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

Pinus koraiensis in broad-leaved Korean pine forests of Changbai Mountain at different successional stages (secondary poplar-birch forest, secondary coniferous and broad-leaved forest and the primitive Korean pine forest) were selected in this paper as the research objects. In this research, 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 between 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 periods were analyzed. The results showed that, in the research period, the correlations between climatic factors and NPP of P. koraiensis at different successional stages were different. With increasing 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. koraiensis 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 temperatures 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 precipitation 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.