Distinct responses of soil fungal and bacterial nitrate immobilization to land conversion from forest to agriculture
Distinct responses of soil fungal and bacterial nitrate immobilization to land conversion from forest to agriculture
复制标题
土壤真菌和细菌硝酸盐固定对土地从森林转变为农业的独特反应
DOI：
10.1016/j.soilbio.2019.03.023
复制
发表时间：
2019-07-01
影响因子：
9.7
通讯作者：
Li, Zhian
中科院分区：
文献类型：
--
作者：
Li, Xiaobo;He, Hongbo;Li, Zhian
最近发现，森林向农业的转变导致土壤中微生物硝酸盐（NO3-）同化的大幅减少，这是NO3-积累的关键原因，从而增加了农业土壤氮损失的风险。然而，土壤中的优势微生物真菌和细菌各自的NO3-同化如何以及为什么响应土地利用变化仍然是未知的。本研究采用氨基糖基稳定同位素探测（AS-SIP）方法发现，在中国亚热带地区，真菌和细菌的NO3-同化在转化为农业用地后均显著降低，真菌的NO3-同化降低水平（81%）比细菌的NO3-同化降低水平（61%）高20%。此外，真菌和细菌的NO3-同化抑制与土壤有机碳数量和质量的消耗密切相关，但前者也与土壤有效磷和ph的增加高度相关。本研究通过对土壤中真菌和细菌的NO3-固定过程的分离，进一步揭示了土地退耕还林后NO3-固定抑制的微生物驱动机制。
Forest conversion to agriculture has recently been found to result in a substantial decrease in microbial nitrate (NO3-) assimilation in soil, which is a key cause of NO3- accumulation and thus increases the risk of nitrogen losses from agricultural soils. However, how and why the respective NO3- assimilation of fungi and bacteria, the dominant microorganisms in soil, respond to land-use change is still unknown. Here we show, by adopting amino sugar-based stable isotope probing (AS-SIP), that both fungal and bacterial NO3- assimilation are significantly reduced after conversion to agricultural land-use in subtropical zones of China and the reduced level of fungal NO3- assimilation (81%) was 20% higher than that of bacteria (61%). Moreover, the depression of both fungal and bacterial NO3- assimilation was closely associated with the depletion of the quantity and quality of soil organic carbon, but the former was also highly correlated with the increase in available phosphorus and pH. Our study, through disentangling fungal and bacterial NO3- immobilization processes in soil, further reveals the microbially driven mechanisms underlying the depression of NO3- immobilization after land conversion from forest to agriculture.