氮磷供给对荒漠草原土壤和白草C∶N∶P化学计量特征的影响  

Effects of N and P Supply on the C∶N∶P Stoichiometry in Both Soil and a Desert Steppe Species Pennisetum centrasiaticum

作　　者：康扬眉 马凯博 黄菊莹[2] 杜雅仙 余海龙[1] KANG Yangmei;MA Kaibo;HUANG Juying;DU Yaxian;YU Hailong(College of Resources and Environment,Ningxia University,Yinchuan 750021,China;Institute of Environmental Engineering,Ningxia University,Yinchuan 750021,China)

机构地区：[1]宁夏大学资源环境学院,银川750021 [2]宁夏大学环境工程研究院,银川750021

出　　处：《西北植物学报》2018年第8期1507-1516,共10页Acta Botanica Boreali-Occidentalia Sinica

基　　金：宁夏自然科学基金(NZ17015)

摘　　要：大气氮(N)沉降增加是全球变化的一个重要方面。长期N沉降增加会提高生态系统N:磷(P)比,导致系统P限制增加以及植物P需求增强。该试验通过对白草(Pennisetum centrasiaticum)设立的N∶P供给(在统一施用N10.0g·m^(-2)·a^(-1)的基础上,通过改变P施用量,形成6个N∶P处理水平)盆栽控制试验,研究了连续2年(2013~2014年)N∶P供给处理对土壤和白草碳(C)∶N∶P化学计量特征的影响,并分析了C∶N∶P化学计量特征对白草生长和养分利用的指示意义。结果显示:(1)降低N∶P供给(提高P施用量)能够显著降低土壤和白草的C∶P和N∶P,缓解白草生长的P受限性,从而促进白草的生物量积累。(2)随着N∶P供给进一步降低,土壤N受限性增加。(3)白草通过提高其枯叶N回收能力,减少对土壤N库的依赖,反映了白草对N受限环境的弹性适应。研究表明,人为适当的添加P能够通过调节土壤和植物C、N、P计量平衡关系,减轻土壤和植物间P的供需压力,从而缓解N添加引起的荒漠草原P受限性增强。该研究结果可为N沉降增加背景下脆弱生态系统的适应性管理提供科学指导。The increase in atmospheric nitrogen(N)deposition is an important aspect of global change.Numerous studies have shown that long-term N deposition would increase N:phosphorus(P)of ecosystems,leading to the increase of P limitation in ecosystems and hence accelerating the P demand of plants.In this paper,we conducted a 2-year(2013-2014)N∶P supply(10 g·m-2·a-1 N combined with different P amounts)pot-cultured experiment for a common desert steppe species Pennisetum centrasiaticum.We determined the effects of N∶P supply on C∶N∶P stoichiometry in both soil and P.centrasiaticum(leaves and belowground parts).We also analyzed the indication of C∶N∶P stoichiometry for the growth and nutrient utilization of P.centrasiaticum.The results showed that:(1)reducing N∶P supply(thereby increasing P fertilization)significantly decreased C∶P and N∶P in both soils and P.centrasiaticum,alleviating P limitation for the growth of P.centrasiaticum,and further promoting the biomass accumulation of P.centrasiaticum.(2)The gradual decrease of N∶P supply would shift P limitation to N limitation for P.centrasiaticum.(3)In this case,P.centrasiaticum increased the ability of N resorption from its senescing leaves,which reduced its dependence on soil N pool,reflecting the adaptation of P.centrasiaticum to N-limited environments.Our results suggest that appropriate artificial P addition could adjust the stoichiometry balance of C,N,and P between soil and plants,alleviate the pressure between soil P supply and plant P demand,and thus mitigating N-induced increase of P limitation.The results could provide scientific guidance for the adaptive management of fragile ecosystems under increasing N deposition.

关 键 词：脆弱生态系统 N沉降 化学计量特征 养分回收 养分摄取 P限制 

分 类 号：Q948.113[生物学—植物学]