Cancan Zhao

Thinning, as a critical forest management practice, has multidimensional impacts on forest ecosystem environments. Soil nematode communities, which serve as sensitive bioindicators of ecosystem health, can effectively reflect the effects of different thinning intensities on forest ecosystems. Based on a long‐term thinning experiment with varying intensities in a Pinus taiwanensis plantation, this study examines how thinning influences the structure and function of soil nematode communities. The results showed that the total abundance of soil nematodes changed significantly across varying intensities of thinning ( p < 0.05). Different trophic groups exhibited distinct responses: bacterivorous nematodes achieved the highest relative abundance under light thinning (10% removal), plant‐parasitic nematodes showed no significant change in relative abundance, while fungivorous and omnivorous‐predatory nematodes were significantly enriched under moderate thinning (20% removal). The synergistic changes in the latter two groups reflected trophic cascading effects. Moderate thinning significantly enhanced nematode diversity indices (Shannon‐Wiener index, evenness index), increased the proportion of K‐strategists, and strengthened the bacterial decomposition channel. These changes are attributed to moderate thinning better optimizing soil nutrient regimes and alleviating competitive exclusion through more rational allocation of food resources. Therefore, moderate thinning helps improve the structure of soil nematode communities and increases the complexity of belowground food webs. These changes further indicate improved ecosystem stability and support the healthy development of belowground ecosystems.

Litter and understory are key components of forest ecosystems, playing vital roles in soil carbon inputs and microhabitat regulation. Their removal is a common forest management practice: litter removal (L) reduces fire and pest risks while promoting nutrient cycling, whereas understory removal (U) alleviates nutrient competition between understory plants and trees. However, the combined effects and underlying mechanisms of litter removal (L) and understory removal (U) on soil nematode communities remain unclear. This study investigated the individual and interactive effects of L and U on soil nematode communities in a coniferous–broadleaved mixed forest in a subtropical–warm temperate transition zone. The results showed that L significantly reduced soil nematode abundance by 18.1%, increased the relative abundance of bacterivores and omnivores-predators by 21.1% and 103.3%, respectively. U significantly elevated the relative abundance of fungivores by 30.8%, while both L and U reduced the relative abundance of plant-parasitic nematodes. Significant interactive effects between L and U were observed on soil nematode abundance, relative abundances of fungivores, plant-parasites, maturity index, and plant parasite index. Litter plus understory removal (LU) alleviated soil nematode resource limitation through synergistic regulation of resource pulses and microhabitat modification. Faunal analysis based on structure and enrichment indices indicated that LU enhanced food web structural complexity and resource-use efficiency. Redundancy analysis identified microbial biomass carbon, microbial biomass nitrogen, and soil total carbon as key drivers of nematode community differentiation. This study reveals the synergistic regulatory patterns of litter and understory vegetation on soil nematode communities, providing a theoretical reference for understanding the responses of soil nematodes to understory disturbance during the growing season in climate transitional forests, and offering basic data for long-term monitoring and forest soil management.

Soil microbial communities play a critical role in soil carbon dynamics. However, knowledge gaps exist regarding responses of heterotrophic respiration to compound climate drivers. We conducted a field manipulative experiment in a semiarid grassland of northern China, exploring the effects of precipitation addition, nitrogen addition, warming and their interplays on soil microbial community and metabolic function. Results obtained demonstrate that main effects of precipitation and nitrogen enhanced microbial respiration through increased microbial biomass and nitrogen availability, whereas warming showed no evident effect. Furthermore, precipitation and nitrogen acted synergistically to stimulate respiration, whereas nitrogen and warming exerted antagonistic effects. Microbial carbon use efficiency was positively influenced by both nitrogen and warming, with precipitation interactively modulating these individual effects. These results highlight the complex interactions among multiple climate change factors in regulating microbial carbon cycling. We predict that alterations in microbial metabolic functions in resource-limited temperate grasslands will modify soil carbon–climate feedbacks by regulating soil carbon fluxes.. The study advances understanding of climate change–carbon feedbacks through improved characterization of multi – factor interactions.

Microplastics persisting in soil can modify soil structure and nutrient status and alter biological activity, thereby influencing soil respiration. However, the mechanisms by which microplastics regulate soil respiration remain poorly understood. In this study, a field experiment was conducted in a winter wheat farmland to examine the effects of microplastic type (polypropylene and polyethylene) and particle size (13 and 500 μm) on soil respiration and to identify the associated driving factors. Soil respiration was significantly increased by microplastics, with a greater impact observed for 13 μm than for 500 μm microplastics. Microplastics increased root biomass and microbial biomass carbon, whereas they reduced aboveground biomass and soil available nitrogen content. Structural equation modeling indicated that the microplastic‐induced increment in soil respiration was primarily driven by root biomass. Microplastics stimulated root growth by changing soil physical structure, such as reducing bulk density, increasing soil porosity, and altering aggregate stability, thereby promoting soil respiration. Overall, this study highlights that microplastics can substantially alter belowground carbon dynamics by reshaping plant–soil–microbe interactions, and provides a scientific basis for evaluating the ecological consequences of microplastic pollution in agricultural soils.

Soil microorganisms play a crucial role in alpine grassland ecosystem as indicators of environmental change. Rest-grazing in spring has been shown to effectively curb grassland degradation, and while the effects on plants and soil have been widely studied, the response of soil microbial communities and the underlying driving factors remain unclear. In this study, two types of winter-spring pastures, steppe meadow (StM) and swamp meadow (SwM), were conducted for rest-grazing and grazing in spring, and vegetation community characteristics, soil properties and microbial community composition were measured to investigate the response of soil microbial communities to rest-grazing and its mechanisms. The results showed that rest-grazing in spring significantly increased above-ground biomass and soil organic carbon in alpine grasslands. In the steppe meadow, microbial groups were lower in the first year of rest-grazing compared to grazing but higher in the second year. In the swamp meadow, microbial groups and the ratio of Gram-positive to Gram-negative bacteria were higher under rest-grazing than under grazing. Stress indices in both grassland types were lower under rest-grazing than under grazing. Fungi showed an increasing trend with above-ground biomass (P < 0.05), while total PLFAs, bacteria, and actinomycetes increased with below-ground biomass (P < 0.05). Variance partitioning analysis (VPA) revealed that the combination of soil and vegetation properties explained 40.87% of the variation in the soil microbial community. Redundancy analysis (RDA) indicated that species diversity (Simpson index), vegetation coverage, soil total phosphorus, and bulk density were significant influencing factors, with species diversity explaining the largest proportion of variation (60%). In summary, rest-grazing in spring can beneficially affect the soil microbial community by improving plant diversity and restoring soil properties in alpine grasslands.

Soil respiration is an important pathway of carbon release from the terrestrial biosphere to the atmosphere, which plays a key role in ecosystem carbon cycling. However, the response and mechanism of soil respiration to nitrogen and phosphorus addition in legume plants are still unclear. Here, a pot experiment planted with soybean (Glycine max (L.) Merr.) was conducted to investigate the effects of nitrogen (N) and phosphorus (P) addition on soil respiration. Four treatments were designed: control, N addition, P addition, and both N and P addition. Soil respiration was measured twice a month from June to September in 2022. Our results showed that nutrient addition treatments presented significantly negative effects on soil respiration. In particular, nitrogen addition not only directly affected soil respiration, but also indirectly impacted soil respiration by altering soil nitrate nitrogen content. Elevated soil nitrate nitrogen content could inhibit soybean root nodule number and reduce biomass allocation to roots, thereby decreasing soil respiration. Furthermore, phosphorus addition and nitrogen-phosphorus co-addition strongly inhibited soybean nodulation by changing soil pH value, thus inhibiting soil respiration of soybean. The findings provide baseline information for optimizing nutrient management in legume crops.