| As the main structure of the terrestrial ecosystem, the forest ecosystem cover approximately30%of the terrestrial surface. Through the exchange of energy and matter between soil and atmosphere, the forest ecosystem profoundly influenced and shaped the terrestrial ecosystem. The relationship between forests and water is the core direction of the study of forest ecology and soil and water conservation. Water move from the soil into the forest canopy through stalks, then evaporate in the form of water vapor into the air marginal layer, and finally participate in the exchange of atmospheric turbulence. The formation of a unified continuous interaction and dynamic system, namely soil-vegetation-atmosphere continuum (SPAC).In this study, research mainly focus the forest plantation of Beijing mountainous area. Relying on the State Forestry Administration metropolitan Forest Ecosystem Research Station, the area of forest ecosystems typical positioned for long-term observation. By analyzing the energy exchange between the interface and the SPAC SPAC each water transfer system and its drive mechanism, this study made following conclusions:(1) In the non-growing season when the soil is one of the heat of forest ecosystems, the heat is passed up from the soil. And when the growing season, by contrast, is a heat sink. The yearly mean soil heat was-1.48w/m2, the instructions on-year scale, the soil is one heat source of forest ecosystem. Soil heat flux, especially the soil surface heat flux is closely related to the net radiation, soil heat flux in the study area and the regression equation for net radiation. Indicating that the soil heat flux greatly affected by the net radiation, may be due to the higher forest canopy, making a greater proportion of net radiation reaches the earth’s surface, soil heat flux outside influence by more intense. Use of net radiation to soil heat flux is an effective way.(2) Beijing regions typical forest ecosystems are associated with the heat balance of the net radiation has the same diurnal variation, the relationship between the number of generally expressed as net radiation> latent heat flux> sensible heat flux> soil heat fluxes. Growing season ecosystem net radiation received by the majority for latent heat exchange and sensible heat exchange, rather than the growing season, the vast majority of net radiation for latent heat exchange. Latent heat flux ratio of net radiation decreased from August to September, the fastest decline in early September, while the proportion of latent heat flux and soil heat flux gradually increased from September to October, reflecting the seasonal changes in vegetation life activity.(3) Species stands with soil infiltration law has some differences, the size of initial infiltration rate is sort of cork oak forest> side Berlin> pine forest> locust forest, steady infiltration rate of side order of magnitude Berlin> pine forest> locust forest> cork oak forest, sorting average penetration rate and the total amount of permeate side of the Berlin> pine forest> locust forest> cork oak forests, soil infiltration capacity in general seems to be significantly higher than the coniferous forest broadleaf forest. By stepwise regression analysis showed that soil infiltration rate initial soil moisture and non-capillary porosity has the closest relationship.(4) Through the automatic selection of the former CCA to factors affecting soil moisture sort order of magnitude of the impact of rainfall> soil heat flux> soil water> air temperature> atmospheric humidity. This sort results show that soil moisture change the timing of the long main factor is rainfall, followed by heat is an important factor affecting soil moisture transfer.(5) based on the measured and literature after COUP model adjustment parameters can be appropriate applied to the study area. R2and root mean square error using simulation to evaluate the effect of the model, COUP model can appropriate soil moisture and plant transpiration dynamics simulation. |
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