Research on Change of Land Use Based on Decision Tree in the Horqin Sandy Land in the Past 25 Years

Abstract

Horqin Sandy Land is a key area for the construction of northeast shelterbelts. Ecological environment of the area is fragile and vulnerable to damage. However, there is a lack of research on the long time series and continuous system in Horqin Sandy Land. Therefore, it is urgent to grasp the impact of policies of the Three-North Shelterbelt Program on Horqin Sandy Land and analysis the differences in land use patterns in the Horqin Sandy Land before and after implementing restoration projects. In this paper, six counties in Horqin Sandy Land are used as the research areas. Six Landsat TM / ETM + / OLI remote sensing images from 1990 to 2015 are collected. Based on the NDVI, NDWI, NDBI, and the principle of spectral hybrid analysis, a decision tree classification method is used to put the satellite image data divided into seven categories: sandy land, cultivated land, waters, forest land, grassland, residential land, and saline-alkali land. The accuracy of the classification results is verified on the basis of high-resolution images and yearbook data. The results show that: (1) Analysis is made from the perspective of land use dynamics. During the period of 1990–2015, the area of cultivated land and residential land continued to increase. The area of salinized land, water body and grassland fluctuated little, and decreased generally. The forest land and desertification area fluctuated greatly and the overall trend was “increase-decrease-increase”; the overall trend of sandy land was “decrease-increase-decrease”. The areas of grassland, woodland and sandy land showed a negative correlation. (2) Analysis is made from the perspective of spatial distribution pattern of land use types, each of land types has undergone dramatic changes, among which grassland, cultivated land, forest land, and sandy land are the most important types of change. (3) Twenty-five years after the implementation of the Three-Norths Shelter Program, the ecological environment of Horqin Sandy Land has been initially restored. The ecological environment in this area is extremely fragile and requires long-term and continuous protection at a later stage. This study analyzes the change of land use pattern in Horqin Sandy Land in the past 25 years through an effective decision tree classification method, explores the impact of the Three-North Shelterbelt Program on the evolution of the pattern, and provides a recommendation of rationalization for future sustainable land use in Horqin Sandy Land.