Abstract: Based on the field investigation data of 128 Ulmus lamellosa target trees and 1093 competing species individuals in a 100 m×100 m sampling plot in Taiyue Mountain of Shanxi, this paper analyzed the intra- and inter-specific competition intensities of U. lamellosa by using Hegyi’s competition index (CI). The intraspecific competition intensity of U. lamellosa decreased gradually with its increasing DBH. In the plot, there were many other species, but their individual number was fewer than that of U. lamellose, and thus, the interspecific competition intensity of U. lamellosa was relatively weaker than its intraspecific competition. The order of the intra- and inter-specific competition intensities was U. lamellosa-U. lamellosa > Carpinus cordata-U. lamellosa > Acer elegantulum-U. lamellosa> other species-U. lamellosa. The relationships between the competition intensity and the DBH of U. lamellosa followed the equation CI=AD-B. When the DBH of U. lamellosa reached 25 cm, the competition intensity had less change, and the model could well simulate and predict the intra-and inter-specific competition intensities of U. lamellosa.

Key words: Chinese bulbul (Pycnonotus sinensis), photoperiod, digestive tract morphology., body mass, energy budget, temperature