Understanding the relationship between plant diversity and productivity can provide essential information for forest management. We surveyed plant communities in Pinus massoniana dominated plantations from four regions of Guangxi. Using correlation analysis, automatic linear modeling and variance partitioning, we assessed the effect of species diversity, functional diversity, and functional dominance on productivity. We found that productivity was extremely positively correlated with species richness, Shannon index, functional richness and functional evenness (P < 0.01). Species evenness, RaoQ, functional dispersion, functional group richness and aspect were also positively correlated with productivity (P < 0.05), while forest age was negatively correlated with productivity (P < 0.01). Four functional diversity parameters positively correlated with four species-diversity indices. No evidence of negative density-dependence was found. In the best variance partitioning model, functional diversity parameters, functional dominance and forest age explained 56%, 43% and 33% of variance in productivity respectively; and the overlap between functional diversity parameters and functional dominance was up to 27%. Functional richness and functional evenness were major contributors of complementary effects while community weighted mean (CWM) of growth form contributed to selection effects. Plots identified as dominantly shrub had higher productivity than plots identified as dominantly herbs or trees, suggesting that subordinates and transients may have important effects on ecosystem functions. The best-fit subset model built by automatic linear modeling included forest age, growth form CWM, functional richness, functional evenness and functional group richness (FGR) indescending order. We recommend that to maintain diversity and forest function, protection of understory plant species should be strengthened. Further, to enhance productivity and biodiversity we recommend planting functionally important species through compensatory photosynthesis and growth competition in understorey layers.

Wild pollinator bees play an important role in ecosystem function and food security. In recent years, natural forests have been lost, while afforestation programs are primarily monoculture plantation, whether commercial or restorative. The net effect for bees has been fragmentation and sometime wholesale loss of habitats. For instance, diversity of wild bees in pure forest, Camellia oleifera and rubber (Hevea brasiliensis) plantation was found to be unexpectedly low. The rampant use of neonicotinoid pesticides and herbicide is known to negatively impact development and behavior of bees. Urbanization has dramatically impacted bee communities, with significant changes in species richness between suburban and central business areas. These are likely tied to the effect of effluent, exhaust gas and dust on foraging, growth and development. Climate change from greenhouse gas emissions can disrupt the mutualistic relationship between pollinating bees and plants via rapid phenological shifts. The above environmental changes occurring in China are likely cause wide declines in diversity and decreases in populations. Although China has rich natural heritage for bees, there is a lack of long term monitoring programs for species of pollinator bees and a dearth of data on distributions of bee species. As a result, the drivers of bee community composition and population decline are poorly understood. We emphasize the need to prioritize surveys of pollinating bees, continue ongoing monitoring programs and build wider research networks for the study of wild pollinator bees. These steps will ensure that sufficient data can accumulate for developing a prediction and risk assessment framework to help manage the declines in pollinating bee populations and mitigate the attendant economic and non-economic impacts.

Nature reserves are a cornerstone of global conservation strategies. However, the effectiveness of the reserve in conserving ecosystem function such as carbon storage is poorly understood. The Shennongjia National Nature Reserve is a conservation icon and has taken exceptional efforts to protect forests. It provides a unique case to address this question. Here, we quantified the carbon storage from aboveground carbon, belowground carbon, litter, coarse woody debris, and soil organic carbon inside and outside the Shennongjia National Nature Reserve between 1990 and 2010, based on inventory data and digitized historical land cover maps. The result showed that the woodland covered 92.76% of the reserve, most of which was coniferous forest (51.85%), deciduous broad-leaved forest (35.11%), and evergreen broad-leaved forest (4.47%). Between 1990 and 2010, the area of the woodland has increased 0.11%, while the area of shrubland and cropland has declined 8.85% and 6.06%, respectively. The Shennongjia National Natural Reserve has accumulated 24.24 Tg carbon (22.57-26.62 Tg C) until 2010, of which 90.68% was contributed by soil organic carbon and aboveground carbon. A total of 95% of the carbon storage in Shennongjia National Nature Reserve are contributed by evergreen broad-leaved forest, deciduous broad-leaved forest and coniferous forest. Between 1990 and 2010, the aboveground carbon pool and soil organic carbon pool has increased 14.50 kt C (11.81-18.31 kt C) and 6.84 kt C, respectively. The carbon density inside the reserve is 22.37 t C/ha higher than that outside the reserve. Our results indicated that the Shennongjia National Nature Reserve is efficiently conserving forest carbon.

The study of the relationship between biodiversity and ecosystem functioning (BEF) is a hot topic in the field of terrestrial ecosystem ecology, and is of great significance for the efficient use and management of ecosystems. Furthermore, it plays an important role in the restoration of degraded ecosystems and biodiversity conservation. Alpine grassland is the main ecosystem type found in the Qinghai-Tibet Plateau. In recent years, progress has been made on species diversity and ecosystem functioning and their mutual relationship in alpine grasslands. This paper analyzes existing problems in the research of grassland biodiversity and ecosystem functioning in terms of the study of underlying ecological processes and the impacts on ecosystem multi-functionality under global change. The effects of different grassland types, grassland degradation, grazing disturbance, simulated climate change, mowing, fertilization, enclosure, and replanting on the relationship between biodiversity and ecosystem functioning in alpine grasslands are also thoroughly reviewed in this paper. Moreover, deficiencies and future research directions of alpine grassland BEF are identified: carrying on the BEF research of alpine grasslands based on the functional diversity of species, comprehensively considering the effects of abiotic factors such as resource supply levels, disturbance intensity and scale, and environmental fluctuation on the relationship between species diversity and ecosystem function, and paying attention to the effect of scale and element coupling on BEF research of alpine grasslands under global climate change. Finally, based on research progress and conclusions of BEF in alpine grasslands, we put forward suggestions to improve the utilization rate of alpine grassland resources and biodiversity conservation, including strengthening grazing management, protecting biodiversity, improving governance of degraded grasslands, maintaining biodiversity function, strengthening innovation and protection concepts and enhancing ecosystem functioning that has been seriously weakened by climate change and human disturbance.

Under global climate change, biodiversity is decreasing rapidly due to deforestation and habitat fragmentation, which has serious consequences for ecosystem functioning. In recent years, the relationship between biodiversity and ecosystem functioning has been a core research area in ecology. Previous researchers have paid great attention to the relationship between biodiversity and individual ecosystem functioning, and seldom consider multiple functions (multifunctionlity), especially in forest ecosystems. Here, based on survey data from 94 plots of Pinus yunnanensis in a natural secondary forest, we selected variables related to ecosystem functioning: woody plant biomass, soil organic carbon, plant nitrogen, plant phosphorus, soil total nitrogen, soil hydrolyzable nitrogen, soil total phosphorus, and soil available phosphorus. We used an averaging approach, single threshold approach, and multiple threshold approach to evaluate the effects of species richness on ecosystem multifunctionality and impacting factors. Results showed that the relationship between species richness and ecosystem multifunctionality was stronger than that of individual ecosystem functioning. Species richness had a significant positive effect on multifunctionality within thresholds ranging from 3% to 88%. When using a moderate threshold (54%), species richness had the strongest positive effect, and the percentage of maximum possible species richness was 53.53%. Path analysis of a structural equation model showed that species richness had the strongest (positive) effect on multifunctionality in the Pinus yunnanensis natural secondary forest. Mean annual temperature, mean annual precipitation, and soil pH had insignificant effects on multifunctionality, but indirect effects via influences on species richness. Species richness may be of primary importance when considering ecosystem multifunctionality. Increasing species numbers may not always lead to the optimal state of all functions. Increasing species numbers had the strongest effects on multifunctionality, but only once multifunctionality reached moderate levels.

World Natural Heritage site is recognized globally as the pinnacle of natural protected areas that are the cornerstones of biodiversity conservation. The World Natural Heritage of Shennongjia represents one of the worldwide biodiversity hotspots. But, until now, it has not been clear how outstanding the universal value of Shennongjia is worldwide, and this study presents one of the most compelling challenges to conservation efforts. Here, we compiled literature and conducted additional field surveys in the Shennongjia region to illustrate the outstanding universal value of Shennongjia World Natural Heritage Site using World Heritage criteria (ix) and (x), following the operational guidelines for the implementation of the World Heritage Convention. Results show that the heritage of Shennongjia offers an outstanding example of the ongoing ecological processes occurring in the development of intact subtropical mixed broad-leaved evergreen and deciduous forests in the Northern Hemisphere. This region presents a typical example of mountain altitudinal biological zones in the Oriental Deciduous Forest Biogeographical Province. Shennongjia is also a vital origin location for global temperate flora, and harbors the highest concentration of global temperate genera of trees. Moreover, the heritage of Shennongjia displays exceptional biodiversity and is a key habitat for numerous relic, rare, endangered and endemic species. The richness of deciduous woody species in Shennongjia is the highest in the world. Our study provides great insight into protecting, monitoring and managing the outstanding world heritage in the Northern Hemisphere.

High-quality biodiversity data are the scientific basis for understanding the origin and maintenance of biodiversity and dealing with its extinction risk. Currently, we identify at least seven knowledge shortfalls or gaps in biodiversity science, including the lack of knowledge on species descriptions, species geographic distributions, species abundance and population dynamics, evolutional history, functional traits, interactions between species and the abiotic environment, and biotic interactions. The arrival of the current era of big data offers a potential solution to address these shortfalls. Big data mining and its applications have recently become the frontier of biodiversity science and macroecology. It is a challenge for ecologists to utilize and effectively analyze the ever-growing quantity of biodiversity data. In this paper, I review several biodiversity-related studies over global, continental, and regional scales, and demonstrate how big data approaches are used to address biodiversity questions. These examples include forest cover changes, conservation ecology, biodiversity and ecosystem functioning, and the effect of climate change on biodiversity. Furthermore, I summarize the current challenges facing biodiversity data collection, data processing and data analysis, and discuss potential applications of big data approaches in the fields of biodiversity science and macroecology.

As the most direct and active ecological interface of the interaction between forest and its environment, the forest canopy, known as the earth’s “eighth continent”, contains the greatest forest biological diversity, and plays an important role in the formation and maintenance of biodiversity as well as the processes and functions of the ecosystem. However, the forest canopy is highly sensitive to global climate change and human disturbance. In the wake of increasing human activities and global climate change, the forest ecosystem, especially the forest canopy, is facing a serious threat. Therefore, protection of forest canopy biodiversity and sustainable utilization are increasingly important issues in modern ecology research under the scenarios of climate change, and have gained more and more attention in the fields of forest ecology, climatology, and environmental science. Accordingly, in 2015, the Chinese Forest Canopy Biodiversity Monitoring Network was created within the framework of Sino BON. This network includes biodiversity monitoring plots those were or will be equipped with forest canopy cranes. According to international standards, the network will unify monitoring parameters of forest canopy biodiversity using monitoring standards and norms, and conduct long-term monitoring of plant diversity (including epiphytic seed plants and epispore plants), fauna diversity, microbial diversity and their dynamic changes, through large scale zonal forest canopies. Combined with monitoring of the microclimate, we will build four dynamic databases (including a forest canopy microclimate database, canopy plant, canopy arthropod, and canopy microbial). The network is expected to discern the change patterns of forest canopy biodiversity of typical forest ecosystems in China, and to reveal how they influence the functioning of forest ecosystems and respond to global change.

The application of phylogenetic relationships helps us to understand species composition and species distribution patterns, which provide a scientific basis for the effective protection and sustainable use of biological diversity. Phylogenetic diversity (PD_faith), based on branch lengths of the phylogenetic tree, is the most basic measurement index. Many indices are derived from PD_faith, which makes difficult to choose the most appropriate parameters. The most effective and feasible way is to select suitable indices based on specific research questions, and some examples have been presented in plant phylofloristics and biodiversity conservation. DNA sequences have rapidly accumulated particularly through the global DNA barcoding project, which provides a standardized mass data, and can be used to reconstruct mega-phylogeny. But studies conducted around the phylogenetic diversity require more information, specifically data on species distribution, environmental factors, and climatic data. In addition, some fundamental questions need to be verified, such as the relationship between phylogenetic diversity and ecosystem functions.

Aims The aim of this guide is to provide practical help for ecologists who analyze data from biodiversity–ecosystem functioning experiments. Our approach differs from others in the use of least squares-based linear models (LMs) together with restricted maximum likelihood-based mixed models (MMs) for the analysis of hierarchical data. An original data set containing diameter and height of young trees grown in monocultures, 2- or 4-species mixtures under ambient light or shade is used as an example.
Methods Starting with a simple LM, basic features of model fitting and the subsequent analysis of variance (ANOVA) for significance tests are summarized. From this, more complex models are developed. We use the statistical software R for model fitting and to demonstrate similarities and complementarities between LMs and MMs. The formation of contrasts and the use of error (LMs) or random-effects (MMs) terms to account for hierarchical data structure in ANOVAs are explained.
Important findings Data from biodiversity experiments can be analyzed at the level of entire plant communities (plots) and plant individuals. The basic explanatory term is species composition, which can be divided into contrasts in many ways depending on specific biological hypotheses. Typically, these contrasts code for aspects of species richness or the presence of particular species. For significance tests in ANOVAs, contrast terms generally are compared with remaining variation of the explanatory terms from which they have been 'carved out'. Once a final model has been selected, parameters (e.g. means or slopes for fixed-effects terms and variance components for error or random-effects terms) can be estimated to indicate the direction and size of effects.

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Aims Plant diversity has been linked to both increasing and decreasing levels of arthropod herbivore damage in different plant communities. So far, these links have mainly been studied in grasslands or in artificial tree plantations with low species richness. Furthermore, most studies provide results from newly established experimental plant communities where trophic links are not fully established or from stands of tree saplings that have not yet developed a canopy. Here, we test how tree diversity in a species-rich subtropical forest in China with fully developed tree canopy affects levels of herbivore damage caused by different arthropod feeding guilds.
Methods We established 27 plots of 30×30 m area. The plots were selected randomly but with the constraint that they had to span a large range of tree diversity as required for comparative studies in contrast to sample surveys. We recorded herbivore damage caused by arthropod feeding guilds (leaf chewers, leaf skeletonizers and sap feeders) on canopy leaves of all major tree species.
Important findings Levels of herbivore damage increased with tree species richness and tree phylogenetic diversity. These effects were most pronounced for damage caused by leaf chewers. Although the two diversity measures were highly correlated, we additionally found a significant interaction between them, whereby species richness increased herbivory mostly at low levels of phylogenetic diversity. Tree species with the lowest proportion of canopy leaf biomass in a plot tended to suffer the highest levels of herbivore damage, which is in contrast to expectations based on the resource concentration hypothesis. Our results are in agreement with expectations of the dietary mixing hypothesis where generalist herbivores with a broad spectrum of food plants benefit from increased resource diversity in tree species-rich forest patches.

Aims Litterfall, as an important link between aboveground and belowground processes, plays a key role in forest ecosystems. Here, we test for effects of tree species richness on litter production and litter quality in subtropical forest. The study further encompasses a factorial gradient of secondary succession that resulted from human exploitation. Given that a large percentage of subtropical forests are in secondary successional stages, understanding the role of biodiversity on forest re-growth after disturbance appears critical.
Methods From January 2009 to December 2014, we monitored forest litterfall in 27 Comparative Study Plots that spanned a gradient of tree species richness (3–20 species) and secondary successional ages (~20 to 120 years) in Gutianshan Natural Nature Reserve, Zhejiang Province, China. The experiment is part of the biodiversity–ecosystem functioning research platform 'BEF-China'. Tree litterfall was collected in monthly intervals using litter traps. Samples were separated into leaf and non-leaf components. Leaf litter was further sorted into dominant and other species. Community level monthly leaf litter C and N contents were analysed through a full year. General linear mixed-effects models were applied to test for effects of tree species richness and successional age on litter quantity and leaf litter C/N.
Important findings Litterfall increased with species richness among and within successional age and this effect was consistent across years. Successionally older stands had higher litterfall and this effect was related to increased tree species richness. However, species richness did not change the intra- and inter-annual temporal stability of litterfall. Increasing tree species richness increased leaf litter quality (decreased C/N), while successional age had no effect. Our study indicates that more diverse forest stands produce more leaf litter and that this litter has higher N concentrations, which could promote forest growth through accelerated nutrient re-cycling.

Aims Mycorrhizal fungi can re-distribute nutrients among plants through formation of underground common mycorrhizal networks and therefore may alter interspecific plant competition. However, the effect of ectomycorrhizal (EM) fungi on interspecific plant competition in subtropical forests is poorly understood. In this study, we investigated the effects of EM fungal identity and diversity on the outcome of interspecific competition of plant species in relation to different successional stages in a Chinese subtropical forest.
Materials and Methods This study selected four woody plant species, i.e. a pioneer tree Pinus massoniana, a late-pioneer tree Quercus serrata, a mid- successional tree Cyclobalanopsis glauca and a late-successional tree Lithocarpus glaber in a Chinese subtropical forest. The outcomes of interspecific competition were investigated in the seedlings of three plant pairs, i.e. between Cy. glauca and Pin. massoniana, between Q. serrata and Pin. massoniana, and between Li. glaber and Q. serrata in a pot experiment. In the Cy. glauca – Pin. massoniana combination, plants in monoculture and two-species mixture were uninoculated or inoculated with EM fungi Paxillus involutus, Pisolithus tinctorius, Cenococcum geophilum, Laccaria bicolor and a mixture of these four fungal species. In the Q. serrata – Pin. massoniana and Li. glaber – Q. serrata combinations, plants in monocultures and two-species mixtures were uninoculated or inoculated with EM fungi Pis. tinctorius, Ce. geophilum, La. bicolor and a mixture of these three fungal species. EM root colonization rate and seedling biomass of each plant species were measured, and the outcomes of interspecific competition were estimated using competitive balance index after 6-month cultivation.
Important findings All EM fungal inoculation significantly promoted a competitive ability of the mid-successional tree Cy. glauca over the pioneer tree Pin. massoniana compared with the uninoculated control treatment, and the extent to which EM fungi affected the outcome of interspecific competition was dependent on EM fungal identity in the Cy. glauca and Pin. massoniana combination. EM fungal inoculation had no significant effect on the outcomes of interspecific competition between the late-pioneer tree Q. serrata and Pin. massoniana combination and between the late-successional tree Li. glaber and Q. serrata combination, compared with the uninoculated control treatment. However, amongst the EM fungal inoculation treatments the competitive ability of Q. serrata over Pin. massoniana was significantly higher in EM fungi Ce. geophilum and La. bicolor treatments than in Pis. tinctorius treatment. EM fungal diversity did not show a complementary effect on the outcomes of interspecific competition in all three plant pairs. This study demonstrated that the effect of EM fungi on the outcome of interspecific competition was dependent on the plant pairs tested in the subtropical forest ecosystem.

Aims Ericaceous plant species can host diverse fungi in their roots, including ericoid mycorrhizal fungi (ERMF), endophytes, pathogens and some species with unknown functions. However, how this diversity of fungi responds to different human disturbances is not well understood.
Methods In this study, we examined the effects of different human disturbance on fungal diversity in hair roots of Vaccinium mandarinorum, an ericaceous plant. Fungal DNA was extracted from hair roots of V. mandarinorum and high-throughput sequencing was applied to detect the diversity of root-associated fungi along a human disturbance gradient in subtropical forests in Gutianshan National Nature Reserve (GNNR) in East China. The four forest types with different disturbance regime were: old growth forest (OGF), secondary forest with once cut (SEC I), secondary forest with twice cut (SEC II) and Cunninghamia lanceolata plantation (PLF).
Important findings The results showed that: (i) diverse fungal operational units (OTUs) were detected in hair roots of V. mandarinorum in the four types of forests, covering fungal phyla of Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Zygomycota; (ii) Community composition of root-associated fungi of V. mandarinorum in PLF was distinct from those in the other three forest types, and two types of secondary forests had similar fungal community composition; (iii) Different fungal families respond differently to human disturbances: fungal families with significant preference to OGF were ectomycorrhizal or saprophytic fungi while fungal families with higher relative abundance in PLF were plant pathogenic or saprophytic fungi; (iv) The first principal component (PC1) of plant community had a significant effect on composition of root-associated fungal community, while edaphic parameters showed no significant effect on fungal community composition in roots of V. mandarinorum. Our results help to better understand the responses of both ericaceous plants and their fungal partners to human disturbances and forest managements.

Aims Asymmetric competition for light may depress the growth rates (GRs) to different extents for different-sized tree individuals. Various responses of different functional groups to light availability result that tree individuals of different functional groups may experience different competition intensities, e.g. canopy and deciduous species grow faster and demand more light than understory and evergreen species. In this study, we estimated the effects of asymmetric competition for light using individual GRs and explored the effects of asymmetric competition on growth among different functional groups (e.g. canopy vs. understory species and deciduous vs. evergreen species).
Methods We measured growth in circumference to determine the radial increments of a total of 2233 stems with diameter at breast height ≥ 5.0 cm in a permanent plot (140 × 80 m 2) located in a typical evergreen and deciduous broadleaved mixed forest on Mt Shennongjia, China. All of the measurements were carried out at ~6-month intervals every April and October from 2012 to 2014, and biomass of each individual was calculated based on its diameter and species-specific allometry. We then calculated GRs of annual biomass growth (growth between October and the next October). Considering the hypothesis that asymmetric competition for light among trees of different sizes may result in a steeper allometric growth curve with increasing tree size, we further divided the sampled trees into different subsets according to their height, at intervals of 1 m, and then fitted the scaling relationship between the logarithm of the biomass GR (logGR) and the logarithm of diameter (logD) for each height class using standardized major axis regression. Finally, we used simple linear regression to test whether the scaling exponent was related to tree height. The above analyses were conducted for the annual growth of all tree species, canopy species, understory vs. treelets species and deciduous vs. evergreen species.
Important findings We observed a concave curve for the relationship between logGR and logD with an increase in the scaling exponent between logGR and logD with increasing tree height. This pattern held for the annual growth of canopy species and deciduous species but not for the annual growth of understory species, treelets or evergreen species. These results suggest that asymmetric competition for light is more important in regulating the GRs of the fast-growing species, such as canopy species and deciduous species, than those of shade-tolerant species, such as understory species, treelets and evergreen species.

Aims Soil sample preservation is a challenging aspect in molecular studies on soil microbial communities. The demands for specialized sample storage equipment, chemicals and standardized protocols for nucleic acid extraction often require sample processing in a home laboratory that can be continents apart from sampling sites. Standard sampling procedures, especially when dealing with RNA, comprise immediate snap freezing of soils in liquid nitrogen and storage at ?80°C until further processing. For these instances, organizing a reliable cooling chain to transport hundreds of soil samples between continents is very costly, if possible at all. In this study we tested the effect of soil sample preservation by freeze-drying with subsequent short-term storage at 4°C or ambient temperatures compared to ?80°C freezing by comparative barcoding analyses of soil microbial communities.
Methods Two grassland soil samples were collected in Central Germany in the Biodiversity Exploratory Hainich-Dün. Samples were freeze-dried or stored at ?80°C as controls. Freeze-dried samples were stored at 4°C or ambient temperature. Investigated storage times for both storage temperatures were 1 and 7 days. Total DNA and RNA were extracted and bacterial and arbuscular mycorrhizal (AM) fungal communities were analyzed by amplicon 454 pyrosequencing of the 16S (V4-V5 variable region) and 18S (NS31-AM1 fragment) of ribosomal RNA (rRNA) marker genes, respectively.
Important findings Bacterial communities were sufficiently well preserved at the rDNA and rRNA level although storage effects showed as slightly decreased alpha diversity indices for the prolonged storage of freeze-dried samples for 7 days. AM fungal communities could be studied without significant changes at the rDNA and rRNA level. Our results suggest that proper sampling design followed by immediate freeze-drying of soil samples enables short-term transportation of soil samples across continents.

Aims Growth rates of plants are driven by factors that influence the amount of resources captured and the efficiency of resource use. In trees, the amount of light captured and the efficiency of light use strongly depends on crown characteristics and leaf traits. Although theory predicts that both crown and leaf traits affect tree growth, few studies have yet to integrate these two types of traits to explain species-specific growth rates. Using 37 broad-leaved tree species of subtropical forests in SE China, we investigated how interspecific differences in wood volume growth rates were affected by crown and leaf traits. We tested the hypotheses that (i) larger crown dimensions promote growth rates, (ii) species-specific growth rates are positively related to leaf stomatal conductance, leaf water potential and leaf chemical components, and negatively related to leaf C/N and leaf toughness and (iii) the two sets of traits better explain growth rates in combination than either alone.
Methods Our study was conducted in a large-scale forest Biodiversity and Ecosystem Functioning experiment in China (BEF-China), located in a mountainous region in Jiangxi Province. We related 17 functional traits (two crown dimension and three crown structure traits; six physiological and six morphological leaf traits) to the mean annual growth rate of wood volume of young trees of the studied species. Interrelationships between crown and leaf traits were analyzed using principal component analysis. Simple linear regression analysis was used to test the effect of each trait separately. We used multiple regression analysis to establish the relationship of growth rate to each set of traits (crown traits, physiological and morphological leaf traits) and to the combination of all types of traits. The coefficients of determination (R 2 adj) of the best multiple regression models were compared to determine the relative explanatory power of crown and leaf traits and a combination of both.
Important findings The species-specific growth rates were not related to any of the single crown traits, but were related positively to leaf stomatal conductance and leaf water potential individually, and negatively to leaf toughness, with approximately 13% variance explained by each of the traits. Combinations of different crown traits did not significantly explain the species-specific growth rates, whereas combinations of either physiological or morphological leaf traits explained 24% and 31%, respectively. A combination of both crown and leaf traits explained 42% of variance in species-specific growth rates. We concluded that sets of traits related to carbon assimilation at the leaf-level and to overall amount of leaves exposed at the crown-level jointly explained species-specific growth rates better than either set of traits alone.

Aims Fine roots play an important role in the biogeochemical cycles of terrestrial ecosystems and are vital for understanding forest ecosystem functioning and services. Higher plant species diversity has been largely reported to increase aboveground community biomass, but how biodiversity affects fine-root production and the related mechanisms in forests remain unclear. In this study, we aim to answer two questions: (i) does fine-root production increase with tree species richness? (ii) Can this effect be explained by niche complementarity among species?
Methods We analyzed data from a large forest biodiversity experiment (BEF-China) with 5-year-old trees. Fine-root growth was measured as standing biomass and annual fine-root regrowth was estimated using ingrowth cores. Moreover, relative yield was calculated to test whether over- or under-yielding occurred when mixtures were compared with the average monoculture of the species included in the mixtures. We calculated functional diversity for fine-root (≤2mm in diameter) traits by Rao's quadratic entropy index for each species mixture. The effects of manipulated tree species richness and identity on fine-root traits were analyzed with linear mixed-effects models. Mixed models were also used to test the relationships between tree species richness and fine-root standing biomass, annual regrowth and vertical heterogeneity.
Important findings Fine roots of more than one species were found in half of the soil cores in mixtures indicating that belowground interactions in these young forest stands occurred much earlier than canopy closure. We found significant differences among species in fine-root traits such as diameter and specific root length (SRL), which suggested different resource-use strategies and niche partitioning among species. Mean fine-root diameter of species ranged from 0.31 to 0.74mm, mean SRL ranged from 12.43 m·g^-1 to 70.22 m·g^-1 and mean vertical distribution index β ranged from 0.68 to 0.93. There was a significant positive relationship between species richness and the evenness of the vertical distribution of fine-root standing biomass. Moreover, marginally significant positive relationships existed between species richness and standing biomass as well as annual regrowth of fine roots. Relative yields and Rao's quadratic entropy index were both not significantly affected by species richness. However, the relative yield of fine-root standing biomass was marginally correlated with Rao's quadratic entropy index, implying that belowground niche complementarity between species does contribute to diversity effects. In conclusion, our study showed positive effects of species richness on the filling of soil volume by fine roots in the studied experimental forest communities. This has positive effects on fine-root standing biomass and may also lead to increased aboveground biomass.

Aims Although the net biodiversity effect (NE) can be statistically partitioned into complementarity and selection effects (CE and SE), there are different underlying mechanisms that can cause a certain partitioning. Our objective was to assess the role of resource partitioning and species interactions as two important mechanisms that can bring about CEs by interspecific and intraspecific trait variation.
Methods We measured tree height of 2493 living individuals in 57 plots and specific root length (SRL) on first-order roots of 368 of these individuals across different species richness levels (1, 2, 4, 8 species) in a large-scale forest biodiversity and ecosystem functioning experiment in subtropical China (BEF-China) established in 2009. We describe the effects of resource partitioning between species by a fixed component of interspecific functional diversity (RaoQ) and further effects of species interactions by variable components of interspecific and intraspecific functional diversity (community weighted trait similarity and trait dissimilarity, CWS and CWD). Finally, we examined the relationships between biodiversity effects on stand-level tree height and functional diversity (RaoQ, CWS and CWD) in SRL using linear regression and assessed the relative importance of these three components of functional diversity in explaining the diversity effects.
Important findings Our results show that species richness significantly affected SRL in five and tree height in ten out of 16 species. A positive NE was generally brought about by a positive CE on stand-level tree height and related to high values of RaoQ and CWS in SRL. A positive CE was related to high values of all three components of root functional diversity (RaoQ, CWS and CWD). Our study suggests that both resource partitioning and species interactions are the underlying mechanisms of biodiversity effects on stand-level tree growth in subtropical forest.

Aims We studied the influence of tree species diversity on the dynamics of coarse wood decomposition in developing forest communities in a natural, topographically heterogeneous landscape. Using the litter bag technique, we investigated how and to which extent canopy tree species richness or the exclusion of mesoinvertebrates and macroinvertebrates affected wood decomposition in the light of natural variations in the microclimate. We compared the relative importance of the two aspects (experimental treatment versus microclimate) on wood decay rates using Schima superba as a standard litter.
Methods Coarse woody debris (CWD) was deposited in litter bags with two different mesh sizes in a total of 134 plots along a gradient of canopy tree species richness (0–24 species). Wood decomposition was assessed at two consecutive time points, one and three years after deposition in the field. Local climatic conditions were assessed throughout the duration of the experiment. Microclimatic conditions were assessed both, directly in the field as well as indirectly via correlations with local topography. We used analysis of variance based approaches to assess the relative importance of the treatments (community tree species richness and macro invertebrate exclusion) and microclimatic conditions on wood decay.
Important findings No direct influence of tree species richness on wood decay could be detected. However, the exclusion of macroinvertebrates significantly decreased wood decomposition rates. In addition, microclimatic conditions accounted for a substantial proportion of explained variance in the observed data. Here, wood decomposition was negatively affected by low mean temperatures and high variations in local humidity and temperature. However, tree species richness as well as the respective species composition affected the presence of termites within forest communities. These, in turn, significantly increased the decay of CWD. The strength of both, experimental treatment and microclimate increased with ongoing decomposition. We conclude that, while tree species richness per se has no direct influence on wood decomposition, its influence on the local arthropod decomposer community (especially the presence of termites) does have an effect.

Aims Although shrubs are an important component of forests, their role has not yet been considered in forest biodiversity experiments. In the biodiversity–ecosystem functioning (BEF) experiment with subtropical tree species in south-east China (BEF-China), we factorially combined tree with shrub species-diversity treatments. Here, we tested the hypotheses that shrub survival differs between the 10 planted shrub species, with lower survival rates of late- than early-successional species and is affected by environmental conditions, such as topography and top soil characteristics, as well as by biotic factors, represented by tree, shrub and herb layer characteristics.
Methods We analyzed the survival of 42 000 shrub individuals in 105 plots varying in tree and shrub species richness of the BEF-China project four years after planting. Shrub survival was analyzed with generalized linear mixed effects models at the level of individuals and with variance partitioning at the plot level. Random intercept and random slope models of different explanatory variables were compared with respect to the Bayesian Information Criterion (BIC).
Important findings Survival rates differed largely between the 10 shrub species, ranging from 26% to 91% for Ardisia crenata and Distylium buxifolium, respectively. Irrespective of species identity, single abiotic factors explained up to 5% of species survival, with a negative effect of altitude and slope inclination and a positive effect of the topsoil carbon to nitrogen ratio, which pointed to drought as the major cause of shrub mortality. In contrast, neither tree nor shrub richness affected shrub survival at this early stage of the experiment. Among the biotic predictors, only herb layer species richness and cover of the dominant fern species (Dicranopteris pedata) affected shrub survival. Overall, our models that included all variables could explain about 65% in shrub survival, with environmental variables being most influential, followed by shrub species identity, while tree species diversity (species richness and identity) and herb layer characteristics contributed much less. Thus, in this early stage of the experiment the biotic interactions among shrubs and between shrubs and trees have not yet overruled the impact of abiotic environmental factors.

Aims In forests, the herbaceous understory vegetation plays an important role for ecosystem functioning as it represents a significant component of total aboveground productivity. In addition, the herb layer contributes to overall forest species richness and controls tree species regeneration. Vice versa, trees in the overstory control understory herb and shrub growth through competition for resources. Using an experimental forest plantation with manipulated tree richness, we asked to which degree tree species richness and identity affect herb layer composition, richness and productivity and how these relationships across strata change with abiotic environmental conditions and competition intensity.
Methods In the context of the Biodiversity-Ecosystem Functioning project in subtropical China (BEF-China), we made use of the integrated BEFmod experiment arranged along a tree species richness gradient at two sites, with additional subplot treatments of phosphorus addition, herb layer weeding and no weeding. We recorded the understory vegetation and determined herb layer biomass production on a total of 201 subplots.
Important findings We found only minor effects of tree layer richness on herb layer species composition and no significant effect on herb layer richness or productivity yet. However, there were strong tree layer identity effects on all response variables, which were partly explained by differences in leaf area index and by a high share of woody species both in total herb layer species richness and biomass. There were strong treatment effects, which were largest in the 'no weeding' treatment but we did not find any treatment × tree layer richness interaction in herb layer responses. Thus, these effects are mainly explained by increased competition intensity within the herb layer in the absence of weeding. Despite the young age of the experiment, the interactions between tree species identity, tree richness and the herb layer did already emerge and can be expected to become stronger with ongoing runtime of the experiment.

Aims Genetic variation in plant traits represents the raw material for future adaptive evolution. Its extent can be estimated as heritability based on the performance of experimental plants of known relatedness, such as maternal half-sib seed families. While there is considerable heritability information for herbaceous plants and commercially important trees, little is known for woody species of natural subtropical forest. Moreover, it is open whether heritability is higher for species with r- or K-strategies, for more common species with larger distribution ranges than for rarer ones, or for populations closer to the centres of distributional ranges.
Methods For 14 woody species in Chinese subtropical forest, we collected 13–38 maternal seed families, assessed seed size, grew replicates of each seed family in one more and one less benign nursery environment and measured stem diameter and plant height after 7 months.
Important findings For the different species, plants grew 1.8–8.1 times taller in the more benign environment. For all 14 species, variation between seed families (and thus heritability) was significant (with very few exceptions at the P < 0.001 level) for seed size and for stem diameter and plant height in both nurseries. Moreover, significant seed family by nursery interactions for stem diameter and plant height for all species (P < 0.001) indicated significant heritability for plasticity in these traits. Multiple regression analysis suggests that heritabilities were higher for species with higher age at reproduction and higher wood density (traits indicating a K strategy) but also for species with higher specific leaf area (a trait rather indicating an r strategy). Furthermore, heritabilities were higher for species with larger range sizes, while there was no significant relationship between heritabilities and the distance of the study area to the range margins of our study species. In conclusion, the detected large heritability estimates suggest considerable potential for the evolution of plant performance and its plasticity for trees of subtropical forest. Moreover, our study shows that the simple method of comparing plants of different maternal seed families is valuable to address evolutionary ecological questions for so far understudied species.

Aims Litter decomposition is a fundamental process within ecosystem functioning, and it is largely dependent on the biodiversity of ecosystems. We explored the effects of species diversity and genetic diversity of litter on the litter decomposition rate.
Methods We used laboratory microcosms to determine whether species diversity and genetic diversity and their interaction affect leaf litter decomposition. We set up 8 treatments containing 1, 2, 4 diversity levels of four broad-leaf species (Alniphyllum fortunei, Idesia polycarpa, Cinnamomum camphora and Daphniphyllum oldhamii) both in species and genetic sense. Totally 246 microcosms containing same amount of soil and litter of prescribed diversity treatment were stored in the dark at 25°C for 12 weeks.
Important findings The effect of litter species diversity on litter decomposition was largely dependent on species composition of the litter mixture in terms of species identity. Overall, the decomposition rate increased linearly with the richness of seed family when the species identity was disregarded. However, no interactive effect of species diversity and genetic diversity on mass loss was detected. The litter decomposition rate was found to be unrelated to the initial carbon (C), whereas it was negatively correlated with the initial total nitrogen (N) and N:P ratio. However, the regression curves of the litter decomposition rate against the total P and C:N ratio displayed quadratic parabolas opening upward and downward, respectively. This study demonstrated how species and/or genetic diversity and the stoichiometry of litter per se affect litter decomposition. Further studies should be performed in the long term to ascertain how such effects operate and how they change during the decomposition process, particularly in response to varying composition and diversity of standing plants in the environments.

Aims Positive plant diversity–ecosystem function relations are ultimately driven by variation in functional traits among individuals that form a community. To date, research has largely focused on the role of species diversity for ecosystem functioning. However, substantial intraspecific trait variation is common and a significant part of this variation caused by genetic differences among individuals. Here, we studied the relative importance of species diversity and seed family (SF) diversity within species for growth and herbivory in experimental subtropical tree assemblages.
Methods In 2010, we set up a field experiment in subtropical China, using four species from the local species pool. Trees were raised from seeds, with seeds from the same mother tree forming an SF. We established 23 plots containing one or four species (species diversity treatment) and one or four SFs per species (SF diversity treatment). Tree growth (stem diameter, plant height and crown expansion) and herbivory (percentage leaf loss due to leaf chewers) were monitored annually from 2011 to 2013.
Important findings Tree species richness promoted growth but had no effect on herbivory. In contrast, SF diversity reduced growth and increased herbivory but only so in species mixtures. Most of the observed effects were time dependent, with the largest effect found in 2013. Our results suggest that biodiversity can affect plant performance directly via tree species–species interactions, or context dependent, via potential effects on inter-trophic interactions. Two important conclusions should be drawn from our findings. Firstly, in future studies regarding biodiversity and ecosystem functioning (BEF) relationships, intraspecific genetic diversity should be given similar weight as species diversity as it has often been neglected and its effects are not well understood. Secondly, we demonstrate opposite effects of biodiversity among and within species, stressing the importance to consider the effects of multiple levels of biodiversity simultaneously.

Aims Changing biodiversity can affect ecosystem functioning. However, the role of genetic diversity within species, relative to the one of species diversity, has hardly been addressed.
Methods To address the effects of both genetic diversity and species diversity during the important stage of early tree life, we used eight seed families (SF) taken from each of 12 evergreen and deciduous tree species of subtropical forest to perform a factorial experiment. We established 264 communities of 16 trees each. Each community had a species diversity of either one or four species and a genetic diversity of either one, two or four SF per species. We measured plant survival, growth rate, final biomass and herbivory 20 months after sowing.
Important findings Species differed from each other in biomass, growth rate, herbivory and survival (P < 0.001). Deciduous species tended to have much higher biomass (P < 0.1) and experienced higher herbivory (P < 0.05) than evergreen species. Species diversity affected the performance of different species differently (species diversity by species interaction, P <0.001 for all variables but survival). Biomass differed between SF and increasing genetic diversity from one to two, and from two to four, SF per species increased biomass for some species and decreased it for others (P < 0.001). Our study showed pronounced species–specific responses of early tree performance to species diversity and less pronounced responses to genetic diversity. These species–specific responses suggest feedbacks of species diversity and genetic diversity on future species composition.

Aims To quantify the seasonal differences in effects of leaf habit, species identity, initial diameter, neighborhood interaction and stand environment on tree absolute diameter growth rates in a subtropical forest in China.
Methods We used man-made dendrometer bands to record radial increments of all trees with diameter at breast height (DBH) ≥5cm and height ≥3 m within 25 comparative study plots (30×30 m for each) of the 'Biodiversity–Ecosystem Functioning Experiment China' (BEF-China) in the Gutianshan National Nature Reserve, Zhejiang Province, China. We measured stem circumferences twice a year from 2011 to 2014 to calculate absolute diameter growth rate of a warm and wet season (WWS, April to September) and a dry and cold season (DCS, October to the next March) for each individual tree: annual growth (GR year), growth during the WWS (GR WWS) and growth during the DCS (GR DCS). We firstly tested the differences in growth rates between different seasons using paired t -tests with Bonferroni correction. Then we applied linear mixed models to explore the effects of leaf habit, species identity, initial diameter, neighborhood interaction (indicated by richness, density and total basal area of all neighboring trees within a radius of 5 m around target trees), stand age and topography (elevation, slope and aspect) on tree growth rates of the two different seasons in three deciduous and 14 evergreen species.
Important findings GR year, GR WWS and GR DCS varied between 0.04–0.50cm year^-1 (mean = 0.21), 0.03–0.46cm season^-1 (mean = 0.18) and 0.01–0.05cm season^-1 (mean = 0.03) across the 17 species, respectively. GR WWS was significantly higher than GR DCS for all species. Growth rates of faster growing species tended to have larger absolute differences between the WWS and DCS. Tree growth rates of both seasons and of the year (GR year, GR WWS and GR DCS) varied significantly among leaf habit and species, and increased allometrically with initial diameter, decreased with stand age, but were not significantly related to topography and neighborhood richness or density. GR WWS decreased with neighborhood total basal area, while GR DCS did not. In conclusion, species might the temporally complementary, contributing to plot growth at different times of the year.

Aims Soil respiration (Rs) is a major process controlling soil carbon loss in forest ecosystems. However, the underlying mechanisms leading to variation in Rs along forest successional gradients are not well understood. In this study, we investigated the effects of biotic and abiotic factors on Rs along a forest successional gradient in southeast China.
Methods We selected 16 plots stratified by forest age, ranging from 20 to 120 years. In each plot, six shallow collars and six deep collars were permanently inserted into the soil. Shallow and deep collars were used to measure Rs and heterotrophic respiration (Rh), respectively. Autotrophic soil respiration (Ra) was estimated as the difference between Rs and Rh. Litter layer respiration (R L) was calculated by subtracting soil respiration measured in collars without leaf litter layer (R NL) from Rs. Rs was measured every 2 months, and soil temperature (ST) and soil volumetric water content (SVWC) were recorded every hour for 19 months. We calculated daily Rs using an exponential model dependent on ST. Daily Rs was summed to obtain cumulative annual Rs estimates. Structural equation modelling (SEM) was applied to identify the drivers of Rs during forest succession.
Important findings Rs showed significant differences among three successive stages, and it was the highest in the young stage. Ra was higher in the young stage than in the medium stage. Cumulative annual Rs and Ra peaked in the young and old stages, respectively. Cumulative annual Rh and respiration measured from soil organic matter (R SOM) decreased, whereas R L increased with forest age. The SEM revealed that cumulative annual Rs was influenced by fine root biomass and SVWC. Our results indicated that the dominant force regulating Rs on a seasonal scale is ST; however, on a successional scale, belowground carbon emerges as the dominant influential factor.

Aims Acorn weevils (Curculio spp.), endoparasitic granivorous insects, impede recruitment of fagaceous trees, and in turn affect community structure and ecosystem functioning. Previous studies have made considerable progress in elucidating local factors that contribute to seed predation by acorn weevils, but it is still not clear how habitat configurations interplay with local factors in influencing Curculio predation. In this study, we assessed the roles of crop size, landscape configurations (area and isolation) and their interactions on the predation rate of seeds by acorn weevils.
Methods We studied acorn weevils feeding on the seeds of Castanopsis sclerophylla (Fagaceae) on two peninsulas and nine islands with varying areas and isolation levels in the Thousand-island Lake in Chun'an County, Zhejiang Province of China. Overall, crop size was estimated for 130 trees and predation status was assessed for 26 207 seeds from these trees during two years. Generalized linear mixed models were performed to clarify how island area and isolation interplayed with crop size to determine predation rate on a single tree.
Important findings A negative relationship was detected between crop size and seed predation rate, indicating predator satiation at the tree level. This suggests that acorn weevils tend to stay sedentary once they have arrived at a suitable habitat. Habitat fragmentation had significant effects on seed predation such that predation rate was higher on larger, less isolated islands. Furthermore, the relationship between crop size and predation rate was significantly changed by both island area and isolation. This finding highlighted that the effects of habitat isolation might be overlooked relative to those of habitat loss.

Aims The aim of our research was to understand small-scale effects of topography and soil fertility on tree growth in a forest biodiversity and ecosystem functioning (BEF) experiment in subtropical SE China.
Methods Geomorphometric terrain analyses were carried out at a spatial resolution of 5×5 m. Soil samples of different depth increments and data on tree height were collected from a total of 566 plots (667 m 2 each). The soils were analyzed for carbon (soil organic carbon [SOC]), nitrogen, acidity, cation exchange capacity (CEC), exchangeable cations and base saturation as soil fertility attributes. All plots were classified into geomorphological units. Analyses of variance and linear regressions were applied to all terrain, soil fertility and tree growth attributes.
Important findings In general, young and shallow soils and relatively small differences in stable soil properties suggest that soil erosion has truncated the soils to a large extent over the whole area of the experiment. This explains the concurrently increasing CEC and SOC stocks downslope, in hollows and in valleys. However, colluvial, carbon-rich sediments are missing widely due to the convexity of the footslopes caused by uplift and removal of eroded sediments by adjacent waterways. The results showed that soil fertility is mainly influenced by topography. Monte–Carlo flow accumulation (MCCA), curvature, slope and aspect significantly affected soil fertility. Furthermore, soil fertility was affected by the different geomorphological positions on the experimental sites with ridge and spur positions showing lower exchangeable base cation contents, especially potassium (K), due to leaching. This geomorphological effect of soil fertility is most pronounced in the topsoil and decreases when considering the subsoil down to 50cm depth. Few soil fertility attributes affect tree height after 1–2 years of growth, among which C stocks proved to be most important while pH KCl and CEC only played minor roles. Nevertheless, soil acidity and a high proportion of Al on the exchange complex affected tree height even after only 1–2 years growth. Hence, our study showed that forest nutrition is coupled to a recycling of litter nutrients, and does not only depend on subsequent supply of nutrients from the mineral soil. Besides soil fertility, topography affected tree height. We found that especially MCCA as indicator of water availability affected tree growth at small-scale, as well as aspect. Overall, our synthesis on the interrelation between fertility, topography and tree growth in a subtropical forest ecosystem in SE China showed that topographic heterogeneity lead to ecological gradients across geomorphological positions. In this respect, small-scale soil–plant interactions in a young forest can serve as a driver for the future development of vegetation and biodiversity control on soil fertility. In addition, it shows that terrain attributes should be accounted for in ecological research.

Aims Most biodiversity–ecosystem functioning research has been carried out in grassland ecosystems, and little is known about whether forest ecosystems, in particular outside the temperate zone, respond similarly. Here, we tested whether productivity, assessed as leaf area index (LAI), increases with species richness in young experimental stands of subtropical trees, whether this response is similar for early-season leaf area (which is dominated by evergreens) and seasonal leaf area increase (which is dominated by deciduous species), and whether responses saturate at high species richness.
Methods We used a planted tree biodiversity experiment in south-east China to test our hypotheses. LAI was determined three times by digital hemispheric photography in 144 plots that had been planted with 400 trees each, forming communities with 1, 2, 4, 8 or 16 tree species.
Important findings LAI increased significantly with tree species richness in the fifth year of stand establishment. Similar, but weaker, statistically non-significant trends were observed 1 year before. We did not observe leaf area overyielding and the presence of particularly productive and unproductive species explained large amounts of variation in leaf area, suggesting that selection-type effects contributed substantially to the biodiversity effects we found in this early phase of stand establishment. Effects sizes were moderate to large and comparable in magnitude to the ones reported for grassland ecosystems. Subtropical (and tropical) forests harbor substantial parts of global net primary production and are critical for the Earth's carbon and hydrological cycle, and our results suggest that tree diversity critically supports these ecosystem services.

Soil microbial diversity has not been extensively observed due to technique limitations. With the development of the high-throughput sequencing technique and bioinformatics, much progress has been made in observations of microbial diversity. Currently, international microbiome initiatives have been founded (including the Earth Microbial Project). However, problems in these projects include a lack of dynamic observations, differences in observational methods, and data integration. The soil microbial observation network (SMON) is an important part of the Chinese Biodiversity Monitoring and Research Network (Sino BON). The observational network initially selected field observation sites in forest ecosystems along a temperature and precipitation gradient from south to north, in grassland ecosystems along a precipitation transect from east to west, and in typical wetland and agricultural ecosystems in China. Field ecological observation stations have been established in these selected ecosystems. Key tasks for the SMON are to observe spatial and temporal dynamics of soil microbial communities and functional genes in various ecosystems, including bacteria, archaea, fungi, and lichens. Observational data will be published periodically in the format of database, annals, and illustrated handbooks. Key methods used in the SMON are high- throughput sequencing, metagenomics, and bioinformatics. A soil biota database is currently being constructed to store observational data for public inquiry and analysis. Through the efforts of SMON, we plan to explore the driving mechanisms of spatial and temporal variations of soil microbial communities and their functional genes, and understand the relationships between microbial diversity and ecosystem function, in order to predict microbial dynamics under global environmental change scenarios, and to design strategies to protect soil microbial diversity and properly utilize microbial resources.

Increasing attention has recently been focused on the linkages between plant functional traits and ecosystem functioning. A comprehensive understanding of these linkages can facilitate to address the ecological consequences of plant species loss induced by human activities and climate change, and provide theoretical support for ecological restoration and ecosystem management. In recent twenty years, the evidence of strong correlations between plant functional traits and changes in ecosystem processes is growing. More importantly, ecosystem functioning can be predicted more precisely, using plant functional trait diversity (i.e., functional diversity) than species diversity. In this paper, we first defined plant functional traits and their important roles in determining ecosystem processes. Then, we review recent advances in the relationships between ecosystem functions and plant functional traits and their diversity. Finally, we propose several important future research directions, including (1) exploration of the relationships between aboveground and belowground plant traits and their roles in determining ecosystem functioning, (2) incorporation of the impacts of consumer and global environmental change into the correlation between plant functional traits and ecosystem functioning, (3) effects of functional diversity on ecosystem multifunctionality, and (4) examination of the functional diversity-ecosystem functioning relationship at different temporal and spatial scales.

The expansion of Phyllostachys edulis into the adjacent secondary evergreen broad-leaved forest (EBF) is obvious and greatly affects its ecological function. Little research has examined its effects on community structure and biodiversity. We comparatively analyzed the characteristics of species composition, community structure and diversity before and after the expansion of P. edulis forest (PEF), P. edulis-broad-leaved mixed forest (PBMF) and EBF along a gradient of P. edulis expansion in the Jinggangshan National Nature Reserve in Jiangxi Province using a space for time substitution method. Results indicated that: (1) The Bray-Curtis similarity index values of the tree layer, shrub layer and herb layer between PEF and EBF were 0.003, 0.046 and 0.030, respectively. (2) The PEF vertical structure showed a “>” type and the abundance percentage was 33.3% in 12-14 m interval, its diameter at breast height (DBH) class structure concentrated distribution in 5-10 cm interval, whose percentage was as high as 90.0%; while the EBF vertical structure showed a “L” type and the abundance percentages was 54.3% in 2-4 m interval, its DBH class distribution range was relatively wide, the average percentage of four larger diameter grades was 10.3%. (3) The Shannon-Wiener index value in the tree layer declined from 2.56 in EBF to 0.06 in PEF, with a reduction of 98%. In the shrub layer, the index value dropped from 2.58 to 2.03, declining 21%. We suggest that the expansion of P. edulis simplified the community composition and structure of the secondary evergreen broad-leaved forest and reduced species diversity, which can cause adverse impacts on forest ecosystem functioning.

The relationship between biodiversity and ecosystem multifunctionality (BEMF) is a hot issue in current ecological studies. The measurement of ecosystem multifunctionality (EMF) is a crucial aspect of BEMF research; however, the metrics of EMF have been inconsistent among previous studies. We reviewed seven approaches of quantifying EMF (single function approach, turnover approach, averaging approach, single threshold approach, multiple thresholds approach, orthologous approach and multivariate model approach) and classified the related studies based on the metrics of EMF used. We illustrated the multiple-threshold approach with published data from our previous work to help researchers better understand the approach. The inconsistent use of EMF metrics made it difficult to compare different studies, which constrains further development of BEMF research. Hence, there is an urgent need to develop a general approach to measuring multifunctionality appropriately.

As global biodiversity losses accelerate, there is increasing evidence shows that there may be negative impacts on ecosystem functioning, such as declines in plant primary productivity and imbalances in nutrient cycling. Thus, it is critical to understand the relationship between biodiversity and ecosystem functioning (BEF). However, ecosystems can provide multiple functions simultaneously (ecosystem multifunctionality, EMF). Since 2007, the quantification of relationships between biodiversity and ecosystem multifunctionality (BEMF) has generated additional questions and controversies, such as the lack of consensus in appropriate multifunctionality indices and uncertain trade-offs among ecosystem functions. In this review, we briefly summarize the history of BEMF studies and the methods of EMF quantification, then outline the mechanisms of EMF maintenance and current research progress. We emphasize the importance of optimizing EMF quantifications and investigating the relationship between different dimensions of biodiversity and EMF. We also provide suggestions and directions for future research on BEMF.

Aims Species diversity and genetic diversity may be affected in parallel by similar environmental drivers. However, genetic diversity may also be affected independently by habitat characteristics. We aim at disentangling relationships between genetic diversity, species diversity and habitat characteristics of woody species in subtropical forest.
Methods We studied 11 dominant tree and shrub species in 27 plots in Gutianshan, China, and assessed their genetic diversity (A r) and population differentiation (F ′ ST) with microsatellite markers. We tested if A r and population specific F ′ ST were correlated to local species diversity and plot characteristics. Multi-model inference and model averaging were used to determine the relative importance of each predictor. Additionally, we tested for isolation-by-distance (IBD) and isolation-by-elevation by regressing pairwise F ′ ST against pairwise spatial and elevational distances.
Important findings Genetic diversity was not related to species diversity for any of the study species. Thus, our results do not support joint effects of habitat characteristics on these two levels of biodiversity. Instead, genetic diversity in two understory shrubs, Rhododendron simsii and Vaccinium carlesii, was affected by plot age with decreasing genetic diversity in successionally older plots. Population differentiation increased with plot age in R. simsii and Lithocarpus glaber. This shows that succession can reduce genetic diversity within, and increase genetic diversity between populations. Furthermore, we found four cases of IBD and two cases of isolation-by-elevation. The former indicates inefficient pollen and seed dispersal by animals whereas the latter might be due to phenological asynchronies. These patterns indicate that succession can affect genetic diversity without parallel effects on species diversity and that gene flow in a continuous subtropical forest can be restricted even at a local scale.

Long term series of remotely sensed imagery of net primary production (NPP) data could reflect ecosystem health. In this study, we employed NPP to evaluate the effects of ecological engineering (nature reserve and new ecological engineering in 2004 or 2005 techniques) by the sampling area comparison method in the Chang Tang and Sanjiangyuan national nature reserves on the Tibetan Plateau. The results showed that: (1) among the 10 pairs of sampling areas, annual NPP of 9 pairs tended to increase between 1982 and 2009; (2) the new ecological engineering techniques improved the effectiveness of ecosystem conservation, with NPP in 8 pairs of sampling areas increasing faster than before; and (3) among all alpine grassland types, the new ecological engineering techniques remarkably improved the effectiveness of conserving the meadows.

Aims Plants with extrafloral nectaries (EFNs) are common in tropical and subtropical habitats and, despite many other arthropods also forage for EFN, most studies solely focused on the defense mutualisms between EFN plants and ants. This study aims at a quantitative assessment of the entire arthropod community that visits EFN trees to compare visitor communities between different tree species to disentangle the mechanisms that may drive EFN visitor community composition. We also test for tree diversity effects on EFN visitors, as it is unknown if local tree species richness relates to the abundance and species richness of arthropods foraging for EFN.
Methods We sampled EFN-visiting arthropods in the experimental tree species richness gradient of the BEF-China Experiment, the currently largest forest diversity experiment in the world, and tested if tree species richness affects EFN visitors and if visitor community composition differs between EFN tree species. In a second step, we analyzed the EFN of Ailanthus altissima and Triadica cochinchinensis, the two EFN tree species with highest visitor abundance, for sugars and amino acids (AA) to test if tree species-specific differences in nectar chemistry translate to differing visitor communities. Lastly, we conducted a choice experiment using different artificial nectar solutions to test if nectar quality affects foraging decisions of ants, the most frequent EFN visitors in our study sites.
Important findings EFN trees in young successional forests in subtropical South-East China are visited by a diverse assemblage of arthropods including ants, beetles, flies, and spiders. Albeit ants accounted for about 75% of all individuals, non-ant visitors were by far more species rich. Visitor abundance and species richness declined with increasing tree species richness, suggesting a resource dilution effect, because plots with more tree species had proportionally less EFN tree individuals and thus lower nectar availability. Ailanthus altissima and T. cochinchinensis were visited by different arthropods and their nectar had species-specific AA composition and sugar concentration, indicating that differences in visitors may, at least partly, be explained by differences in nectar chemistry. These findings are supported by the choice experiment, in which artificial nectars containing sugar solutions supplemented with essential AAs attracted more ants than pure sugar solutions or sugar solutions supplemented with non-essential AAs. Our results improve the understanding of the complex ecology of EFN trees, a plant life form that might be crucial for understanding how tree diversity influences patterns of tree growth in young successional tropical and subtropical forests.