The Study On Distribution Characteristics Of The Natural Grassland Vegetation Roots In Yunwu Mountain In Ningxia

Studied on the distribution characteristic of the natural grassland in the arid & semi-arid area on Loess Plateau be helpful to investigate the principle of water consumption mechanism, it also can provide the evidence for establish the water extraction function of forest-grass roots and dynamic simulation of soil water. Different types of natural grassland in Yun-wu mountaion in Ningxia were studied in order to know the physical properties of soil, the distribution characteristics of the vegetation roots and the relationships between soil physical properties and distribution characteristics of vegetation roots. It can provide a scientific basis for the vegetation construction in Loess Plateau Region.Research the root distribution characteristics and the soil physical properties by the methods of soil auger(Φ=9cm) and cutting ring; Measurement and analysis the main root indexes of root length, root surface area and root diameter by the root scanner and analysis system of DT-SACN. The main results were as follow:1.There were significant effects of different types of natural grassland on soil moisture and soil bulk density.The change of soil moisture was enclosed grassland>disclosed grassland. The change of soil bulk density was disclosed grassland>enclosed grassland; It was significant effects of slope direction on soil moisture and soil bulk density, the change of soil moisture was shady>sunny, but the change of soil bulk density was sunny>shady. With the increasing of soil depth, the soil moisture was decreasing in shady slope of the different types of natural grassland ,however, the soil moisture was increasing in 0～40cm soil layer and decreasing under 40cm soil layer in sunny slope .2.The root biomass of the natural grassland were mainly distributed in 0～40cm soil layer which maker up the 80 percent of the total root biomass of all concentrated on the soil layer. It shows an exponential decrease with soil depth. The root surface area, root length density and specific root length were show a similar changing tendency with the root biomass. Variance analysis showed that all of the main root parameters were different significantly between 0-20cm soil layer and 20-40cm soil layer, while having no significant difference in deeper soil except specific root length. The root biomass, root surface area and root length density in enclosed grassland were bigger than in disclosed grassland. Variance analysis for all of the main root parameters in the same soil layer in different slope directions indicated that the root biomass root length density and specific root length in shady slope were bigger than in sunny slope and had the extremely significant difference between them.3. All of the main root parameters which were mutually influenced and constrained had correlations in some degree. There were very significant correlations among them.4. There are significant positively correlated between below ground biomass with above ground biomass. the degree of correlation was enclosed grassland>disclosed grassland, the ratio of below ground biomass/above ground biomass was disclosed grassland(9.28)>enclosed grassland(8.21).5. In enclosed grassland the soil moisture was significant positively correlated with root surface area, root length density, root biomass, and specific root length, but the soil bulk density was negatively correlated with them. In disclosed grassland the relationships between the soil moisture and the soil bulk density with the main root parameters is very complicated.