Improvement Of Crown Interception Model Based On Vegetation Structural Parameters

Vegetation structure of dark coniferous stands in Gongga Mountain has important affect on its ecosystem precipitation interception.The paper hereby will employ plant canopy imager(CI-110),principles of fractal geometry,pipe model,landscape ecology and geo-statistic to describe the structural features in Abies fabric dark coniferous ecosystem on individual and community scale. Some statistical models about their structural parameters and interception storage had been initiatively established,including pipe parameter,leaf area index(LAI) and fractal dimension of crown projection patch,based on the analysis of single vegetation structure and forest ecosystem pattern.Through the establishment of the statistical equations between the above-mentioned three vegetation parameters and transmissibility coefficient,the structural parameters was integrated into the Gash model to simulate the 24 rainfall interception calculation of the over-matured dark coniferous stands in Gongga Mountain,then,made the error analysis.Results showed that the pipe parameter,representing the capability of stem and branch to brace foliages,was linearly correlated to canopy interception storage;While LAI of a community standing for the interception capability of community at unit area was also linearly correspond to canopy interception storage.Comparing with crown's closure,the fractal dimension of crown projection patch described its spatial arrangement in more detail,and it was linearly correspond to throughfalls.The linear equation of rainfall and throughfalls was y=1.157x+2.1737(r~2=0.9923) and the water holding capacity of the branches and leaves of over-matured stands was 1.4491mm while the stem was 0.7246mm through the intercede of the equation.The regression equation between transmissibility coefficient and the above-mentioned three vegetation parameters was P=0.78e-1.72F(R~2=0.9761),P=-0.38(FD)+1.34(R~2=0.851) and P=-0.37(LAI)+2.74(R~2=0.7896),which could integrate into the interception model well.From the comparison of the simulative error rate:F＜LAI＜FD,which betrayed that the parameter of the pipe model F could more clearly reflect the influence of vegetation structures on interception.