ゴム園からバルサ植林への転換後の土壌侵食のトレードオフを解明(Study Reveals Trade-Offs in Soil Erosion Dynamics After Rubber-to-Balsa Plantation Conversion)

2026-07-16 中国科学院(CAS)

中国科学院西双版納熱帯植物園(XTBG)の研究チームは、熱帯地域で進むゴム農園からバルサ(軽量木材)農園への転換が土壌侵食に及ぼす影響を調査した。その結果、バルサ農園は大きな葉と疎な樹冠により雨滴衝撃(スプラッシュ侵食)がゴム農園より0.82~1.14倍大きくなる一方、根系の発達によって土壌への浸透能と飽和透水係数が大幅に向上し、表面流出を抑制するため、実際の土壌流亡は大きく軽減されることが明らかになった。研究では2024年8~10月の14回の降雨を対象に、樹齢2~4年のバルサ単一林、混植林、ゴム単一林、裸地を比較し、雨滴特性、スプラッシュ侵食量、浸透能などを現地測定した。特に混植林では単一林に比べスプラッシュ侵食が80.44%減少し、生産性と土壌保全を両立する有効な自然共生型手法であることが示された。地形や土壌条件による影響は残るものの、バルサ農園の高い浸透能力は土壌侵食リスクを緩和し、熱帯人工林の持続可能な管理戦略に重要な知見を提供する。

<関連情報>

ゴムからバルサの植林地への転換後、土壌飛沫と水の浸透の間のトレードオフが侵食の動態を調整する Trade-offs between soil splash and water infiltration modulate erosion dynamics following rubber-to-balsa plantation conversion

Xia Yuan, Xiangzhong Li, Xiai Zhu, Bin Yang, Yajun Chen, Junen Wu, Xiaoyi Cai, Wenjie Liu
Agricultural Water Management  Available online: 27 June 2026
DOI:https://doi.org/10.1016/j.agwat.2026.110581

ゴム園からバルサ植林への転換後の土壌侵食のトレードオフを解明(Study Reveals Trade-Offs in Soil Erosion Dynamics After Rubber-to-Balsa Plantation Conversion)

Highlights

  • Balsa leaves possess less developed drip-tips than acuminate tips of rubber trees.
  • Rubber-to-balsa conversion elevates rain splash erosion via altered canopy traits.
  • Multi-layered understory in balsa systems effectively buffers rainfall erosivity.
  • Superior infiltration decouples splash potential from soil loss in balsa systems.

Abstract

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.

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