Effects of different components of diversity on productivity in artificial plant communities

In an experiment on artificial plant communities, the effects of three components of plant diversity—plant species diversity, plant functional group diversity and plant functional diversity—on community productivity and soil water content were compared. We found that simple regression analysis showed a positive diversity effect on ecosystem processes (productivity and soil water content). However, when three components of diversity were included in the multiple regression analyses, the results showed that functional group diversity and functional diversity had more important effects on productivity and resource use efficiency. These results suggested that, compared with species number, functional differences among species and the range of functional traits carried by plants are the basis of biodiversity effects on ecosystem functioning. These diversity effects of increasing functional group diversity or functional diversity were likely because species differing greatly in size, life form, phenology and capacity to capture and use resources efficiently in diverse communities realize complementary resource use in temporal, spatial, and biological ways.     

种、种的多样性及退化生态系统功能的恢复和维持研究

物种多样性是生态系统的重要特征并维持系统的功能支行,生物种和不同种类构成的群落为人类提供诸如营养物质循环、生物生产力、营养功能等形式的重要生态服务,特种多样性与生态系统抵御逆境和干扰的能力紧密相关,多样性的提高会增加系统的稳定性,与单个种和种类的数量相比,功能群和功能多样性对生态系统功能的影响效应要大得多,且易于被用来测度稳定性和预测群落变化,本文提出并探讨了种对生态系统功能作用的几种形式,理解物种多样性与生态系统的功能关系能指导退化生态系统恢复和维持其功能的实践活动,尤其为恢复的初始阶段进行群落的“种类组装”提供生态理论基础。     

松嫩平原南部主要群落植物多样性的比较研究

应用Ｍａｒｇａｌｅｆ（Ｒ１）和Ｍｅｎｈｉｎｉｃｋ（Ｒ２）丰富度指数、Ｈｉｌｌ多样性指数（Ｎ１,Ｎ２）和Ｐｉｅｌｏｕ均匀度指数（Ｅ）比较研究了松嫩平原南部１４个主要群落的植物多样性、生活型多样性及植物多样性与群落演替的关系结果表明,分布于低平原的羊草－蔓萎陵菜群落的植物多样性和丰富度指数最大,Ｒ１为１１．９６,Ｒ２为５．２４,Ｎ１为１３．９２,Ｎ２为８．７６,分布于固定砂丘的榆树疏林和贝加尔针茅等４个群落有较高的植物多样性,而分布于碱化草甸的角碱蓬等群落植物多样性最小,Ｒ１为１．３１,Ｒ２为０７１,Ｎ１为１．８４,Ｎ２为１．４６．具有较高植物多样性的群落其植物生活型多样性指数也较高．在演替系列中,羊草群落的植物多样性指数介于演替初期和中期阶段之间．     

Exploring the functional significance of forest diversity: A new long-term experiment with temperate tree species (BIOTREE)

Effects of biodiversity on ecosystem functioning have been mainly studied in experiments that artificially create gradients in grassland plant diversity. Woody species were largely excluded from these early experiments, despite the ecological and socioeconomic importance of forest ecosystems. We discuss conceptual aspects of mechanistically driven research on the biodiversity–ecosystem functioning relationship in forests, including the comparison of scientific approaches like ‘observational studies’, ‘removal experiments’, and ‘synthetic-assemblage experiments’. We give a short overview on the differences between herbaceous and forest ecosystems, focusing on canopy characteristics, and the possibilities for individual versus population-based investigations.We present detailed information about the first large-scale, multisite and long-term biodiversity–ecosystem functioning experiment with tree species of temperate forests (BIOTREE – BIOdiversity and ecosystem processes in experimental TREE stands). At three sites of differing geology and local climate, we planted 200,000 saplings on a total area of 70 ha. At two sites, diversity gradients were established by varying the number of tree species (BIOTREE-SPECIES). At a third site, only functional diversity at a constant level of tree species richness was manipulated by selecting mixtures that differ in the functional trait values of the corresponding species (BIOTREE-FD). Additional experimental treatments at the subplot level include silvicultural management options, the addition of subdominant species, and the reduction of genetic diversity. Response variables focus on productivity, biogeochemical cycles and carbon sequestration, and resource use complementarity.We explore the use of different measures of functional diversity for a posteriori classifications of functional richness and their use in the analysis of our tree diversity experiment. The experiment is thought to provide a long-term research platform for a variety of scientific questions related to forest biodiversity and ecosystem processes.     

Cascading extinctions, functional complementarity, and selection in two-trophic-level model communities: A trait-based mechanistic approach

The influence of diversity on ecosystem functioning and ecosystem services is now well established. Yet predictive mechanistic models that link species traits and community-level processes remain scarce, particularly for multitrophic systems. Here we revisit MacArthur's classical consumer resource model and develop a trait-based approach to predict the effects of consumer diversity on cascading extinctions and aggregated ecosystem processes in a two-trophic-level system. We show that functionally redundant efficient consumers generate top-down cascading extinctions. This counterintuitive result reveals the limits of the functional redundancy concept to predict the consequences of species deletion. Our model also predicts that the biodiversity-ecosystem functioning relationship is different for different ecosystem processes and depends on the range of variation of consumer traits in the regional species pool, which determines the sign of selection effects. Lastly, competition among resources and consumer generalism both weaken complementarity effects, which suggests that selection effects may prevail at higher trophic levels. Our work emphasizes the potential of trait-based approaches for transforming biodiversity and ecosystem functioning research into a more predictive science.     

Overyielding and the role of complementary use of nitrogen in wetland plant communities

Biodiversity and ecosystem functioning experiments have demonstrated that plant biomass of species grown in mixtures is often greater than plant biomass of monocultures (i.e., mixtures over yield). While we understand that plant species utilize resources differently, how a combination of species increases resource use and productivity is not well known, especially in wetland ecosystems. Here, we used a mesocosm experiment to explore diversity effects on plant biomass production and to examine the role of N partitioning as a mechanism for overyielding in wetland ecosystems. Plant functional groups (FGs) represented the unit of diversity, and we included five levels of diversity (0-4 FGs). To test for N partitioning, we used a stable isotope technique to determine niche breadth and proportion similarity of inorganic N use (NO₃⁻ and NH₄⁺) for individual FGs as well as mixtures containing 3 and 4 FGs. We found that total plant biomass increased in the first season from an average of 290 ± 60 SE g ash-free dry mass (AFDM) m⁻² at the 1 FG level to 490 ± 70 g AFDM m⁻² at the 4 FG level and in the second season from an average of 560 ± 80 g AFDM m⁻² at the 1 FG level to 1000 ± 90 g AFDM m⁻² at the 4 FG level indicating overyielding. Plant species comprising the majority of mesocosm biomass demonstrated preferential uptake of ¹⁵NO₃⁻, while species with relatively less biomass (e.g., Acorus calamus and Carex crinita) preferred ¹⁵NH₄⁺. Concentrations of ¹⁵N in biomass increased with FG richness, but only in the ¹⁵NO₃⁻ treatment. Niche breadth did not vary among levels of FG richness. We observed a greater niche overlap with an increase of FGs, with species taking up greater proportion of ¹⁵NO₃⁻ than ¹⁵NH₄⁺. Our results indicate that plant overyielding in wetland mesocosms is not the result of niche partitioning of N chemical forms, but is associated with greater uptake of NO₃.     

Biodiversity and resilience of arthropod communities after fire disturbance in temperate forests

Changes in ecosystem functions following disturbances are of central concern in ecology and a challenge for ecologists is to understand the factors that affect the resilience of community structures and ecosystem functions. In many forest ecosystems, one such important natural disturbance is fire. The aim of this study was to understand the variation of resilience in six functional groups of invertebrates in response to different fire frequencies in southern Switzerland. We measured resilience by analysing arthropod species composition, abundance and diversity in plots where the elapsed time after single or repeated fires, as determined by dendrochronology, varied. We compared data from these plots with data from plots that had not burned recently and defined high resilience as the rapid recovery of the species composition to that prior to fire. Pooling all functional groups showed that they were more resilient to single fires than to repeated events, recovering 6–14 years after a single fire, but only 17–24 years after the last of several fires. Flying zoophagous and phytophagous arthropods were the most resilient groups. Pollinophagous and epigaeic zoophagous species showed intermediate resilience, while ground-litter saprophagous and saproxylophagous arthropods clearly displayed the lowest resilience to fire. Their species composition 17–24 years post-burn still differed markedly from that of the unburned control plots. Depending on the fire history of a forest plot, we found significant differences in the dominance hierarchy among invertebrate species. Any attempt to imitate natural disturbances, such as fire, through forest management must take into account the recovery times of biodiversity, including functional group composition, to ensure the conservation of multiple taxa and ecosystem functions in a sustainable manner.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Functional diversity research of forest communities in the Xiaowutai Mountain National Nature Reserve,Hebei

Plant functional traits are the plant physiological characteristics which can response to the changes of the living environment and have a certain impact on the ecosystem structure and function. The objective of our study was to explore characters of present functional diversity indices, the relationships between functional diversity and environmental variables, the relevance of species diversity and functional diversity. In this paper, habitat type, seed dispersal, pollination method, life cycle, life form, leaf form, leaf hair type, flowering period and flowering time were chosen as functional traits, and the research were done in the typical forest communities in the Xiaowutai Mountain National Nature Reserve, Hebei. One hundred and forty-eight quadrats (10 m × 10 m) of forest communities were established along altitude gradients, at the same time, species composition, functional traits, and environmental variables were measured in each quadrat. The results showed that functional diversity indices in forest communities that were calculated by functional distances varied greatly. Functional diversity indices (FAD, MFAD, FDp, FDc, FRic, Rao and FDis) had highly significantly positive correlation with Patrick index and showed a linear increasing trend. All the nine functional diversity indices (FAD, MFAD, FDp, FDc, FRic, Rao, FEve, FDiv, FDis) had significantly correlation with Shannon-Wiener index and Pielou index. Only FDiv showed significantly negative correlation, and the other eight functional diversity indices showed positive correlation. Environmental filtering was important to functional diversity pattern, and functional diversity indices showed correlation with environmental variables. Altitude was a significant factor to functional diversity in forest communities. Except for FDiv, other functional diversity indices displayed a decreasing trend along altitude gradients. Among all the functional diversity indices, only Rao and FDis showed significantly positive correlation with aspect. The functional diversity indices (FAD, MFAD, FDp, FDc, FRic, Rao and FDdis) showed a negative correlation with slope, slope position, litter layer thickness, soil thickness, while, they showed a positive correlation with soil temperature and disturbance. All the nine indices were proved successful in the analysis of functional diversity in forest communities with different effectiveness. They were divided into three categories, functional richness (FAD, MFAD, FDp, FDc, FRic), functional divergence (Rao, FDis), functional evenness (FEve, FDis). Meanwhile, each category was highly inter-correlated and each category was relatively independent with other categories. The study of functional diversity provides a number of ecological indication and monitoring methods for the forest, and it can address a wide range of important ecological questions that links species and ecosystems through mechanisms in biodiversity research.     

Woody species diversity influences productivity and soil nutrient availability in tropical plantations

We investigated the relationship between plant diversity and ecological function (production and nutrient cycling) in tropical tree plantations. Old plantations (65–72 years) of four different species, namely Araucaria cunninghamii, Agathis robusta, Toona ciliata and Flindersia brayleyana, as well as natural secondary forest were examined at Wongabel State Forest, in the wet tropics region of Queensland, Australia. Two young plantations (23 years) of Araucaria cunninghamii and Pinus caribaea were also examined. The close proximity of the older plantations and natural forests meant they had similar edaphic and climatic conditions. All plantations had been established as monocultures, but had been colonised by a range of native woody plants from the nearby rainforest. The extent to which this had occurred varied with the identity of the plantation species (from 2 to 17 species in 0.1 ha blocks). In many cases these additional species had grown up and joined the forest canopy. This study is one of the few to find a negative relationship between overstorey plant diversity and productivity. The conversion of natural forest with highly productive, low-diversity gymnosperm-dominated plantations (young and old Araucaria cunninghamii and Pinus caribaea) was found to be associated with lower soil nutrient availability (approximately five times less phosphorus and 2.5 times less nitrogen) and lower soil pH (mean = 6.28) compared to the other, less productive plantations. The dominant effects of two species, Araucaria cunninghamii and Hodgkinsonia frutescens, indicate that ecosystem functions such as production and nutrient availability are not determined solely by the number of species, but are more likely to be determined by the characteristics of the species present. This suggests that monoculture plantations can be used to successfully restore some functions (e.g. nutrient cycling and production), but that the level to which such functions can be restored will depend upon the species chosen and site conditions. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A partial ordering approach for functional diversity

Functional diversity is generally regarded as the constituent of biological diversity that considers how the species functional traits affect ecosystem processes. Due to its ecological relevance, a number of indices of functional diversity have been proposed to date based on distinct objectives and motivations. Such proliferation of indices can be at least partially overcome by a more fundamental mathematical approach. In this paper we propose an intrinsic ordering approach for abundance-weighted measures of functional diversity that is similar to the Lorenz curves used by ecologists for ordering evenness measures. We then discuss the relevance of a number of functional diversity indices that have a behavior compatible with the proposed partial ordering.     

青龙河底栖无脊椎动物群落结构及其水质评价

本文论述了青龙河底栖生物种类、数量、分布和结构等特点及其与环境因子间的关系。应用Beck、Gleason、Shannon、Simpson等生物指数对水质状况进行评价。结果表明青龙河除个别断面受污染外,大部分河段属尚清洁水。     

Environmental variables explaining structural and functional diversity of seagrass macrofauna in an archipelago landscape

Thirteen seagrass beds located over a 80-km range in the brackish waters of SW, Finland, northern Baltic Sea were investigated in order to determine the environmental variables important for univariate community measures and for number, composition and redundancy of functional groups of benthic macrofauna. For species assemblages, fetch and shore angle were the best explanatory variables, followed by sediment granulometry (fine gravel) and then sediment organics. Similarly, fetch, shore angle and Zostera marina shoot density were the best explanatory variables for functional group patterns. Small (< 50 m²) inner-archipelago beds were functionally and structurally equal to the most extensive (500 to > 1000 m²) seagrass beds in the study area. Community measures (density, number of species and diversity) and functional diversity (number of functional groups) equalled or exceeded levels previously recorded in deeper, non-vegetated communities in the northern Baltic Sea. In comparison with marine seagrass assemblages, the total number of species and number of species per function were low. However, species density and derived diversity measures (Shannon-Wieners index H′) equalled or exceeded those reported for other seagrass ecosystems. It is concluded that in terms of seagrass infauna, the Baltic Sea should not be regarded species poor, as is often generally stated, and that conservation initiatives and management strategies should consider both minor as well as more extensive occurrences of seagrasses in coastal waters.     

Drivers of beta diversity of macroinvertebrate communities in tropical forest streams

1. There has recently been increasing interest in patterns of beta diversity but we still lack a comprehensive understanding of these patterns in various regions (e.g. the tropics), ecosystems (e.g. streams) and organism groups (e.g. invertebrates). 2. Our aim was to investigate the patterns of beta diversity of stream macroinvertebrates in relation to key environmental (i.e. stream size, pH and habitat degradation) and geographical variables (i.e. latitude, longitude, altitude) in a tropical region. We surveyed a total of 8–10 riffle sites in each of 34 streams (altogether 337 riffle sites were sampled) in Peninsular Malaysia to examine variation in macroinvertebrate community composition at within‐stream and among‐stream scales. 3. Based on test of homogeneity of dispersion, we found that the streams studied differed significantly in within‐stream variation in community composition (i.e. among‐site variation of within stream beta diversity). The patterns were similar based on Bray–Curtis coefficient on abundance data, Sorensen coefficient on presence–absence data and Simpson coefficient on presence–absence data. We also found that within‐stream beta diversity was significantly related to stream size, pH and latitude, with each of these variables individually accounting for around 20% of the variation in beta diversity in simple regressions, while the total variation explained by the three significant variables amounted to around 50% in multiple regressions. By contrast, habitat degradation, longitude and altitude were not significantly related to beta diversity. We also found that the factor drainage basin accounted for much of the variation in beta diversity in general linear models, suppressing the effects of environmental variables. 4. We concluded that within‐stream beta diversity is mainly related to a combination of the identity of a drainage basin and stream environmental factors. Our findings provide important background for stream environmental assessment and conservation planning by emphasising that (i) macroinvertebrate communities within streams are not homogeneous, but show considerable beta diversity, (ii) streams differ in their degree of within‐stream beta diversity, (iii) stream size and water pH should be considered in applied contexts related to within‐stream beta diversity and (iv) historical effects may be different in different drainage basins and may affect present‐day patterns of within‐stream beta diversity.     

A novel comparative research platform designed to determine the functional significance of tree species diversity in European forests

One of the current advances in functional biodiversity research is the move away from short-lived test systems towards the exploration of diversity-ecosystem functioning relationships in structurally more complex ecosystems. In forests, assumptions about the functional significance of tree species diversity have only recently produced a new generation of research on ecosystem processes and services. Novel experimental designs have now replaced traditional forestry trials, but these comparatively young experimental plots suffer from specific difficulties that are mainly related to the tree size and longevity. Tree species diversity experiments therefore need to be complemented with comparative observational studies in existing forests. Here we present the design and implementation of a new network of forest plots along tree species diversity gradients in six major European forest types: the FunDivEUROPE Exploratory Platform. Based on a review of the deficiencies of existing observational approaches and of unresolved research questions and hypotheses, we discuss the fundamental criteria that shaped the design of our platform. Key features include the extent of the species diversity gradient with mixtures up to five species, strict avoidance of a dilution gradient, special attention to community evenness and minimal covariation with other environmental factors. The new European research platform permits the most comprehensive assessment of tree species diversity effects on forest ecosystem functioning to date since it offers a common set of research plots to groups of researchers from very different disciplines and uses the same methodological approach in contrasting forest types along an extensive environmental gradient.     

Hydrological connectivity drives patterns of macroinvertebrate biodiversity in floodplain rivers of the Australian wet /dry tropics

1. Floodplain rivers in Australia's wet/dry tropics are regarded as being among the most ecologically intact and bio-diverse lotic ecosystems in the world, yet there have been relatively few community-based studies of their aquatic fauna.
2. To investigate relationships between hydrological connectivity and biodiversity in the region, macroinvertebrates were collected from sites within two contrasting floodplain rivers, the 'tropical' Gregory River and 'dryland' Flinders River systems, during the dry season and analysed at various spatial scales. A subset of sites was re-sampled in the following dry season to explore temporal variation. The fauna consisted of 124 morphotaxa, dominated by gatherers and the Insecta.
3. As predicted, hydrological connectivity (the lotic or lentic status of waterbodies) had a major influence on macroinvertebrate assemblage composition and diversity, both in space and time. Assemblages from waterbodies with similar connection histories were most alike, and beta-diversity between assemblages was greatest between lotic and lentic waterbodies, tending to increase with increasing spatial separation.
4. At smaller spatial scales, a number of within-waterbody, habitat and water quality characteristics were important for explaining variation (61%) in the taxonomic organization of assemblages, and characteristics associated with primary productivity and habitat diversity were important for explaining variation (45%) in the functional organization of assemblages. However, much of the small-scale environmental variation across the study region appeared to be related to broad-scale variation in hydrological connectivity, which had both direct and indirect effects on macroinvertebrate assemblages.
5. Conservation of the biodiversity in Australia's wet/dry tropics may depend on conserving the natural variation in hydrological connectivity and the unregulated flow of floodplain rivers.