Functional Diversity Measures Research Articles

Species and functional diversity of direct‐seeded vegetation declines over 25 years

SummaryThe re‐establishment of native vegetation on disturbed land has been adopted widely as a form of ecological restoration in the past few decades. It is often suggested that establishing native plantings will lead to increasing biodiversity at restoration sites over time. However, this prediction has not been tested over long periods. Now that some pioneering projects and monitoring programs have become older, it is possible to quantify the long‐term benefits of native vegetation plantings. We asked how the plant diversity and function of 12 biodiverse native vegetation plantings has changed over approximately 30 years. We found that sites declined in measures of functional and species diversity over time. Shorter‐statured woody species were not as common at older sites. Surprisingly, sites initially seeded with a greater richness of species did not have higher standing richness at any later census period. While all sites produced net native biodiversity benefits relative to the exotic pastures they replaced, ongoing management and monitoring will be needed to ensure they continue to do so. Understanding the relationship between ageing native vegetation plantings and other components of the ecosystem (e.g., mammals, birds, invertebrates, soil, microorganisms) is a priority. Our results suggest that recruitment barriers in ex‐agricultural ecosystems are high and that the biodiversity benefits provided by shorter‐lived species will only be transient without ongoing management of these systems. Research confronting these recruitment barriers is a priority, and managers (and funders) of these kinds of restoration projects may need to be prepared for ongoing management of sites to promote lost components if they are desired as continual features of these ecosystems.

Assessing taxonomic, functional and phylogenetic diversity of giant clams across the Indo‐Pacific for conservation prioritization

AbstractAimGiant clams are iconic bivalves known to serve numerous ecological roles contributing to the functioning of coral reef ecosystems. In the next decade, giant clams will continue to face critical anthropogenic pressures from over‐exploitation for their meat and shells, the aquarium trade and global warming that threaten the persistence of their species. Here, we assess the relationships between different biodiversity components to inform conservation prioritization and management.LocationIndo‐Pacific marine realm.MethodsWe quantified taxonomic, functional and phylogenetic diversity measures throughout 25 marine provinces and assessed their relationships for all 12 giant clam species in the subfamily Tridacninae. These biodiversity measures were used to identify potentially threatened species that contribute disproportionately to trait and evolutionary diversity and to highlight areas for global conservation prioritization of giant clam species.ResultsAnalyses show positive correlations among species richness (SR), functional diversity (FD) and phylogenetic diversity (PD), with the strongest relationship between FD and PD. However, spatial patterns of higher‐than‐expected FD and PD are incongruent with SR patterns, indicating that SR omits information associated with functional and phylogenetic diversity. Among the giant clam species, Tridacna gigas and Hippopus spp. have the greatest functional and evolutionary diversity contributions within assemblies, respectively. Spatial analyses reveal that the Bay of Bengal, Andaman and numerous parts of the eastern Indo‐Pacific potentially hold higher‐than‐expected FD and PD levels relative to their SR and thus warrant more attention with respect to conserving the diversity of giant clams.ConclusionsOur findings underscore the importance of integrating functional trait contributions and evolutionary diversity into conservation planning to better differentiate giant clam assemblages, as it remains challenging to implement dedicated conservation given the limited resources. This study provides comprehensive biodiversity information for managers to initiate measures that holistically capture species' ecological and evolutionary standings across global reef ecosystems.

Bird dependence on wetlands determines functional responses to flood pulse in the Brazilian Pantanal

Hydrological regimes in floodplains are essential to support biodiversity that depend on wetlands, and understanding how these organisms are associated to this ecosystem could be useful, as they can act as important agents for the maintenance of diversity and natural processes. We aimed to assess the bird functional responses to the Pantanal flood pulse, considering the hydrological periods and three bird groups with different degrees of wetlands dependence. For this, bird survey was conducted in the Paraguay River floodplain system, covering the hydrological periods of the 2017–2018 cycle. We considered species richness, abundance, four functional diversity measures, and functional trait composition as ecological responses. Species richness was higher for bird group with lower degree of wetland dependence, mainly in drought and ebb periods. On the other hand, we found that the higher the degree of wetland dependence by birds, the higher the differences in the functional-trait values over periods. Abundance was affected by the variation of the hydrological periods for all bird groups. Bird groups had distinct niches, and functional traits associated with waterbirds were dominant in all periods. We found that degree of wetland dependence is driving the response of birds to changes in hydrological periods. Measuring only species richness may not reflect the inherent characteristics of this ecosystem. Bird groups such as waterbirds and wetland birds showed greater functional diversity throughout the hydrological periods, evidencing the importance of the flood pulse regime for species that are highly dependent on these environments and that perform many ecological services.

Resilience of Avian Communities to Urbanization and Climate Change: an Integrative Review

The concept of ecological resilience is widely used to assess how species and ecosystems respond to external stressors but is applied infrequently at the level of the community or to chronic, ongoing disturbances. In this review, we first discuss the concept of ecological resilience and methods for quantifying resilience in ecological studies. We then synthesize existing evidence for the resilience of avian communities to climate change and urbanization, two chronic disturbances that are driving global biodiversity loss, and conclude with recommendations for future directions. We only briefly discuss the theoretical framework behind ecological resilience and species-specific responses to these two major disturbances, because numerous reviews already exist on these topics. Current research suggests strong heterogeneity in the responses and resilience of bird communities to urbanization and climate change, although community disassembly and reassembly is high following both disturbances. To advance our understanding of community resilience to these disturbances, we recommend five areas of future study (1) the development of a standardized, comprehensive community resilience index that incorporates both adaptive capacity and measures of functional diversity, (2) measurement/modeling of both community resistance and recovery in response to disturbance, (3) multi-scale and/or multi-taxa studies that include three-way interactions between plants, animals, and climate, (4) studies that incorporate interactions between disturbances, and (5) increased understanding of interactions between ecological resilience and socio-ecological dynamics. Advancement in these areas will enhance our ability to predict and respond to the rapidly accelerating effects of climate change and urbanization.

Subtle Effects of Experimental Grassland Fragmentation on Density, Species Composition and Functional Dispersion of Gastropods

The fragmentation of continuous habitats has significant consequences for species and for the functional diversity of plant and animal communities. Fragmentation effects can be indirect, can occur at different spatial scales and may vary over years. Small fragmentation-related effects may only be detected in standardized, controlled field experiments accounting for the natural variation in environmental conditions and in remnants of habitat. Using a non-invasive trapping approach, we examined the responses of terrestrial gastropods (snails and slugs) to small-scale habitat fragmentation in a controlled experiment conducted in three species-rich, nutrient-poor calcareous grasslands in the Jura Mountains, Switzerland, over four years. We found site-specific differences in species richness, individual density, and species composition. Experimental grassland fragmentation did not significantly affect species richness or density, but affected functional dispersion (a measure of functional diversity) in the final year, indicating that fragmentation-related changes may occur with a time delay. Similarly, experimental fragmentation influenced the mean shell size of the snail assemblage and the proportions of individuals with certain life-history traits or habitat preferences in some years. The observed fragmentation effects were subtle and varied over time, underlining the importance of controlled field experiments.

A network-based measure of functional diversity in food webs.

Biodiversity is measured from various perspectives. One of them, functional diversity, quantifies the heterogeneity in species traits and roles in an ecosystem. One important aspect of species roles is their interactions with other species, i.e. their network role. We therefore investigate here functional diversity from the network perspective. Species differ in their network positions in a food web, having different interaction patterns. We developed a measure for quantifying the diversity in species interaction patterns in a food web. We examined the relationship between interaction diversity and several global network properties for 92 food webs. Our results showed that high interaction diversity occurs in sparsely connected and less cohesive food webs. High interaction diversity also occurred in food webs with more clusters and high network modularity. We also quantified several conventional functional diversity indices and demonstrate that they show little or no correlation with interaction diversity. Our proposed diversity index therefore provides a measure complementary to current concepts of functional diversity.

Disturbance has lasting effects on functional traits and diversity of grassland plant communities.

BackgroundLocalized disturbances within grasslands alter biological properties and may shift species composition. For example, rare species in established communities may become dominant in successional communities if they exhibit traits well-suited to disturbance conditions. Although the idea that plant species exhibit different trait ‘strategies’ is well established, it is unclear how ecological selection for specific traits may change as a function of disturbance. Further, there is little data available testing whether disturbances select for single trait-characters within communities (homogenization), or allow multiple trait-types to persist (diversification). We investigated how (a) traits and (b) functional diversity of post-disturbance gap communities compared to those in adjacent undisturbed grasslands, and (c) if altered functional diversity resulted in the homogenization or diversification of functional traits.MethodsHere we emulate the impacts of an extreme disturbance in a native grassland site. We measured plant community composition of twelve paired 50 × 50 cm plots (24 total) in Alberta, Canada. Each pair consisted of one undisturbed plot and one which had all plants terminated 2 years prior. We used species abundances and a local trait database to calculate community weighted means for maximum height, specific leaf area, specific root length, leaf nitrogen percent, and root nitrogen percent. To test the impacts of disturbance on community functional traits, we calculated functional diversity measures and compared them between disturbed and undisturbed communities.ResultsWithin 2 years, species richness and evenness in disturbed communities had recovered and was equivalent to undisturbed communities. However, disturbed and undisturbed communities had distinct community compositions, resulting in lower functional divergence in disturbed plots. Further, disturbance was linked to increases in community-weighted mean trait values for resource-acquisitive traits, such as specific leaf area, and leaf and root nitrogen.DiscussionDisturbance had lasting effects on the functional traits and diversity of communities, despite traditional biodiversity measures such as richness and evenness recovering within 2 years. The trait space of gap communities shifted compared to undisturbed communities such that gap communities were dominated by traits enhancing resource uptake and growth rates. Overall, these results show that short-term disturbance fundamentally changes the functional character of early-successional communities, even if they superficially appear recovered.

Quantifying the post‐fire recovery of taxonomic and functional diversity of dung beetles in the Brazilian Pantanal

Abstract The Pantanal is the largest wetland in the world and a World Heritage Site. During 2019–2020, the Pantanal has experienced the most severe burning in its history, with vast destroyed areas of vegetation and killed wildlife. Since the long‐term damage caused by fire to the Pantanal is still unknown, understanding how the biodiversity responds to post‐fire disturbance over a short‐term is an important step for conservation initiatives. The authors studied the effects of fire on dung beetle communities, a recognised bioindicator group, in the Brazilian Pantanal. For this, the authors assessed the patterns of taxonomic and functional diversity between unburned and burned sites (16 months post‐fire). The authors found that taxonomic and functional diversity of dung beetles were similar between unburned and burned grasslands, but with a distinct taxonomic composition post‐fire. The functional traits composition was similar between unburned and burned sites, demonstrating that this metric is less sensitive to fire effects in the Brazilian Pantanal. The study's results provide evidence that dung beetles exhibit high resistance to the occurrence of fire and fast recovery from its consequences. Thus, due to its ecological functions (secondary seed dispersion, nutrient cycling and others), these insects may assist ecological restoration of burned sites, being useful tools in restoration approaches for areas of the Pantanal that have been affected by fire. Finally, combining traditional taxonomic community attributes with functional diversity measurements provides a more comprehensive picture of responses of dung beetle communities, post‐fire, over a short‐term in the Brazilian Pantanal.

Common species contribute little to spatial patterns of functional diversity across scales in coastal grasslands

Abstract Spatial patterns of functional diversity are important in understanding community assembly as well as spatial variation in ecosystem functioning, yet the contribution of different species to these patterns remains unclear, making it difficult to generalise. Several studies have previously used a sequential addition approach to determine the subsets of species that contribute to the spatial distribution of species richness, frequently showing the importance of common species to richness patterns. This approach, however, has not been applied to functional diversity despite the central role of species traits in community ecology. Here we use a multiscale survey of plants from the Machair grassland system of the Western Isles of Scotland to ask the following questions: (i) Do functional diversity patterns correlate better with geographically common or geographically rare species?; (ii) Do their relative contributions vary with spatial scale?; and (iii) Do these patterns vary between functional diversity measures? We show that while species richness patterns correlate with geographically common species, common species contribute less than expected to spatial patterns of functional diversity at frequently used spatial monitoring scales. The relative contribution of species to overall biodiversity patterns, however, can vary with spatial scale. Synthesis. Surveying only common species may be inadequate for estimating spatial patterns of functional diversity, especially if using occurrence as opposed to percentage cover or abundance data, and spatial scale needs to be considered when designing surveys. Our approach highlights the species that may be adequate indicators of different dimensions of biodiversity and contributes to our understanding of the distribution of functional diversity in space.

The recovery of functional diversity with restoration

Ecological restoration aims at recovering biodiversity in degraded ecosystems, and it is commonly assessed via species richness. However, it is unclear whether increasing species richness in a site also recovers its functional diversity (FD), which has been shown to be a better representation of ecosystem functioning. We conducted a quantitative synthesis of 30 restoration projects and tested whether restoration improves FD. We compared actively and passively restored sites with degraded and reference sites with respect to four key measures of FD (functional richness, evenness, dispersion, and turnover) and two measures of species diversity (richness and evenness). We separately analyzed longitudinal studies (which monitor degraded, reference, and restored sites through time) and space-for-time substitutions (which compare at one point in time degraded and reference sites with restored sites of different ages). Space-for-time studies suggested that species diversity and FD improved over time. However, replicated longitudinal data showed no sustained benefits of active or passive restoration for FD measures, relative to degraded sites. This could suggest that the positive results in space-for-time designs may have been unreliable, but the relatively short duration of longitudinal studies suggests a need for longer-term longitudinal research to robustly demonstrate the absence of any effect. These differences across study designs may explain the variable results found in recent studies directly measuring the response of FD to restoration. We recommend that future assessments of ecological community dynamics include control sites in monitoring, to ensure that the consequences of treatments, including but not limited to restoration, are correctly partitioned from unassisted temporal changes.

Incorporating genome-based phylogeny and functional similarity into diversity assessments helps to resolve a global collection of human gut metagenomes.

Tree-based diversity measures incorporate phylogenetic or functional relatedness into comparisons of microbial communities. This can improve the identification of explanatory factors compared to tree-agnostic diversity measures. However, applying tree-based diversity measures to metagenome data is more challenging than for single-locus sequencing (e.g. 16S rRNA gene). Utilizing the Genome Taxonomy Database for species-level metagenome profiling allows for functional diversity measures based on genomic content or traits inferred from it. Still, it is unclear how metagenome-based assessments of microbiome diversity benefit from incorporating phylogeny or function into measures of diversity. We assessed this by measuring phylogeny-based, function-based and tree-agnostic diversity measures from a large, global collection of human gut metagenomes composed of 30 studies and 2943 samples. We found tree-based measures to explain phenotypic variation (e.g. westernization, disease status and gender) better or equivalent to tree-agnostic measures. Ecophylogenetic and functional diversity measures provided unique insight into how microbiome diversity was partitioned by phenotype. Tree-based measures greatly improved machine learning model performance for predicting westernization, disease status and gender, relative to models trained solely on tree-agnostic measures. Our findings illustrate the usefulness of tree- and function-based measures for metagenomic assessments of microbial diversity, which is a fundamental component of microbiome science.

荒漠植物性状权衡策略及功能多样性研究进展

PDF HTML阅读 XML下载 导出引用 引用提醒 荒漠植物性状权衡策略及功能多样性研究进展 DOI: 10.5846/stxb202107151909 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（41961007）；甘肃省重点研发计划项目（21YF5FA082） Research progress on the trade-off strategy and functional diversity of desert plants Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:荒漠植物是干旱区具有独特功能性状与资源权衡表征的地带性植物。植物功能性状及其多样性格局与资源权衡策略对群落结构优化和生态系统功能改善起着关键作用。该综述主要从荒漠植物组织、器官功能性状特征、功能性状权衡策略、功能多样性组分及测度3个方面梳理了荒漠植物性状权衡策略与功能多样性研究的进展脉络：1）荒漠植物独特的根、茎、叶功能性状特征揭露了植被对环境变化的响应以及对生态系统功能的影响，基于植物功能性状的研究有助于解决许多生态学的关键性问题；2）作为植物功能性状之间存在的最普遍的联系，权衡策略是经过自然筛选后形成的性状组合，关键性状已经被发掘并创造性的提出了"经济谱"概念。荒漠植物研究过程中，应分析其根、茎、叶的特征属性筛选关键性状，着眼于关键性状间及整株植物性状间的权衡策略；3）功能多样性是影响生态系统运行和发挥作用的生物多样性的重要组成部分，荒漠植物功能多样性能预测和指示群落中物种对于荒漠生态系统功能发挥和过程变化的影响。功能多样性的组分可以从不同角度反映群落的生态位占据状况和资源利用程度，指数的选择要体现在群落内部物种的功能特征之间的差异程度，同时要考虑这些物种自身在群落内的优势程度。本研究为未来荒漠植物功能性状及多样性研究梳理了一些新的研究方向和内容，期望为荒漠植物生理生态学研究的选题和发展提供一些新的思路。 Abstract:Desert plants are zonal plants with unique functional traits and resource balance in arid areas. Plant functional traits and their diversity patterns and resource balancing strategies play a key role in the optimization of community structure and the improvement of ecosystem functions. This review summarized the research progress on functional diversity and trade-off strategies from three aspects:the functional traits of desert plant tissues and organs, the trade-off strategy of functional traits, components and measures of functional diversity. 1) The unique root, stem, and leaf functional traits of desert plants reveal the response of vegetation to the environmental changes and the impact on ecosystem functions. Research based on plant functional traits can help solve many key ecological problems; 2) As the most common relationship between plant functional traits, the trade-off relationship is a combination of traits formed after natural screening. Key traits have been discovered and the concept of "economic spectrum" has been creatively proposed. In the process of desert plant research, the characteristic attributes of desert plant roots, stems and leaves should be analyzed to screen key traits, focusing on the trade-off relationship between key traits and the whole plant traits; 3) The functional diversity is an important part of biodiversity that affects the operation and function of ecosystems. The functional diversity of desert plants can predict and indicate the impact of species in the community on the functioning and process changes of desert ecosystems. The components of functional diversity can reflect the niche occupancy status and resource utilization degree of the community from different angles. The choice of index should be reflected in the degree of difference between the functional characteristics of the species within the community, and at the same time, the species themselves should be considered the degree of dominance within the community. Finally, this article combs some new research directions and contents for future research on the functional traits and diversity of desert plants, and hopes to provide some new ideas for the topic selection and development of desert plant physiology and ecology. 参考文献 相似文献 引证文献

长白山森林生态系统凋落物层和土壤层跳虫物种多样性和功能多样性对海拔梯度的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 长白山森林生态系统凋落物层和土壤层跳虫物种多样性和功能多样性对海拔梯度的响应 DOI: 10.5846/stxb202104221060 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31861133006,41571052,U20A2083);科技部基础资源调查专项(2018FY100300) Taxonomic and functional diversity of Collembola in litter and soil along an altitudinal gradient at Changbai Mountain,China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:山脉是生物多样性研究的热点地区,以往关于山脉的研究多集中于地上植物和脊椎动物,无脊椎动物相关的研究明显滞后。跳虫(Collembola)是土壤无脊椎动物的主要类群之一,在分解有机质、疏松和活化土壤过程中发挥着重要的作用。以跳虫为研究对象,采用梯度格局法,在长白山北坡自海拔800 m至1700 m,每隔150 m进行凋落物层和土壤层样品的采集,对比分析了土壤层和凋落物层的群落组成与群落结构,采用4个物种多样性指数(丰富度指数、Pielou均匀度指数、Shannon-Weiner多样性指数和Simpson多样性指数)和4个功能多样性指数(功能丰富度FRic指数、功能均匀度FEve指数、二次熵Rao's Q指数和功能离散FEiv指数),探讨了多样性沿海拔梯度的分布格局。共获得跳虫5542头,隶属于12科42属83种,其中等节跳科为绝对优势类群(相对密度>50%)。非度量多维尺度分析结果表明,凋落物层和土壤层的跳虫群落结构差异显著,长角跳科、鳞跳科和疣跳科物种多分布于凋落物层,而棘跳科物种多分布于土壤层。线性或二次回归模型结果表明,在凋落物层跳虫的丰富度指数,Shannon-Weiner多样性指数和Simpson多样性指数沿海拔梯度的变化呈增加格局;但在土壤层跳虫物种多样性指数沿海拔梯度的变化无明显趋势。在凋落物层,跳虫的功能丰富度指数和功能离散度Rao's Q指数随海拔梯度的变化呈现单峰分布格局;在土壤层,跳虫的功能丰富度指数随海拔梯度的变化也呈现单峰分布格局,但其他功能多样性指数沿海拔梯度的变化无明显趋势。研究表明凋落物层和土壤层跳虫的群落组成,群落结构及多样性存在显著差异,跳虫的物种多样性指数和功能多样性指数对海拔梯度变化的响应不同,未来在探讨土壤动物沿海拔梯度的分布格局及其物种共存机制时,应综合考量垂直分层(凋落物层和土壤层)和多个度量维度(物种多样性和功能多样性)。 Abstract:Mountains are hotspots for biodiversity research because they harbor high number of species and cover a wide range of abiotic factors along altitudes. Compared with above-ground plants and animals, soil animal communities along altitudinal gradients have been little studied. Collembola are among the most abundant soil invertebrates contributing to essential ecosystem functions such as decomposition processes. We used Collembola as model soil animals and analyzed changes in their community structure in litter and soil of forests along a gradient ranging from 800 to 1700 m at the Changbai Mountain. Further, changes in four taxonomic diversity indexes (richness index, evenness index, Shannon-Wiener index, and Simpson diversity index) and four functional diversity indexes (functional richness index, functional evenness index, Rao's quadratic index, and functional divergence index) were studied. A total of 5,542 Collembola individuals, belonging to 12 families, 42 genera, and 83 species were sampled, with Isotomidae being most dominant (>50% of total individuals). Non-metric multidimensional scaling showed that Collembola community composition varied in both litter and soil. Species of Entomobryidae, Tomoceridae, and Neanuridae mostly colonized the litter layer, whereas Onychiuridae mostly colonized the soil. We used linear and quadratic regression models to explore altitudinal patterns in Collembola diversity. In litter, the richness, Shannon-Wiener diversity index and Simpson diversity index significantly positively correlated with altitude. By contrast, in soil, the taxonomic diversity indexes did not change significantly with altitude. For functional diversity, in litter functional richness index and Rao's quadratic index followed a hump-shaped pattern along the altitudinal gradient. In soil the functional richness index also showed the same trend, but other functional diversity indexes did not change in a consistent way with altitude. Overall, the results highlight that it is crucial to consider the vertical distribution of soil animals in litter and soil, and use multiple dimensions including taxonomic and functional diversity measures for understanding changes in diversity patterns of soil fauna along altitudinal gradients. 参考文献 相似文献 引证文献

Does anthropogenic fragmentation selectively filter avian phylogenetic diversity in a critically endangered forest system?

SummaryDocumenting phylogenetic diversity for conservation practice allows elucidation of ecosystem functioning and processes by highlighting the commonality and divergence of species’ functional traits within their evolutionary context. Conserving distinct evolutionary histories has intrinsic value, and the conservation of phylogenetically diverse communities is more likely to preserve distinct or relic evolutionary lineages. We explored the potential for anthropogenic forest fragmentation to act as a selective filter of avian phylogenetic diversity within the community of forest-dependent birds of the critically endangered Indian Ocean Coastal Belt Forest (IOCBF), South Africa. We conducted avian point count surveys during the austral breeding season, and calculated fragmentation metrics of forest structural complexity, patch size and isolation. We constructed a maximum likelihood phylogeny using the combined analysis of two mitochondrial genes and three nuclear markers and measured the influence of the fragmentation metrics on six measures of phylogenetic diversity. Our results indicated that the avian community was variously affected by anthropogenic forest fragmentation, with the different metrics of phylogenetic diversity responding with no definitive overall pattern. However, forest structural complexity emerged as an important metric explaining phylogenetic structuring. While the avian community’s phylogenetic diversity displayed resilience to anthropogenic fragmentation, previous research showed a reduction in functional diversity along the fragmentation gradient. Therefore, we recommend studies that especially aim to guide conservation management, incorporate both phylogenetic and functional diversity measures to sufficiently interrogate communities’ resilience to the threats under investigation.

On two dissimilarity-based measures of functional beta diversity

In this paper, we propose two related versions of a dissimilarity-based measure of functional beta diversity, together with the associated tests for differences in beta diversity among different groups of samples. Both measures are based on the optimal functional matching between the species in two samples. As such, they are tightly connected to Hurlbert's seminal work on encounter-based diversity measures. The behavior of the proposed measures is illustrated with one worked example on the functional turnover of Alpine species along a successional gradient. Results show that both measures proved able to detect the functional turnover of vegetation along the chronosequence. The method, for which we provide a simple r function, further allows to evaluate the functional contribution of single sampling units to the overall beta diversity of any kind of species assemblages.

Human activities uncouple the cascading effects of hydrological gradients on plant diversity and ecosystem functions in the Lake Dongting wetland

AbstractHuman activities markedly modify diversity patterns of plant communities and their response to environmental conditions, with subsequent consequences for ecosystem functions. We measured 11 key functional traits of 47 plant species and assessed both taxonomic and functional composition as well as above‐ground biomass (AGB) of plant communities from 127 plots in the Lake Dongting wetland. Using a generalized multilevel path model, we examined the cascading effects of hydrological gradients on plant diversity and ecosystem functions in two distinct habitat types (short grassland with a natural community dominated by Carex spp. and tall grassland with a managed artificial community dominated by Triarrhena lutarioriparia and Phragmites australis). We found significant differences in the response of plant diversity and AGB to hydrological gradients. Species richness, Shannon–Wiener diversity, multiple‐trait functional diversity measures (i.e., functional richness, functional dispersion & Rao's quadratic entropy) and community‐weighted mean (CWM) of shoot height were all significantly higher and functional divergence and CWM of tuber significantly lower in tall grassland. AGB was significantly higher in short grassland, largely driven by variations of functional diversity rather than of taxonomic diversity. Moreover, we found a significant cascading effect of elevation and soil moisture on AGB, directly or indirectly induced by changes in functional diversity in the short grassland, while only direct effects of elevation on AGB were observed in the tall grassland. Therefore, our study provides strong evidence that human‐induced changes in habitat types uncoupled the cascading effects of hydrological gradients on ecosystem functions mediated by either the taxonomic or the functional diversity.

Fish functional diversity as an indicator of resilience to industrial fishing in Patagonia Argentina.

The relationship between fish functional diversity and fishing levels at which its baselines shift is important to identify the consequences of fishing in ecosystem functioning. For the first time, the authors of this study implemented a trait-based approach in the Argentine Patagonian Sea to identify the vulnerability and spatiotemporal changes in functional diversity of fish assemblages incidentally captured by a trawling fleet targeting the Argentine red shrimp Pleoticus muelleri (Spence Bate, 1888) between 2003 and 2014. The authors coupled seven fish trophic traits to a reconstructed fish assemblage for the study area and by-catch and evaluated changes in fish species richness and four complementary functional diversity measures (functional richness, redundancy, dispersion and community trait values) along with fishing intensity, temporal use, latitudinal location and depth of fishing grounds, and vessel length. Resident fishes larger than 30 cm in length, with depressed and fusiform bodies, intermediate to high trophic levels, and feeding in benthic, demersal and midwater areas were vulnerable to by-catch. In addition, fish assemblages exhibited a low functional trait redundancy, likely related to species influxes in a biogeographic ecotone with tropicalisation signs. Significant increases in fish trait richness and dispersion poleward and deep suggested new functional roles in these grounds, matching trends in community body size, reproductive load, maximum depth and trophic level. Finally, a temporal increase in fish species and functional trait removal in fishing grounds led to trait homogenisation since 2003. The authors identified that tipping points in temperate fish functional trait diversity showed the importance of trait-based approaches within ecosystem-based fisheries management.

Numerical abundance and biomass reveal different temporal trends of functional diversity change in tropical fish assemblages.

Understanding how the biodiversity of freshwater fish assemblages changes over time is an important challenge. Until recently most emphasis has been on taxonomic diversity, but it is now clear that measures of functional diversity (FD) can shed new light on the mechanisms that underpin this temporal change. Fish biologists use different currencies, such as numerical abundance and biomass, to measure the abundance of fish species. Nonetheless, because they are not necessarily equivalent, these alternative currencies have the potential to reveal different insights into trends of FD in natural assemblages. In this study, the authors asked how conclusions about temporal trends in FD are influenced by the way in which the abundance of species has been quantified. To do this, the authors computed two informative metrics, for each currency, for 16 freshwater fish assemblages in Trinidad's Northern Range that had been surveyed repeatedly over 5 years. The authors found that numerical abundance and biomass uncover different directional trends in these assemblages for each facet of FD, and as such inform hypotheses about the ways in which these systems are being restructured. On the basis of these results, the authors concluded that a combined approach, in which both currencies are used, contributes to our understanding of the ecological processes that are involved in biodiversity change in freshwater fish assemblages.

Effects of dam construction and fish invasion on the species, functional and phylogenetic diversity of fish assemblages in the Yellow River Basin

An understanding of the consequences of human-mediated disturbances from multi-facet diversity (i.e. species, functional and phylogenetic) perspectives is of great significance in biodiversity assessment and conservation planning. Most previous studies have concentrated on anthropogenic effects on species diversity in the Yellow River Basin (YRB) in China, but information on anthropogenic effects on phylogenetic and functional facets is still pending. Here, we identified the temporal changes in species, functional, and phylogenetic alpha diversity of fish assemblages in 18 reaches (i.e. 15 mainstream reaches and 3 tributaries) of the YRB under the background of long-term cascade hydropower construction and widespread introduction of non-native fish species. The results showed that native fishes experienced a sharp decline through time, with an average of 25.6 (extirpation rate 46.7%) native species extirpated per sub-region, and 89 of 182 (48.9%) native species extirpated across the whole basin during the period considered. However, the number of non-native fish species substantially increased, with an average increase of 8.6 species (invasion rate 26.9%) per sub-region. Furthermore, the percentage of non-native species showed a significant unimodal relationship with average altitude, with highest invasion rates (ca. 70%) in upstream reaches. The extirpation rate was negatively related to altitude, increasing from upstream to downstream reaches. Interestingly, the functional diversity indices (FEve, FDiv, FDis, RaoQ) and phylogenetic diversity indices (Δ+ and Λ+) of the entire fish fauna significantly increased through time, whereas these indices based on native fish fauna only did not change. Such increases in functional and phylogenetic diversities were mainly triggered by introductions of non-native species, which were functionally distinct and phylogenetically distant from native species, and extirpation of congeneric endemic species. In general, the present study revealed anthropogenic impacts on the multi-faceted diversity of fish assemblages in a large river and highlighted the negative effects of cascaded hydropower developments and non-native fish invasions on native fish. Moreover, evaluating the responses of multi-faceted diversity to anthropogenic disturbances is a suitable means to understand assemblage reorganization and to assess how such impacts lead to the decline of biodiversity. The complementary information derived from using the multi-faceted diversity approach indicate functional and phylogenetic diversity measures could be implemented in biodiversity planning in the sediment-laden and ecologically important Yellow River Basin.

Disentangling the Ecological Determinants of Species and Functional Trait Diversity in Herb-Layer Plant Communities in European Temperate Forests

Forest herb-layer vegetation responds sensitively to environmental conditions. This paper compares drivers of both taxonomic, i.e., species richness, cover and evenness, and functional herb-layer diversity, i.e., the diversity of clonal, bud bank and leaf-height-seed plant traits. We investigated the dependence of herb-layer diversity on ecological determinants related to soil properties, climatic parameters, forest stand characteristics, and topographic and abiotic and biotic factors associated with forest floor structure. The study was conducted in different forest types in Slovenia, using vegetation and environmental data from 50 monitoring plots (400 m2 each) belonging to the ICP Forests Level I and II network. The main objective was to first identify significant ecological predictors and then quantify their relative importance. Species richness was strongly determined by forest stand characteristics, such as richness of the shrub layer, tree layer shade-casting ability as a proxy for light availability and tree species composition. It showed a clear positive relation to soil pH. Variation in herb-layer cover was also best explained by forest stand characteristics and, to a lesser extent, by structural factors such as moss cover. Species evenness was associated with tree species composition, shrub layer cover and soil pH. Various ecological determinants were decisive for the diversity of below-ground traits, i.e., clonal and bud bank traits. For these two trait groups we observed a substantial climatic signal that was completely absent for taxonomy-based measures of diversity. In contrast, above-ground leaf-height-seed (LHS) traits were driven exclusively by soil reaction and nitrogen availability. In synthesis, local stand characteristics and soil properties acted as the main controlling factors for both species and trait diversity in herb-layer communities across Slovenia, confirming many previous studies. Our findings suggest that the taxonomic and functional facets of herb-layer vegetation are mainly influenced by a similar set of ecological determinants. However, their relative importance varies among individual taxonomy- and functional trait-based diversity measures. Integrating multi-faceted approaches can provide complementary information on patterns of herb-layer diversity in European forest plant communities.