School of Life Sciences and Engineering, Southwest University of Science and Technology, Mianyang 621010, China; Department of Microbiology and Plant Biology and School of Civil Engineering and Environmental Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, OK 73019, USA.
School of Life Sciences and Engineering, Southwest University of Science and Technology, Mianyang 621010, China.
Sci Total Environ. 2020 May 10;716:136414. doi: 10.1016/j.scitotenv.2019.136414. Epub 2020 Jan 27.
Effects of natural forest conversion (NFC) on soil nutrient turnover are substantially mediated by soil microbial extracellular hydrolytic enzymatic activities (Hy-EEAs) and oxidative enzymatic activities (Ox-EEAs). Yet it remains largely unknown the indicative links between soil Hy- and Ox-EEAs and soil carbon (C), nitrogen (N) and phosphorus (P) supplies based on economic theories of microbial metabolism under NFC. Here we used a meta-analysis approach to synthesize the responses of the soil C-, N-, P-degrading Hy-EEAs and Ox-EEAs, soil microbial biomass, soil organic C, total N, P and available P parameters to natural forest conversion from 51 peer-reviewed studies. Our results showed that NFC notably decreased soil Hy-EEAs but statistically insignificant reduction of soil Ox-EEAs. The changes of soil Hy- and Ox-EEAs were significantly and positively associated with soil organic C, available P as well as microbial biomass C and N but significantly and negatively correlated with soil pH, whereas the changes of soil C/N impacted on soil Ox-EEAs remarkably but not for soil Hy-EEAs. The depletion of soil organic carbon stimulated soil microbial secretion of Hy- and Ox-EEAs. The soil total N scarcity only provoked soil microbial Hy-EEAs rather than Ox-EEAs. The soil total P dearth quickened the soil Ox-EEAs, however, the plenitude of soil available P suppressed soil Hy- and Ox-EEAs. Moreover, the eco-enzymatic stoichiometry of soil Hy-EEAs indicated that soil N and P nutrient limitation after NFC restricted soil microbial N- and P-acquiring enzymes secretion, which ultimately reduced resources availability for C acquisition. Altogether, the distinct responses of soil Hy- and Ox-EEAs depended on substrate availability peculiarly for soil N and P gains of microorganisms for further enzymatic ability on soil C decomposition and highlighted the abundant or absent supply of soil N and P for positive or negative enzymatic activities on metabolic requirement of soil edaphons.
天然林转换（NFC）对土壤养分转化的影响主要通过土壤微生物胞外水解酶活性（Hy-EEAs）和氧化酶活性（Ox-EEAs）来调节。然而，根据 NFC 下微生物代谢的经济理论，基于 NFC，土壤 Hy-和 Ox-EEAs 与土壤碳（C）、氮（N）和磷（P）供应之间的指示联系在很大程度上仍然未知。在这里，我们使用荟萃分析方法，综合了 51 篇同行评议研究中 NFC 对土壤 C、N、P 降解的 Hy-EEAs 和 Ox-EEAs、土壤微生物生物量、土壤有机 C、总 N、P 和有效 P 参数的响应。我们的结果表明，NFC 显著降低了土壤 Hy-EEAs，但对土壤 Ox-EEAs 的影响无统计学意义。土壤 Hy-和 Ox-EEAs 的变化与土壤有机 C、有效 P 以及微生物生物量 C 和 N 呈显著正相关，与土壤 pH 呈显著负相关，而土壤 C/N 的变化则显著影响土壤 Ox-EEAs，但对土壤 Hy-EEAs 没有影响。土壤有机碳的消耗刺激了土壤微生物分泌 Hy-和 Ox-EEAs。土壤总氮的缺乏只引起土壤微生物分泌 Hy-EEAs，而不是 Ox-EEAs。土壤总磷的缺乏加快了土壤 Ox-EEAs 的产生，然而，土壤有效磷的丰富抑制了土壤 Hy-和 Ox-EEAs 的产生。此外，土壤 Hy-EEAs 的生态酶化学计量表明，NFC 后土壤 N 和 P 养分限制限制了土壤微生物获取 N 和 P 的酶的分泌，最终减少了土壤 C 获取的资源可用性。总的来说，土壤 Hy-和 Ox-EEAs 的不同反应取决于底物的可用性，特别是对于土壤微生物对土壤 N 和 P 的获取，以进一步提高土壤 C 分解的酶活性，并强调了土壤 N 和 P 的丰富或缺乏对土壤 edaphons 代谢需求的正或负酶活性的影响。
