四翅滨藜叶片C、N、P生态化学计量特征对N添加的响应

Responses of C:N:P Ecological Stoichiometry in the Leaves of Atriplex canescens to N Addition

以宁夏平罗西大滩四翅滨藜人工林为研究对象,通过设置N添加的野外实验,研究四翅滨藜叶片C、N、P化学计量比的季节动态及其对N添加的响应特征。结果显示:(1)四翅滨藜叶片C、N、P化学计量比在生长季初期和末期较高,在生长季旺期(8～9月)较低。(2)N添加提高了绿叶N浓度和N∶P比,降低了绿叶C∶N、N回收度(NRP)和P回收度(PRP),对其他指标的影响无明显的规律性。(3)N回收效率(NRE)和NRP均与枯叶C∶N比显著正相关;P回收效率(PRE)与绿叶P浓度显著正相关,与枯叶P浓度显著负相关;PRP分别与绿叶P浓度和枯叶C、N、P化学计量比显著正相关,与枯叶C浓度显著负相关。研究表明,N添加促进了四翅滨藜绿叶N摄取,降低了叶片从枯叶中回收N和P的能力,改善了枯叶N分解质量;未来大气N沉降增加会改变干旱半干旱区植物N吸收、分配和回收等策略,促进枯叶中N的释放速率,直接影响N循环,进而间接影响到植被-土壤系统C和P的循环过程。

In this paper,we arranged a field experiment of N addition for the plantation of Atriplex canes- cens in Xidatan,Pingluo County,Ningxia Province. Based on the data of leaf C,N and P concentrations collecting in different seasons,we mainly explored the seasonal dynamics of leaf C ： N,C： P and N：P ratios of A. canescens, and their responses to N addition. We also discussed the correlation between leaf C：N, C ： P and N：P with leaf nutrient resorption. The results showed that：（1）During whole growing season, leaf C, N ,P concentrations were higher in August and September but lower in June and November, whereas leaf C：N,C：P and N：P ratios showed contrary trends;（2）N addition increased N concentration and N：P ratio in green leaves,decreased C： N ratio in green leaves,leaf N resorption proficiency （NRP） and P re-orption proficiency （PRP）,but had not clear effects on C concentration in green leaves,P concentration in green leaves,C：P ratio in green leaves, leaf N resorption efficiency （NRE） and P resorption efficiency （PRE） ;（3）Both NRE and NRP had positive correlations with C ： N ratio in senescing leaves. PRE posi-tively correlated with P concentration in green leaves,but negatively correlated with that in senescing leav- es. PRP positively correlated with P concentration in green leaves and C ＂ N ＂ P in senescing leaves,respec- tively, but negatively correlated with C concentration in senescing leaves. The above results suggest that,N addition accelerates N uptake in green leaves, reduces the ability of N and P resorption from senescing leav- es, consequently improves decomposition quality of senescing leaves. Thus, future increase in atmospheric N deposition will alter plant N strategies in the way of N uptake,N distribution and N transfer, accelerate N release in senescing leaves, further have a direct effect on N cycling process and indirect effects on C and P cycling in plant-soil system.