TY - GEN A1 - Wei, Yuqi A1 - Wei, Bin A1 - Ryo, Masahiro A1 - Bi, Yixian A1 - Sun, Xiangyun A1 - Zhang, Yingjun A1 - Liu, Nan T1 - Grazing facilitates litter-derived soil organic carbon formation in grasslands by fostering microbial involvement through microenvironment modification T2 - CATENA N2 - Grasslands store 10–30 % of the global soil organic carbon (SOC) and have the potential to mitigate the increase in atmospheric CO2 concentrations. Grazing plays a crucial role in regulating SOC storage in grassland ecosystems. However, the mechanistic understanding of how grazing influences the SOC dynamic still needs to be improved. We investigated how grazing-induced microenvironment changes influence the microbial assimilation of plant litter C and SOC formation from decomposed litter C in a multi-year field experiment, where grazing was simulated with mowing, dung and urine return, and trampling. We incubated 13C labeled litter in PVC collars to trace the microbial assimilation of litter C and the fate of litter C in the SOC after decomposition. While the grazing treatments changed soil properties marginally, mowing decreased above-ground plant biomass, litter mass, plant height, and plant cover (−12 % to −79 %). Accordingly, mowing treatment increased the exposure of litter to UV radiation (+38 %) and therefore facilitated the microbial assimilation of litter C (+20 %) and the SOC formation (+15 %). Trampling treatment promoted the transformation of litter C to SOC pools by mixing litter and soil (+34 %). Dung and urea return treatment did not affect SOC formation due to a marginal change in available nitrogen. Collectively, our results suggest that grazing facilitates litter-derived SOC formation by regulating microbial involvement through changes in the microenvironment. Our study indicates that grazing promotes SOC formation from plant litter, which maintains SOC storage in grasslands. Accurate quantification of the contribution of plant C input to SOC pools in different grasslands under various utilization is the next step to better predict SOC dynamics. KW - 13C-stable isotope KW - Grazing KW - Microenvironment KW - PLFA-SIP KW - Soil microbial assimilation KW - Soil organic carbon (SOC) formation Y1 - 2023 U6 - https://doi.org/10.1016/j.catena.2023.107389 SN - 0341-8162 VL - 232 PB - Elsevier BV ER - TY - GEN A1 - Guo, Tongtian A1 - Guo, Meiqi A1 - Pang, Yue A1 - Sun, Xiangyun A1 - Ryo, Masahiro A1 - Liu, Nan A1 - Zhang, Yingjun T1 - Ungulate herbivores promote beta diversity and drive stochastic plant community assembly by selective defoliation and trampling: From a four‐year simulation experiment T2 - Journal of Ecology N2 - 1. Ungulate herbivores shape grassland plant communities at multiple scales, ultimately affecting ecosystem function. However, ungulates have complex effects on grasslands, including defoliation, trampling, excreta return and their interactions. Moreover, the effects of ungulate density on grasslands are regulated by these three mechanisms. Nevertheless, how these three mechanisms affect biodiversity at multiple scales and community assembly remains poorly understood. 2. Here, we conducted a 4‐year novel field experiment to disentangle the effects of defoliation, trampling, and excreta return by ungulates on plant community assembly in a temperate grassland in Inner Mongolia, China. This experiment set two different scenarios: moderate ungulate density (Moderate, characterised by selective defoliation and moderate trampling) and high ungulate density (Intense, characterised by non‐selective defoliation and heavy trampling), including different combinations of defoliation, trampling and excreta return in each scenario. 3. We found that defoliation and trampling increased stochasticity in community assembly and promoted alpha and beta diversity under both scenarios. Specifically, defoliation promoted the coexistence of species with multiple resource acquisition strategies (higher functional trait diversity) by reducing interspecific competition; trampling tended to facilitate random species colonisation. Conversely, excreta return favoured grasses, promoting deterministic assembly and impacting species coexistence. Notably, selective defoliation in the Moderate scenario led to a dominance of stochastic processes during community assembly, whereas non‐selective defoliation still did not change the dominance of deterministic processes. Further, communities subject to selective defoliation were insensitive to changes in soil properties caused by trampling and excreta return, maintaining a high‐level beta diversity and the stochastic of community assembly. 4. Synthesis: Our study provides important insights into the mechanisms by which ungulate herbivores influence plant community assembly, suggesting that defoliation and trampling have the potential to drive stochastic processes, while excreta return plays the opposite role. Our study also suggests that selective foraging by ungulates acts as stronger stochastic forces during community assembly compared to non‐selective defoliation. These results imply that considering ungulate feeding preferences and foraging behaviour in grassland management will help prevent biodiversity loss and biotic homogenisation. KW - ungulate herbivores KW - community assembly KW - selective defoliation KW - trampling KW - excreta return KW - grassland KW - stochastic and deterministic processes KW - plant–herbivore interactions Y1 - 2024 U6 - https://doi.org/10.1111/1365-2745.14370 SN - 0022-0477 VL - 112 IS - 9 SP - 1992 EP - 2006 PB - Wiley ER - TY - GEN A1 - Guo, Tongtian A1 - Guo, Meiqi A1 - Ryo, Masahiro A1 - Rillig, Matthias C. A1 - Liu, Nan A1 - Zhang, Yingjun T1 - Ungulate herbivory affects grassland soil biota β‐diversity and community assembly via modifying soil properties and plant root traits T2 - New phytologist : international journal of plant science N2 - Summary Ungulate herbivory, a widespread and complex disturbance, shapes grassland biodiversity and functions primarily through three mechanisms: defoliation, trampling, and excreta return. However, the specific effects of these mechanisms on soil biodiversity and community assembly remain unclear. We conducted a 4‐yr factorial experiment in the Eurasian steppe to investigate how defoliation, trampling, and excreta return influence soil bacterial, fungal, and nematode β‐diversity and community assembly under moderate‐ and high‐density ungulate grazing scenarios. Our findings reveal that herbivores affect soil biota through multiple pathways at different grazing intensities. Specifically, selective defoliation in the moderate‐density scenario promoted stochastic community assembly of nematodes and fungi by increasing the specific root length of plant communities. Excreta return encouraged stochastic bacterial communities by carbon input, while urine‐induced acidification and elevated ammonium levels promoted environmental filtering of bacteria and nematodes. In the high‐density scenario, non‐selective defoliation and heavy trampling created harsher soil conditions, reducing bacterial and nematode β‐diversity via habitat filtering and diminishing association of soil biota with plant roots. This study explored how different components of ungulate behaviour influence soil community assembly and highlighted the crucial role of root traits in mediating soil biota responses, providing insights into the mechanisms of soil biodiversity maintenance under complex disturbances. KW - Aboveground–belowground interactions KW - Community assembly KW - Grassland KW - Root traits KW - Soil microbe KW - Soil nematodes KW - Ungulate herbivory KW - β-diversity Y1 - 2025 U6 - https://doi.org/10.1111/nph.70199 SN - 0028-646X VL - 247 IS - 1 SP - 281 EP - 294 PB - Wiley CY - Oxford ER -