Integrative analysis of nutrient dynamics and its hydrological pathways in a tropical montane forest watershed: Implications for landscape management

This study addresses a significant knowledge gap regarding the relationship between nutrient exports and abiotic factors in tropical forested watersheds. Focusing on a tropical forest watershed located on Hainan Island, we investigated the interactions between nitrogen (N) and phosphorus (P) exports and topographic, hydrological, and landscape elements. Using a model-data integration approach, our findings revealed that nutrient exports are predominantly in organic N and P forms, with the values of 15.66 ± 1.87 kg ha⁻¹ yr⁻¹ and 0.26 ± 0.07 kg ha⁻¹ yr⁻¹, respectively. Inorganic N and P were primarily sourced from orchards, while organic N predominantly originates from forest areas. Additionally, lateral flow was identified as the dominant hydrological pathway for nutrient transport, significantly influenced by topographical gradients. A parabolic relationship between organic N export and forest landscape fragmentation was also observed. These findings emphasize the importance of targeted landscape management strategies, such as selective logging, to mitigate N limitation in tropical forest watersheds, advancing the understanding of nutrient export dynamics and providing practical implications for sustainable forest management and conservation efforts.