Heterogeneity Effect of Human Disturbances on Landscape Patterns in the Yellow River Delta Wetland, China

Wetland landscapes have undergone tremendous changes and the spatial heterogeneity of wetlands has increased. It's a huge challenge to accurately assess the effect of human disturbance on the landscape patterns in such a complex environment. This paper, taking the Yellow River Delta as a case, proposed a new framework to evaluate the heterogeneity effect of human disturbances on landscape patterns. A pixel-based Human Disturbance Index (HDI) with the addition of ecological conditions and the buffer influence is first established to quantify the spatial difference of human disturbances. Besides, Geographically Weighted Regression (GWR) model was introduced to analyze the spatial correlation between HDI and landscape indices, i.e., Shannon's Diversity Index (SHDI), Contagion Index (CONTAG), and Area-Weighted Mean Shape Index ($SHAPE_{AM}$), which strongly correlated with HDI. The results show that HDI in the Yellow River Delta has increased gradually and its spatial heterogeneity has continued to increase in the past 30 years. The increase of human disturbances mainly occurred in coastal areas due to H-level human disturbances in Dongying Port and M-H level human disturbances along the coast. But in most areas inland of study area, the HDI reduced slightly benefit from the wetland conservation measurements. The landscape pattern in the Yellow River Delta wetland has changed tremendously. The spatial heterogeneity of landscapes is enhanced, and the connectivity is reduced. Patches tend to be regularized. Different levels of human disturbance have different effects on the landscape patterns. The M-H level HDI leads to low landscape different and more connected. While the H level HDI leads to stronger landscape heterogeneity, complex patch shapes and decreased spatial connectivity. These implicate the proposed framework is efficient for evaluating the heterogeneity effect of human disturbance and landscape patterns in a complex wetland ecosystem. These methods and findings will provide suggestions and guidance for wetland conservation and management.