Hollow-bearing characteristics of Populus euphratica in the lower reaches of Tarim River, China

Abstract

We analzyed the hollow ratio of tree trunks, tree hole parameters, and its distribution characteristics among different DBH and tree height classes in a long-term monitoring plots of Populus euphratica forest at the Argan section in the lower reaches of Tarim River. The results showed that P. euphratica in the study area had a high hollow ratio, in that trees with hollowness accounted for 56% of the total individuals, with a absolute value of 159 tree·hm-2. The hollow ratio of P. euphratica showed significant difference among different DBH classes and tree height classes. The hollow ratio was positively correlated with DBH, and negatively correlated with tree height. The density of P. euphratica with hollowness was 560 ind·hm-2 and 2 ind·tree-1. Most of tree holes appeared on the tree trunk (57.1%) and mainly in the middle of the trunk (31.3%). The hole with a diameter of 5-15 cm accounted for the largest proportion (38.2%). The total number of tree holes, the number of tree holes per tree, and the diameter of holes were positively correlated with DBH and negatively correlated with tree height. The distribution of different tree hole types among different DBH classes and tree height classes was different, with inconsistent changing trends. The distribution of tree holes showed significant difference acorss orientations, with most of which mainly toward the west. The occurrence rate of tree hollow in P. euphratica desert riparian forest was more serious. The larger the DBH of poplar tree was, the more obvious the degree of hollow. Therefore, it is of great significance to strengthen the conservation of young poplar trees and to restore degraded desert riparian forests.