Trade-offs between soil splash and water infiltration modulate erosion dynamics following rubber-to-balsa plantation conversion

Accelerated soil erosion driven by improper land-use changes severely threatens the sustainability of global plantation ecosystems. Although forest conversion is known to intensify splash erosion—the critical initial phase of water erosion—it remains elusive how the interplay between modified canopy traits and soil hydraulic properties modulate these erosion dynamics. This study assessed in-situ splash erosion and its primary drivers (i.e., rainfall parameters, leaf morpho-functional traits, and soil infiltrability) during the transition from rubber ( Hevea brasiliensis ) to emerging balsa ( Ochroma lagopus ) plantations, alongside an open field control. Results showed that splash erosion rates and throughfall kinetic energy in these plantations ranged from 0.10 to 0.54 kg m −2 and 542.30–801.31 J m −2 , respectively, exhibiting temporal fluctuations that aligned with rainfall patterns. Splash erosion in balsa monocultures was 0.82–1.14 times higher than in rubber plantation, driven by reduced canopy cover, less developed leaf drip-tips, and significantly higher kinetic energy of droplets and throughfall. However, the mixed balsa plantation reduced splash erosion by 80.44% compared to balsa monocultures. This mitigation is attributed to a multi-layered canopy that acts as a physical buffer by intercepting high-energy raindrops and attenuating their erosive power. Furthermore, balsa plantations exhibited a 5.07-fold increase in infiltration rates and a 4.65-fold increase in saturated hydraulic conductivity over rubber systems, likely due to enhanced root-mediated macro-pore connectivity benefiting from the fast growth of balsa trees. These optimized hydrological properties facilitate rapid penetration of rainwater into the deeper soil profile, thereby decoupling high splash potential from actual soil loss by minimizing surface runoff generation in balsa plantations. These findings suggest that soil conservation practices may be less essential for balsa cultivation compared to rubber systems. Notably, incorporating native species into balsa plantation provides a superior nature-based solution for soil conservation and sustainable forest management in tropical regions.