Effect Of Gap Size, Soil Moisture And Light On The Plant In The Pinus-Koraiensis Broadleaved Mixed Forest

Pinus koraiensis-dominated broadleaved mixed forest is typical zonal forest vegetation of mountain area in the northeast in our country, But due to the heavy mining light foster in history, now the original Pinus koraiensis-dominated broadleaved mixed forest resources are dried up, so it is urgent to protect and restore Pinus koraiensis-dominated broadleaved mixed forest. Gap is an important part of forest regeneration as a process of the Pinus koraiensis-dominated broadleaved mixed forest ecosystem succession. But less studies on its internal mechanism, especially on the gap size effect on soil moisture, light, plant diversity of comprehensive research is very lack, This research will make up for the inadequacy of our country in this respect.Regard six gaps as research object in the Pinus koraiensis-dominated broadleaved mixed forest in this research. Within the designated large, medium, small gaps. Grid nesting method was employed, we used TDR to measured soil water content (SWC) continuously at different depths in the different gaps in Pinus koraiensis-dominated broadleaved mixed forest of Lesser Khingan between August and October in2011. The coverage and abundance of plants at different height level were measured within these quadrats by using estimation method, and their matrix characteristics were recorded. Overcast days were chosen, the Canopy Analyzer was used to take fish-eye photos. Relative light intensity, canopy openness were calculated by using Gap Light Analyzer2.0software. Based on the approach and theory of geostatistics to analyze spatial heterogeneity of soil moisture, the difference in relative light intensity, coverage and richness of plants between different size gaps, and the correlation between the coverage of each species and direct light, diffuse light, matrix were analyzed by SPSS19.0. Analysis on coverage differences of the different height levels species, and effect of coverage and canopy openness of plant on its density.The results showed that:Soil water content (SWC) was most abundant in middle gap, followed by large gap and small gap; Maximum differential of sample points was biggest in the large gap, followed by middle gap and small gap. The range of variation of nugget was:0.001-0.404,0.001-0.273,0.001-0.261, in the large middle small gap at different depths in different gaps between August and October in2011, respectively. The order of heterogeneity result from random part and system total space heterogeneity degree was:large gap>middle gap>small gap. Spatial distribution pattern was most complicated in the middle gap. High-grade patches occupied the largest area in the middle gap, followed by large gap. There is no high-grade patches distribution in the small gap. Level of distribution in the small gap is the most simple, and is relatively complex in the large gap and middle gap. The maximum of soil moisture increased with the gap size.In opening areas and under the canopy, total relative light intensity was higher in large gap than in small gap. Meanwhile, the variation range of diffuse light, direct light from the center to the edge in large gap was bigger than in small gap; the direct light reaching at the surface at different areas both in large gap and small gap was higher in the north than in the south; In the Z1, Z2, Z3and Z4zones, the order of coverage and richness of plants were:large gap>small gap, the differences of species richness between in large and small gaps reached significant level. In addition, their coverage for the majority of plants had significant correlation with diffuse light and matrix, only the coverage for a few plants were correlated with direct light. Canopy openness was high also plants was sparse where the density of Fagus sylvatica was high; on the contrary, canopy openness was low also the coverage of plants was high whereas the density of Fagus sylvatica was low.