Study On Soil Water Ecological Process In Qilian Mountains Forest Region

A great variety of woods absorb their physiologically needed water through roots in the soil. The condition of soil water is one of the environmental factors that determines configurations, growth and development of forests and grass, it is also one of the key factors of the forests' sustainable development. Qilian Mountains is one of an important water resource conservation forest in the northwest of china, its soil's function of conserving water and the growth of the forests and woods are directly affected by the condition of soil water of the forests. This paper is just about the studies on the dynamics of soil water and its main related factors of the major forests types in Qilian Mountains.On the basis of the research statistics of the fixed location about the ecological system of the water resources conservation forest in Qilian Mountains, a comprehensive analysis on the first-hand statistics was made, making use of some methods and principles of Forest Hydrography, Soil Physics, Ecology and Agricultural Systematic Engineering. Through analysis, the changing rule of the soil water of all kinds of vegetation types in different growing seasons was revealed. Meanwhile, the availability, permeability and circulation of soil water were evaluated and analyzed. The results are just as follows:The vertical characteristics of the main vegetation types in Qilian Mountains are: the soil is divided into easy-changing layer, utilizing layer and adjusting layer respectively, according to the increasing depth of the soil.And according to different season, the soil water of the Qilian Mountains forests are divided into consuming period, accumulating period, losing and stabilizing period.In accordance with availability of soil water for plants, it has been classified into three habitus: easy available water, semi-available water and difficult available water, and the condition ofPicea crossifolia has been considered as the best soil water supply.Soil permeability The sequence of the soil permeability of the water resource conservation forest in Qilian Mountains, from strong to weak are: Picea crassifolia, bush, Sabina przewalkii and the grazing grass; and the vary capacity of storing water of the forests are: bush> Picea crassifolia> Sabinaprzewalskii> grazing grass.Through the analysis on the relationship between soil water and precipitation of the waterresource conservation forest in Qilian Mountains, it is discovered that there is a tendency of dry season prior to damp season. The dry season of the soil lasts until the second half of the May or the first half of the June before the damp season begins. But sometimes the damp season of soil will prior to dry season, especially in the year of drought. This is mainly because the precipitation was abundant on the previous year or at the very beginning of the growing season of this year, the storing water of soil is relatively rich at the end of the growing season, and therefore, at the very beginning of the growing season, the water content of soil will remain at a relatively higher level. The precipitation and its distribution in growing season are the main factors determined the changing tendency of soil water in the growing season of the year. Nevertheless, the precipitation in the previous year also affects such a tendency a lot. Among all the forests of the water resource conservation forest in Qilian Mountains, Picea crassifolia have a stronger adjustment capacity between years, which, therefore, further proves that Picea crassifolia has an obvious effect of storing permeability.Accumulation of Picea crossifolia is the largest, and the greatest waterholding of litter is 124t/hm . But the accumulation of litter of Sabina przewalskii are relatively smaller, so are their waterholding. The waterholding rate of the bushes is the greatest, that is: 414.96%.