氮沉降下西南亚高山针叶林生长的养分限制特征

长期氮(N)沉降及其诱导的N、磷(P)养分平衡性对森林生长与生产力的生态反馈效应已成为当前森林生态学研究的前沿与热点,但目前大多研究主要基于已有文献数据整合分析,而缺乏野外原位系统性研究与试验证据.以西南亚高山两种典型人工针叶林——云杉(Picea asperata)林和华山松(Pinus armandii)林为对象,...

Nutrient limiting characteristics of subalpine coniferous forests under conditions of nitrogen deposition in the southwest mountains of China

The effect of long-term nitrogen(N) deposition and the induced N-phosphorus(P) nutrient balance on the ecological feedback of forest growth and productivity has become a research focus. However, most of the current studies are based on data integration from the existing literature and there is a lack of systematic field research and related empirical evidence. In this study, two typical artificial subalpine coniferous forests in Southwest China, a Picea asperata plantation and a Pinus armandii plantation, were examined. By adding N in situ in the field to simulate atmospheric N deposition, the nutrient limiting characteristics of tree growth in this region under conditions of N deposition were verified by studying the leaf nutrient status and physiological characteristics. The results showed that:(1) the addition of N significantly decreased the foliar P concentration in the two plantations, resulting in an increase in foliar N:P ratio by 9.9% and 5.8% over the control in the P. asperata plantation and P. armandii plantation, respectively. This indicated that N addition drove P nutrient limitation in both plantations to a certain extent, and the degree of P nutrient limitation was more severe in the P. asperata plantation;(2) N addition significantly reduced the NRE/PRE ratio of P. asperata leaves, but had no significant effect on P. armandii leaves. The results showed that the growth of P. asperata plantations in response to N addition was significantly restricted by P;(3) N addition significantly reduced the concentration of foliar P fractions, and markedly increased the foliar acid phosphatase activity in both plantations. Collectively, based on the interpretation of the leaf nutrient status and physiological characteristics, this study showed that N deposition induced P nutrient limitation to the growth of subalpine forest trees to different degrees, and that the degree of P nutrient limitation was more severe in the P. asperata plantation. We speculated that the P nutrient limitation degree of the stand driven by N deposition might be related to the initial soil nutrient status of the two stands. The findings of this study provide an important scientific basis for forest adaptive management in response to global climate change.