Comprehensive Evaluation Of Water Conservation Function Of Typical Forest Types In Country Parks In Shanghai

In order to improve the management level of forest resources in country parks in Shanghai,and improve the ability of forest ecosystems to conserve water and maintain soil and water,give full play to the ecological conservation function of country parks.This paper took the Pujiang Country Park as a test site,selected five typical artificial pure forests(the Cinnamomum camphora forest;Osmanthus fragrans forest;Koelreuteria paniculata foerst;Sapindus mukorossi forest and Taxodium ascendens forest)as the research objects,and water conservation function of forest canopy layer,litter layer and soil layer were studied and analyzed respectively.Finally,AHP and TOPSIS methods were used to comprehensively evaluate the water conservation functions of five forest stands,which provided the theoretical basis for the transformation and management of stand structure.The main results are as follows:(1)The result of the canopy study was that the stem flow rate of the four forest stands were between 3.28%and 12.55%,Koelreuteria paniculata foerst>Sapindus mukorossi forest>Taxodium ascendens forest>Cinnamomum camphora forest.The Canopy interception rate of the five forest stands ranged from 10.54%to 56.75%,Osmanthus fragrans forest>Cinnamomum camphora forest>Taxodium ascendens forest>Sapindus mukorossi forest>Koelreuteria paniculata foerst.The results showed that Osmanthus fragrans forest and Cinnamomum camphora forest had the strongest ability to intercept rainfall,followed by Taxodium ascendens forest,and Sapindus mukorossi forest and Koelreuteria paniculata foerst were the worst.(2)The result of litter layer research was that the accumulation of litter of the five foerst stands were between 5.32 and 16.42 t/hm~2,Taxodium ascendens forest is the largest and Cinnamomum camphora forest is the smallest.The maximum water-holding rate was between183.18%and 272.17%,Sapindus mukorossi forest>Koelreuteria paniculata foerst>Taxodium ascendens forest>Cinnamomum camphora forest>Osmanthus fragrans forest.The water-holding capacity of the litter and the immersion time satisfied the Logarithmic function relationship,and the water absorption speed rate and the immersion time satisfied the Power function relationship.The maximum water-holding capacity of litter was between 10.39 and 37.83t/hm~2,which was equivalent to the water depth of 1.04 to 3.78mm.The modified interception amount of litter in the five forest stands was between 7.74 and 27.90 t/hm~2.The orders were Taxodium ascendens forest>Sapindus mukorossi forest>Osmanthus fragrans forest>Koelreuteria paniculata foerst>Cinnamomum camphora forest.The results showed that the litter layer of Taxodium ascendens forest had the strongest water-holding capacity,and Cinnamomum camphora forest was the weakest.(3)The results of soil layer study showed that the soil bulk density of the five forest stands were between 1.42 and 1.46 g/cm~3,and Osmanthus fragrans forest and Cinnamomum camphora fores were larger than the other three forest stands.The total porosity of soil was between 42.23%and 43.25%,Taxodium ascendens forest was the largest,and Cinnamomum camphora forest was the smallest.The non-capillary porosity of soil was between 1.75%and2.90%,Koelreuteria paniculata foerst was the largest,and Osmanthus fragrans forest was the smallest.The saturated water storage capacity of 0~60cm soil was between 2 533.54 and 2 595.06t/hm~2,Taxodium ascendens forest>Osmanthus fragrans forest>Koelreuteria paniculata foerst>Sapindus mukorossi forest>Cinnamomum camphora forest.The effective water storage capacity of 0~60cm soil was between 104.87 and 174.01t/hm~2,Koelreuteria paniculata foerst>Sapindus mukorossi forest>Cinnamomum camphora forest>Taxodium ascendens forest>Osmanthus fragrans forest.The 10°C stable permeability coefficient of soil was between 0.37and 0.48 mm/min,Koelreuteria paniculata foerst>Taxodium ascendens forest>Osmanthus fragrans forest>Sapindus mukorossi forest=Cinnamomum camphora forest.In general,the soil water storage and infiltration capacity of Taxodium ascendens forest was the strongest,and Cinnamomum camphora forest was the weakest.(4)The comprehensive evaluation results of water conservation functions of five forest stands showed that Taxodium ascendens forest(0.6606)?Koelreuteria paniculata foerst(0.4508)?Sapindus mukorossi forest(0.3787)?Cinnamomum camphora forest(0.2937)?Osmanthus fragrans forest(0.2388).The results showed that the deciduous conifer forest stand had the best water conservation function,followed by the deciduous broad-leaved stand,and the evergreen broad-leaved stand was the worst.