Impact of historical pattern of human activities and natural environment on wetland in Heilongjiang River Basin

Mid and high latitude wetlands are becoming fragmented and losing ecosystem functions at a much faster rate than many other ecosystems. This is due in part to increasing human activities and climate change. In this study, we analyzed wetland distribution and spatial pattern changes for the Heilongjiang River Basin over the past 100 yr. We identified the driving factors and quantified the relative importance of each factor based on landscape pattern metrics and machine learning algorithms. Our results show that wetlands have been fragmented into smaller and regular patches with dominant factors that varied at different periods. Geographic features play the most important role in patterns of wetland change for the entire basin (with 50%–60% of relative importance). Human activities are more important than climate change at the century scale, but less important when magnified at the decadal scale. In the early 1900s, human activities were relatively low and localized and remained that way in the subsequent decades. Thus, the effect of human activities on wetland area of the entire basin is weaker when examined at the magnified decadal scale. The results also show that human activities are more important on the Chinese side of the Heilongjiang River Basin, in the Zeya-Bureya Plain on the Russian side, and at lower altitudes (0–100 m). Revealing the spatial and temporal processes and driving factors over the past 100 yr helps researchers and policymakers understand and anticipate wetland change and design effective conservation and restoration policies.