Effects Of Stand Factors On Spatial Heterogeneity Of Litter Properties

In the forest ecosystem,the spatial heterogeneity of litter properties and stand factors was less studied compared to soil properties.In order to explore the influence of stand factors on the spatial heterogeneity of litter properties,four 1 hm2 plots of natural mixed spruce-fir forests in Jingouling Forest Farm,Wangqing County,Jilin Province were selected for litter collection and stand survey.The standing crop,moisture content,organic carbon content of litter in semi-decomposed(F)and compete decomposed(H)horizons were determined and stand density,forest canopy density and leaf area index were calculated for the semi-variance function analysis and correlation analysis.The spatial distribution pattern of the above indicators was also drawn.This study will help to clarify the status of litter in forest ecosystem and understand its role in material cycle and energy flow so as to provide a theoretical basis for sustainable development of forests.The main results and conclusions are as follows:(1)The standing crop of litter in the F and H horizons was 17.42-22.46 t·hm-2 and 6.73-13.93 t·hm-2 and the total was 25.18-31.34 t·hm-2;the moisture content of litter was 61.55-68.15%and 146.44-182.37%,and organic carbon content was 377.58-453.22 g·kg-1 and 321.32-368.89 g·kg-1 in the F and H horizons,respectively.There were significant differences between the F and H horizons as for these three litter properties.(2)Litter standing crop showed a patch structure with similar pattern in the F horizon and for the total;Moisture content in the F horizon had no difference in large-area color,which may be due to more susceptible to weather,whereas it had a patch distribution in the H horizon;the spatial pattern of organic carbon was diverse but with a clear directional trend,and a stronger autocorrelation was found in the H horizon.(3)In order to fit the principle of spatial heterogeneity,we introduced the concept of point stand density and compared it with traditional stand density.The point stand density can be used for the study of spatial heterogeneity.(4)Litter standing crop in the H horizon of plot 1 and 4 were significantly and positively correlated with forest canopy density(r=0.218,P=0.029;r=0.208,P=0.038);litter standing crop in the F horizon of plot 4 was significantly and positively correlated with point stand density(r=0.282,P=0.004),and was significantly and negatively correlated with the leaf area index(r=-0.265,P=0.008).There was a significant negative correlation between litter moisture content and point stand density in the H horizon of plot 1 and 2(r=-0.238,P=0.017;,r=0.246,P=0.014),and a very significant negative correlation was found in the H horizon of plot 4(r=-0.330,P=0.001);litter organic carbon content was not correlated with forest canopy density,point stand density and leaf area index in all four plots.