tropical forest soil microbial community in China

Between 30% and 50% of the carbon (C) respired from tropical forests originates from soil, most of which is derived from the decomposition of organic matter. Subsoils contain more than half of the global soil organic C stocks, which have much slower turnover compared to the soil organic C in topsoil. Because of very slow process rates, the temperature sensitivity (Q10) of subsoil organic C decomposition to rainfall changes is nearly unknown. Therefore, we investigated the responses of Q10, soil organic acids, microbial communities and necromass of tropical forest soil to a delayed and wetter rain season in a 10-year manipulation experiment. Microbial respiration absence of differences in response to shifts in rainfall patterns. The delayed rain season did not affect Q10, soil organic acids, bacterial and fungal communities and microbial necromass in 0–70 cm soil layers. Wetter rain season significantly increased the Q10, which mainly due to wetter rain season increased C inputs and resulted in nitrogen limitation, and subsequently contribute to the decomposition of subsoil organic C. The concentrations of acetic acid and the relative abundance of Glomeromycota in 30-50 and 50–70 cm soil layers. Q10 was positively associated with acetic acid and the relative abundance of Glomeromycota, and was negatively associated with bacterial necromass/soil organic C. Rare Glomeromycota taxa was the best microbial predictor in predicting the response of Q10 to rainfall changes in tropical forests. Thus, our study suggested that rising temperature may trigger deep soil C loss from tropical forests under rainfall changes.

热带森林释放的碳（C）中有30%至50%来自土壤，其中大部分源于有机质的分解过程。全球土壤有机碳储量有一半以上储存在深层土壤中，其周转速率远慢于表层土壤的有机碳。由于周转过程速率极慢，深层土壤有机碳分解对降雨变化的温度敏感性（Q10）几乎尚未被探明。因此，本研究依托一项为期10年的野外控制实验，探究了热带森林土壤的Q10、土壤有机酸、微生物群落及微生物残体（necromass）对降雨季节延迟且降雨更充沛的响应。微生物呼吸对降雨格局变化的响应未表现出显著差异。降雨季节延迟并未对0–70 cm土层的Q10、土壤有机酸、细菌与真菌群落及微生物残体产生影响。降雨更充沛的雨季则显著提升了Q10值，其主要原因在于充沛的降雨增加了碳输入并引发氮限制，进而促进了深层土壤有机碳的分解。在30–50 cm与50–70 cm土层中，乙酸浓度与球囊霉菌门（Glomeromycota）的相对丰度。Q10值与乙酸浓度及球囊霉菌门的相对丰度呈正相关，而与细菌残体/土壤有机碳比值呈负相关。稀有球囊霉菌门类群是预测热带森林中Q10对降雨变化响应的最佳微生物指标。综上，本研究表明，在降雨格局改变的背景下，气温升高可能会引发热带森林深层土壤的碳流失。