Spatial-Temporal Analysis on Land Reclamation and Loss Patterns in Xinjiang
新疆耕地开发流失模式时空特征分析

To study reclamation and loss patterns of cultivated land in Xinjiang Uygur Autonomous Region, the authors examined spatial-temporal dynamics of cultivated land in Xinjiang during since the late 1980s based on four land use databases and interpreting four scenes of satellite images acquired in 1990, 2000, 2005 and 2008 in combination with GIS spatial analysis techniques and field surveys. Changes in soil texture and irrigation patterns during the processes of land reclamation were analyzed in detail, with unraveling reasons for cultivated land losses over the past two decades with the environmental database for Xinjiang. To investigate influencing factors for reclamation and reasons for cultivated land losses, the authors accounted for factors of soil texture, irrigation pattern and loss reasons. In terms of soil texture, the cultivated land was categorized into three classes by interpreting the remote sensing images with the aid of field survey, which were sandy soils, loamy soil and grave soils. In terms of irrigation patterns, the cultivated land was divided into three classes, which were surface water irrigation, groundwater irrigation and dry farmland. In terms of loss reasons, the loss of cultivated land was divided into arable land occupation by construction, natural abandonment land and returning farmland. Results showed that land reclamation exhibited a increasing trend and then slowed down, reaching the maximum between around 2000 and 2005. The reclamation was generally shifted from the oasis to the unused land, such as desert and gobi desert. The irrigation pattern was shifted primarily from surface water irrigation to groundwater irrigation. The losses of cultivated land maintained decreasing, being converted in part into natural abandoned land. The ratio of arable land occupation by construction showed a decreasing trend and that of conversion from farmland to forests increased. It was also found that the impact of human activities on land losses was manifested incrementally. Arable land occupation by construction and conversion of farmland into forests mostly occurred in oasis. Abandoned land expanded from oasis to desert and gobi desert. In a word, the reclamation and loss patterns of cultivated land have changed greatly. With the changes in land reclamation and losses, sustainable land utilization and reclamation would have to be affected; hence the coordination between sustainable land reclamation and loss patterns becomes the key for mitigating land degradation and realizing intensive land use in the future.