沙地小叶锦鸡儿群落持续经营的对策

主要研究了极度干旱对小叶锦鸡儿生长的影响及小叶锦鸡儿人工固沙林的密度和现有林的经营利用对策,探讨了干旱条件下土壤水分与植株密度、植被盖度的关系。结果表明:天然群落表现出对干旱条件极强的适应性,人工群落则出现了生长衰退甚至大面积枯萎现象,这主要是由于人工群落密度过大所造成的。轻度放牧可以增加小叶锦鸡儿可食部分,是持续经营利用小叶锦鸡儿群落的有效途径。

Sustainable Management of Caragana microphylla Community in Sandy Land

Natural Caragana microphylla community is one of stable communities in Horqin sandy land. It can keep normal growing even on the extremely arid condition. While the drought resistant ability of artificial Caragana microphylla community is weaker. Its fruiting and growth are constrained by extreme drought seriously. (2) The natural distribution of Caragana microphylla in fixed, semi fixed and shifting sand dunes is random group distribution, which performs an important function in harmonizing the water relationship between soil and plant. While the artificial community in uniform distribution and big plant density and community coverage has not the ability of harmonizing soil water, which results in too much water are consumed and the drought resistant ability and stability of community decrease. The method to solve the problem is to control the community by decreasing density and ground biomass. (3) Caragana microphylla growing in sand dune has a large root system, usually more than 5.0 m long and 2.0 m deep. The root of artificial Caragana microphylla is only 1.5~2.0 m long. The most of roots of Caragana microphylla distribute in 30~70 cm soil layer. On the extremely arid condition, the depth of drysand layer in artificial community can reach 65~140 cm, soil moisture at 100 cm depth is no more than 0.7% and the moisture in leaf and stem decreases dramatically, which make most of plants withered. The depth of drysand layer in the natural community is 30~45 cm, and most plants grow normally. (4) Over grazing can make soil surface bare and desertified and make plant species number and plant height reducing, also change the age structure of branches. The average height on the condition of enclosure is more than 100 cm, however plant height is no more than 55 cm on the over grazing condition. Slightly grazing can increase the number of new branches and edible part. Each branch slightly grazed can produce 3~5 new branches, while the ungrazed branch produces only one new branch. Cutting can make plant back to its young stage, and promotes its generation. So in order to use Caragana microphylla sustainably, grazing by round enclosing, controlling grazing intensity should be carried out. Meanwhile the combination of cutting, grazing and closing should be adopted according to age structure and disturbance situation of the community.