| By means of quantitative analysis methods, the author has investigated the stand composition, canopy interception, water-holding capacity of litter layer and transpiration rate of Quercus aquifolioide in upper reaches of Minjiang area. Meanwhile, the effects of stands were studied on rainfall redistribution process and water usage process, in order to understand hydrological adjustment mechanism of that forest type. The research results could be used as a reference to the conservation of natural subalpine forest and the promotion of soil and water conservation of shrub forest. The main conclusions are described as follows:(1)As the altitude increasing, the richness of shrubs and grasses in Quercus aquifolioide forest decreased. In the low altitude area, Jaccard index which represents the community similarity was smaller than that in the higher altitude community, but there existed a trend of the Cody index which represents species substitution situation. Quercus aquifolioide shrubs distributed in a clumped horizontal pattern. The stand density increased with the increase of altitude, while the tree height significantly decreased as the altitude increased.(2) The total 50 rainfall events were recorded from June to September in 2006, and the total rainfall were 486.7mm, the canopy interception, stem flow and throughfall values were 80.2mm, 4.53mm and 402.0mm respectively. The canopy interception rate, stem flow rate and throughfall rate were 16.5%, 1.02%, 82.6% respectively.(3)There existed a significant linear correlation between the canopy interception, throughfall, stem flow and precipitation, while a logarithmic relationship between canopy interception rate, stem flow rate and precipitation, an exponential relationship between throughfall and the precipitation.(4)The maximum litterfall biomass of Quercus aquifolioide forest occurred in June and October, and presented a seasonal change: summer>fall>spring>winter. There existed a great difference of the litter biomass in all forest communities among different seasons as September>July>May. The percentage of the litter biomass in undecomposed layer was always smaller than that of the half-decomposed and decomposed layer.(5) There was a logarithmic relationship between water-holding capacity of litter and saturation time.(6)The sap flow of Quercus aquifolioide tree in upper reaches of Minjiang River area showed an obvious daily dynamics. Sap flow was significantly different among different basal diameter trees.(7)The monthly sap flow of Quercus aquifolioide increased from June to September. The result of relationship analysis showed that there existed different relationship coefficients between environmental factors and the sap flow flux: relative air humidity>solar radiation intensity ahead of 10 minutes>simultaneously radiation intensity>wind velocity>air temperature>soil moisture below 20cm. The change of the sap flow lagged the change of the solar radiation.(8)In the growth season, daily average accumulated sap flow increased with the increase of basal diameter of Quercus aquifolioide, and daily average sap flow flux accumulation varied significantly among trees with different basal diameters. The accumulated sap flow flux accumulation apparently increased with all basal diameter grades in August and September. |
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