Carbon isotope in tree ring is an effective indicator of climate and environmental change. However, few studies have analyzed the indication effect of tree ring carbon isotope on net primary productivity (NPP) of forests. Based on meteorological factors of growing seasons, we analyzed the variation trend and the relationship between the tree ring δ13C chronosequence of Korean pine (Pinus koraiensis) and net primary productivity (NPP) of Korean pine in Changbai Mountain. We found that before 1970, the change of Korean pine tree ring δ13C and NPP was synchronous, with a highly significant linear positive correlation between them, indicating that tree ring δ13C recorded the impacts of climate change on NPP. After 1970, tree ring δ13C was negatively correlated with NPP but not statistically significant, meaning that other environmental factors such as severe droughts reduced the sensitivity of tree ring δ13C to climate change and the recording of NPP by tree ring δ13C. The δ13C of the current year was also correlated with the corresponding NPP in the following year, which indicated that the current year's environmental conditions were of great significance to the growth of Korean pine in the following year. This study showed that tree ring δ13C was a good indicator of the NPP of Korean pine in Changbai Mountain and that tree ring δ13C had the potential to reconstruct long-term changes of forest NPP in the history.
解析树木年轮碳同位素变化是揭示气候与环境变化的有效途径,然而少有研究分析年轮碳同位素对森林净初级生产力(NPP)的指示效应.基于生长季气象因子,分析了长白山红松年轮δ13C记录序列与阔叶红松林红松种群NPP变化趋势以及两者之间的相关关系.结果表明: 1970年以前,研究区红松年轮δ13C与红松种群NPP变化同步,且两者间呈极显著线性正相关关系,年轮δ13C记录了气候变化对红松种群NPP的影响;1970年以后,红松年轮δ13C与红松种群NPP变化出现分异,两者呈负相关关系但相关性不显著,表明干旱等其他环境因子的影响使年轮δ13C对气候变化的敏感性和对NPP指示性降低.这一相关关系在红松年轮δ13C与当年和下一年红松种群NPP之间都存在,表明当年环境状况对来年红松生长的重要意义.说明长白山红松年轮δ13C对红松种群NPP有良好的指示性,树木年轮δ13C有重建森林历史NPP长期变化的潜力.
Keywords: carbon isotope; climate change; net primary productivity; tree ring.