| Phyllostachys edulis is an important part of forest in southen area of China, and it has an imporantan economic value, so the reasrch focuses on high yield cultivation techniques and high yield mode and so on. But some study showed that phyllostachys edulis kept expansion and pure because of its strong proliferation, and this leaded to a reduction of biological diversity, and the single of landscape structure. But the study of the reasons of its pure is still rare, and the tree growth and renewal have a close relationship with light factors, so the influence of the changes of light environment on the woody plant in phyllostachys edulis stands is an important theoretical significance for the study of pure of phyllostachys edulis stands. It has practical significance for reasonable management of phyllostachys edulis forest and protection of species diversity in reserves.This study setted the plots in Tianmu mountain nature reserve, monitored the light intensity in needle board leaved mixed forest, needle board leaved-bamboo mixed forest and phyllostachys edulis forest with Quantum Meter and wireless sensor network(WSN), detected the light compensation point (LCP) of the main trees and shrubs in three different plots with Li-6400 to analyse the influence of changes of light intensity on the photosynthesis of trees and shrubs; analysed their respective absorbance with Spectrophotometer UV-2550 to compare them with the absorption spectrum of bamboo leaves.The result shows:1. There are three characteristics in the Changes in lght intensity as the follow: (1) The variety of light intensity in a single sunny day was bimodal cure, the peak showed at 14:00 and 16:00; (2) The light intensity reduced 10μmol·m-2.·s-1 in needle board leaved mixed forest, 37.6μmol·m-2.·s-1 in needle board leaved-bamboo mixed forest and 35μmol·m-2.·s-1 in phyllostachys edulis forest as the month change; (3) The light intensity in different plots was phyllostachys edulis forest > needle board leaved-bamboo mixed forest > needle board leaved mixed forest, and the minimum of sunny average daily light insity was 9.8μmol m-2 s-1 in needle board leaved mixed forest.2. The light compensation point of Moso bamboo is the highest, followed by Liquidambar formosana, fir, fir seedlings, Eucommia ulmoides Oliver, and Camellia Oleifera. The light compensation point of these plant species are 19.6μmol·m-2.·s-1, 14.3μmol·m-2.·s-1, 9.77μmol·m-2.·s-1, 9.76μmol·m-2.·s-1, 8.94μmol·m-2.·s-1,and 3.07μmol·m-2.·s-1 respectively.3. Comparison of the light intensity and light compensation point of main plant species shows the light intensity is not under the light compensation point of main plant species during the process of phyllostachys edulis expansion. Therefore, the photosynthesis of main plant species is still stronger than their respiration, which means there is enough nutrition to sustain their growth. Change in light intensity has no influence on growth of main plant species. However, increase in light intensity will impact on fir regrowth because the fir seedlings are apt to shade condition.4. The plant absorbs the same range of visible light, and the peak values locate at 665nm and 435nm.The absorption was different, Eucommia ulmoides > phyllostachys edulis > Chinese sweet gum > China fir sapling > China fir > Camellia oleifera, at both the two peaks. The growth of plants that absorption ability was lower than phyllostachys edulis would be effected by the expansion of phyllostachys edulis. Camellia oleifera can absorb and use ultraviolet radiation, it may get less effect. |
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