【作者】 王阳；

【导师】 赵传燕；

【作者基本信息】 兰州大学 ， 农业生态学， 2013， 硕士

【摘要】 从土壤中释放出的CO2被认为是地球碳循环中最大的通量之一,土壤呼吸的微小变化都将对大气中CO2浓度产生巨大的影响,导致全球气候发生变化加剧或减缓,同样的,减少土壤CO2释放量、增加土壤的碳储量可以降低大气中CO2的浓度。研究表明,高纬度和高海拔生态系统对温度升高的响应更为敏感和迅速。祁连山地处青藏、黄土两大高原和蒙新荒漠的交界处,高原生态系统十分脆弱并且对全球气候的变化十分敏感,其独特的陆地生态系统在全球气候和碳收支方面起着重要的作用。本文应用Li-8100土壤碳通量自动测量系统对祁连山青海云杉林下和亚高山草甸生长季CO2通量进行野外测定,研究两种不同植被类型通量的时间变化规律及和温湿度等其它环境因子的相关性。获得以下主要结论：青海云杉土壤呼吸日变化的结果显示,由于苔藓和枯落物的覆盖均使得地表释放出的CO2通量在土壤呼吸的基础上有所增加,并且在8月份地表向大气中释放的CO2量比6月份多50%左右。6月通量的最大值和近地气温有较好的一致性；在8月份生长季中期,苔鲜表面通量最大值表现出和土壤温度有较好的一致性。枯落物表而和去枯落物C02、苔藓表面和去苔藓CO2通量在7月下旬到8月上旬在整个生长季中达到通量的最大值,此时日均地面温度和土壤温度均达到最大值,土壤湿度在8月中旬达到整个生长季的最大值。无论是否去除苔藓或枯落物,所测得的CO2通量均与土壤温度和空气温度达到极显著水平,其中苔藓表面和去苔鲜CO2通量与土壤温度的相关性大于和近地气温的相关性,枯落物表面和去枯落物C02与空气温度和土壤温度均表现出较高的相关性,加入土壤含水量和土壤温度共同来解释土壤C02通量的变化,可以提高苔藓表面CO2通量和去苔藓土壤呼吸的变异程度。但是对枯落物表面CO2通量和去枯落物土壤呼吸没有显著影响。Van’t Hoff模型可以很好地表达土壤CO2通量、CO2总通量和土壤温度和近气温之间的关系,可以解释50%-70%左右土壤呼吸变化。但是土壤湿度和碳通量之间通过线性模型、二次项模型、幂函数模型的模拟均没有显著关系。亚高山草甸日变化的结果显示无论是否去掉植物的地上部分,生态系统呼吸和土壤呼吸的最大值均与近气温有很好的同步性。土壤呼吸和生态系统呼吸的最大值在13：00-15：00左右。土壤温度的最大值和土壤湿度的最小值相比较土壤呼吸和生态系统呼吸的最大值有滞后现象。土壤含水量的最小值均出现在17：00左右。土壤呼吸的最小值均出现在凌晨5：00-7：00左右。月变化的结果显示：草甸在自然状态下释放出的CO2和刈割测得的土壤呼吸相比要多30%左右。与刈割地上部分的土壤呼吸测量的结果相比,土壤呼吸的最大值提前出现在7月底,平均比刈割的多出36.3%。土壤温度平均值为12.1℃,近地面空气温度平均为15.54℃,比刈割的分别降低1.8%和6.3%,土壤含水量在九月份之前变化不大,平均值为43.7%。比刈割后平均多出1.4%。土壤呼吸和空气温度用指数模型和多项式拟合均比较理想,和土壤温度用指数模型拟合若去掉晚上观测结果解释率能提高20%-30%, Q10值显示在生长季随着月份的增加,夜间相同的温度下土壤呼吸的量有增大的趋势。生态系统呼吸与空气温度和土壤温度有显著地相关性并且可以解释生态系统呼吸变异的60%左右,去除夜间观测的结果能提高拟合结果的精度。Q1o值显示升高相同的温度,生态系统放出的CO2的速率要比去除地上部分的土壤呼吸要多。土壤呼吸和土壤20cm-60cm的水热状况相关性相对较高,其次为和太阳辐射和由太阳辐射引起的大气状况变化；相对相关性较小的为土壤表层的水热状况因子；生态系统呼吸和太阳辐射及其由于太阳辐射引起的大气状况变化有非常明显的相关性,受到土壤20cm-60cm土壤水热状况的信息,10cm处土壤温度和5cm处土壤湿度土壤表层水热状况的信息的影响相比较不是很大。更多还原

【Abstract】 Carbon dioxide released from the soil is considered to be one of the largest flux in the carbon cycle of the earth, slight changes of Soil respiration will have an enormous impact on the concentration of CO2in the atmosphere,, exacerbate or mitigate global climate change.Similarly, reducing soil CO2emission and increasing soil carbon storage can reduce the concentration of CO2in the atmosphere. Studies have shown that high-latitude and high-altitude ecosystem is more sensitive and rapid response to the temperature rise. Qilian Mountain is located at the junction of the Qinghai-Tibet Plateau and the Loess Plateau and desert in Inner Mongolia and Xinjiang, plateau ecosystem is fragile and sensitive to changes in the global climate, its unique terrestrial ecosystems play an important role in the global climate and the carbon budget.In this paper, CO2flux was measured understory Picea crassifolia forest and sub-alpine meadow in Qilian Mountains using Li-8100Automated Soil CO2Flux System in growing season in the field, Study the temporal variation of the flux and the correlation with temperature and humidity and other environmental factors. For the following main conclusions:Diurnal variation of soil respiration in Picea crassifolia forest results show that, CO2flux released from the earth’s surface increases on the basis of soil respiration due to the covering of moss and litter and the CO2flux released from the earth’s surface into the atmosphere in August is more than50%than that in June.The max flux in June had better consistency with near-Earth temperature; in mid-August growing season, the maximum flux on moss surface had better consistency with soil temperature.CO2fluxes on litter surface and cleared litter surface, moss surface and de-moss surface reached the maximum in late July to early August throughout the growing season, at this time, the average near-Earth temperature and soil temperature reached maximum value. Soil moisture reached the maximum value in mid-August during the entire growing season. The measured CO2fluxes and soil temperature and air temperature reached a significant level whether or not to remove moss or litter, correlation between CO2flux on the moss surface de-moss surface and soil temperature greater than the temperature of near-Earth,CO2fluxes on litter surface and cleared litter surface showed a high correlation with air temperature and soil temperature. Using soil moisture and soil temperature to explain the changes in soil CO2fluxes common can improve the degree of explanation on moss surface and de-moss surface. But had no significant effect on the CO2flux on the litter surface and cleared litter surface.Van’t Hoff model can better express the relationship between soil CO2flux, total CO2fluxes and soil temperature, near-Earth temperature, can explain about50%-70%soil respiration. But the simulation between soil moisture and carbon fluxes through the linear model, quadratic model, power function model showed no significant relationship.diurnal variation of Subalpine meadow results show whether or not to remove the above-ground parts of plants, the maximum value of ecosystem respiration and soil respiration had good synchronization with near-Earth temperature.Soil respiration and ecosystem respiration reached maximum at about13:00-15:00. Compare the maximum of soil respiration and ecosystem respiration, the minimum of the soil moisture and the maximum of the soil temperature had hysteresis. The minimum of soil moisture was around17:00. The minimum soil respiration was around5:00-7:00am.The monthly variation resulted:CO2released in the natural meadow state was30%more comparing with soil respiration which was mowed.Compared with the soil respiration which was removed the above-ground parts of plants, The maximum value of ecosystem respiration in advance at the end of July, with an average of36.3%more than mowing.The average of soil temperature was12.1℃. the average of near-earth air temperature was15.54℃,1.8%and6.3%lower than mowing. Little change in soil moisture before September, an average of43.7%.1.4%more than mowing.Index and polynomial model can better expressed the relationship between Soil respiration and air temperature, and the explain rate of soil temperature observations can be improved20%-30%if removed observations at nights when using exponential model.Q10value displayed in the growing season, with the month increased, The amount of soil respiration has a tendency to increase in the same night temperature.Ecosystem respiration have a significant correlation with near-earth air temperature and soil temperature and can be explained60%of the ecosystem respiration variation, removal of night-time observations can improve the fitting accuracy of the results.The Q10value shows that raising the same temperature, the CO2released rate of ecosystem respiration was larger than that of soil respiration.Relatively high correlation of soil respiration and the water and heat conditions of soil20cm-60cm layers, followed by solar radiation and atmospheric conditions caused by solar radiation; ecosystem respiration between solar radiation and atmospheric conditions caused by solar radiation have a very clear correlation, and have relatively less effects by the water and heat conditions of surface and20cm-60cm soil layers.更多还原