【作者】 李洋；

【导师】 傅华；

【作者基本信息】 兰州大学 ， 生物学·草地营养生物学， 2015， 硕士

【摘要】 准确了解草地生态系统地上、地下生物量及土壤碳库的大小及影响因素,有助于理解陆地生态系统对全球气候变化的响应,并对全球气候变化做出应对策略。青海湖是全球第七大内陆湖泊,对青藏高原的环境及可持续发展有着重要影响,但目前该区域草地生态系统碳库的大小及其影响因素尚不明确。为此,我们与2012-2013年间在青海湖流域共选取52个样点进行地上生物量的测定,在地上生物量测定样点中选取具有代表性的30个样点进行土壤及根系样品的采集。利用野外调查和实验室分析数据以及遥感(AVHRR-NDVI)和气象信息数据,并借助经典统计方法及克里格插值等手段研究了青海湖流域植被和土壤有机碳储量的大小、空间分布及其影响因素。主要结果如下:1.青海湖流域高寒草甸、高寒草原、温性草原及温性荒漠草原的地上和地下生物量分别为 106.4 g/m2、84.3g/m2、126.1 g/m2、68.3 g/m2和5145.2 g/m2、3373.8 g/m2、2296.4g/m2和2416.7 g/m2,总生物量分别为5251.6 g/m2、3458.1 g/m2、2422.5g/m2和2485.0 g/m2;地下部分碳库占整个植被系统碳库分别为97.1%、97.5%、93.9%、95.6%。2.温度和降水对整个区域地上和地下生物量无显著影响。但当降水量大于400mm时,地上和地下生物量均与生长季温度的增加呈先降低后增加的二次项关系;地上和地下生物量随海拔高度的增加也呈先增加后降低的二次项关系(p<0.05)。短期围封能够显著的增加地上和地下生物量,降低根冠比,显著增加禾本科占总生物量的比例(p<0.05)。3.高寒草甸、高寒草原、温性草原和温性荒漠草原的土壤有机碳密度分别为10.11 kg/m2、6.88 kg/m2、5.50kg/m2和4.33 kg/m2;土壤全氮密度分别为 1.01 kg/m2、0.69 kg/m2、0.55 kg/m2和0.46 kg/m2。结合遥感信息法估算青海湖0-30cm平均土壤有机碳密度为6.86kg/m2。4.青海湖流域草地土壤有机碳密度与海拔高度呈显著的正相关关系(p<0.05),与温度及降水无显著相关关系(p>0.05)。此外,土壤有机碳密度随地下生物量的增加而线性增加,地上生物量对土壤有机碳密度无显著影响。短期围封能够显著增加表层(0-10cm)土壤有机碳、全氮含量(p<0.05),而未能增加土壤碳储量(p>0.05)。5.植被、土壤和生态系统碳密度除湖心东北方向受沙漠影响和西南方向地形影响外,沿青海湖流域向四周均呈现出递减的空间分布格局。6.基于植被生物量和土壤剖面实测数据结合遥感信息,估算青海湖流域草地生态系统植被、土壤和生态系统碳储量分别为68.54Tg、383.31Tg和468.07Tg。更多还原

【Abstract】 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.更多还原