Research On Spatial Distribution Characterists Of Plant Roots Of Agroforestry Systems In The Loess Region Of West Shanxi

The distribution characterists of plant roots reflect the underground interaction of agroforestry syetem. Study on root systems of trees,and roots distribution characterists of fruit tree and crop,are the bedrock on understanding the competition mechanism between different components, selecting trees pecies, designing and managing the system.The dissertation selected main paterns of agroforestry in the Loess Region Of West Shanxi of China,for:Robinia pseudoscacia-grass composite and fruit tree-crop interplanting patterns.The distribution characteristic of Robinia pseudoscacia roots of different aspects and roots distribution characterists of fruit tree and crop were researched,using soil drilling and hierarchical digging method.Meanwhile,the roots distribution model of differnent plants were builded.The results showed as follows:1) There is obvious difference in the root distribution characters of Robinia pseudoscacia trees on different aspects,both roots biomass,roots length and roots surface-area on sunny slope are smaller than that on semi-shady slope.2) Root extinction coefficient P of Robinia pseudoscacia on sunny slope is also obvious different from that on semi-shady slope, results showed that the value ofβon semi-shady slope was more than that on sunny slope,which indicated that the vertical root distribution depth of Robinia pseudoscacia on semi-shady slope is deeper than that on sunny slope.3) Roots biomass or roots length or roots surface-area of Robinia pseudoscacia on different aspects decline with soil depth conforming to R=aebz(Where R is roots biomass or roots length or roots surface-area,z is soil depth,a and b are constants).4) Vertically, the roots of walnut or apple tree concentrated at the 0-60 cm soil zone; horizontally, the amount of the roots within 1.5m from the tree row.5) Fine Roots(0≤d＜2mm) extinction coefficientβof walnut is more than that of thicker roots(2≤d＜5mm), fine Roots(0≤d＜2mm) extinction coefficient P of apple tree is more than that of thicker roots(2≤d＜5mm), which indicated the distribution depth of roots(φ＜1mm) is deeper than that of thicker roots.This distribution depth of roots is in favor of the uptake of water and nutrients from deeper soil layers.The study suggests:1) The results suggest that making an intensive study of distribution characterists of Robinia pseudoscacia roots of in the Loess Region of West Shanxi is essential,so as to fix the planting density.2) The results suggest that the distance of crops from the tree row should be controlled more than 1.5m in the Loess region, irrigation and fertilization should be enhanced, so as to reduce the competition as possible.