Carbon Storage And Its Influencing Factors In The Grassland Ecosystems Of Qinghai Lake Basin

Accurate understanding of size and influencing factors of the above-ground biomass,under-ground biomass and soil carbon(C)storage is critical for predicting the response of terrestrial ecosystem to climate change,and it is also helpful for making the strategies to global climate change.Qinghai Lake is the seventh largest inland lake around the world and has an important impact on the environmental and sustainable development of Tibetan Plateau.However,little research on carbon storage and influencing factors is avaible in the Qinghai Lake,Basin.From 2012 to 2013,52 sampling plots were selected in Qinghai Lake Basin for the measurement of plant biomass.In addition,30 of 52 sampling plots were selected for the collection of underground biomass and soil.Based on the field data,laboratory analysis data,remote sensing data and meteorological data,and with the classical statistical method and Kriging Interpolation method,the size,spacial distribution and influencing factors of C storage in vegetation and soil were investigated.The main results are as follows:1.Based on the field data,the above-ground biomass of alpine meadow,alpine steppe,temperate steppe and temperate desert steppe in Qinghai Lake Basin were 106.4 g/m2,84.3g/m2,126.1 g/m2 and 68.3 g/m2,respectively,while the under-ground biomass were 5145.2 g/m2,3373.8 g/m2,2296.4g/m2 and 2416.7 g/m2,respectively.The total biomass was 5251.6 g/m2,3458.1 g/m2,2422.5g/m2 and 2485.0 g/m2,respectively.The carbon storage in the under-ground biomass accounted for 97.1%,97.5%,93.9%and 95.6%of the carbon storage in the vegetation,respectively.2.Affected by the megarelief around the Qinghai Lake Basin,temperature and precipitation had no significant effects on the above-ground and under-ground biomass.However,when the precipitation was over 400 mm,the average temperature in growing season exerted a significant impact on the aboveground and under-ground biomass,and a quadric relationship was observed.With the increase of altitude,the above-ground and under-ground biomass changed significantly,and the correlation between altitude and the biomass could be explained by a mono-peak curve(p<0.05).Enclosure could increase the above-ground and under-ground biomass(p<0.05),and significantly reduced root/shoot ratio(p<0.05),it also increased the proportion of Gramineae in the total biomass(p<0.05).3.The soil organic carbon(SOC)density of alpine meadow,alpine steppe,temperate steppe and temperate desert steppe in Qinghai Lake Basin were 10.11 kg/m2,6.88 kg/m2,5.50 kg/m2 and 4.33 kg/m2,respectively.And total nitrogen density of alpine meadow,alpine steppe,temperate steppe and temperate desert steppe were 1.01kg/m2,0.69 kg/m2,0.55 kg/m2 and 0.46 kg/m2,respectively.Based on remote sensing data,the average SOC density in Qinghai Lake Basin was 6.86 kg/m2.4.SOC density was significantly and positively correlated with altitude(p<0.05),and was not affected by the temperature and precipitation(p>0.05).The SOC density increased linearly with the under-ground biomass(p<0.05),but the above-ground biomass had no significant influence on SOC density.Short-term exclosure could significantly increase the SOC and total nitrogen contents in surface soil(0-10cm)(p<0.05),but did not affect the soil carbon storage(p>0.05).5.Carbon density in vegetation,soil and ecosystem showed a decreasing spatial distribution pattern as the distance from the Qinghai Lake increased,except the southwestward and northeastward due to the influence of dessert and topography.6.Based on the remote sensing data,the vegetation carbon storage in Qinghai Lake Basin was estimated as 68.54Tg,the soil carbon storage was 383.31Tg and the ecosystem carbon storage was 468.07Tg.