The spatial pattern and dynamic evolution of the landscape are jointly influenced by its physical environment, animals and vegetations and human activities on a basin scale. Physical environmental factors including the elevation, climate, hydrology and soil constitute the backdrop of the general landscape pattern formation and evolution. Biological processes exert a significant impact on patch features on a small scale. Human activities, including population growth, economic development and policy factors, play their due roles on any scale.
Landscape pattern analysis, a basis of further researches on landscape functions and dynamics, contributes to analyzing spatial distribution characteristics of landscape components in a quantitative manner. During recent years, great developments have been made on researches about indices and models of landscape pattern evolution in a quantitative way. However, little has been known about gradient patterns and its relationship with environmental factors on a basin scale.
Gradient analysis, which is conducive to revealing driving forces behind landscape evolutionary processes, can reflect the evolutionary laws of spatial landscape patterns. At present, there is still lack of systematic studies on selections among diversified transects and their reflected differences of calculation results of landscape gradient patterns.
During the past two decades, tremendous changes have taken place in its landscape patterns in Haihe River basin. This paper, taking Haihe River Basin as its study area and based on GIS (Geographic Information System) technologies, aims to analyze complete landscape patterns and its spatial differences within the whole basin through standard methods and moving window analysis of Fragstats3.3, and to investigate the relationships between the landscape gradient pattern and environmental factors through detrended canonical correspondence analysis (DCCA); to obtain gradient patterns of the landscapes, two transects which have been set up along both longitudinal (i.e. along river's flow direction) and lateral (i.e. perpendicular to river's flow direction) transects were cut off from the origin landscape data. Then 6 metrics (AREA_MN、CONTAG、ED、LSI、PD、SHDI) under the landscape level were calculated by Moving window approach; And the relationships between landscape gradient patterns and their driving environmental factors including elevation, precipitation, temperature, population and GDP, with the aforesaid 6 metrics as targets were studied by using DCCA. The results show that farmlands, accounting for 55.9% of the total landscape, compose a major part and were the matrix in Haihe River basin on year 2000. The spatial distribution pattern of landscapes metrics characterized in block structure associated with ring structure and banded (corridor) structure. Blocks dominate the landscape structures in the basin with structures in the forms of ring or banded (corridor) dispersed on it; Two transects showed similar features: they fluctuated in different amplitudes along these transects as landscape types changes, and both existing evident transitional zone. The DCCA analysis results also showed that gradient changes of landscape metrics and environmental factors were closely correlated: regional elevation, precipitation and temperature were the decisive factors for the landscape distribution pattern in the basin scale; yet, population quantity and GDP were also affected the landscape pattern dramatically in regional scale.