Study On Factors Affecting The Stem Growth In An Evergreen Broadleaved Forest In Zhejiang Tiantong

A thorough understanding to forest dynamics pattern is crucial for the enhancement of knowledge to the driving dynamics of forest dynamics. Forest dynamics data can be directly acquired through collecting stem growth data of each tree and shrub in the grand plot. This study is based on a forest stem database. Apart from basic data collection of forest growth dynamics, all stems in the plot were divided into 2 stages, saplings and grown trees, and investigated their responses to environmental factors. The aims of the study were to resolve the following questions:Which factors influence individual growth most? What similarity do the growth responses of various species to environment bear? Do environmental factors have a coherent impact on species of different growing stages? Former environmental and biologic database on the 20-ha plot were used in the study, as well as vegetation data from the 2014-2015 census. Non-parametric methods were applied to analyze environmental factors of different individuals.Concerning data of 30203 surviving grown trees and 52107 surviving saplings, it was found that in the 5 years interval, Tiantong 20-ha dynamic observation plot witnessed an increase in wood stems abundance (13.9%) and total basal area (by 3.6%), as well as a decrease in average basal area of individuals and a greater percentage of slim stems. Various species of deciduous trees considerably differentiated in basal area increment in the 5 years.Having studied the con-elation between surviving stem growth and environmental variables, the research found that among all topographic factors, elevation acted prominently on up to 85% of all species, while all edaphic factors had impacts on 55% species or so, and neighboring biotic environment would affect the growth of most species; among species that were prominently influenced by topographic factors, less kinds of grown trees existed than saplings on most factors. When saplings were prominently influenced, they performed a more consistent influence; only few species correlated their growth to environmental variables in both stages. For most species, prominence of the correlation of their growth to environment faded as the species grew up.