| In Dengsheng Long-term Ecological Research Station located in Wolong nature reserve of Sichuan Province,the water resources conservation function of four types of forests have been investigated such as Quercus aquifolioide,Shrub-bamboo, Broad-leaved and Abies faxonian,including return quantity of litter,interception rate of canopy and water-holding capacity of litter layer.Some basic data and results have been also made useful for the comprehensive evaluation on ecological function in Wonglong nature reserve.Some main conclusions were described as follows:(1)Leaf area indexes (LAI) of Quercus aquifolioide forest, Shrub-bamboo forest Broad-leaved forest and Abies faxonian forest in research area were measured by the capopy analysis instrument as follows:(2.54±0.11),(4.04±0.25),(3.29±0.10) and (2.80±0.08).LAI of Shrub-bamboo forest was the highest and the lowest in Quercus aquifolioide forest,and there existed remarkable differences among the LAI values of four types of forest stands(F(23.478)>F0.01(3,63)).(2)The total annual litterfall quantity of Quercus aquifolioide forest increased by 391.5kg·hm-2 and 1019.6 kg·hm-2,in comparison with those of Shrub-bamboo forest and Abies faxonian forest respectively.It was indicated the arid microhabitat of sunlight slope was good for return and circling of nutrients. The changing trends of annual lifferfall fluxes of three types of forests were similar. The annual litterfal fluxes of three types of forests were mainly distributed by leaves and branches. The return patterns of those forests in seasonal litterfall fluxes were different.The seasonal litterfall fluxes of Quercus aquifolioide forest showed in order: summer> autumn>spring>winter;and the Shrub-bamboo forest showed in order: autumn> winter>summer>spring respectively,but the Abies faxonian forest presented no remarkable difference in seasonal litterfall fluxes.The monthly dynamics of litterfall fluxes of three types of forests were also different.The maximum litterfall accumulation of Quercus aquifolioide forest appeared in June and October,and that of the Shrub-bamboo forest did in October,but the Abies faxonian forest didn't present any peaks.(3)The results indicated that the average canopy interception was 278.2 mm, 362.1mm, 353.7mm, and the average canopy interception rate accounted for 35.77%, 46.55%,45.47% in Quercus aquifolioide forest,Shrub-bamboo forest and Abies faxonian forest respectively.The stem-flow quantity or rate of Abies faxonian forest was 5.9mm or 0.76% respectively.The canopy interception,throughfall and stem-flow were significantly correlated with annual precipitation; meanwhile the regression models between canopy interception, throughfall, stem-flow and rainfall were simulated.(4)The litterfall amount of four types of forest community presented obvious difference in different periods of growing season,which ranged from 10.00t·hm-2 to 25.20t·hm-2.The maximum effective water-holding capacities of the whole litter layer of four forest communities were very high,and the maximum effective water-holding depth was ranged in order:Abies faxonian forest(5.33mm)> Broad -leaved forest(3.82mm)>Quercus aquifolioide forest(3.17mm)> Shrub-bamboo forest(2.70mm).The correlation analysis results indicated that there existed an extremely definite relationship between the maximum water-holding amount of litter and its dry weight,and a significant relationship between that and the maximum water-holding ratio of litter,but no relationship between that and LAI of forest communities.Both logarithm and power function relationship were presented between water holding capacity and water-immersing time, water absorption velocity and water-immersing time in four types of forest communities respectively.
|
PDF Full Text Request