• 关键词：土壤侵蚀  土壤CO₂通量  坡度  雨强  历时

• 基金项目：国家自然科学基金(No.41371279)

• 李如剑
• 西北农林科技大学水土保持研究所, 杨凌 712100

• 张彦军
• 西北农林科技大学水土保持研究所, 杨凌 712100

• 赵慢
• 西北农林科技大学资源环境学院, 杨凌 712100

• 杜兰兰
• 西北农林科技大学水土保持研究所, 杨凌 712100

• 王志齐
• 西北农林科技大学水土保持研究所, 杨凌 712100

• 郭胜利
• 1. 西北农林科技大学水土保持研究所, 杨凌 712100;2. 西北农林科技大学资源环境学院, 杨凌 712100;3. 中国科学院水利部水土保持研究所, 杨凌 712100

• 摘要：坡度和降雨是影响土壤侵蚀发生和发展的重要因素,分析二者对土壤CO₂通量变化的影响,有助于深入理解侵蚀条件下土壤和大气CO₂之间交换的机理.选取黄土高原典型侵蚀性土壤黄绵土,于中国科学院水利部水土保持研究所人工模拟降雨大厅,研究不同坡度(5°、15°和25°)、降雨强度(30、60和90mm·h^-1,即I₃₀、I₆₀、I₉₀)及历时(0.5、1和1.5h,即H_0.5、H₁、H_1.5)下土壤CO₂通量变化.结果表明:同历时和雨强下,坡度显著影响土壤CO₂通量变化(p<0.001),且各坡度下土壤CO₂通量呈现出5°>15°>25°的趋势,但5°与15°之间差异未达到显著水平,而25°坡度下土壤CO₂通量较5°、15°下显著下降(16.3%~36.5%,10.8%~27.1%);同坡度和历时(H₁)下,随着雨强的增加,土壤CO₂通量呈现下降的趋势,相较I₃₀雨强下,I₆₀、I₉₀雨强下对应坡度的土壤CO₂通量降低了2.3%~14.3%,但差异均未达到显著性水平;同坡度和雨强(I₉₀)下,随着历时的增加,土壤CO₂通量也表现出降低的趋势,H₁、H_1.5历时下,土壤CO₂通量相较H_0.5下降1.7%~20.9%,历时对土壤CO₂通量影响达显著性水平(p<0.1);土壤CO₂通量的变化与坡面SOC流失量呈线性负相关关系(R²=0.69~0.77,r=-0.83~-0.88,p≤0.1).SOC的流失是导致坡面土壤CO₂通量降低的重要因素.

• Abstract：Slope and rainfall are the key factors to influence detachment, transport and deposition of soil materials by the erosive forces of raindrops and runoff. The investigation of soil CO₂ flux under slope and rainfall is helpful to understand the CO₂ exchange mechanism between soil and atmosphere in the eroded region. A simulated experiment of rainfall and slope was conducted in State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau. The treatments consist of three slopes(5°,15° and 25°), three rainfall intensities(30, 60 and 90 mm·h^-1,I₃₀, I₆₀ and I₉₀) and three rainfall durations(0.5, 1 and 1.5 h, H_0.5, H₁ and H_1.5). Soil CO₂ flux significantly decreased as the slope increased(p<0.001), but there was no significant difference between 5° and 15°. Soil CO₂ flux with slope 25° was declined significantly compared to 5° and 15°(16.3%~36.5%,10.8%~27.1%). For the same slope and rainfall duration(H₁), soil CO₂ flux decreased with the increase of rainfall intensity. Compared with the I₃₀, the soil CO₂ flux of I₆₀ and I₉₀ decreased by 2.3%~14.3%, but the difference did not reach the significant level. With the increase of rainfall duration, soil CO₂ flux also showed a reduced tendency under the same slope and rainfall intensity(I₉₀). Compared with H_0.5, the soil CO₂ flux of H₁ and H_1.5 decreased by 1.7%~20.9%, and the rainfall duration had a significant influence on the soil CO₂ flux. With the increase of slope, rainfall intensity and rainfall duration, the loss content of SOC had increased significantly(p<0.1). There were negative linear correlation between soil CO₂ flux and SOC losses(R²=0.69~0.77,r=-0.83~-0.88,p≤0.1). SOC loss contribute significantly to the decline in soil CO₂ flux during an erosion event.

• Key words：soil erosion  soil CO₂ flux  slope  rainfall intensity  rainfall duration

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