Species richness and identity both determine the biomass of global reef fish communities

Changing biodiversity alters ecosystem functioning in nature, but the degree to which this relationship depends on the taxonomic identities rather than the number of species remains untested at broad scales. Here, we partition the effects of declining species richness and changing community composition on fish community biomass across >3000 coral and rocky reef sites globally. We find that high biodiversity is 5.7x more important in maximizing biomass than the remaining influence of other ecological and environmental factors. Differences in fish community biomass across space are equally driven by both reductions in the total number of species and the disproportionate loss of larger-than-average species, which is exacerbated at sites impacted by humans. Our results confirm that sustaining biomass and associated ecosystem functions requires protecting diversity, most importantly of multiple large-bodied species in areas subject to strong human influences.

Dynamics of Community Biomass and Soil Nutrients in the Process of Vegetation Succession of Abandoned Farmland in the Loess Plateau

The interaction between vegetation and soil is important for vegetation restoration and reconstruction during the succession of abandoned farmland. We chose four kinds of abandoned farmlands with the time of 1, 6, 12, and 22 years to experiment in the Loess Plateau. The community composition, community biomass, and soil nutrients of the four kinds of abandoned farmlands were studied by the method of temporal–spatial alternation, and the interaction effects among vegetation, biomass, soil nutrients, and abandonment time were analyzed. The results showed there were 33 species belonging to 13 families during the succession and 15 species of Gramineae and Compositae, accounting for 47% of the total community species. The succession trend of abandoned farmland was as follows: The vegetation was the weed community of Heteropappus altaicus + Artemisia capillaris in the beginning of the abandonment stage and became the weed community of Tragus racemosus + Enneapogon borealis after 6 years of abandonment. Then, Leymus secalinus became the dominant population in the community after 12 years of abandonment. When the succession lasted for 22 years, the vegetation became a common advantageous community of Stipa breviflora and Cleistogenes songorica. Soil moisture (SM) was positively correlated with soil nutrients and negatively correlated with abandonment time and community biomass. Soil organic matter (SOM), soil total nitrogen (STN), and alkali hydrolyzable nitrogen (AHN) were the highest in 0–10 cm soil layer, showing obvious surface accumulation. The three decreased with the soil layer, and there was a positive correlation among them. The abandonment time had a positive effect on the above-ground biomass (AGB) and below-ground biomass (BGB) and a negative effect on the SOM, STN, and AHN. The root/shoot ratio (R/S) was positively correlated with SOM and negatively correlated with abandonment time. With the progress of succession, the hierarchical differentiation of the community was gradually obvious, and the community structure begun to complicate. The community better adapted to the arid environment and toward the local top community succession.

The Biodiversity–Biomass Relationship of Aquatic Macrophytes Is Regulated by Water Depth: A Case Study of a Shallow Mesotrophic Lake in China

The relationship between biodiversity and productivity (or biomass production) (BPR) has been a popular topic in macroecology and debated for decades. However, this relationship is poorly understood in macrophyte communities, and the mechanism of the BPR pattern of the aquatic macrophyte community is not clear. We investigated 78 aquatic macrophyte communities in a shallow mesotrophic freshwater lake in the middle and lower reaches of the Yangtze River in China. We analyzed the relationship between biodiversity (species richness, diversity, and evenness indices) and community biomass, and the effects of water environments and interspecific interactions on biodiversity–biomass patterns. Unimodal patterns between community biomass and diversity indices instead of evenness indices are shown, and these indicate the importance of both the number and abundance of species when studying biodiversity–biomass patterns under mesotrophic conditions. These patterns were moderated by species identity biologically and water depth environmentally. However, water depth determined the distribution and growth of species with different life-forms as well as species identities through environmental filtering. These results demonstrate that water depth regulates the biodiversity–biomass pattern of the aquatic macrophyte community as a result of its effect on species identity and species distribution. Our study may provide useful information for conservation and restoration of macrophyte vegetation in shallow lakes through matching water depth and species or life-form combinations properly to reach high ecosystem functions and services.

Plant functional groups mediate effects of climate and soil factors on species richness and community biomass in grasslands of Mongolian Plateau

Aims Functional group composition of a plant community is mainly driven by environmental factors and is one of the main determinants of grassland biodiversity and productivity. Therefore, it is important to understand the role of plant functional groups (PFGs) in mediating the impact of environmental conditions on ecosystem functions and biodiversity. Methods We measured plant biomass and species richness (SR) of grasslands in 65 sites on the Mongolian Plateau and classified 157 perennial herbaceous plants into two main PFGs (namely grasses and forbs). Using the random forest model and ordinary least squares regression, we identified that environmental factors (i.e. aridity index, soil total nitrogen [STN] and pH) were significantly related to the SR and aboveground biomass (AGB) of PFGs. We then used structural equation modeling to explore the relationship between the identified environmental factors and community SR and biomass, and the role of PFGs in driving this relationship. Important Findings We found that aridity index had unimodal relationships with both AGB and SR of the PFGs and the whole community. All SR and biomass metrics were significantly related to STN and pH. The relationship between aridity index and community biomass was mediated by an increase in the AGB of grasses. The influence of STN and pH on community SR was mainly due to their regulation in the SR of forbs. Our results indicate that community composition and the identity of the PFGs play a key role in linking environmental factors to ecosystem functioning.