不同径级红松挥发性碳贡献变化特征及其影响因子分析

目的植物含碳率是研究森林碳储量的关键因素之一，精确测定含碳率及其影响因子有利于提高森林碳储量的预测准确率。方法以吉林蛟河阔叶红松成熟林固定样地内红松为研究对象，获取冷冻干燥、自然干燥和烘干干燥3种处理方式下的红松茎干连年含碳率，对比分析3种处理方式下不同径级红松含碳率年际变化特征。发现自然干燥含碳率波动较大，因此本文的挥发性碳贡献由冷冻干燥含碳率和烘干干燥含碳率来量化。通过比较大小径级红松挥发性碳贡献年际变化特征，分析其在时间尺度上的差异与稳定性，并构建挥发性碳贡献与气候因子和生长量等因子的相关关系，揭示影响挥发性碳贡献的主要因子。结果(1) 不同干燥方式仅对大径级红松的含碳率的测定结果有显著影响(P < 0.05)，而3种干燥方式下小径级红松含碳率不存在显著差异。(2)红松挥发性碳贡献有一定阶段性。小径级红松挥发性碳贡献较大径级波动更大，小径级红松挥发性碳贡献最高和最低值分别为24.46%和0.03%，大径级红松挥发性碳贡献最高和最低值则为9.72%和1.18%，同时大径级红松挥发性碳贡献存在明显的滞后现象。(3)红松挥发性碳贡献主要受到冬季温度的影响，其中小径级红松挥发性碳贡献仅与当年12月的温度呈现显著负相关(P < 0.05)，而大径级红松则与上一年12月的温度呈显著负相关(P < 0.05)。(4)当年1月降水对大径级红松挥发性碳贡献有促进作用(P < 0.05)，而当年6月的干旱指数对小径级红松挥发性碳贡献有促进作用(P < 0.05)。推测挥发性碳可能与树木非生长季的生理活动有关。结论在评价森林碳储量时要考虑挥发性碳贡献，同时不能忽视径级差异的影响及挥发性碳的时间稳定性，从而实现对不同特征林分碳储量的精确估算。 

Dynamic characteristics and its influencing factors of the volatile carbon content of Pinus koraiensis at different diameter classes

ObjectiveCarbon content is one of the key factors when estimating carbon storage. Accurate measurement of carbon content and finding its influencing factors can improve the accuracy of the prediction of carbon storage.MethodTree cores collected in the plots of mature forests in the broardleaved Korean pine forest of Jiaohe, northeastern China were taken as samples in this study. Carbon content of frozen, oven-dried and natural air drying samples of Pinus koraiensis from 1987 to 2016 were attained in order to qualify the volatile carbon content and to compare the characteristics of the interannual variation of the carbon content attained by different drying methods. In this passage, volatile carbon content was qualified with frozen and oven-dried carbon content considering the relative stability of them. The relationship between volatile carbon content and three climate factors as well as size class and annual growth was developed.Result(1) The results showed that significant difference among carbon content of different drying methods was only found in trees of large diameter class.(2)The fluctuation characteristics of volatile carbon contribution differed in small and large class and the interannual variations were more remarkable in small class. The volatile carbon contribution reached 24.46% in small class and 9.72% in large class. Also, the volatile carbon contribution in large class lagged behind that of small class. (3)The volatile carbon contribution was mainly limited by the temperature in winter. In small class, the volatile carbon contribution showed negative response to temperature in December of that very year, while in large class, it responsed negatively to the temperature in last December. (4)The precipitation of this January had positive influence in volatile carbon contribution of large class and the volatile carbon contribution of small class showed positive response to PDSI of this June, which inspired us that the effect of volatile carbon may be related to trees' dormancy or other defensive mechanisms.ConclusionTherefore, it is necessary to take volatile carbon content into account while estimating the forest carbon storage without ignoring the influence of size class. It is also necessary to make a deep analysis of the influencing factors of volatile carbon contribution.