Cascading effects of land use on ecosystem function in Afrotropical headwater streams

作者：Florence Nansumbi, Gabriele Weigelhofer, Robinson Odong, Thomas Hein · 发表于：Aquatic Sciences · 年份：2025 · DOI：10.1007/s00027-025-01219-6 · 被引用次数：2 · 研究领域：Fish Ecology and Management Studies、Water Quality and Pollution Assessment、Aquatic Ecosystems and Phytoplankton Dynamics

Abstract Anthropogenic activities in catchments, such as urban and agricultural land use, negatively impact the biogeochemical cycles of carbon, nitrogen and phosphorus in streams by increasing concentrations of these nutrients and altering the composition of dissolved organic matter (DOM). In tropical climates with high temperatures and intense precipitation, streams are particularly vulnerable to high loading from the catchment. The combination of high nutrient loading from the catchment and high processing rates at high temperatures can lead to even higher concentrations and more severe impacts on biogeochemical cycles. However, studies linking human activity to changes in nutrient and DOM composition, and the resulting impacts on stream functions, are still scarce in tropical streams. This study addressed this gap by examining the relationships between land use and water column chromophoric DOM (CDOM), nitrogen and phosphorus across seasons in an Afrotropical watershed. In addition, the effects of nutrient enrichment and changes in DOM composition on stream metabolism were investigated. The results showed that urban land use had the most substantial influence on nutrient concentrations and DOM composition in the studied streams. Streams with a high proportion of urban land use in their riparian zone had high nutrient concentrations and a pronounced autochthonous DOM signal. In contrast, streams with more forest cover in their riparian zone had lower nutrient concentration...