A significant loop of lake sedimentation state links catchment eco-surroundings and lake biogenic regime shifts

Abstract

As an important destination for upstream materials and element accumulation, lake sediments hold a multitude of contextual information about climatic changes and anthropogenic disturbances. However, understanding the lake sedimentation state to link catchment pressures and biogenic regime shifts remains challenging. To address this, research was conducted on the lake sedimentation state, including the dynamics, catchment drivers, effects on biogenic regimes, and responses to typical historical events using nine sediment cores from Dongting Lake, China, a typical global priority ecoregion. Three transitions of lake sedimentation state were distinguished over the century (1937, 1968, and 1993), whereby hydrologic dynamics and land-use changes in the watershed were the direct drivers with relative contributions of 16.30% and 14.56%, respectively. Lake sedimentation state and organic matter inputs not only preceded sediment biogenic elements at the shift time but also exhibited nonlinear trigger effects on biogenic element contents (R² = 0.47, p < 0.01), which promoted an increase in sediment biogenic element burial rates. Rate of change analysis indicated that intensive human activities altered the relationship between the sedimentation state and biogenic regime shift, thus revealing the response to anthropogenic events in the catchment. Pathways quantified by the partial least squares path model established the link between watershed attributes and lake biogenic properties via the lake sedimentation state. Our findings revealed a cascading linkage among catchment eco-surroundings, lake sedimentation states, and biogenic regime shifts. The research further provided insights into driver-response relationships in lake-catchment systems.