Research On Landscape Dynamic And Ecological Pattern Optimization In Desert Steppe

Landscape dynamics and ecological pattern optimization are one of the hot issues in landscape ecology research.This paper which combined the traditional ecological problems with their geospatial attributes adopted the "pattern-process-mechanism-sustainable" dynamic research paradigm of desert steppe landscape,according to the research framework of "Landscape Dynamic Analysis-Drive Mechanism Exploration-Ecological Quality Evaluation-Safety Pattern Construction-Development Simulation Selection".We studied the landscape pattern and its productivity dynamics and explored the driving mechanism of desert steppe landscape change based on the grassland ecological footprint division analysis period,and then evaluated the ecological quality of grassland landscape,constructing the ecological landscape-based landscape pattern zoning to simulate the resource allocation plan of the future desert steppe under the three scenarios of natural development,economic driving and ecological security,aiming at providing reference for grassland ecological protection planning and regional ecological civilization construction.Main research conclusions are as follows:(1)The ecological evolution of grassland in the study area can be divided into three stages:low-level synergy stage(1987-2002),policy-driven stage(2002-2009)and rapid development stage(2009-2016).The absolute value of the short-term fluctuation coefficient(-2.289,-1.082 and 0.495,respectively)gradually decreased over time,indicating that the previous period fluctuates sharp and the later changes gentle.The long-term trend(0.292%,0.728%and 1.355%,respectively)gradually increased over time,reflecting the improvement of the utilization efficiency of grassland resources per unit and the decline of the proportion of grassland consumption in economic contribution,indicating that extensive resource utilization is being transformed into sustainable development of the ecological economy.(2)The average annual vegetation productivity showed the spatial distribution of southeast high and northwest low.In the 94.23%of the study area from 1987 to 2016,NPP of the average annual vegetation showed a dynamic growth trend with an average growth of 3.77g C m-2a-1.The southeast hilly area of the towns showed a dynamic increase in NPP of vegetation,and NPP of vegetation showed a dynamic decrease in Wulanhua town which was significantly disturbed by human activities.NPP of vegetation was significantly positive correlation with annual mean temperature and annual average precipitation,and the correlation coefficient with annual average rainfall was higher.From 1987 to 2016,the number of landscape types changed significantly,and the distribution of forest landscape and artificial landscape increased while the landscape of grassland,desert landscape,farmland landscape and water area decreased.From the dynamic direction,112696.3ha of grassland and farmland converted into forests and 76574.41 ha deserts converted to grassland.From the perspective of dynamic rate,the changes of various landscape types experienced a process of "slow change-continuous change-fast change".From the perspective of type,the degree of fragmentation of grassland landscape was increasing and the landscape of farmland was opposite that the plaque enlarged and the shape was contiguous.The landscape of the study area tends to be fragmented,the edge effect reduced,the connectivity was relatively stable,and heterogeneity changed significantly.(3)Natural factors and human disturbances are the fundamental driving forces of landscape dynamics,and the degree of human disturbance is more significant.Agricultural production,population status and economic development are the main reasons for changes in farmland landscape,grassland landscape and artificial landscape in the study area.The landscape of farmland is greatly affected by the population situation,the grassland landscape is deeply affected by agricultural production and population distribution,and the artificial landscape is increasing with economic development and population growth.Affected by the time scale,the driving force of the same landscape type will change significantly with time and the effect will change accordingly.(4)The grassland ecological quality of each village in the study area was sensitive and fragile,the comprehensive index ranged from 0.003 to 0.765,and the sensitive and vulnerable villages accounted for 82.73%of the study area.And there were regional differences in the north that was higher than the south,indicating that the overall level of grassland ecological quality was low.There was spatial auto-correlation of grassland ecological quality,and local spatial correlation reflected the non-equilibrium and spatial dependence of spatial distribution of grassland ecological quality in the study area.The impact of economic pressure and environmental pressure on grassland ecological quality was significantly higher than population pressure and resource pressure.(5)The cumulative cost distance of different landscapes was divided into five categories of ecological security pattern,including key optimization areas,potential optimization areas,key concern areas,ecological protection areas and ecological management areas.In the future research area,the ecological pattern simulation under three scenarios of natural development,economic driving and ecological optimization showed that farmland,forest,water,artificial and even desert landscapes had different degrees of growth,but the difference of new farmland,forest and artificial landscape Mainly reflected in the size and spatial distribution.The ecological security scenarios which could maintain the supply of land resources for economic development and considered the demand for ecological space in grassland protection was more in line with the future development trend compared among the configuration schemes.