Identification Of The Priority Ecological Land In Sand Fixation Regions Of Hulunbeier Grassland

Important eco-function areas refer to the regions that play an important role in water and soil conservation, bio-productivity, and sand-fixation etc., so the studies related are significant in natural disasters prevention and mitigation, biodiversity conservation, and regional ecological protection as well as national and local ecological security. China has large areas of important eco-function regions, resulting in more complex and difficult management that needs the cooperation between local government and state. Therefore, based on "less cost to make more profit", it will be effective method for environmental management to assess the importance of ecological land, classify the levels and identify the priority of Northern eco-function regions.Using high-spectral data from field survey, we conducted the following study: established the remote sensing model to analyze the spatial pattern of grassland degradation and desertification, and evaluated its effect on sand-fixation functional areas; used the PSR model to construct assessment index system of regional ecological security and assessed the security level and the spatial differences based on leading service function; analyzed the major factors influencing the grassland ecological security; from the importance of ecosystem service function, landscape component, and landscape structure and layout, we comprehensively assessed ecological land use, classified importance level, and identified the priority level of ecological land. Here are the main study contents and conclusions:(1)Spatial distribution of grassland degradationAssociating the measured ground hyperspectral data with MODIS image data of the same period, hyperspectral ANPP productivity model and vegetation coverage model were established based on the MODIS remote sensing image.Hyperspectral ANPP productivity model was as follows: ANPP=295.5l ×(0.977×NDVIMODIS-0.028)1.7414 (1)hyperspectral vegetation coverage model was as follows: Vc=0 (NDVIMODIS≤0.1689) (2) Vc=131.981×NDVIMODIS-22.29 (0.1689<NDVIMODIS≤0.8779) (3) Vc=1(NDVImodis>0.8699) (4)Grassland degradation indices based on the realistic productivity and potential productivity as well as vegetation coverage index of the hyperspectral vegetation coverage model were established respectively. The identification results of grassland degradation spatial distribution in 2000,2005,2010 and 2014 showed that non-degraded and light degraded grassland accounted for about 30.71% and 27.42% of the total study area in 2000; compared with 2000, medium degraded grassland increased 5049.13 km2 in 2005; non-degraded grassland was 30.59% of total area, and the severely degraded grassland was smallest in 2014, only accounting forl 1.91% of the total area.(2) Ecological security assessment based on sand-fixation functionAccording to the research purpose, we used the PSR model to construct regional ecological security assessment index system, and analyzed the index weight by hierarchy analytic method, as well as comprehensively assessed the ecological safety based on sand-fixation function. The results showed that:overall, the ecological security situation was the largest level from 2000 to 2014, and security area accounted for 34.57% to 39.70%, of which the security areas were minimum in 2014 and maximum in 2010; more safety area accounted for 22.90% to 30.35%, while extremely unsafe zone area showed a decline trend since 2000.(3) Identification of priority ecological landBased on importance theory of landscape ecology, the index system of ecological function and ecological sensitivity was built, and then identified the ecological land as different levels such as the extremely important region, very sensitive region and highly unsafe region, finally identified the priority ecological land. The results showed that:priority ecological land mainly distributed in the eastern warm meadow grassland, sand strip area and the western part of the drought areas, accounting for 38.20%, with a total area of 29240.5km2.(4) Drive factor analysisAccording to land use data of remote sensing in 2000,2005,2010 and 2014, the results showed that:grassland and unused land was the main body of landscape types in the study area, accounting for 87.64%,89.95%,86.09% and 89.95% respectively; Landscape pattern index analysis showed that the landscape inside the plaque number increased, plaque area was smaller, the landscape spatial connectivity reduced, and landscape diversity and heterogeneity was higher. An altitude impact on the various types of landscape were mainly distributed in low altitude of 500 m-850 m segment; Different slope and aspect direction had no impact on the landscape pattern change; Rainfall has extremely significant linear regression relationship with interannual productivity fluctuation, and the grassland vegetation productivity increased with the precipitation. In addition, spatial heterogeneity study resulted showed that, enclosed grassland led to the smaller spatial heterogeneity, while the spatial heterogeneity of grazed grassland was weak and the spatial distribution pattern was relatively simpler compared with that of enclosure grassland.