退耕还林还草过程中不同土地利用方式土壤呼吸作用及其碳收支评估

Soil Respiration and Assessment of the Carbon Budget in the Process of Returning Farmland to Forest and Grassland Under Different Land Use Patterns

采用动态密闭气室法对黄土高原水蚀风蚀交错区9种土地利用方式植物生长季节内(2010年6—10月)土壤呼吸速率及其主要影响因子进行测定,分析不同土地利用方式间土壤呼吸的差异性和土壤呼吸对温度、土壤水分、叶面积指数等因子的响应,对7种土地利用方式土壤碳收支进行了估算。结果表明,植物生长季节内,不同土地利用方式下土壤呼吸速率呈多峰型变化趋势。裸地、农地、梯田农地、苜蓿地、撂荒地、长芒草地、荒草地、沙柳地、沙蒿地的土壤呼吸速率季节变化范围分别为0.18～1.05、0.30～2.08、0.50～1.71、0.53～2.78、0.26～1.08、0.39～1.93、0.30～2.27、0.43～1.43、0.39～1.26μmol·m-2·s-1。9种土地利用方式下土壤呼吸速率均与气温和5、10、15cm地温呈显著相关(P<0.05)或极显著相关(P<0.01),而与0～6cm土壤水分相关性不显著。9种土地利用方式下地温对应的Q10值均表现为15cm地温>10cm地温>5cm地温。研究区域内土壤呼吸速率与其地上植被叶面积指数呈极显著线性相关关系(r=0.679,P<0.01)。

Soil respiration rate and its impact in nine land use patterns were determined within the vegetation growing season（June to October,2010） in the water-wind erosion crisscross region on the Loess Plateau.We analyzed the response relationship and difference between soil respirations and soil temperature,soil moisture,leaf area index and other factors under the varoius land use patterns,and estimated the soil carbon balance in seven land use patterns.The results showed that the soil respiration rate followed a trend of multiple peaks under different land use patterns during the vegetation growing season.Seasonal ranges in soil respiration and bare land,farmland,terrace farmland,Medicago sativa land,abandoned farm land,Stipa bungeana land,wasted land,Salix babylonica land,and Artemisia desterorum land,were 0.18～1.05,0.30～2.08,0.50～1.71,0.53～2.78,0.26～1.08,0.39～1.93,0.30～2.27,0.43～1.43,and 0.39～1.26 μmol·m-2·s-1,respectively.There were significantly（P0.05） or highly significant（P0.01） correlations between soil respiration rate and the temperature of the air or soil at 5,10,15 cm soil depths,but there were no significant correlation with soil moisture at 6 cm depth in nine land use patterns.Soil temperatures at different soil depths corresponding to the Q10 values followed the order：15 cm10 cm 5 cm.Soil respiration rate and the vegetation leaf area index were significantly and linearly correlated（r=0.679,P0.01）.Bare net ecosystem showed significantly carbon ＂source＂;and farmland,terraced farmland were the weak performance of the carbon ＂sink＂;but Medicago sativa land,abandoned land,Stipa bungeana land,wasted land had a significant carbon ＂sinks＂.