Studies On Response Of Artemisia Frigida Population To Grazing Disturbance

Artemisia frigida population can tolerate drought, browsing, trample and soil erosion. It has strong regenerating ability of radication and germination, and can still renew and reproduce under intensive livestock browse and soil erosion. It helps pasturage keep certain productivity under utilization intensity. Thus it plays a very important role in preventing the community from further degeneration. The study discussed A. frigida population response to grazing interference through variances of morphological characters, physiological characters, genetic diversity under different grazing intensities. The results were as follow:1. With the increase of grazing intensity, height of vegetative shoot and reproductive shoot decreased, density of vegetative shoots and adventitious roots increased, length of stolen increased, density of reproductive shoots and the differentiation ratio of reproductive shoots (reproductive shoots density/total shoots density) trend to decrease. With the increase of grazing intensity, the reproductive pattern changed from sexual and asexual reproductive to asexual reproductive mainly, the changeover was the key for A. frigida to become constructive species under heavy grazing.2. With the increase of grazing intensity, a. frigida population biomass of leaves, stems, roots and total biomass increased. the static change was that biomass allocation to roots increased, while that to stems and leaves decreased; biomass allocation to asexual reproductive increased, while that to sexual reproductive decreased. the dynamic change was that the biomass allocated priority to above ground portion from early to middle growth period, especially to leaves; the biomass allocated priority to sexual reproductive or storage organs from middle to late growth period, the change of resource allocation pattern was the material base for a. frigida to become constructive species under heavy grazing.3. With the increase of grazing intensity, soluble sugar content had no significant change, except it decreased in late growth period. With the increase of grazing intensity, starch content and total nonstructural carbohydrate (TNC) content decreased, nonstructural carbohydrate pool of leaves, stems, roots and TNC pool increased. The allocation of nonstructural carbohydrate pool to roots increased, while that to stems and leaves decreased; the allocation to reversible storage pool increased, while that to irreversible storage pool decreased; the allocation to sexual reproductive decreased, while that to asexual reproductive increased. All these were ecological strategies that A. frigida population adopted to reduce energy losing, enhance utilized energy, advance the capability of regeneration and the fitness of population, and to adapt and respond to grazing interference.4. With the increase of grazing intensity, chlorophyll a, b and total chlorophyll had no...