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SCI论文目录 |
红 壤 坡 地 干 旱 季 节 地 表/大 气界 面 水 分 传 输 |
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| 出 版 社：中科院硕士学位论文 |
| 台 站：
桃源农业生态试验站
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| 作 者：段华平 |
| 点 击 率：4154 |
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| 关 键 字：红壤坡地；季节性干旱；地表/大气界面；水分传输 |
| 摘 要：南方红壤丘陵地区水资源丰富，但由于时间和空间上的分布不均，加之受地貌影响，岗坡地旱情更加突出，伏秋季节性干旱往往成为该区农业可持续发展的主要障碍因素。本文以中国科学院桃源生态试验站为依托，在季节性干旱期以红壤坡地茶园为研究对象，研究水分在土壤/大气界面，冠层/大气界面中的传输过程及其与环境生态条件的关系，从界面角度深入了解南方季节性干旱中植物对干旱胁迫的响应特征，并寻求调控各个界面过程的途径，这对红壤坡地开发利用的防旱、抗旱的农业技术措施的制定有重要的理论和实际意义。所得的主要研究结果如下：
1） 当作物因素对土壤/大气界面水分传输季节变化影响不大时，水汽通量除受气候条件的影响外，还明显受到土壤含水量特别是表层（0-20cm）土壤含水量的影响。相关分析表明，棵间土壤蒸发与空气温度、叶温、相对湿度呈极显著相关性，相关系数分别为0.63**、0.76**、-0.61**，n=19；与净辐射、土壤表面温度、日照时数呈显著相关性，相关系数分别为0.48*、0.50*、0.51*，n=19。当茶园叶面积指数为2.2左右时，相对蒸发量E/ET0随表层(0-20cm)土壤含水量θ之间的关系式为：E/ET0=1.1807+0.3876Lnθ，R2=0.6009，P<0.01。
2） 气孔行为具有响应环境变化的机制。干旱条件下，气孔阻力日变化曲线为W型，不受旱时气孔阻力日变化为U型，且在干旱时的气孔阻力明显大于不受旱情况；气孔导度与光强、气温、相对湿度回归分析的复相关系数R和F检验值均达极显著水平(R=0.702, F=15.21, P<0.01)，偏相关系数t检验得出3个因子都强烈的影响着气孔行为。茶园蒸腾速率具有明显的早、晚低，中午高的日变化趋势，但在不同的日期蒸腾速率日变化曲线存在一定的差异。蒸腾速率受到许多田间小气候因子的影响，相关分析及多元逐步回归分析表明净辐射与空气饱和水汽压差是影响茶园蒸腾作用的2个主要气象因子。蒸腾速率与叶片气孔导度关系密切，且随着气孔导度的增加，蒸腾速率增大。
3） 茶园能量平衡的分配特征说明了土壤水分对垂直于地表/大气界面的水分和能量传输过程有重要的抑制或加快作用。对于显热和潜热输送,土壤水分起决定作用,土壤水分越小,显热通量越大,潜热通量越小,反之亦然。水量平衡的分配特征说明了坡地茶园(LAI=2.2)由降水而被土壤持蓄的水量仅占降雨量的58.5%，占降雨量20%的径流水被流失掉。当土壤水分胁迫严重时，地表/大气界面水汽通量明显降低。忽略降雨期间的蒸散量，得出观测期间蒸散耗水量比同期降水量还要多60.02mm，这正是该区发生季节性干旱的重要原因。在观测期间，棵间蒸发量占总蒸散量的32%，因此通过减少田间土壤水分蒸发来提高农田水分利用效率大有可为。探讨了土壤水在地表/大气界面水分传输中的地位与作用，叶/气界面、土/气界面水分传输的驱动力及抑制的可能，为红壤坡地界面节水提供理论支撑。
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| 关 键 字(英文)： Red soil slopes; seasonal drought; land-atmosphere interface; water transport |
| 摘 要(英文)：Water resource is very rich in red soil regions of China. But for the dramatic changes and spatial unbalances of rainfall in these regions, the agricultural sustainable development of this land is usually obstructed. Based on Taoyuan Agro-ecological Experimental Station, Chinese Academy of Sciences, water transport processes through soil-atmosphere and leaf- atmosphere interface and their relationships with the environmental conditions were studied on red soil slopes tea plant, the aim was to find out the response characteristics of plant to seasonal drought, and to search the approaches for regulating the interface processes and to provide the theoretical and practice basis for avoiding from or fighting against drought during the agricultural exploitation of red soil slopes. Through the experiments, the main results were obtained as follows:
1.When the effects of crop was neglected, seasonal variation of water transfer flux of soil-atmosphere interface was affected significantly by microclimatic and soil surface (0-20cm) water contents. Correlation analysis suggested that the correlation coefficients between soil evaporation under crop canopy and air temperature, leaf temperature, relative humidity were highly significant (0.63**, 0.76**, -0.61**, n=19); the correlation coefficients between soil evaporation under crop canopy and net radiation, soil surface temperature, sunlight hour were significant (0.48*, 0.50*, 0.51*, n=19). When the LAI was 2.2 on red soil slopes, the function of relative evaporation (E/ET0) to soil water content(θ) was as follow: E/ET0=1.1807+0.3876Lnθ，R2=0.6009，P<0.01.
2.Stmomatal behavior had the mechanisms of respond to environment change. The daily variation curve of stmomatal resistance was W form in drought condition, and the daily variation curve of stmomatal resistance was U form in wetness condition, and stmomatal resistance in drought condition was more than that of in wetness condition. Multi-regression results of stmomatal conductivity and light intensity, air temperature, relative humidity suggested that plurality correlation coefficients (R) and F test were highly significant level (R=0.702, F=15.21, P<0.01), t test of deflection correlation coefficients revealed that every factors affected stmomatal behavior significantly. Daily variation of transpiration rate of the tea plantation appeared in a shape of inverted saddle, low in the morning and evening and high at noon, and the shape of the inverted saddle was changed from day to day. The transpiration rate was subjected to a number of micro-meteorological factors on the tea plantation. Correlation analysis and multi-factor successive regressional analysis revealed that net radiation and water vapor saturated deficit were the two major meteorological factors affecting transpiration of the tea plants. Transpiration rate was closely related to leaf stmomatal conductivity. The former increased with the rise of the latter.
3.The distributive characteristics of energy balance suggested that water and energy transport through interface between land and atmosphere was affected significantly by soil moisture. Soil moisture played an important role in latent and sensible heat transfer. The drier the soil, the higher the sensible heat flux and the smaller the latent heat flux, and vice versa. The distributive characteristics of water balance suggested that the soil conserved water occupied about 58.5% of total precipitation on tea plantation (LAI=2.2), and surface runoff occupied about 20%. Vapor flux through interface between land and atmosphere decreased significantly in soil-water stress condition. During the observation, neglecting the evapotranspiration of rainfall process, evapotranspiration was 60.02mm more than homochronous precipitation, which was the major reasons of seasonal drought in red soil regions. The ratio of water which lost directly to the atmosphere without through plant body to the total field evapotranspiration was 32%, which illustrated the water-saving regulation potential on soil-atmosphere interface. The paper discussed the status and function of soil water in water transport through interface between land and atmosphere. It also discussed the driving factors of water transport processes through soil-atmosphere and leaf- atmosphere interface and the probability of preventing them, which provided the theoretical supporting for interfacial water-saving on red soil slopes.
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