| 黄土区农田和草地生态系统土壤呼吸差异及其影响因素 |
| 摘要点击 4448 全文点击 2009 投稿时间：2012-05-22 修订日期：2012-07-10 |
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| 中文关键词 土壤呼吸速率 农田 草地 土壤温度 土壤水分 黄土高原 |
| 英文关键词 soil respiration cropland grassland soil temperature soil mosture Loess Plateau |
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| 中文摘要 |
| 明确土地利用方式变化对土壤呼吸速率的影响,对预测黄土区退耕还草条件下的土壤碳循环变化具有重要的意义. 于2010年7月~2011年12月,利用Li-8100系统(Li-COR, Lincoln, NE, USA)监测黄土高原沟壑区塬坡上相邻农田和草地的土壤呼吸速率,用以验证不同土地利用方式是否导致土壤呼吸速率的变化. 结果发现,土地利用方式的改变导致了土壤呼吸速率的显著(P<0.05)变化,试验期间草地平均土壤呼吸速率[1.67 μmol·(m2·s)-1]较相邻农田[1.35 μmol·(m2·s)-1]提高24%(P<0.05),累积土壤呼吸草地(856 g·m-2)较农田(694 g·m-2)提高了23%(P<0.05). 农田与草地的土壤温度差异显著,草地平均土壤温度(14.9℃)较农田(12.4℃)高2.5℃(P<0.05). 农田和草地生态系统土壤温度与土壤呼吸均呈显著的指数关系(P<0.0001). 但农田和草地生态系统中土壤呼吸对温度响应存在本质差异(α=0.05),农田土壤呼吸的Q10(2.30)高于草地(1.74). 土壤温度能够很好地解释农田和草地生态系统之间土壤呼吸的差异. |
| 英文摘要 |
| Understanding the effect of land-use change on soil respiration rates becomes critical in predicting soil carbon cycling under conversion of arable into grassland on the Loess Plateau. From July 2010 to December 2011, CO2 efflux from the soil surface was measured between 08:00 to 10:00 am in clear days by a Licor-8100 closed chamber system (Li-COR, Lincoln, NE, US). Also, soil temperature and soil moisture at the 5-cm depth was measured using a Li-Cor thermocouple and a hand-held frequency-domain reflectometer (ML2x, Delta-T Devices Ltd, UK) at each PVC collar, respectively. We found marked differences(P<0.05) in soil respiration related to different land-use: the mean cropland soil respiration[1.35 μmol·(m2·s)-1] was 24%(P<0.05) less than the paired grassland soil respiration[1.67 μmol·(m2·s)-1] (P<0.05) during the period of experiment and the cumulative CO2-C emissions in grassland (856 g·m-2) was 23%(P<0.05) higher than that in cropland (694 g·m-2). Soil moisture from 0-5 cm depth was much drier in cropland and significantly different between cropland and grassland except for winter. However, there were no clear relationships between soil moisture and soil respiration. Soil temperature at 5-cm depth was 2.5℃ higher in grassland during the period of experiment (P<0.05). Regression of soil temperature vs. soil respiration indicated significant exponential relationships both in grassland and cropland. Besides, there were intrinsic differences in response of soil respiration to temperature between the cropland and grassland ecosystems: grassland and cropland respiration response was significantly different at the α=0.05 level, also expressed by a higher temperature sensitivity of soil respiration (Q10) in cropland (2.30) relative to grassland (1.74). Soil temperature of cropland and grassland can explain 79% of the variation in the soil respiration in grassland, compared to 82% in cropland. Therefore, land-use change can alter soil CO2 efflux under similar edaphic and climate conditions in the gully region of the Loess Plateau. The soil temperature difference between cropland and grassland can explain the soil respiration difference caused by land-use change, which was confirmed by the validation results. |
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