Study On Dynamic Changes Of Landscape Pattern In Loess Hilly And Gully Region

With the surface broken, gully density, low vegetation coverage rate and serious soil erosion in loess hilly gully region, Ningxia Pengyang county belongs to the typical loess gully region, the unreasonable land use make the land ecological system now facing great pressure. Small watershed is the basic research unit of and the social economy and comprehensive control of soil erosion in Loess Plateau, research of the county scale and small watershed land use/cover has the important theory and practical significance. In this study, based on the former research achievements and experience, "the theory and method of landscape ecology" as the guide, based on the field investigation, the use of remote sensing, global positioning system and geographic information system technology, with a typical county in the Loess Hilly Region and the small watershed as the study area, in the large scale to discuss the land use and landscape pattern and dynamics in recent 20 years in Pengyang county, and to do a detailed analysis about the main driving force of land use pattern change of the corresponding period; in the small scale with the typical small watershed in Loess Hilly Area as the representative, according to the ecological restoration measures to diviside the landscape type, reveal the relationship between spatial distribution of different landscape types and altitude, slope, slope direction.et terrain factors, to provide the basis for rational utilization of river ecological restoration and natural resources.The research results show that:(1) Between the 20 years, unused land has the highest conversion rate of Pengyang County, mainly convert to the grassland and cultivated land. Farmland is the dominant landscape between 1995-2000, grassland landscape become the region’s dominant landscape in 2005-2014. The land use changes in Pengyang county is the largest and fastest between 2000-2005, this phase is the stage of rapid improvement of returning farmland to forestry engineering, impact of human activities on the natural environment is larger, the grassland landscape increase fastest in this stage, during the period of 2010-2014, the increase speed of urban construction land is the fastest, reflected the region affected by effects of ecological immigration policy, landscape fragmentation degree decreased year by year. Grassland landscape has become the region’s dominant landscape between 2005-2014. From the type of land use change in the study area, speed and landscape pattern change data shows the corresponding period of national policy of returning farmland to forestry, ecological migration policy and the policy adjustment is the main driving force of land use pattern change in Pengyang county.(2) The spatial distribution of ecological restoration and topographical factors significantly related in Gaojianpu watershed, vertical distribution is obvious. Altitude from low to high, the distribution of landscape types showed the order of ditch bottom foreast-> economic fruit forest-> reforestation-> natural enclosing for barren hill-> level terrace-> fish-scale pits-> barren hill afforestation; the spatial distribution of landscape impact most by slope, the ratio of distribution cases were gradually increased first and then gradually decreased; aspect from north to south in the process, the distribution ratio of reforestation, level terrace and barren hill afforestation decreases, natural enclosing for barren hill and economic fruit forest increases, fish-scale pits and ditch bottom foreast landscape are basically not affected by influence of slope aspect.