Land use change in metropolitan fringe based on topography factors: a case study of Pinggu District, Beijing.

Topography is the basis for land use spatial pattern formation.This study analyzed the land use structure of Pinggu District from 1993 to 2008 and the land use change on the different classification of elevation,slope and slope direction.The results showed thatarable land,orchard,woodland were the main land use type of Pinggu District.The arable land decreased but both orchardand construction land increased.The land use change was significantly different between different classifications of elevation,slope and slope direction.Most conversions between arable and construction land occurred in the place with an elevation less than 300 meters and the slope lower than 15 degree.The conversion between woodland and grassland was mostly taken place in the sunny slope and semi-sunny slope,with the elevation between 300 to 800 meters and the slope lower than 8 degree.The conversion between orchard and grassland was mostly taken place in the semi-sunny slope,the elevation less than 300 meters and the slope between 2 to 25 degrees.The conversion between orchard and woodland was usually taken place in the semi-sunny slope,the elevation less than 800 meters and the slope between 2 to 25 degrees.Little conversion was found in the area of elevation more than 800 meters and slope larger than 25 degrees.The main conversion in this area was that woodland was changed into other land types.The dramatic land use change had a high correction with elevation,slope and slope direction in Pinggu District.The change in land use could be characterized by an increase of construction land and orchard but a decrease of arable land in the lower elevation and slope zone of Pinggu.There was a little change in land use with the increase of elevation and slope.