The Effect Of Ecological Field Of Farmland Shelter-Forest On Rainfed Highland In The North Of Weihe River

The farmland shelter-forest is planted forest ecosystem to protect harvest and benefits for peasant. In order to provides theoretical basis for building and operating agroforestry system. It depend on research interact mechanisms and investigate effect of farmland shelter-belt ecological field in the agroforestry system. In this study,based on plentiful data of soil moisture content, nutrient, solar radiation was collected, quote ecological field theory and build illumination model of forest, analysis the distribution features of soil moisture content, nutrient, solar radiation, after that the shelter belt ecological interference potential was simulated in agroforestry system on rainfed highland in the north of Weihe River(in ChunHua in ShaanXi). (1) The results show that light field situate in the region of 1.0H (mean height of forest belt) from the under tree, it's ecological interference potential from 75% descend to 10% with the distance from under tree to 1.0H. The effect of forest belt shading to occur in this region. (2) Soil moisture field situate in the region of 5.0H, it's ecological interference potential greater than zero means(Ψ3 >0) occur competition moisture between forests and crops when the distance less than 1.5H; moisture ecological interference potential less than aero(Ψ3 <0)means occur plus moisture in the region of 1.5H-5.0H. (3) Soil nutrient field situate in the region of 15.0H, soil nutrient field to play a role is increase soil nutrient contents. (4) Analyzed the features of shelter belt ecological interference potential, the result show that the effect of the farmland shelter belt ecological field diminished the resources contents and incur crops failure in the region of 1.0H(Ψ3 >0); In the region of 2.0H-15.0H(Ψ3 <0), the effect of the shelter belt ecological field increase resources contents and incur crops harvest. In the region of 1.0H-2.0H(Ψ3 ?0), the effect of threat harvest equals increase resources from the forest belt, so the crop yield in the region equivalent to other farmland.Through study the effect of farmland shelter belt ecological field at experiment area, the result show that the effect of farmland shelter belt to increase resources contents obviously. However, the effect of threat harvest also occurred in agroforestry interface. Therefore, for the purpose of increase harvest and reduce the shading area from forest belt on rainfed highland in the north of Weihe River, we will do something such as dig a gullet to prevent tree root inside the farmland, take the forest belt direction into account when planting forest, enlarge the distance between forest belt and farmland, and trim the branches that under the tree crown and so on.