| Vegetation is closely related to water and soil loss,and different vegetation types,community structure and species composition play different roles in controlling soil erosion.By selecting four different vegetation types of bare land(contrast),grassland,shrubbery and secondary evergreen broad leaved forest in Paiyang Mountain Forest Park,this paper studies their effects on soil erosion on sloping land.The research results are as follows:(1)Through the determination of soil characteristics,the soil bulk density of bare land in the study area was 1.15g/cm~3,and the soil moisture content was 34.28%;The soil bulk density of grassland was 1.14g/cm~3,and the soil moisture content was 31.80%;The soil bulk density of shrubbery was 1.04g/cm~3,and the soil moisture content was 38.82%;The soil bulk density of evergreen broad leaved forest was 0.90g/cm~3,and the soil moisture content was30.10%.The unit weight was:bare land>grassland>shrub>evergreen broad-leaved forest;The soil moisture content was:shrub>bare>grassland>evergreen broad-leaved forest.The total soil water storage capacity in evergreen broad-leaved forest is the largest,5940t/hm~2,while the total soil water storage capacity in bare land is the smallest,5380t/hm~2.The total soil water storage capacity in bare land is:evergreen broad-leaved forest>shrub>grassland>bare land.(2)During the observation period,a total of 47 rainfall data were collected in the study area,and the total rainfall outside the forest was 1385.27mm.The through fall rate of different vegetation types was as follows:shrubbery(85.91%)>evergreen broad-leaved forest(76.73%)and>grassland(74.04%);The canopy interception rate was:grassland(25.96%)>evergreen broad-leaved forest(11.20%)>shrubbery(7.40%).(3)There is a linear proportional relationship between the rainfall of bare land and the through fall of other three vegetation,showing a"J"curve.The variation coefficient of through fall decreases with the increase of rainfall and then tends to a fixed value.The critical rainfall of green broad-leaved forest,grassland and shrub was 50 mm,30mm and 10mm respectively.Through the comparative analysis of the clearing shrub layer of evergreen broad-leaved forest with simulated anthropogenic interference,it was found that its effect on through fall was not significant(P>.05).Trunk flow was positively correlated with bare land rainfall,rainfall intensity and DBH of trees;The fitting equation indicates that the relationship between canopy interception and bare land rainfall was binomial or logarithmic,and the relationship between canopy interception and rainfall is a logarithmic function.(4)Compared with bare land,the effect of slope runoff on different vegetation was as follows:shrub(60.23%)>grassland(36.63%)>evergreen broad-leaved forest(33.43%).The runoff increasing effect of human disturbance on slope under evergreen broad-leaved forest was as follows:removing litters layer(169.79%)>removing shrub layer(16.50%),and the difference between the two reached a significant level(P<0.05).The fitted equation demonstrates that the slope runoff is positively correlated with the bare land rainfall and rainfall intensity;By using the grey relational analysis,the ranking of factors that influence the higher degree of association of slope runoff was obtained as follows:rainfall(0.75)=average rainfall intensity(0.75)>litter biomass(0.64).(5)Compared with bare land,the sediment reduction effect of different vegetation was as follows:evergreen broad-leaved forest(80.33%)>grassland(63.80%)>shrub wood(58.29%).The sequence of the sand-increasing effect of human disturbance under evergreen broad-leaved forest was:cleared the shrub layer group<cleared the litter layer.There was a positive correlation between monthly rainfall and monthly sediment loss of different vegetation types.Under the rainstorm intensity,the sediment loss of evergreen broad-leaved forest and bare land was more sensitive than that of grassland and shrubbery.The control effect of soil loss in evergreen broad-leaved forest weakened significantly under the condition of high-insensitive rainstorm. |
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