Spatial Distribution Of Aboveground Biomass Of Shrubs In Tianlaochi Catchment Of The Qilian Mountains

Biomass is gross organic matter per unit area in some time, manifestation ofecosystem structure and its function, important symbol of carbon fixation quantity ofvegetation and important parameter of the assessment of vegetation budget. It issignificant to determine biomass in the research of carbon cycle and climate changeand so on. Shrub is an important part of forest vegetation types of Qilian Mountain,which mainly distributed in middle and lower mountain desert belt below an altitudeof2800m and alpine region above the altitude of3000m, the distribution area ofwhich takes71.5%of Qilian Mountain forestry land, which plays an important part inforest system protection, biodiversity, conservation of water and soil, especially waterconservation. But at present, there are a few systematical studies on the shrub biomassmodel of Qilian Mountain and the space distribution feature of biomass is to bedefined. Therefore, this thesis focuses on the study of typical shrubs of Tianlaochiwatershed of Qilian Mountain, such as Potentilla fruticosa, Caragana jubata, Salixgilashanica and Spiraea alpine. First established relationship between shrub aboveground biomass and feasibly measured factors with quantitative model, then builtmodel according to the quadrat data of total shrub aboveground biomass, coverdegrees and quadrat area, combining to the high resolution image Geoeye-1toestimate the total shrub aboveground biomass in the research district, and analyzedthe spatial distribution rule of shrub aboveground biomass in elevation gradient andslope, in this way, to provide scientific basis for Qilian Mountain vegetationprotection and recovery and accurate estimates of shrub aboveground biomass andcarbon reserve. Major findings of the study are as follows:1. An estimation model W=a+b（P2H） was established with the product（P2H）of squareof canopy circumference （P） and its height（H） as variables to estimate theaboveground biomass of shrub, which reaches good imitative effect, coefficientdetermination is R2>0.8; The absolute value of average relative error （RMA） and totalrelative error （RS） of four types of aboveground biomass estimation model is less than20%, with higher model accuracy. 2. Establish the relationship model between quadrat of shrub aboveground biomass（Ws）, quadrat of shrub distribution area and cover degree:Ws=793.692S0C2+496.8312S0C+188.79（R2=0.629,F=289.697,P<0.05）, the totalrelative error is5.67%, the absolute value of average relative error is17.89%. Toclassify high-resolution image GeoEye-1in accordance with object-orientedclassification method, extract the shrub coverage factor and shrub area, figured outthat shrub biomass of the research district is1.8x10³t, per unit area·biomassis1598.45kg·hm^-2.3. The above-ground biomass of shrub is mainly distributed at the altitude of3000m-3700m. As the altitude rises, the shrub above-ground biomass of sunny slopefollows a unimodal curve and shady slope follows wave curve that decreases first thenincreases, decreases again, and that maximum biomass are12101.6g hm^-2and5130.2kg·hm^-2,respectively located at the altitude of3200m and3400m.4. The space distribution of shrub above-ground biomass in slope aspect, sunny slope（1.15×10³t）>shady slope（0.65×10³t）. The four shrub biomass in the sunny sloperanks: Potentilla fruticosa(3653.57kg·hm^-2)>Caragana jubata(2220.13kg·hm^-2)>Salix gilashanica(319.4kg·hm^-2)>Spiraea alpina(193.87kg·hm^-2).And the four shrubbiomass in the shady slope ranks: Caragana jubata(4510.11kg·hm^-2)>Potentillafruticosa(1549.01kg·hm^-2)>Salixgil ashanica(1235.05kg·hm^-2)>Spiraea alpina(111.23kg·hm^-2).