气候变化对阔叶红松林不同演替阶段红松种群生产力的影响

Effect of climate change on net primary productivity of Korean pine( Pinus koraiensis) at different successional stages of broad-leaved Korean pine forest

本文以长白山地区阔叶红松林不同演替阶段(次生杨桦林、次生针阔混交林、原始红松林)内红松种群作为研究对象,采用树轮学与相对生长式相结合,获取红松种群净初级生产力(NPP)连年生长(1921—2006年)数据以及相对增长率的年际变化数据,建立红松种群NPP与年际和季节性气候因子的关系,分析不同气候时期长白山阔叶红松林不同演替阶段内红松种群NPP年际变化特征及其对气候变化的响应差异.结果表明:研究期间,不同演替阶段红松种群NPP与气候因子响应关系存在差异.随着温度上升,次生杨桦林红松种群NPP与上年生长季和当年生长季低温由显著负相关关系转变为显著正相关关系;次生针阔混交林红松种群NPP由与当年春季最低温度的正相关关系转变为与上年和当年生长季温度的显著正相关关系,气候因素对次生针阔混交林红松种群NPP影响的滞后效应增强;原始红松林红松种群NPP与温度的相关性减弱,与上年生长季降水量的正相关关系增强.研究区气候变化表现为低温和平均温度显著上升,而最高温度和降水没有明显变化.气候变化有利于提高演替初级阶段次生杨桦林和演替中级阶段次生针阔混交林内红松种群生产力,尤其是次生针阔混交林,而对演替顶极阶段红松种群NPP影响不明显.

Pinus koraiensis in broad-leaved Korean successional stages （secondary poplar-birch forest, pine forests of Changbai Mountain at different secondary coniferous and broad-leaved forest and the primitive Korean pine forest） were selected in this paper as the research objects. In this re- search, the annual growth of net primary productivity （NPP） （1921-2006） of P. koraiensis was obtained by combining the tree-ring chronology and relative growth formulae, the correlation be- tween NPP of P. koraiensis and climatic factors was developed, and the annual growth of NPP of P. koraiensis at different successional stages in relation to climatic variation within different climate pe- riods were analyzed. The results showed that, in the research period, the correlations between cli- matic factors and NPP of P. koraiensis at different successional stages were different. With increas- ing the temperature, the correlations between NPP of P. koraiensis in the secondary poplar-birch forest and the minimum temperatures of previous and current growing seasons changed from being significantly negative to being significantly positive. The positive correlation between NPP of P. ko- raiensis in the secondary coniferous and broad-leaved forest and the minimum temperature in current spring changed into significantly positive correlation between NPP of P. koraiensis and the tempera- tures in previous and current growing seasons. The climatic factors had a stronger hysteresis effect on NPP of P. koraiensis in the secondary coniferous and broad-leaved forest, but NPP of P. koraiensis in the primitive Korean pine forest had weaker correlation with temperature but stronger positive correlation with the precipitation of previous growing season. The increases of minimum and mean temperatures were obvious, but no significant variations of the maximum temperature and pre- cipitation were observed at our site. The climatic variation facilitated the increase of the NPP of P. koraiensis in the secondary poplar-birch forest at the initial successional stage and in secondary coniferous and broad-leaved forest at the intermediate successional stage, and this effect was especially obvious for the secondary coniferous and broad-leaved forest, but very small for the primitive Korean pine forest which was at the climax phase.