Underground Interaction Mechanism And Management Of Agroforestry Systems In The Loess Plateau

Bio-bank and hedge are main patterns of agroforestry on the slopes in the Loess Plateau in China. Study on root systems of trees and shrubs on the bio-bank and hedge, and their influences on soil moisture nearby the interface, is the bedrock on understanding the competition mechanism between different components, selecting tree species, designing and managing the system. Consequently, the study is very significant in theory and practice.This dissertation researched the characteristics of root systems of salt cedar (Tamarix ramosissima), Salix purpurea, Caragana korshinskii, poplars (Populus bolleana and Populus hopeiensis), Prunus davidiana and Prunus armeniaca var. planted on the banks of terrace, using whole plant excavations with coordinates. Meanwhile, the soil moisture change nearby the interface of the typical bio-banks (with salt cedar, Salix purpurea, Caragana and poplars ), apricot (Armenniaca vulgaris) and apple (Malus pumila) hedges on slopes, also investigated on sites in the dry season. In order to provide suggestions for management of agroforestry, some measures were discussed based on interaction theory in ecology. The results showed as follows:1) Salt cedar is a typical shrub species with vertically developing root system. Its foraging space (FS) can penetrate through the soil layers more than 7.0 m, and rooting plasticity is demonstrated indifferent sites and density. The FS is sorted into the type of weakly-invasion/vertical -developing. The ranges of soil moisture deficit go beyond 2.0 m both in depth and width.2) Salix purpurea has no obvious taproots and its root system distributes in shallower layers. The root system demonstrates the characteristic of multiple root architecture, and in the meantime with the characteristics of metamorphic architecture. The FS is extremely-invasion/laterally-developing. In vertical direction, the range of soil moisture deficit is as deep as 2.0 m, but it goes up to 4.37 m laterally.3) Caragana has the characteristics of multiple root architecture and metamorphic architecture, indicating obvious plasticity. The FS is typical extremely-invasion/vertically -developing.4) Root systems of poplars (Populus bolleana and Populus hopeiensis) are typical multiple root architecture, and show plasticity when planed on different sites. The FSs of two poplar varieties change from mildly-invasion/laterally-developing to extremely-invasion/laterally-developing. The...