@misc{WeiWeiRyoetal., author = {Wei, Yuqi and Wei, Bin and Ryo, Masahiro and Bi, Yixian and Sun, Xiangyun and Zhang, Yingjun and Liu, Nan}, title = {Grazing facilitates litter-derived soil organic carbon formation in grasslands by fostering microbial involvement through microenvironment modification}, series = {CATENA}, volume = {232}, journal = {CATENA}, publisher = {Elsevier BV}, issn = {0341-8162}, doi = {10.1016/j.catena.2023.107389}, pages = {9}, abstract = {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.}, language = {en} } @misc{GuoGuoPangetal., author = {Guo, Tongtian and Guo, Meiqi and Pang, Yue and Sun, Xiangyun and Ryo, Masahiro and Liu, Nan and Zhang, Yingjun}, title = {Ungulate herbivores promote beta diversity and drive stochastic plant community assembly by selective defoliation and trampling: From a four-year simulation experiment}, series = {Journal of Ecology}, volume = {112}, journal = {Journal of Ecology}, number = {9}, publisher = {Wiley}, issn = {0022-0477}, doi = {10.1111/1365-2745.14370}, pages = {1992 -- 2006}, abstract = {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.}, language = {en} }