Study On Hydrological Characteristics Of Forest Ecosystem In Daxing'anling

In the dissertation,the main purpose is the influence of different forest types to hydrological characteristics in south and north of Daxing'anling.Among months 7-10 in 2006 and months 5～10 in 2007 we choose 12 forest types in south Daxing'anling and 5 forest types in north Daxing'anling as research object.Position research is applied as main method in the paper,Atmosphere,plant and soil subsystems are three major research spaces.Through researching rainfall characteristics,canopy interception characteristics,water retention characteristics of litter,soil infiltration characteristics,water chemical characteristics,to disclose the relationship between forest and hydrological functions and eco-hydrological functions of Daxing'anling Mountains.These researches are conducive to accurate appraisal of forest functions of Daxing'anling Mountains,to provide theoretical proofs for natural forests protection project at Daxing'anling as well as technological supports for local forest management.Main research results:(1)Results indicate that the biggest canopy interception is Larix gmelinii for 16.93mm,it is increasing with rainfall.Rainfall inside forest accounts for about 70%of rainfall.There is an obvious linear correlation between them,equation is y=ax-b,R~2 is bigger than 0.9.which can be used to make simulation model or forecast rainfall inside forest.Rainfall inside forest for Betula plytyphyla is the highest,rainfall inside forest of broad-leaves forest is higher than that of conifers.Stem runoff volume only accounts for less parts,the biggest stem runoff volume accounts for 2.11%of the total rainfall,the least stem runoff volume accounts for 0.35%of the total rainfall.There is a linear correlation between stem runoff and rainfall,but the close degree is less than that of relation of rainfall inside forest and rainfall.Stem runoff volume of Pinus korensis is the biggest,and Larix gmelinii is smallest.(2)The accumulated mass of litter of Grass-Larix is the biggest for 48.46t/hm~2 in south Daxing'anling.The accumulated mass of litter of half-decomposed layer is bigger than that of undecomposed layer.There was greatly absorption amount in the first 4 hours for the water-holding of the litter, then the water-absorption extent is getting less and reach saturation in 20 hours.The absorption processe of different forest litter is different,but there is a similar trend.The relation between water-holding amount of different forest litter and soaking time is y = aLn(x)+b,correlation index is bigger than 0.8.(3)The change range of soil water-holding capacity are between 6.17%-39.78%.The soil water-holding capacity of Larix gmelinii is highest for 39.78%.The soil water-holding capacity of upper layer is higher than deep layer.The soil water-retaining capacity of Betula-Larix gmelinii is biggest for 892.00mm,the soil available water-retaining capacity of Pinus sylvestris is biggest for 249.07mm.The deeper the soil is,the bigger the soil bulk density is, the less the soil non-capillary porosity is,the smaller the soil available water-retaining capacity is.The deeper the soil layer is,the bigger the soil bulk density is,the smaller the soil porosity,soil capillary porosity,soil non-capillary porosity is.soil bulk density of Grass-Larix is the biggest in all forest types in south and north Daxing'anling,betulla is second;soil non-capillary porosity of betulla is the biggest for 14.52%,the smallest is Grass-Larix for 7.09%in south Daxing'anling;soil non-capillary porosity of oak-Larix is the biggest for 14.15%and the smallest is Grass-Larix for 10%in north Daxing'anling.The soil infiltration processes is similar for different forest types,soil infiltration rate is decrease with the time increase,and gradually tend to stability.The soil infiltration rate,average infiltration rate and firm infiltration rate is between 15.9～48.2mm/min,6.27～22.83mm/min, 2.7-12.1mm/min.The soil infiltration rate,average infiltration rate and firm infiltration rate of fir is biggest,the bigger the soil bulk density is,the smaller the soil non-capillary porosity is,the smaller the soil firm infiltration rate is.Comparing two modal show that,Kostiakov modal has better effect in simulating soil infiltration.(4)In growing season,the content of macroelements,including K,Na,Ca,Mg,P,N accounts for 100%of the total nutrient input,the content of K accounts for 46%of the total nutrient input.According to nutrient input,macronutrients order are K＞N＞Ca＞Na＞Mg＞P. micronutrients order are Fe＞Mn＞Cu.the nutrient content of of rainfall belong to middle and higher,but because the less rainfall in the area,the nutrient content of rainfall in the total nutrient input of per year is lower.The Mg content of rainfall inside forest of Oak is 8 times higher than in rainfall.K content of stem flow of Larix gmelinii is highest for 42.601mg/L and is 6 times higher than in rainfall. Some nutrient content in rainfall inside forest and stem flow is lower than in rainfall.Nutrient content of stem flow is relatively higher than that of precipitations inside and outside forest.The monthly change of Na content of rainfall inside forest of Oak is bigger,Na content in July is 24.8 times higher than in August,monthly change range for 0.427mg/L～10.61mg/L; The monthly change of Na content of stem flow is bigger,in June it is 6.8 times higher than in May,monthly change range for 0.63mg/L～4.3mg/L.K,Cu,Mn,N,P of rainfall inside forest of Betula is highest;Ca,Mg of Populas- Betula is highest;Na,Fe of Oak is highest.K,Fe,Mn,P of stem flow of Larix is highest, Na,Ca,Cu,N of Oak is highest,Mg of Populas-Betula is highest.