Zhongqiang Li

Biogenic volatile organic compounds (BVOCs) emitted by aquatic primary producers play an important role in carbon exchange processes and regional atmospheric chemistry, yet BVOCs production from submerged macrophytes remains poorly understood. In this study, we investigated the effects of growth period and light intensity on BVOCs production in the submerged macrophyte V. natans using a controlled experiment with three light treatments. The results showed that significant interactions between growth period and light intensity were observed for multiple BVOCs. The contents of most individual compounds decreased from the seedling stage to the mature stage and increased again during senescence. Light intensity significantly affected the production of several key BVOCs, including 2‐pentylfuran, phenylacetaldehyde, trans‐2, cis‐6‐nonadienal, and β‐ionone, with effects strongly dependent on growth period. Moderate shading promoted the production of 2‐pentylfuran and phenylacetaldehyde, whereas severe shading resulted in higher trans‐2, cis‐6‐nonadienal and β‐ionone concentrations. Overall, BVOCs production in submerged macrophytes is jointly regulated by plant growth cycles and underwater light intensities and cannot be reliably predicted based on a single factor, underscoring the importance of incorporating biological development and light‐driven variability into assessments of BVOCs emissions from freshwater ecosystems and their links to carbon cycling and atmospheric processes.

Understanding the link between biodiversity and ecosystem functioning is imperative for ecosystem-based management. The role of multitrophic diversity in sustaining multifunctionality remains unclear, especially in highly diverse aquatic ecosystems. We performed a species-addition experiment consisting of one, two, three, and five species in simulated multitrophic ecosystems to evaluate biodiversity and ecosystem functioning relationships within and across trophic levels. Our results showed that there are positive species richness–productivity relationships within and across trophic levels. We found significant negative correlations between species richness and the cumulative variation of total phosphorus, and between species richness and ecosystem multifunctionality across trophic levels. Also, we found that the relationships between ecosystem multifunctionality and species richness within and across the trophic levels are mediated by a combination of environmental factors, including water temperature, dissolved oxygen, pH, irradiance, and time, rather than by species richness. Our results imply that species richness–ecosystem functioning relationships vary for different ecological functions; the individual ecosystem functions selected and the way multifunctionality calculated are critical when examining links between biodiversity and ecosystem multifunctionality. Our study highlights that multitrophic richness, such as for consumers, is crucial for driving ecosystem multifunctionality. Furthermore, our study implies that management practices for restoring the diversity of aquatic macrophytes in wetlands should consider not only macrophyte richness but also different functional groups and life-forms.

Forest restoration and soil structure stabilization are the focus of forestry and ecology. However, the combined mechanisms of soil microorganisms and organic and inorganic aggregate binding agents on soil aggregation is unclear. In order to explore the effects of subtropical forest restoration types on soil aggregates and the underlying mechanisms, we collected soil samples from subtropical natural forests and coniferous and broad-leaved plantations that are commonly used for forest restoration. The mean weight diameter (MWD) of the soil aggregate was used to indicate the aggregates’ stability. The soil microbial diversity and structure, the organic and inorganic aggregate binding agents including the mycorrhizal density, the glomalin-related soil protein and the Fe and Al oxides were investigated. Results showed that the Shannon and Simpson indices of soil microbial communities in the coniferous plantations were both significantly higher than those in the natural forests. At the annual level, compared with the natural forests, the plantations decreased the proportion of 0.25–1 mm aggregates while the MWD significantly increased. The forest type also significantly affected the mycorrhizal density, the easily extractable glomalin-related soil proteins (EEG) and the Fe oxide. A variance decomposition analysis showed that soil microbial communities, organic and inorganic binding agents, and their interactions together contributed to the aggregates’ composition and stability by 75.07%. The MWD was positively correlated with the microbial diversity, mycorrhizal density and Fe oxide. We therefore suggest that the combined effects of the soil microbial communities and the organic (mycorrhizal density) and inorganic binding agents (Fe oxide) can be the main mechanisms of soil aggregation in the study area, resulting in a higher soil aggregate stability in the subtropical coniferous plantation than in the natural forest.