小兴安岭南部天然林掘根倒木丘坑复合体形态特征及其与胸径关系

Morphological characteristics of mound-pit complexes by uprooted trees and its relationship with DBH in natural forest in the south of Xiaoxing’anling Mountains of northeastern China

【目的】为探究小兴安岭南部天然林内掘根倒木胸径及其形成的丘坑复合体面积、体积之间的关系,并用倒木胸径预测丘坑复合体形态特征,为未来丘坑复合体形态特征的预测提供参考。【方法】以小兴安岭南部天然林为对象,采用野外调查和统计分析相结合的方法,通过对相近海拔下不同腐烂等级倒木及其形成的320个丘坑复合体特征进行调查,记录倒木、丘坑复合体特征及其地形特征,根据掘根倒木不同的腐烂等级推理倒木及其丘坑复合体形成的时间,分析倒木胸径、腐烂等级对丘坑复合体形态特征的影响,并对其形态特征与倒木胸径之间的关系进行拟合。【结果】(1)掘根倒木发生频率最高的3个树种是臭冷杉、红皮云杉、红松,以针叶树为主;(2)腐烂等级最轻的Ⅰ级倒木数量>腐烂程度中等的Ⅱ级倒木数量>腐烂程度最高的Ⅲ级倒木数量,其中优势腐烂等级Ⅰ级倒木的数量占比为58%.(3)随着倒木腐烂等级增大,形成的坑面积、坑体积减小,形成的丘面积、丘体积增大;(4)倒木胸径与丘坑复合体面积、体积呈极显著正相关(P <0.01)。【结论】倒木腐烂等级与形成的坑面积、坑体积呈显著负相关,与形成的丘面积、丘体积呈显著正相关;丘坑复合体面积、体积随倒木胸径增大而增大;倒木形成的坑的面积、坑的体积随着倒木胸径的变化呈指数形式变化。

[Objective] This paper aims to explore the relationship between DBH and the area and volume of mound-pit complexes formed by uprooted trees in the natural forest in the south of the Xiaoxing’an Mountains of northeastern China. The DBH of uprooted trees was used to predict the morphological characteristics of the mound and pit complex, which could provide reference for the future prediction of morphological characteristics of the mound and pit complex. [Method] In this paper, the natural forest in the south of the Xiaoxing’an Mountains area was taken as the object, and the combined methods of field investigation and statistical analysis were adopted. By investigating 320 mound-pit complexes formed by uprooted trees with different decay levels at the similar altitude, the characteristics of uprooted trees, moundpit complexes and topographic features were recorded. The formation time of uprooted trees and its moundpit complex was deduced according to different decay levels of uprooted trees, and the influence of DBH and decay level of uprooted trees on the morphological characteristics of mound-pit complex was analyzed,and the relationship between the morphological characteristics and DBH of uprooted trees was fitted.[Result](1) Three tree species with the highest frequency of uprooted trees were Abies nephrolepis, Picea koraiensis and Pinus koraiensis, which were mainly coniferous trees.(2) The quantities of uprooted trees of decay level Ⅰ with the lightest level > those of level Ⅱ with the medium level > those of Ⅲ level with the highest level, and the quantities of dominant decay level Ⅰ accounted for 58% of the total quantities of uprooted trees in the study area.(3) With the increase of uprooted trees’ decay level, their area and volume of pits decreased, but the area and volume of mounds increased.(4) DBH of uprooted trees was positively correlated with the area and volume of mound-pit complexes(P < 0.01). [Conclusion] The decay level of uprooted trees is significantly negatively correlated with the area and volume of pit, significantly positively correlated with the area and volume of mound. The area and volume of mound-pit complexes increase with the increase of uprooted trees’ DBH. The area and volume of pits formed by uprooted trees change exponentially with the variation in their DBH.