| Taking the understory soil and litter of Larix principis-rupprechtii young,near mature and mature in Wangyedian Experimental Forest Farm as the research object,the effects of near natural management,conventional management and non management measures on the characteristics of understory soil and litter of Larix principis-rupprechtii plantation were investigated.The differences in soil physical properties,preferential flow characteristics,nutrient characteristics and litter characteristics of Larix principis-rupprechtii plantation under different management modes and different forest ages were compared and analyzed.Based on the measured data of each characteristic factor,the comprehensive evaluation index of water and fertilizer retention capacity of Larix principis-rupprechtii plantation was screened by principal component analysis,Norm value calculation and correlation analysis.The entropy weight method was used to comprehensively evaluate the water and fertilizer conservation capacity of Larix principis-rupprechtii plantation,in order to provide a theoretical basis for the management of Larix principis-rupprechtii plantation and the formulation of water and fertilizer conservation measures in the study area.The main results are as follows:(1)The soil bulk density of Larix principis-rupprechtii forest increased with the increase of soil depth,and the soil porosity showed the opposite change rule.The degree of soil looseness under different forest ages showed the trend of near-mature forest>mature forest>young forest.The average saturated water holding capacity of soil under different management modes showed the trend of near-natural management(558.60t/hm~2)>non-management(546.80t/hm~2)>conventional management(545.97t/hm~2).Different forest ages showed the order of mature forest>young forest>near-mature forest.(2)The variation of soil dyeing area ratio with soil depth in Larix principis-rupprechtii forest was well fitted with exponential function,and the determination coefficient R~2was greater than 0.95.The soil preferential flow fraction and length index of mature forest and near-mature forest were higher than those of young forest.The infiltration depth of soil matrix and the staining area ratio of preferential flow area under different management modes showed the trend of conventional management>near-natural management>non-management.(3)There is a big difference in soil nutrient content of Larix principis-rupprechtii forest.With the increase of soil depth,soil organic matter content showed a decreasing trend.The contents of soil organic matter,total nutrients and available nutrients under different management modes were the highest under conventional management measures,which were 47.58g/kg,28.99g/kg and 356.82mg/kg,respectively.The contents of soil organic matter and total nutrient in the three forest ages showed that the young forest was the largest,and the available nutrient content in the mature forest was the largest,which was 378.11 mg/kg.(4)The thickness and volume of litter in different decomposition stages showed a trend of semi-decomposed layer>undecomposed layer.The maximum water holding capacity,maximum water holding rate and effective interception of litter under different management modes of Larix principis-rupprechtii forest showed the order of non-management>conventional management>near-natural management.The maximum water holding capacity and effective interception capacity of litter under different forest ages were the highest in mature forest,followed by near-mature forest.(5)The non-management measures have the highest water and fertilizer retention capacity under the mature forest of Larix principis-rupprechtii.The comprehensive index of water and fertilizer conservation capacity of Larix principis-rupprechtii plantation under different management modes showed the change rule of near-natural management(0.7127)>conventional management(0.3374)>non-management(0.2318).Different forest ages showed the order of mature forest>young forest>near-mature forest. |
