A Precisely Measuring Method And The Spatio-temporal Heterogeneity Of Forest Light Regimes

Light is a very important environmental factor in the process of plants’ growth. All living things on the earth depend on the sun for their growth. Plants accumulate organic matter by photosynthesis and provide food for other living things to ensure the entire ecosystems can operate orderly. Therefore, the study of light has been the focus and hot spots of the researches in the field of vegetation ecology. Studies of forest light environment have been widely spread throughout the world, and also have obtained a lot of important results. These results can be shown in two aspects:on the one hand is focusing on the measuring methods of forest light environment, and on the other hand is focusing on the changes of light in intensity and quality as well as the impact on the renewal of the forest vegetation caused by the changes of light environment. In spite of this, due to the subtropical evergreen broad-leaved forest has a concentrated distribution in our country, so the studies about forest light environment based on subtropical evergreen broad-leaved are still lagging behind. In view of this kind of background, our study took Tiantong forest 20 ha dynamic monitoring plot (hereinafter referred to as Tiantong forest dynamic plot) which located in Zhejiang province as the research object, with the help of information technology, we compared the measuring methods of forest light environment and analyzed the seasonal and spacial dynamics of forest light environment deeply. Through this study, we expect that we can grasp the light changes of central subtropical evergreen broad-leaved forest and prepare for the study on the relationship between light and plant distribution pattern. The results of our study are as follows:1) The method of RGB value based on WinSCANOPY, at the same time combined with the relationship between geological compass and camera position which can draw the path of the sun correctly and measure the slope and aspect of tiny terrain, optimized the measuring method of forest light regimes.2) We can not substitute canopy openness for forest radiation in the subtropical evergreen broad-leaved forest which has a higher forest canopy closure;3) There is a higher spatio-temporal heterogeneity of canopy openness and forest radiation at different sites in Tiantong forest dynamic plot.