Spatial Variation in the Loss Rate of Wetland Natural Vegetation Subject to Human Influences

Human activities have profoundly influenced natural ecosystems, especially wetlands. There is an urgent need for comprehensively understanding the causes, processes and consequences of human-induced environmental impacts. This paper presented rapid landscape change and differentiate the impact of human activities on reductions in wetland natural vegetation in the Lixiahe wetlands based on remote sensing data. We quantified land-use change in the study area using classified Landsat TM (1988-10-25, 2006-05-20) and ETM+ (2000-09-16) images. Over the study period, wetland natural vegetation declined by 69%, which was largely attributable to aquaculture development. The loss speed of natural vegetation rose significantly with increasing proximity to rural settlements and secondary roads, with a curve of the inverted "U" shaped response to the presence of towns. These trends are reasonable in that wetland use activities in the study area are directly associated with the settlements and roads in the rural areas at local scales, but are also indirectly associated with the major transportation network from a regional perspective. Meanwhile, we should notice that this change was not of a continuous linear feature, and instead it showed a typical sub-segment function characteristic, which indicated that the impact of the driving factors on natural vegetation was non-linear.