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.

Driver–response relationships in a large shallow lake since the Anthropocene: Short‐term abrupt perturbations versus long‐term sustainable pressures

“…As the first large lake regulating the water and sediments of the Yangtze River, Dongting Lake covers approximately 2.67 × 10 5 km 2 watershed area and 2625 km 2 water area. Over the past century, the significant impacts of human‐induced modifications on hydrologic conditions, sediments, vegetation, and biogeochemical processes within the lake were widely discussed and uniformly acknowledged (Li et al., 2009; Ran, et al., 2023; Yu et al., 2020, 2018). These long‐term variables were the primary drivers of the dynamics of shallow lake sediments both globally and regionally (Benito et al., 2021).…”

“…These long‐term variables were the primary drivers of the dynamics of shallow lake sediments both globally and regionally (Benito et al., 2021). Watershed activities associated with agriculture, urbanization, land‐use changes, and hydrologic dynamics have accelerated by approximately threefold on MAR average in the global lakes since 1950 (Baud et al., 2021; Ran, et al, 2023; Rose et al., 2010). Nutrients and warming mainly forced alterations in the ecological states of mountains and shallow lakes using lake sediments (Huang et al., 2022; Oleksy et al., 2020).…”

“…Simultaneously, significant differences were present in the internal spatial distributions of most sediment proxies and CVs across the same type of environmental proxy (Figure S4). The contrasts and similarities identified in Dongting Lake suggest an interaction influence between the types of lake sediment proxies (Dean, 1999; Ran, et al., 2023). Theoretically, distinct types of lake sediment proxies can exhibit causal links in addition to temporal and spatial variations (Leavitt et al., 2009).…”

“…Catchment environmental proxies primarily represent indicators whose contents are highly influenced by physical processes such as erosion and runoff within regional ecosystems, including sand, 210 Pb ex , MAR, and MS (Kenney et al., 2022; Rose et al., 2010). Lake biogenic proxies, for example, TOC, TN, TP, and TS, are mainly use to infer primary production, nutrient supply, and biogenic states within the lake (Anderson et al., 2020; Ran, et al., 2023). Mixed‐source proxies are primary indicators including C/N ratio, δ 13 C, and δ 15 N for determining the source of organic matter in lakes (e.g., terrestrial exogenous inputs or lake endogenous contributions; Lamb et al., 2006; Sun et al., 2021).…”

“…Although the social development of Dongting Lake in terms of population, economy, agrarianizing, and urbanization has varied among the sub‐basins since 1950, it has continuously affected land‐use changes over a long period, thus triggering soil erosion and material deposition in the lake (Wang, et al., 2021; Xiao et al., 2023). These watershed ecological changes recorded in the sediments have been explored in terms of sediment source, material composition, and content dynamics (Du et al., 2001; Ran, et al., 2023; Wang et al., 2023). However, challenges still persist in the socio‐ecological integrity of lake‐watershed systems regarding different typical events that are timely, lagged, or not captured by lake sediments and regarding the linear or nonlinear impacts of long‐term pressures and when they were significant.…”