|
The Sunada Is China's northwest arid, semi-arid areas, one of the traditional drought-resistant form of farming. The traditional the Sunada tillage process actually the Sunada aging process. Sunada aging degradation renovation, will not be able to continue to grow food crops and cash crops, they formed a large area of ??abandoned Sunada. In this study, the field test, the combination of survey observations and laboratory analysis method, starting from the abandonment of the Sunada the soil moisture conditions, through the the shrubs, afforestation trials and observations of shrub land has been abandoned Sunada analysis study vegetation restoration of abandoned Sunada conditions and the possibility of re-use. Its main conclusions are as follows: (1) abandoned the Sunada plantation to restore vegetation feasibility test results show that the survival rate of afforestation in abandoned Sunada, Elaeagnus, Tamarix ramosissima, Caragana, flower sticks, Calligonum and other drought-resistant species can 93%, 88%, 72%, 64%, 48%, respectively; 2 years after abandonment Sunada afforestation, shrubs, plant height annual increment sequence: more than of Tamarix gt-; Calligonum gt; scoparium gt; Caragana microphylla gt; the Elaeagnus ground diameter annual growth descending order: Multibranch Tamarix gt; scoparium gt; Calligonum gt; Caragana microphylla gt; angustifolia, the size of the total root biomass in turn : Tamarix ramosissima gt; scoparium gt; Elaeagnus gt; Caragana microphylla gt; Calligonum that shrubs can not only survive the in abandoned Sunada environment, and can maintain a certain growth capability. (2) observation of the shrubs, underground and aboveground growth relationship, shrubs, young forest stage roots are mainly distributed in 0 ~ 40cm soil, and along with the depth of the soil layer, shrubs root biomass distribution downward trend. 0 to 20cm soil root distribution most shrubs, young forest stage in the soil water and nutrient strongest; five kinds of deep-rooted shrubs / plant height, root pieces / crown are greater than 1,5 shrubs, underground and aboveground biomass ratio: 1.62,1.4,1.05,1.15,1.3 are greater than the growth of 1.5 kinds of shrubs underground and aboveground biomass allocation are conducive abandoned Sunada arid environment The absorption and utilization of limited soil moisture, which is five shrub species to adapt to the abandonment the Sunada arid site environment performance. This shows that with strong drought resistance shrub reforestation abandoned Sunada vegetation restoration feasibility. (3) abandonment of the observations of the dynamic changes in the Sunada the afforestation ground water: 0 ~ 40cm layer of soil moisture throughout the observation period, the abandonment of the plantation and Sunada an average of 12.6%, 40.7% higher than the rainfed Tsuchida water content, indicating that although water retention effect abandoned Sunada newer Sunada declined, but still better than the rainfed Tsuchida moisture retention capacity. Abandoned Sunada moisture necessary basic conditions for vegetation recovery and utilization; abandonment the Sunada afforestation soil moisture changes although fluctuations throughout the growing period, but the overall downward trend, and the lowest in July. After 8 to September rainy season, soil moisture is replenished rapidly increase. The abandoned good to keep soil moisture for the coming year Sunada the plantation and tree growth to create the basic conditions. (4) of abandoned Sunada artificial afforestation, soil moisture conditions change and shrub growth impact of observational studies show that: 4 years old Tamarix ramosissima plant height annual growth of the amount of the maximum, while the six-year students Multibranch T. Liu ground diameter of years the growth of the amount of the maximum, to 12 years old, its plant height, diameter annual growth volume is low. Visible, along with the increase of age, Tamarix ramosissima age reached 12 years, due to the growth of Tamarix ramosissima restrictions required moisture and other factors, stem diameter and height growth slows. 4-year-old Tamarix ramosissima roots are mainly distributed in the soil shallow (0-150cm), the growth of the main soil shallow water, part of the water depends mainly on rainfall recharge With the increase of age, the growth of Tamarix ramosissima need moisture the more soil shallow water to 6-year-old can no longer meet its growth needs, Tamarix ramosissima root growth through more extended to deeper soil layers, the absorption and use of soil deep groundwater. Throughout the growing season, three different forest age more than sticks of tamarisk stands under soil moisture is generally low, but the growth of shrubs and not be significantly affected because of low soil moisture, that is abandoned sands environmental conditions artificial Tamarix ramosissima shrubbery still basically normal growth, with the growth of forest age yet to show significant signs of recession. (5) arid vegetation to restore the most critical success factor is moisture. Experimental study on preliminary findings indicate that the abandonment of the Sunada the soil moisture conditions drought-resistant shrub, basically to meet the growth needs. Therefore believe that by creating artificial shrubbery to promote abandoned the Sunada the vegetation recovery feasibility.
|