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

  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, mound-pit complexes and topographic features were recorded. The formation time of uprooted trees and its mound-pit 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.