内蒙古温带草原根系周转模式及其对土壤有机质的贡献

Root turnover is an important source of the soil organic matter and plays critical roles in regulating carbon (C) cycling response and feedback to the global climate change in grassland ecosystem. However, root turnover and its contribution to soil organic carbon pool, the influence of soil humus substance formation and transformation process are still the most unclear part in grassland ecosystem's carbon cycle. So far, very few informations about global climate change's impact on root turnover and soil humification process driven by precipitation and temperature at a regional scale have been reported. Therefore, in this study, Stipa baicalensis, Stipa grandis, Stipa krylovii and Stipa breviflora plants community distributing across natural climate gradient in temperate steppe were taken as research object. This study was conducted to investigate whether there is a regional pattern of root turnover, to quantifying the carbon number in the soil by the input of root death, to estimate the root turnover's contribution to soil organic matter in Inner Mongolia's temperate steppe by adopting modified minirhizotron technique, ingrowth core, soil core and δ13C methods. The research whereby reveals the adjustment regulation of climate driven factors (precipitation and temperature) and human activity (grazing) on grassland plants root turnover and humification processes of soil organic matter. It provides scientific parameter for temperate grassland ecosystem carbon cycle under the background of model predicted climate change.

根系周转是土壤有机质的重要来源，在调节草原生态系统碳循环对全球气候变化的响应与反馈中至关重要。然而，根系周转及其对土壤有机碳库的贡献、土壤腐殖物质形成和转化过程的影响仍然是草原生态系统碳循环中最不清楚的部分，至今尚未见区域尺度上以降水和温度为主要驱动因素的全球气候变化对草原根系周转及其对土壤腐殖化过程影响的报道。因此，本研究以内蒙古温带草原自然气候梯度上分布的代表性植被类型贝加尔针茅、大针茅、克氏针茅和短花针茅草原植物群落为研究对象，利用改进的微根窗方法、内生长法、原状土柱法和δ13C法等研究手段，来探讨内蒙古温带草原根系周转是否具有一个区域模式？量化根系死亡输入土壤中碳的数量，估算根系周转对土壤有机质的贡献。借此，揭示气候驱动因素（水分和温度）和人类活动（放牧）对温带草原植物根系周转及其对土壤有机质腐殖化过程的调控规律，为模型准确预测气候变化背景下温带草原生态系统碳循环提供科学的参数。