strong negative correlation between evenness and biomass at late succession. In early succession both community biomass and richness depend directly on dispersal from the regional pool, whereas the late successional pattern shows that if interactions allow the most productive species to become dominant, diverting resources from this species (i.e. higher evenness) reduces production. Our study emphasizes the difference in biodiversity–function relationships over time, as different mechanisms contribute to the regulation of richness and evenness in early and late successional stages.     

Negative impacts of human land use on dung beetle functional diversity

The loss of biodiversity caused by human activity is assumed to alter ecosystem functioning. However our understanding of the magnitude of the effect of these changes on functional diversity and their impact on the dynamics of ecological processes is still limited. We analyzed the functional diversity of copro-necrophagous beetles under different conditions of land use in three Mexican biosphere reserves. In Montes Azules pastures, forest fragments and continuous rainforest were analyzed, in Los Tuxtlas rainforest fragments of different sizes were analyzed and in Barranca de Metztitlán two types of xerophile scrub with different degrees of disturbance from grazing were analyzed. We assigned dung beetle species to functional groups based on food relocation, beetle size, daily activity period and food preferences, and as measures of functional diversity we used estimates based on multivariate methods. In Montes Azules functional richness was lower in the pastures than in continuous rainforest and rainforest fragments, but fragments and continuous forest include functionally redundant species. In small rainforest fragments (<5 ha) in Los Tuxtlas, dung beetle functional richness was lower than in large rainforest fragments (>20 ha). Functional evenness and functional dispersion did not vary among habitat types or fragment size in these reserves. In contrast, in Metztitlán, functional richness and functional dispersion were different among the vegetation types, but differences were not related to the degree of disturbance by grazing. More redundant species were found in submontane than in crassicaule scrub. For the first time, a decrease in the functional diversity in communities of copro-necrophagous beetles resulting from changes in land use is documented, the potential implications for ecosystem functioning are discussed and a series of variables that could improve the evaluation of functional diversity for this biological group is proposed.     

Diversity of pselaphine beetles (Coleoptera: Staphylinidae: Pselaphinae) in eastern Thailand

Pselaphine beetles (Coleoptera: Staphylinidae: Pselaphinae) are cosmopolitan, species‐rich, and yet poorly studied, particularly in the tropics. We sampled beetles in three types of primary forest and two types of disturbed forest habitats in eastern Thailand to assess the utility of pselaphine beetles as bioindicators of forest disturbance. We simultaneously measured leaf litter mass, soil moisture, soil acidity and canopy cover at each site to infer which environmental factors affect pselaphine beetle diversity and abundance. At each site, pselaphine beetles were extracted from ten 1 m² samples of leaf litter and soil with Tullgren funnels. We sampled 1867 adult beetles representing six supertribes, 51 genera and 114 morphospecies; 7% of the genera and 92% of the species were undescribed. Forest types differed significantly in species richness, abundance, diversity and evenness. Primary forest had greater numbers of species and individuals, and higher diversity indices (H′). Teak plantation and secondary forest had substantially fewer individuals and species of pselaphine beetles. Species composition differed between primary and degraded forests. Canopy cover, soil moisture, and leaf litter mass positively correlated with beetle species richness and abundance. Leaf litter mass and soil moisture were the two most important factors affecting the diversity of pselaphine beetle assemblages. Among the 114 morphospecies collected, 43 morphospecies were specific to two or three habitats and 64 morphospecies were found only in a single habitat. Thus pselaphine beetles appear to have rather narrow habitat requirements and their presence/absence was correlated with environmental differences. These traits make pselaphine beetles a suitable bioindicator taxon for assessing forest litter diversity and monitoring habitat change.     

Regional zooplankton dispersal provides spatial insurance for ecosystem function

Changing environmental conditions are affecting diversity and ecosystem function globally. Theory suggests that dispersal from a regional species pool may buffer against changes in local community diversity and ecosystem function after a disturbance through the establishment of functionally redundant tolerant species. The spatial insurance provided by dispersal may decrease through time after environmental change as the local community monopolizes resources and reduces community invasibility. To test for evidence of the spatial insurance hypothesis and to determine the role dispersal timing plays in this response we conducted a field experiment using crustacean zooplankton communities in a subarctic region that is expected to be highly impacted by climate change – Churchill, Canada. Three experiments were conducted where nutrients, salt, and dispersal were manipulated. The three experiments differed in time‐since‐disturbance that the dispersers were added. We found that coarse measures of diversity (i.e. species richness, evenness, and Shannon–Weiner diversity) were generally resistant to large magnitude disturbances, and that dispersal had the most impact on diversity when dispersers were added shortly after disturbance. Ecosystem functioning (chl‐a) was degraded in disturbed communities, but dispersal recovered ecosystem function to undisturbed levels. This spatial insurance for ecosystem function was mediated through changes in community composition and the relative abundance of functional groups. Results suggest that regional diversity and habitat connectivity will be important in the future to maintain ecosystem function by introducing functionally redundant species to promote compensatory dynamics.     

Land‐use effects on the functional distinctness of arthropod communities

Land‐use change is a major driver of the global loss of biodiversity, but it is unclear to what extent this also results in a loss of ecological traits. Therefore, a better understanding of how land‐use change affects ecological traits is crucial for efforts to sustain functional diversity. To this end we tested whether higher species richness or taxonomic distinctness generally leads to increased functional distinctness and whether intensive land use leads to functionally more narrow arthropod communities. We compiled species composition and trait data for 350 species of terrestrial arthropods (Araneae, Carabidae and Heteroptera) in different land‐use types (forests, grasslands and arable fields) of low and high land‐use intensity. We calculated the average functional and taxonomic distinctness and the rarified trait richness for each community. These measures reflect the range of traits, taxonomic relatedness and number of traits that are observed in local communities. Average functional distinctness only increased significantly with species richness in Carabidae communities. Functional distinctness increased significantly with taxonomic distinctness in communities of all analyzed taxa suggesting a high functional redundancy of taxonomically closely related species. Araneae and Heteroptera communities had the expected lower functional distinctness at sites with higher land‐use intensity. More frequently disturbed land‐use types such as managed grasslands or arable fields were characterized by species with smaller body sizes and higher dispersal abilities and communities with lower functional distinctness or trait richness. Simple recommendations about the conservation of functional distinctness of arthropod communities in the face of future land‐use intensification and species loss are not possible. Our study shows that these relationships depend on the studied taxa and land‐use type. However, for some arthropod groups functional distinctness is threatened by intensification and conversion from less to more frequently disturbed land‐uses.     

Life-history trait and functional diversity patterns of ground beetles and spiders along a coastal heathland successional gradient

We investigated patterns in species richness and diversity, life-history traits and functional diversity of carabid beetles and spiders along a coastal heathland successional gradient. We sampled in five successional stages on the island of Hiddensee, Germany. Species richness of carabids and spiders and Simpson diversity for spiders did not differ among stages. Functional dispersion (FDis), a measure of functional richness, was lowest in the youngest stage for both carabids and spiders. Older successional stages represent more heterogeneous habitats and offer a broader range of niches, which might enhance functional dispersion. Functional evenness (FEve) differed among successional stages for spiders, indicating an uneven distribution of species abundances in the functional trait space. Functional divergence (FDiv) did not differ among stages for either taxon. Shifts in life-history traits were noted in both arthropod groups, but not always in the same direction: Body size of carabid beetles increased towards older successional stages, but decreased for spiders. The number of flightless carabid species increased towards older habitats. Each successional stage seemingly favors species with distinct life-history traits (species sorting). We conclude that a trait-based approach including the use of functional diversity measurements (FDis) could contribute valuable information for biodiversity conservation.