Studies On Response Mechanism Of Grassland Plant Diversity To Anthropogenic Disturbance In Kanas Scenic Area

The effective conservation of vegetation and plant diversity has become one of the important challenges to rational utilization and scientific development of natural tourism resource in scenic area. And it is also one of the key factors of implementation eco-tourism sustainable development in scenic area. This paper studied the changes of plant diversity composition and structure, habitat, community stability of midmountain meadow community under different anthropogenic disturbance at main scenic spots in Kanas Scenic Area. And it also studied the changes of the structure and pattern of vegetation landscape, the ecological capacity of the whole study area. The purpose of these studies is mainly discussing on the mode, process and ecological consequence of the response of the plant diversity to anthropogenic disturbance at different spatial scale, exploring the response mechanism of grassland plant diversity to anthropogenic disturbance, providing the scientific basis for the protection and rational utilization of grassland system and biodiversity in the eco-tourism area.The main results were the flowing:(1) The plant community height, coverage and biomass were all decreased with increasing grazing disturbance intensity, and the plant community density was increased from light to heavy grazing disturbance intensity in Kanas midmountain meadow community. The values of Patrick richness index, Pielou evenness index and Shannon-Wiener index were all decreased with increasing grazing disturbance intensity, and they were significant different at light to heavy and over grazing disturbance intensity (P<0.05). The species composition and their important value were significantly impacted by tourism disturbance. With increasing tourism disturbance intensity, some tourism-sensitive plants had disappeared or their important value decreased, while some tourism-resistant species had expanded their population. And the important value of total community concentrated on several tourism-resistant species. The values of Patrick richness index and Shannon-Wiener index decreased with increasing tourism disturbance intensity, while the higher values of evenness index were found under the moderate disturbance intensity.(2) The original dominant plant functional groups are perennial forbs and perennial rhizome grasses which have rich species and nutrient. And they were replaced the perennial bunch grasses, annuals and biennials which are low, miniaturized, vegetative reproduction in the meadow community. The important value of perennial forbs, perennial rhizome grasses, sedges and legumes all declined, and the important value of perennial bunch grasses, annuals and biennials all ascended with increasing grazing disturbance intensity. The value of plant functional group richness was the highest under the moderate grazing disturbance. With increasing grazing disturbance intensity, the number of species including perennial forbs, perennial rhizome grasses and legumes all decreased, and the number of species including annuals and biennials increased. With increasing grazing disturbance intensity, the coefficients of variation in biomass at the levels of community and plant functional group increased, the coefficient of variation at the levels of community was lower than at the levels of plant functional group, and the community dominance index too increased, but the coefficient of community structure variation decreased. So the community stability has significantly decreased under unreasonable grazing disturbance. The species turnover rate (βdiversity) was the stage of heavy-over > light-moderate > moderate-heavy grazing disturbance.(3) The important value of perennial forbs, perennial rhizome grasses, sedges and legumes all declined, and the important value of perennial bunch grasses, annuals and biennials all ascended with increasing tourism disturbance intensity. The perennial forbs have strong tolerance and buffering ability under tourism disturbance. The perennial bunch grasses, annuals and biennials have strong resiliency and resistance under tourism disturbance, and they can survive in over disturbance intensity habitat. The perennial rhizome grasses, legumes, shrubs and half shrubs are sensitive to tourism disturbance. In the hierarchy of community diversity, the species turnover rate (βdiversity) was the stage of moderate-heavy >heavy-over > light-moderate tourism disturbance. With increasing tourism disturbance intensity, the community dominance index increased, but the coefficient of community structure variation decreased. The coefficients of variation in biomass at the levels of community and plant functional group were all the lowest value under the moderate disturbance intensity, the coefficient of variation at the levels of community was lower than at the levels of plant functional groups. So the community stability has significantly decreased under unreasonable tourism disturbance.(4) The plant system gradually degraded under unreasonable grazing disturbance. Meanwhile, the soil system, especially surface soil (0-10cm) significantly degraded. In 0-10cm soil layer, soil bulk density was increased and soil water content was decreased with grazing disturbance intensity increasing. And they were significant different from light to heavy grazing disturbance intensity (P<0.05), but no significant different under over grazing disturbance intensity (P>0.05). Soil organic matter, soil hydrolysable N and soil available P were all decreased from light to heavy grazing disturbance intensity in 0-10cm soil layer, but soil available K was increased with grazing disturbance intensity increasing. In over grazing disturbance intensity stage, soil organic matter, soil hydrolysable N and soil available P were increased. The biomass and height of plant community were took on the positive correlations with the distribution of soil organic matter and soil hydrolysable N, and it was only significant different between biomass, height of plant community and soil organic matter (P<0.05). All community properties were took on the negative correlations with the distribution of soil available P and soil available K.(5) The plant system gradually degraded under unreasonable tourism disturbance. Meanwhile, the soil system, especially surface soil (0-10cm) significantly degraded. With increasing tourism disturbance intensity, the soil water content, soil organic matter, content of available nitrogen correspondingly decreased, however the soil bulk density, soil compaction, availability of potassium and phosphorus enhanced. Correlation analyses showed that there was a close correlation between topsoil physical-chemical properties and plant community characteristics (plant species diversity, coverage, height, biomass and litter biomass) of the meadow community in Kanasi scenic area (the values of R2are0.04～0.56). And this indicated that the disturbance processes of meadow community under tourism activities were virtually a synergistically response processes of soil-plant system.(6) The impacts of anthropogenic disturbance on the landscape pattern of Kanas Scenic Area were little in 13 years, and the whole landscape pattern changed little. The landscape diversity of Kanas Scenic Area kept at high levels. The results indicated the Kanas Scenic Area was effectively protected. But the grassland landscape pattern changed dramatically in the local Kanas Scenic Area. The increasing areas of the build-up land were equivalent to the decreasing areas of midmountain meadow. The periods of landscape pattern changes could divide into two period: 1992-2000 year, 2000-2005 year. In 1992-2000, the driving forces of the landscape pattern changes were mainly from natural factors (climate change, the ecological succession of vegetation landscape, other biological factors, etc.). The influence of anthropogenic disturbance on the landscape pattern was little. In 2000-2005, the influence of anthropogenic disturbance on the landscape pattern was increasing gradually, of which grassland landscape (the types of grassland patches are midmountain meadow and shrub grassland) was affected seriously.(7) The sustainable development degree of an ecosystem is best indicated by comprehensive analysis of the relation among ecological resilience state, bearing state and sustainable carrying capacity state. The evaluation indices system of ecological carrying capacity in Kanas Scenic Area was established using principal components analysis (PCA) and analytic hierarchy process (AHP). And the concrete evaluation indices of ecological carrying capacity were screened out by analyzing the correlation between the bearing pressure and the supporting force (negative direction and positive direction). The ecological carrying index using the status space method to calculate was 0.0669 in 1992, it was decreased to 0.0485 in 2000 and 0.0046 in 2005. The Sustainable carrying state was sustainable in 1992 and 2000, and it was feebly sustainable in 2005. The sustainable development degree based on the ecological resilience state, bearing state and sustainable carrying capacity state can integrally reflect the ecological carrying capacity of region and serve as scientific basis for the regional sustainable development.