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• Rare species exhibited higher functional richness and functional evenness; • Functional divergence has the greatest impact on ecosystem multifunctionality; • Rare species contribute more to ecosystem multifunctionality from a functional view. Global environmental change and increased human activities have led to rare species being given vulnerable status, as well as species losses and extinctions in recent years. However, most of the species in the community are rare species and they usually harbor unique functional traits that disproportionately contribute to community functional diversity. Numerous studies have also shown that functional diversity is a better predictor of ecosystem functioning than species diversity. Consequently, the evaluation of functional diversity of rare species and their contribution to ecosystem function is essential for the conservation of rare species. In this study, differences in functional diversity between rare and common plant species were analyzed based on functional diversity indices and species richness metrics in 30 1-ha plots comprising monsoonal evergreen broad-leaved forest in Pu'er City in the Yunnan Province of China. The roles of functional diversity of rare and common species in affecting ecosystem functions were also evaluated, in addition to the extent that either species group contributes to ecosystem functions or multifunctionality. The results indicated that functional diversity metrics including functional evenness and functional richness of rare species were higher than for common species in this subtropical forest. In addition, the functional diversity indices of rare species contributed greater to most ecosystem functions compared to those of common species. Moreover, the functional divergence of both rare and common species exerted obvious effects on ecosystem multifunctionality, although rare species exerted greater overall contributions. Rare species in the forest community of this study exhibited higher functional diversity and played a more important role in ecosystem multifunctionality via their diverse functional traits. Based on these results, it is necessary to focus greater conservation efforts on rare plants in a community. [ABSTRACT FROM AUTHOR]

The relationship between biodiversity and biomass is an essential element of the natural ecosystem functioning. Our research aims at assessing the effects of species richness on the aboveground biomass and the ecological driver of this relationship in a primary Pinus kesiya forest. We sampled 112 plots of the primary P. kesiya forests in Yunnan Province. The general linear model and the structural equation model were used to estimate relative effects of multivariate factors among aboveground biomass, species richness and the other explanatory variables, including climate moisture index, soil nutrient regime and stand age. We found a positive linear regression relationship between the species richness and aboveground biomass using ordinary least squares regressions. The species richness and soil nutrient regime had no direct significant effect on aboveground biomass. However, the climate moisture index and stand age had direct effects on aboveground biomass. The climate moisture index could be a better link to mediate the relationship between species richness and aboveground biomass. The species richness affected aboveground biomass which was mediated by the climate moisture index. Stand age had direct and indirect effects on aboveground biomass through the climate moisture index. Our results revealed that climate moisture index had a positive feedback in the relationship between species richness and aboveground biomass, which played an important role in a link between biodiversity maintenance and ecosystem functioning. Meanwhile, climate moisture index not only affected positively on aboveground biomass, but also indirectly through species richness. The information would be helpful in understanding the biodiversity-aboveground biomass relationship of a primary P. kesiya forest and for forest management. [ABSTRACT FROM AUTHOR]

• Species richness drove mainly ecosystem multifunctionality in a subtropical coniferous forest in southwest, China. • Stand structural complexity mediated relationship between species richness and ecosystem multifunctionality. • Total woody species abundance and dominant species abundance indicated little effect on shaping ecosystem multifunctionality. Forests can provide multiple ecosystem functions simultaneously that are related to biomass production, soil carbon stock, and nutrient cycling, and plant diversity is often important for the maintenance of ecosystem multifunctionality (EMF). However, the underlying mechanisms involved in regulating relationships between species richness and abundance and EMF in a subtropical coniferous forest still remain unclear. Using a randomization test and structural equation model, we show that multiple plant diversity attributes, stand structural complexity, dominant species, and soil conditions affect EMF from 94 plots in Pinus kesiya dominant stands in southwest China. Our results indicate that the direct effects of species richness on EMF were stronger than the effects of woody individual abundance, and species richness increased with increasing EMF. By contrast, EMF declined with increasing total woody species abundance, while functional diversity and dominant species abundance did not exhibit significant effects on EMF. However, Castanopsis echidnocarpa abundance indirectly increased EMF via species richness and total woody species abundance. Simultaneously, our findings suggest that stand structural complexity mediated the relationship between plant diversity and EMF, and species richness, total woody species abundance, and EMF increased strongly with increasing stand structural complexity. Higher soil pH and soil water content were associated with greater stand structural complexity and EMF, which were important drivers in explaining variation in EMF. Our results show that higher species richness promoted EMF provisioning, and provide critical insights to predicting the possible consequences of EMF with a change in biotic and abiotic factors. [ABSTRACT FROM AUTHOR]

• Woody species richness was the main driver in shaping EMF and function indices. • Fungal diversity played an important role in driving EMF depending on main functional guilds. • Phylogenetic diversity indicated significant positive effect on the water regulation. • Multiple biodiversity attributes and soil conditions determined the supply of multiple ecosystem functions. Various biodiversity attributes contribute to ecosystem multifunctionality (EMF) in different ways in terrestrial ecosystems. The relative influence of biodiversity and abiotic factors in driving EMF simultaneously remains relatively unclear. We evaluated the effects of woody species richness along with phylogenetic, functional, fungal, and bacterial diversity as well as abiotic factors on EMF. The analysis also included a review of function indices (including biomass production, water regulation, carbon stock, and nutrient cycling) along the elevation gradient in the Jinsha River valley, southwestern China, based on the bivariate relationship, random forest model, structural equation model (SEM), randomization tests, and redundancy analysis. The results showed that EMF increased with increases in woody species richness, phylogenetic diversity, elevation, and soil water content, while it decreased with increases in bacterial diversity and soil pH. The random forest model showed that elevation, soil pH, soil water content, and woody species richness made the main contribution to EMF and function indices. Further analysis using SEM confirmed these results. Indeed, woody species richness played a relatively important role in driving EMF, biomass production, carbon stock, and nutrient cycling compared to other diversity metrics. Dominant species contributed differently to the EMF and functions. However, phylogenetic diversity also appeared to have a positive effect on water regulation. Simultaneously, as a belowground trophic group, fungal diversity played a vital role in shaping EMF, biomass production, and nutrient cycling, which may be assigned to a change of arbuscular mycorrhizal fungi and ectomycorrhizal fungi along the elevation gradient. In addition, abiotic factors regulated the relationship between biodiversity and EMF. Elevation, soil water content, and soil pH appeared to have direct and indirect effects on the EMF and function indices. Woody species richness, fungal diversity, soil water content, soil pH, and elevation jointly mediated EMF in the Jinsha River valley, whereas woody species diversity was the main driver of EMF and other function indices following the complex environmental conditions. Our result should be useful for land managers involved in ecological restoration in the Jinsha River valley, where biodiversity and soil quality will determine the supply of multiple ecosystem functions. [ABSTRACT FROM AUTHOR]