Topography shapes the structure, composition and function of tropical forest landscapes

Area of Science:

• Ecology
• Forest Science
• Remote Sensing

Background:

• Topography is a primary determinant of tropical forest structure and composition.
• Local nutrient and hydraulic conditions, influenced by topography, affect tree growth.
• The impact of topography-driven physiognomic changes on forest emergent properties like aboveground carbon density (ACD) is not fully understood.

Purpose of the Study:

• To investigate how topography shapes the vertical structure, wood density, diversity, and ACD of old-growth forests in Borneo.
• To understand the relationship between subtle elevation differences and forest characteristics.
• To explain landscape-scale heterogeneity in ACD by incorporating topographic influences.

Main Methods:

• Combination of field data collection with airborne laser scanning (ALS) and hyperspectral imaging.
• Characterization of forest structure, wood density, diversity, and ACD over a 15 km² area.
• Analysis of how topography influences soil chemistry and hydrology.

Main Results:

• Subtle elevation differences profoundly impact canopy structure, composition, and diversity.
• Topography was critical in explaining landscape-scale heterogeneity in aboveground carbon density (ACD).
• Distinct forest types, from tall valley forests to stunted heath forests, were observed across topographic gradients.

Conclusions:

• Topography is a key factor controlling forest structure, composition, and carbon storage in tropical ecosystems.
• Emerging remote sensing technologies are vital for gaining new ecological insights into long-standing questions.
• Understanding topographic influences is essential for accurate forest carbon assessments and ecological modeling.