Plant Community And Soil Environment Response To Winter Wild-fire In The Grassland Of Plateau In Western Sichuan, China

Wildfire, along with soil, water, and temperature, had been one of the major forces that shaped the earth’s vegetation. The overall affected of the fire on ecosystems were complex, ranging from the reduction or elimination of aboveground biomass to impacts on belowground physical, chemical and microbial mediated processes. Although a number of studies have looked at fire effects in the grassland, relatively little is known of the response of alpine grassland in Qinghai-Tibetan Plateau. In winter, under a vast covering of dry airs, and the local life habits and culture, wildfires were common in this area, most were factitious. In December5,2010, wildfire was raging through grassland atop a plateau in Daofu County, Tibetan Autonomous Prefecture of Garze, Sichuan province. In January2011, the area was used to research. We set up18samples random in burned area, and chose18samples random in unburned area. In this study we investigated wildfire effects direct on soil properties and soil enzyme activities, and described vegetation characteristics in the first year post fire, to quickly ask for the information of the role of winter wildfire in alpine grassland.Soil analysis report shows that:Moisture content and density of soils in alpine grassland can not be changed by witer wildfire (p>0.05);The manifestation of soil chemical and biological properties reponsed to Winter wildfire is mainly concentrated in the0-10cm, among which0-5cm is the most significant;Winter fire could increase soil organic matter, total nitrogen, soluble carbon content, available potassium and available phosphorus content (p<0.05), while not changing the soil soluble nitrogen content (p>0.05);Compare to unburned soils, the microbial biomass carbon content increased significantly in the burned soils (p<0.05), but the microbial biomass nitrogen content did not change significantly in the burned soils (p>0.05);Winter wildfire improve the activity of catalase (p<0.001), the β-glucosidase activity, the activity of invertase significantly (p<0.05).In addition, we find the effect of winter wildfire on vegetation community structure of alpine meadow influence is mainly includes the following several points:Winter wildfire does not alter vegetation diversity, evenness and species richness. Winter wildfire would change species composition on vertical direction and horizontal direction. The quantity and biomass of annual grasses, perennial forbs and shrubs would increase following winter wildfire. Besides, although the number of perennial forbs is decreased, the biomass is increased following winter wildfire. Moreover, winter wildfire makes the number and biomass of perennial grasses is highly reduced. Winter wildfire makes the biomass of germinal species group decreased, and makes the biomass of forbs species groups increased. The competition becomes fierce after fire behavior inwinter.On the burned area, the competition abilities of plants in germinal species group are dropped, such as Capillipedium parviflorum and Poa. Relative, the forbs has the advantage of competition of resource, such as Leontopodium leontopodioides, Artemisia sacrorum, Anemone rivularis, and so on. Therefore, the quality of grassland degraded following fire.Fire change species niche, but their response mechanisms are different. The Niche Breadth of Spenceria ramalana, Leontopodium chuii, Potentilla saundersiana, Elymus, Origanum vulgare, Geranium yunnanense, Stellera chamaejasme, Artemisia sacrorum, Tibetia himalaica, Roegneria hirsute, Cymbopogon, Anemone rivularis and Carex are widen. Asperugo procumbens, Poa, Agrimonia pilosa, Aster diplostephioides, Kobresia, Berberi s julianae, Helictotrichon, Saussurea japonica and Vicia are narrow down.