Zheng Jing, She Weiwei, Zhang Yuqing, Bai Yuxuan, Qin Shugao, Wu Bin
School of Soil and Water Conservation Beijing Forestry University Beijing China.
Key Laboratory of State Forestry Administration on Soil and Water Conservation Beijing Forestry University Beijing China.
Ecol Evol. 2018 Sep 24;8(20):9998-10007. doi: 10.1002/ece3.4407. eCollection 2018 Oct.
Increasing nitrogen (N) deposition and precipitation are major drivers of global changes that are expected to influence plant nutrient resorption in desert ecosystems, where plant growth is often nutrient and water limited. However, knowledge on the effects of increased N and precipitation on them remain poorly understood. This study determined the effects of increased N (ambient, 60 kg N ha year) and water supply (ambient, +20%, +40%), and their combination on the leaf nutrient resorption of , a dominant shrub in the Mu Us Desert of northern China. After 2 years of treatments, only N addition significantly decreased the N resorption efficiency of . Both N and water addition had no effect on the phosphorus (P) resorption efficiency of this shrub, and there were no interactive effects of N and water availability on shrub nutrient resorption. The responses of shrub leaf N:P ratio tended to saturate as soil available N:P increased. The aboveground net primary productivity of was positively correlated with leaf P resorption efficiency, rather than N resorption efficiency. Our results suggest that N addition exacerbated the P limitation of the shrub growth and played a more fundamental role than water addition in controlling the nutrient resorption process of the desert shrub . This information contributes to understand the relationship between nutrient conservation strategy and plant growth of desert shrub species under global environmental changes.
氮（N）沉降增加和降水增加是全球变化的主要驱动因素，预计会影响沙漠生态系统中的植物养分再吸收，在这些生态系统中植物生长往往受养分和水分限制。然而，关于增加氮和降水对其影响的了解仍然很少。本研究确定了增加氮（环境水平、60千克氮·公顷·年）和供水（环境水平、增加20%、增加40%）及其组合对中国北方毛乌素沙漠优势灌木油蒿叶养分再吸收的影响。经过两年的处理，仅施氮显著降低了油蒿的氮再吸收效率。施氮和供水对该灌木的磷（P）再吸收效率均无影响，且氮和水分有效性对灌木养分再吸收没有交互作用。随着土壤有效氮磷比增加，灌木叶氮磷比的响应趋于饱和。油蒿的地上净初级生产力与叶磷再吸收效率呈正相关，而非与氮再吸收效率相关。我们的结果表明，施氮加剧了灌木生长的磷限制，并且在控制沙漠灌木油蒿的养分再吸收过程中比供水起着更重要的作用。这些信息有助于理解全球环境变化下沙漠灌木物种养分保存策略与植物生长之间的关系。
