Ecological shift and resilience in China's lake systems during the last two centuries

Abstract

Abstract The worldwide decline of wetland ecosystems calls for an urgent reassessment of their current status from a resilience perspective. Understanding the trajectories of changes that have produced the current situation is fundamental for assessing system resilience. Here, we examine long-term dynamics of wetland ecosystem change by reviewing paleoecological records from 11 representative lakes in China. We identify unprecedented change in alga communities in the context of last two centuries. Striking ecological shifts have occurred in all lakes, yet with spatial and temporal differences. The long-term trajectories of change in diatom species composition and structure indicate gradually eroded system resilience. These ecological shifts were shaped by socio-economic activities as China transformed from a rural agricultural to an industrialized society within the last several decades, during which multiple drivers have accumulated and acted synergistically. The balance between ecosystem and society, which appeared to exist for thousands of years, was broken by increasing population, new technology, and urbanization since the 1980s. The consequences are the emergence of new positive feedbacks with the potential to drive the coupled systems into undesirable states. By linking long-term social and ecological change at a regional scale, our study provides a novel contribution to the understanding of lake ecosystems resilience in present-day China. We argue that sustaining wetland ecosystems requires integrated approaches that incorporate a deeper understanding of social-ecological dynamics over decadal-centennial timescales to address the complex underlying mechanisms leading to the current degradation.