Land use change scenario in Lhasa district using Markov chain model

Abstract

Markov model was used to represent the land-use change data for several reasons.Firstly,land use change is not unidirectional in nature.A given parcel of land theoretically may change from one category of land-use to any other at any time.Markovian analysis uses matrices that represent all the multi-directional land-use changes between all the mutually exclusive land-use categories.Land use changes and scenarios in Lhasa district were analyzed in this paper using Markov model.The main conclusions are as follows: (1) Land use changes in Lhasa district during the last ten years were related to this period's integrated agricultural development project.In 10 years from 1990 to 2000,186.53 ha of cultivated land were converted into forest land,accounting for 54.857% of the total cultivated land area converting into the other land use categories;and 130.05 ha were converted into residential area,being 38.247%.The remaining limited area was converted into the other land use categories such as rangeland and water body. (2) The most extensive changes of land use from 1990 to 2000 in Lhasa district was rangeland conversion.Rangeland was converted into cultivated land,horticultural land,forestland,residential area and water body.Among them,2333.33 ha of forestland were converted from rangeland,or 94.093 %,the largest of all in area.These land use changes were related directly to the integrated development and construction project carried out in the central Tibetan Plateau in the mid 1990s.Because of the implementation of biological and engineering measures consisting of large scale of forestation and construction of field safeguarding forest,since the 1990s,remarkable effects in soil erosion control have been obtained through improving surface vegetation and land cover conditions. (3) Markov chain model prediction indicated that the general trends of land use changes,in Lhasa district in future were that cultivated land,rangeland,water body and unused land will decrease and forest,horticultural land and residential area will increase. (4) It should be pointed out that since there are many factors impacting land use changes,in particular in a short period of time,policies,regulations,important regional projects and human activities and other uncertain factors will affect regional land use changes,hence causing certain errors in prediction accuracy of land use changes in Lhasa district. (5) The simulated areas of land use changes in the future in Lhasa district by Markov mode are very close to the planning areas of land use changes of Tibet,therefore,land use change scenario based on the Markov model has an important value for making land use plan.