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Shvoong Home>Medicine & Health>Water transport through interface between land and atmosphere in dry season on red soil slopes Review

Water transport through interface between land and atmosphere in dry season on red soil slopes

Article Review   by:TsingHua     Original Author: Acta Ecologica Sinica
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Water resource is very rich in red soil regions of China. But the dramatic changes and spatial unbalances of rainfall in these regions is unfavorable for the agricultural sustainable development of this region. 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 of this study was to investigate the response characteristics of plant to seasonal drought and 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. The results are as follows: (1)When the effect of crop was neglected, seasonal variation of water transfer flux of soil-atmosphere interface was affected significantly by microclimate and top layer (0~20cm) soil water contents. Correlation analysis showed 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/ET_0) to soil water content(θ) was as follow: E/ET_0=1.1807+0.3876Lnθ,R~2=0.6009,P<0.01. (2)Stomatal behavior had the mechanisms of respond to environment change. The daily variation curve of stomatal resistance was W form under drought condition, and the daily variation curve of stomatal resistance was U form under wet condition, and stomatal resistance under drought condition was more than that of under wet condition. Multi-regression analysis between stomatal conductivity and light intensity, air temperature, relative humidity showed that plurality correlation coefficients (R) and F test were highly significant level (R=0.
702, F=15.21, P<0.01). t test of partial correlation coefficients revealed that all factors mentioned above affected stomatal behavior significantly. The transpiration rate was subjected to a number of micro-meteorological factors on the tea plantation. Correlation analysis and multi-factor successive regressional analysis showed that net radiation and water vapor pressure deficit were the two major meteorological factors affecting transpiration of the tea plants. Transpiration rate was closely related to leaf stomatal 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. 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 soil evaporation to the total field evapotranspiration was 32%, which illustrated the water-saving regulation potential on soil-atmosphere interface. The paper 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.
Published: March 25, 2004   
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