Changes in ecosystem carbon stocks following grazing exclusion in arid and semiarid grasslands

Grazing exclusion (GE) is widely considered to be an important strategy for restoring overgrazed grasslands and promoting carbon (C) storage. However, the changes in the components of ecosystem C with GE and their related drivers remain largely unexplored. Here, we investigated the effects of GE on the ecosystem C components (plant and soil C) and their key driving factors through sampling inside and outside 15 grazing exclosures across the Inner Mongolia arid and semiarid grasslands in northern China. Our results showed that, except for dead root C, GE significantly promoted plant C stocks. The increase in AGB and litter C stocks resulted from the accumulation of both biomass and C concentration, while the increase in live root C stock was mainly attributed to biomass accumulation. In contrast, although the topsoil soil C concentration (0-20 cm) showed a marginal increase following GE, its bulk density greatly declined, which resulted in little change in the soil C stocks. Overa...禁牧（Grazing Exclusion, GE）被广泛认为是修复过度放牧退化草原、提升碳（C）储量的重要策略。 然而，禁牧措施下生态系统碳组分的变化及其相关驱动因子，目前仍未得到充分研究。 本研究针对中国北方内蒙古干旱半干旱草原的15处禁牧围栏内外开展采样，探究了禁牧对生态系统碳组分（植物碳与土壤碳）及其关键驱动因子的影响。 研究结果显示，除死根碳外，禁牧显著提升了植物碳储量。地上生物量（AGB）与枯落物碳储量的提升源于生物量与碳浓度的双重积累，而活根碳储量的增加则主要归因于生物量积累。与之相反，尽管禁牧后表层土壤（0-20 cm）碳浓度小幅上升，但其容重显著下降，最终导致土壤碳储量几乎无变化。整体而言……