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SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

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changes. The model results indicated that soil heat fluxes increased with<br />

increasing grazing intensity. In comparison with the two ungrazed sites, winter<br />

grazing did not show any effect on the water household components, while<br />

heavy grazing remarkably decreased soil water storage by 25-45%, interception<br />

by 50-55% and transpiration by 20-30%, and increased evaporation by 25-40%,<br />

runoff by 100-300% and drainage by 100-200%. We conclude that intense<br />

grazing deteriorates soil functions, consequently reduces plant available water<br />

and thus grassland productivity.<br />

The incorporation of an extended freezing code in the HYDRUS-1D model<br />

resulted in an improved <strong>und</strong>erstanding of the coupled hydraulic and thermal<br />

processes <strong>und</strong>er frozen condition. The freezing model is capable of predicting<br />

the changes in soil water and heat fluxes accompanied by soil freezing and<br />

thawing behavior, as well as grazing effects. However, soil water content after<br />

spring snowmelt is overestimated and thus surface runoff might be<br />

<strong>und</strong>erestimated.<br />

v

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