Spatial Distribution Pattern Changes of Oasis Soil Types in Manasi River Basin, Arid Northwestern China

Soil distribution pattern play a significant role in the stability conservation and economic development of oasis in arid regions. But the previous studies on soil showed the limited concern to the changes of soil type and the spatial distribution pattern. Manasi River Basin is a typical region in Xinjiang because the oasis is one of the largest areas for agriculture and one of highly developed regions for industry. In addition, it is a focus region of human activities, so it is the representative place in exploring the soil spatial distribution change.

Based on two maps of soil type, Prof. XU Hailiang and his research team attempt to analyze the changes of soil spatial distribution pattern in the Manasi River Basin. This report is the continuation of their previous study, in which the same study area was sampled just once in a year. Such studies will help to show how to control the soil type changes.

Soil types and soil distribution pattern changes were assessed and compared by using two soil maps made in 1987 and 2006. 14 soil types were classified and analyzed in the study area. Results indicated many differences among the changes of different soil types. During the period from 1987 to 2006, there were widespread changes in spatial distribution of soil types in Manasi River Basin at class-level. The area of Petrocambids decreased, whereas Aquicambids increased. The small patches began to coalesce into large ones and the patch numbers decreased during the past 20 years, which brought about the fragmentation decrease in Manasi River Basin. In contrast to the decrease of the patch density, the average patch area of 12 soil types increased. With the increasing man-made disturbance, more soil type patches, especially the agricultural soil patches were close to square in shape. During the recent 20 years, the decreased patch shape indexes occupied about 57% of all while the increased patch shape indexes were over 40%. The split index of most soil types has also declined during the same period. The landscape-level indexes also reflected the spatial distribution changes of oasis soil types. The landscape diversity index and landscape evenness index have increased while the landscape dominance index has decreased in the recent 20 years, which showed that more equirotal soil patches were formed and various soil types dominated the soil landscape in Manasi River Basin. Changes of different soil types are one of major indictors to show environment changes and impacts of human activities. Therefore, it is necessary to emphasize the study of soil type changes in the arid and semiarid region.

The result has been published on Catena, 2011, 87(2): 253-259. This paper is also archived at http://www.sciencedirect.com/science/article/pii/S0341816211001159.

Soil type maps of 1987 and 2006