Physio-ecological Adaptability Of Salix Gordejevii In Hunshandak Sandland

Salix gordejevii is a kind of dune-fixing pioneer shrub in Hunshandak Sandland, China. Salix gordejevii takes a vital role in improvement of ecological environment .We had conducted a series of explorative research, which included morphological and structural adaptability, physiological adaptability, regular of natural regeneration and artificial regeneration and restoration and so on. Eco-physiological adaptability countermeasures of Salix gordejevii were showed, with main conclusions being achieved as follows:The leaves of Salix gordejevii, under all the observed habitats, were thicker with total-palisade type, identical face leaf and thicken epidermis cell wall with cuticle. Its structural characteristics were typical psammophyte. The results also showed that the sequence of drought resistance is in the order of Salix gordejevii on the drifting sand dune, Salix gordejevii on the semi-fixed sand dune, Salix gordejevii on the fixed sand dune and Salix microstachya var. bordensis. Meanwhile, from a structure of leaves perspective, Salix gordejevii were confirmed which it is a xeromesophytes.The main conclusions being achieved by studied on root system distribution and biomass of Salix gordejevii: Artificial forest root system were made up fine root and middle root (diameter<2.0mm),and fine root(diameter<0.5mm) took high proportion. The fine root took more than 50% of the total amount. Root system of Salix gordejevii mostly distributed in 10~30cm depth of soil ,and in order to absorb the moisture content and nutrient in this soil layer; with deepened soil layer, The weight of root system took on reduced tendency; The root system took on the level distribution, and the horizontal root system was developed. At the same time, with the plant growth, the characteristic would even more obvious.Seed germination characters and seedling development of Salix gordejevii were affected by some environmental factors. In this research the soil moistures, soil thickness, temperature and light that influenced the seed germination and seedling development were studied. The results showed: Seeds were very sensitive to water. The optimal sand water content for seed germination was 3% to 20%. If sand water content was less than 3% or more over 20%, seed could not germinate; Seed germination needed sand bury. The optimal sand thickness was 0.1cm to 0.4cm. However, when the sand that buried seed was thicker than 0.6 cm, seedling emergence would be restrained. When the sand was thicker than 1.2cm, seed would not germinate; The optimal temperature for seed germination was 15℃to 35℃. When the temperature was higher than 45℃, seed could not germinate, and died finally; Heat tolerance of the seedling was strong. Seedling will be damaged when temperature was 40℃, and died after 90min when temperature was 60℃; Seed longevity was about 120d when seed were stored under the indoor condition.Salix gordejevii belongs to r-countermeasure type, which was more seed, high germination rates and lower livability. The regenerate manners of Salix gordejevii had seed regeneration and sprouting regeneration, but seed regeneration was hard. At the same time, growth of Salix gordejevii would decline when the drifting sand dune was fixed.In order to achieve the purpose of regeneration and restoration, people might adopt cutting measure by making use of its characteristic. Therefore, not only the cutting increased biomass of shrub, but also edible parts, canopy density and effects of sand-fixing and sind-preventing.Under the conditions of water deficiency, relative water content , bound water content and water-holding capacity of Salix gordejevii were high; With increasing the degree of water deficiency, soluble sugar content and Pro content of leaves increased,and effect of osmoregulation to Salix gordejevii; The SOD activity and POD activity raised, and assorted with CAT, in order to mitigate hurt of O2-; The content of MDA raised gradually, and showed that hurtful degree of membrane protective system increased with increasing the degree of water deficiency. Therefore, as viewed from physiological characteristics, Salix gordejevii exhibits adaptive characteristics of drought too.