竞争和气候对新疆阿尔泰山西伯利亚五针松树木径向生长的影响

Effects of competition and climate on tree radial growth of Pinus sibirica in Altai Mountains, Xinjiang, China

阿尔泰山的北方森林是中亚以及全球的生态系统的重要组成部分,其生长动态可以影响到全球范围的热辐射、碳平衡等。因此,探究影响阿尔泰山树木径向生长的主要因素至关重要。该研究以新疆喀纳斯国家级自然保护区的西伯利亚五针松(Pinus sibirica)为研究对象,建立西伯利亚五针松年表,通过分析不同时间间隔累年生长量、竞争指数以及气候因子之间的关系,运用线性混合效应模型、相关分析等方法,探究竞争和气候对新疆阿尔泰山西伯利亚五针松树木径向生长的影响。结果表明:(1)线性混合效应模型结果显示竞争树胸径和与西伯利亚五针松过去30年的累年生长量之间的拟合效果最好;(2)标准年表与3月的平均气温、平均最高气温、平均最低气温之间有显著正相关关系;(3)累年生长量最高值出现在气温0–5℃,竞争指数低于100的时候。累年生长量最低时,气温达到–10℃,竞争指数也超过了300。目标树的树木径向生长受到竞争树胸径和及生长季前期气温的影响,两者共同作用。但相较于气候因子而言,竞争对西伯利亚五针松的树木径向生长有更大的影响作用。

Aims As an important part of the ecosystems of Central Asia and the whole world,forest growth dynamics of the boreal forest in Altai Mountains can affect global thermal radiation,carbon balance and so on.Therefore,it is crucial to explore the main factors affecting tree radial growth of the boreal forest in Altai Mountains.Methods We selected Pinus sibirica in Kanas National Nature Reserve of Xinjiang as the target tree species,and established tree-ring chronology of P.sibirica.To explore the influence of competition and climate on radial growth of P.sibirica in the Altai Mountains,Xinjiang,we analyzed the relationships among the cumulated basal area increment(BAI),competition index and climate factors at different time intervals by applying various methods like linear mixed effect model and correlation analysis.Important findings The results of the linear mixed effect model showed that:(1)the BAI over the past 30 years can be best predicted by the sun of competitors’diameter at breast height(SDBH).(2)Significant positive correlations were found between the standard chronology,and mean air temperature,mean maximum air temperature and mean minimum air temperature in March.(3)The highest value of the cumulated BAI was observed when air temperature was from 0 to 5℃,and the competition index was below 100.The lowest value of the cumulative growth occurs when air temperature reaches–10℃and the competition index exceeds 300.Tree radial growth of subject trees was influenced by both the diameter at breast height of the competing trees and the early growing season air temperature.Competition plays a more important role in affecting radial growth of P.sibirica than climate factors in this area.Therefore,our results would provide a scientific basis for forest management of P.sibirica in Kanas National Nature Reserve of Xinjiang.