The importance of tropical forests in the global climate system is widely known. However, their productivity needs a continuous supply of nutrients, mainly nitrogen (N) and phosphorus (P). However, the availability and biogeochemical cycling of these nutrients is highly variable in space and time and the understanding of different nutrient loss pathways is still lacking. The influence of soil erosion on the availability of these nutrients in pristine forests of the tropics is not well understood. To gain a better mechanistic understanding of the aquatic loss processes of N and P, we monitored different headwater streams in three distinct tropical forests of the Congo Basin and determined the influence of soil erosion on soil N. This knowledge is important to assess the response of these ecosystems to changing climate and land use. The first part of the thesis focussed on the fundamental understanding of the dynamics and drivers of sediment export in headwater streams of a tropical lowland forest and a deciduous Miombo woodland. We used high temporal resolution turbidity data and analysed the turbidity-discharge hysteresis patterns during storm events. Although these forest systems are situated in very old and stable landscapes, the obtained sediment yields were substantial and comparable to forests in more geomorphic active sites of the tropics. In the second part, it was shown that soil erosion and storm events play also a crucial role in aquatic nutrient export from these forest ecosystems. At both sites, N and P were dominantly exported in particulate or dissolved organic forms and the yields of those nutrient constituents were driven by intense discharge pulses due to storm events. Although these losses are significant, there is no indication that erosion leads to local nutrient limitations in the N and P rich montane and lowland forests. In the last part of this thesis, the influence of land use in the lowlands on aquatic sediment and nutrient export was examined. Results from a field campaign, during which baseflow was intensively sampled, revealed that there was significant higher export of dissolved organic N and particulate inorganic P, while the yields of nitrate were lower in an agricultural catchment compared to the pristine forest catchment. Continuous sensor measurements indicated that our findings most probably underestimated these differences because of the lack of storm event data. The results of this thesis highlight the importance of particulate N and P losses from pristine tropical forests and their inclusion in biogeochemical studies are important, even in so believed low erosive ecosystems. The predicted increase in rainfall intensity and the ongoing loss of primary forests will further enhance the importance of these processes.