Determination Of The Initial Depth Of Water Uptake By Roots Of Steppe Plants In Restored And Overgrazed Communities

We studied water uptake by plant roots in two typical steppe communities, at the Inner Mongolia Grassland Ecosystem Research Station of the Chinese Academy of Sciences, Xilin Gol League, Inner Mongolia, China. Water uptake by roots forms the base of the Soil-Plant-Atmosphere Continuum. Previously, a model of root water uptake has been used, based on root distribution, but there has been no effective way to research water uptake of steppe plants directly. We used a new method to determine where the plant roots begin the uptake of water. We found that the initial depth of water uptake by roots could be measured using the soil excavation method described. Determination being obtained of two different communities in succession, between the 1983 enclosed recovery plot and open grazed and degraded plot. Second, measure some major plants in different succession communities. The experimental results show that, Leymus chinensis, Stipa grandis, Carex korshinskyi, Cleistogenes squarrosa, Agropyron michnoi and Artemisia frigida, the 6 kinds of plants above whose root water uptake initial position were at the same depth range in the degraded community. In the restored community, root water uptake initial depths of Carex korshinskyi, Cleistogenes squarrosa, Allium bidentatum and Artemisia frigida are hallower than Leymus chinensis, Stipa grandis and Agropyron michnoi, Caragana microphylla is the deepest. In a same community, there were different root water (?)ptake initial depths among species. Here a spatial niche overlap and separation exists in the exploitation of water. In a different restored community, the initial depth of root water uptake of Carex korshinskyi, Cleistogenes squarrosa and Artemisia rigida did not change with a transition to overgrazing. However, Leymus chinensis, Stipa grandis and Agropyron michnoi began to take up water more shallowly following degradation. As plants miniaturized and root systems became shallower, the initial layer of water uptake also becomes increasingly shallow. This indicated that the steppe plant community was able to vary its use of water resources. In a typical steppe community, there was more substantial niche overlap and less niche separation among plant species, niche separation had a smaller degree and the overlap had a greater degree. Meanwhile, we observed the roots and found that the root structure with a root set exist on Leymus chinensis, Agropyron michnoi, Stipa grandis and Cleistogenes squarrosa roots in the restoration of communities. Then, determinated this structure, the results showed during the formation of root sets, large particle size of soil particles were gathered, and its special distribution of the soil particles on structure conducive to root absorption and utilization of water.