Study On Water Conservation Capacity Of Typical Forest Types In The Upstream Miyun Reservoir

The quantity of inflow of Miyun Reservoir,which is an important water sources in Beijing,has a downward trend.In order to provide reference and data support for the protection,transformation and reconstruction of existing forests based on actual ecological needs and long-term afforestation planning,this study selected six typical forests of Populus,Juglans regia,Castanea mollissima,Pinus tabulaeformis,Platycladus orientalis and Vitex negundo as objects in the upstreamof Miyun Reservoir.The litter amount investigation,water immersion test,soil physical and chemical properties measurement and double-ring infiltration test were carried out to compare and analyze the water conservation capacity of the litter layer and the soil layer,then the principal component analysis method was used to comprehensively evaluate the water conservation capacity of stands..The results show:(1)The order of the litter amount in 6 stands is Populus>Juglans regia>Pinus tabulaeformis>Castanea mollissima>Platycladus orientalis>Vitex negundo.Populus has the largest water holding capacity and effective storage capacity,followed by Pinus tabulaeformis and Juglans regia,Castanea mollissima and Platycladus orientalis coming along,and the smallest is Vitex negundo.The maximum water holding rate and effective intercepting rate are in descending order of Populus>Castanea mollissima>Juglans regia>Pinus tabulaeformis>Platycladus orientalis>Vitex negundo.(2)The effective water holding capacity of different stands from 0 to 60 cm was Populus>Pinus tabulaeformis>Vitex negundo>Castanea mollissima>Platycladus orientalis>Juglans regia;the water holding capacity of the capillary was Castanea mollissima>Juglans regia>Populus>Platycladus orientalis>Pinus tabulaeformis>Vitex negundo;the maximum water holding capacity from large to small in order is Populus>Castanea mollissima>Pinus tabulaeformis>Juglans regia>Platycladus orientalis>Vitex negundo.With the increase of water immersion time,the soil infiltration rate of the six stands showed a trend of decreasing first and then stabilizing.(3)The maximum water holding capacity of the six different stands was from Populus>Castanea mollissima>Pinus tabulaeformis>Juglans regia>Platycladus orientalis>Vitex negundo.The effective water holding capacity from pop to small was Populus>Pinus tabulaeformis>Vitex negundo>Castanea mollissima>Juglans regia>Platycladus orientalis.Principal Component Analysis(PCA)analysis showed that the water conservation capacity order was Populus>Pinus tabulaeformis>Castanea mollissima>Juglans regia>Vitex negundo>Platycladus orientalis.Among the six types of stands,Populus,Pinus tabulaeformis and Castanea mollissima have a better water conservation capacity.This study is expected to promote the scientific management of existing water conservation forests in the upstream of Miyun Reservoir,and provide support and reference for the protection and transformation of water conservation forests in the upstream of Miyun Reservoir.