Erguna Forest-Steppe Ecotone Research Station, CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Erguna Forest-Steppe Ecotone Research Station, CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
Sci Total Environ. 2022 Nov 25;849:157916. doi: 10.1016/j.scitotenv.2022.157916. Epub 2022 Aug 11.
The nitrogen‑phosphorus (N-P) imbalance induced by N enrichment has received increasing concerns, because N:P ratios play a critical role in driving many fundamental ecological processes. Given the simultaneous occurrence of different global change drivers, it is important to understand whether and how would such N-induced N-P imbalance would be mediated by other global change factors. We examined the interactive effects of N addition (10 g N m yr) and extreme drought (-66 % rainfall during the growing season) on species- and community-level N:P ratios in both green and senesced leaves in a temperate grassland of northern China. Extreme drought did not alter soil available N:P ratio under ambient N conditions, but increased that under N enriched conditions. Further, extreme drought did not alter the community-level N:P in both green and senesced leaves under ambient N conditions but significantly enhanced that under N enriched conditions. The drought-induced species turnover made a significant positive contribution to the changes in the community-level N:P ratio under N enriched conditions, but not under ambient N conditions. Our results suggest that the N-induced ecosystem N-P imbalance would be exacerbated by extreme drought event, the frequency of which is predicted to increase across global drylands. Such N-P imbalance would have consequences on litter decomposition, nutrient cycling, and the structures of above- and below-ground food webs. Our findings highlighted the complexity in predicting ecosystem N-P imbalance given the interactions between different global change drivers.
氮磷(N-P)失衡是由氮富集引起的,越来越受到关注,因为 N:P 比值在驱动许多基本生态过程中起着关键作用。鉴于不同全球变化驱动因素的同时发生,了解这种由 N 引起的 N-P 失衡是否以及如何会受到其他全球变化因素的影响非常重要。我们研究了氮添加(10 g N m yr)和极端干旱(生长季期间减少 66%的降雨量)对中国北方温带草原中绿色和衰老叶片的种和群落水平 N:P 比值的交互影响。极端干旱并没有改变环境氮条件下土壤有效 N:P 比值,但在氮富集条件下增加了。此外,极端干旱并没有改变环境氮条件下绿色和衰老叶片的群落水平 N:P 比值,但在氮富集条件下显著增强了。干旱引起的物种更替对氮富集条件下群落水平 N:P 比值的变化有显著的积极贡献,但对环境氮条件下的群落水平 N:P 比值没有显著影响。我们的结果表明,极端干旱事件会加剧由氮引起的生态系统 N-P 失衡,而全球干旱地区的极端干旱事件频率预计将会增加。这种 N-P 失衡将对凋落物分解、养分循环以及地上和地下食物网的结构产生影响。我们的研究结果强调了在不同全球变化驱动因素相互作用下预测生态系统 N-P 失衡的复杂性。
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