气候变暖背景下红松的固碳动态及其对气候因子响应的纬度差异

Latitudinal differences in carbon sequestration dynamics of Pinus koraiensis and their responses to climatic factors against a background of climate warming

作为阔叶红松林的建群种,红松的固碳动态直接会影响到阔叶红松林的固碳能力.为探究气候变暖背景下红松的固碳变化及其对气候因子响应是否存在纬度差异,运用树木年轮学方法,研究气候变暖显著的40多年中我国境内原始阔叶红松林分布区内白石砬子自然保护区(40.92°N)、长白山自然保护区(42.40°N)、凉水自然保护区(47.18°N)和胜山自然保护区(49.45°N)4个纬度样地的红松固碳量及其变化动态,以及影响不同纬度红松固碳量的关键气象因子.结果显示,当年6月和4月的气象因子对南部3个地区红松的年固碳量影响较大,3个地区红松固碳量都与当年6月份的月平均最高气温呈显著负相关,与当年6月份的平均相对湿度和总降水量呈显著正相关(白石砬子自然保护区除外,其年固碳量与当年6月的降水量的相关性不显著).最北端的红松年固碳量对气温因子非常敏感,与所有月份的月平均气温和月平均最低气温呈显著正相关.在气候变暖显著的40多年中,长白山自然保护区红松的年均固碳量最高,每株红松年均固碳量为11.78±2.31 kg,胜山自然保护区每株红松年均固碳量第二,凉水自然保护区排第三,白石砬子自然保护区每株红松年均固碳量最低,为5.34±1.13 kg.随着气温不断升高,最南端的白石砬子自然保护区每株红松年均固碳量显著下降,而长白山自然保护区和胜山自然保护区的红松的年固碳量显著上升,凉水自然保护区红松的年固碳量变化不显著.可见,在气候变暖情景下,红松的年固碳量及其对气候变暖的反映存在纬度异质性,对红松年固碳量造成显著影响的气象因子也存在纬度异质性.(图5表3参58)

Pinus koraiensis is a constructive species of broad-leaved Korean pine forests,and its carbon(C)sequestration dynamics directly affect the C sequestration capacity of broad-leaved Korean pine forests.To investigate whether there are latitudinal differences in the C sequestration dynamics of P.koraiensis and their responses to climatic factors against climate warming,dendrochronological methods were used.The C sequestration rates and dynamic characteristics of P.koraiensis from different latitudinal gradients over the past 40 years were investigated throughout the natural range of broad-leaved Korean pine forests,including the Baishilazi Nature Reserve(40.92°N),Changbai Mountain Nature Reserve(42.40°N),and Liangshui Nature Reserve(47.18°N),three southern districts,as well as the Shengshan Nature Reserve(49.45°N),the northernmost district.The results revealed that climatic factors in June and April of the current year had a significant influence on the annual C sequestration rates of P.koraiensis in all three southern districts.The C sequestration rates of P.koraiensis in these three areas were significantly negatively correlated with the average maximum temperature but significantly positively correlated with the relative humidity and precipitation in June of the current year,except for the Baishilazi Nature Reserve,in which no significant correlation was observed.However,in the Shengshan Nature Reserve,the northernmost sample plot,the annual C sequestration of P.koraiensis was very sensitive to temperature and had a significant positive correlation with the monthly mean and average minimum temperatures.Over the last four decades,with increasing temperature,the Changbai Mountain Nature Reserve had the highest average annual C sequestration value for P.koraiensis(11.78±2.31 kg per tree per year),followed by the Shengshan Nature Reserve,Liangshui Nature Reserve,and Baishilazi Nature Reserve(5.34±1.13 kg per tree per year).With the continuous climate warming,the annual C sequestration rate of P.koraiensis in the Baishilazi Nature Reserve,the southernmost point,decreased significantly,whereas in the Shengshan Nature Reserve and Changbai Mountain Nature Reserve,the northernmost and mid-latitude areas,respectively,these rates increased significantly.In the Liangshui Nature Reserve,there was no significant change in the annual C sequestration value.Both the climatic factors affecting the C sequestration of P.koraiensis and the annual C sequestration rates of P.koraiensis in response to climate change showed latitudinal differences.