PROGRESS IN GEOGRAPHY ›› 2013, Vol. 32 ›› Issue (2): 308-317.doi: 10.11820/dlkxjz.2013.02.017

• Original Articles • Previous Articles    

Gradient distribution of belt transects and characteristics of spatial clustering of point pattern of woodland landscapes: A case study of ecological barrier zone of Three-Gorges Reservoir in Chongqing

WANG Jinliang1,2, HUANG Zhilin1, SHAO Jing'an2,3, LI Yangbing2   

  1. 1. Key Laboratory of Forest Ecology and Environment, State Forestry Administration, Research Institute of Forest Ecology Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China;
    2. College of Geography and Tourism, Chongqing Normal University, Chongqing 400047, China;
    3. Institute of Mountainous Ecology and Regional Development in Three-Gorges Reservoir Area, Chongqing Normal University, Chongqing 400047, China
  • Received:2012-06-01 Revised:2012-08-01 Online:2013-02-25 Published:2013-02-07

Abstract: From the perspective of point pattern, this paper presents a study of the distribution mechanism of spatial characteristics of woodland and its different types of landscapes, in order to explore the continuous change and the trend of spatial heterogeneity distribution of woodland landscapes, and provide the basis for rational planning and construction of woodland landscapes. By using point process density and Ripley K function, we established different belt transects for the ecological barrier zone of Three Gorges Reservoir in Chongqing, created the point pattern database for the woodland landscapes from 1997 to 2005, and then analyzed the gradient distribution of the belt transects and the change of the spatial clustering of the woodland and its three different types of landscapes. The results indicated that: (1) the gradient distribution of the belt transects as a whole was strikingly unbalanced, with the point process density showing“twin peak”distribution upstream of center point, and gradient distribution downstream of it. (2) As for the changes in different spatial and temporal scales, the point patterns of all woodland landscapes in the barrier zone showed distribution of local spatial clustering. Although the largest L(d) value of the spatial scale were both 40 km in 1997 and 2005, the range of woodland distribution expanded since 2005; Uniform spatial distribution increased, and spatial clustering decreased. (3) The characteristics of spatial clustering of forest land coincided with overall woodland landscapes, the largest L(d) value of the spatial scales were both 40 km in 1997 and 2005, but the forest land started to lose its natural advantages. Distribution of shrub land was more clustered in space in comparison to forest land, and the degree of clustering increased with time, with the largest L(d) values of spatial scales being 50 km in both 1997 and 2005. Open forest land expanded rather fast, and became dispersed in space as a result of reduced spatial clustering. The largest L(d) value of spatial scales was 40 km in 1997 and 30 km in 2005.

Key words: Chongqing, ecological barrier zone, forest landscape, point pattern, Ripley K function, spatial cluster, Three-Gorges Reservoir