| Due to the pit and mound microsites formed by treefall in the Pinus koraiensis-dominated broadleaved mixed forest, increased the complexity of the forest, promoted the regeneration ability of surrounding trees and grasses in the forest community, and improved the light, temperature, moisture and other environmental conditions of gaps at the same time. So the microsites formed by uprooting trees play an important role in maintaining forest species diversity and forest landscape pattern.This paper researched on characteristics, pattern and dynamic change in the microclimate of pit and mound complex within different size of forest gaps in Pinus koraiensis-dominated broadleaved mixed forest. An investigation was conducted in a2.25hm2plot of Pinus koraiensis-dominated broadleaved mixed forest to study basic characteristics of7small gaps,5middle gaps,3large gaps and7closed stand within pit and mound complex caused by treefall in May2012. From June to September2012, the soil temperature, soil water content and relative humidity on five microsites (mound top, mound face, pit wall, pit bottom and undisturbed closed forest) was measured for six sunny days on each month. We compared the differences of microclimate factors of different microsites on pit and mound complex in different mouths. We also compared the differences of microclimate factors of same microsites on pit and mound complex of different size gap and closed stand in different mouths. And then we analyze the dynamic change in the microclimate of pit and mound complex within different size of forest gaps in Pinus koraiensis-dominated broadleaved mixed forest. In August2013,we used tape to measure value for characteristics (pit width,pit depth, pit length, mound thickness, mound length, mound height, volume of pit and mound) of38pit and mound complex in sample plot, and then compared with the value for characteristics of2011. On the basis of group standard for the type of pit and mound complex presented by Beatty in1981, after careful observation and recognition, we confirmed the type (hinge or rational) and shape (semi-ellipse, triangle,:rectangle,lrregular) of pit and mound complex, we used10multiply by10grid method to confirm the coordinate of38pit and mound complex in sample plot. Finally, we use the intensity of pit and mound complex in sample plot compared with the intensity of region to confirm the pattern of pit and mound complex. Accordingly, we preliminary analysis the characteristics and pattern of pit and mound complex within different size of forest gaps.The result showed that from June to September, among five microsites in every month, mound top had the highest soil temperature while pit bottom have the lowest one, pit bottom had the highest soil water content and relative humidity but mound top had the lowest one. Mostly, the differences in the above indicators between five microsites were significant (P<0.05). From June to September, total mean of soil temperature for all microsites at pit and mound complex in various gaps and closed stand was in the order of large gap>middle gap>small gap>closed stand; but soil water content ranked in different order every month; In June, August and September, total mean in relative humidity for all microsites at pit and mound complex in various gaps and closed stand was in the order of closed stand>small gap>middle gap>large gap, but it is in another different order in July. Mostly, the differences in the above indicators between all microsites at pit and mound complex in various gaps and closed stand was significant (P<0.05). The mean monthly soil temperature and relative humidity were highest in July, but lowest in September. Except that maximal mean monthly soil water content occurred in June in undisturbed closed forest, in July in the other microsites, minimal one was present in September. From here we see that dynamic change in the microclimate of pit and mound complex were caused by microsites, size of gap and season.The mean length of pit width, pit depth and pit length were larger than the mean length of mound thickness, mound length and mound height of pit and mound complex in small gap, middle gap, large gap and closed stand. In the numerical, the large gap has the biggest one,2.85meters,0.37meters,2.00meters,2.99meters,2.10meters,0.39meters,respectively.the closed stand has the lowest one,2.35meters,0.19meters,1.60meters,2.66meters,1.65meters,0.21meters,respectively. The volume of mound were larger than pit. The characteristic value of different microsites on pit and mound complex in different size gap and closed stand were significant differently, but it was almost significant. The characteristic value of pit and mound complex in different size gap and closed stand was almost significant. The characteristic value of pit and mound complex in2011and2012was almost significant. The characteristic value of pit and mound complex in2011were larger than2012. The frequency of hinge pit-mound and ellipse pit-mound was biggest in sample plot,89.47%and60.53%respectively. The distribution of pit and mound complex in sample plot was relatively centralized. |
