Delineating a detailed mountain ecosystem using spatial statistics: A case study in Kodil Watershed, Menoreh-Sumbing Mountain, Central Java, Indonesia

Mapping mountain ecosystems is needed for local planning. Ecosystem boundaries are influenced by interrelated physical and environmental factors rather than singular physical features. Tropical mountain landscapes exhibit diverse surface patterns, impacting their terrestrial ecological systems. Using river network data and digital terrain models (DTMs), we delineated ecosystem groups based on seven surface parameters: river order, channel sinuos-ity, elevation, slope, aspect, roughness index, and curvature. A multivariate clustering method identified ecosystem groups with similar attributes, further clarified using geological and land cover maps to account for surface and subsurface material variations and their processes. Our analysis identified five distinct ecosystem units: the young Sumbing volcanic peak, old Sumbing volcanic peak, old Sumbing volcanic slope, transitional volcanic, and old Menoreh volcanic ecosystems. The parameters that have a strong influence in limiting these units are elevation, slope, curvature, and roughness. Despite being part of the same mountain range, these ecosystems exhibit mark-edly different physical land characteristics. The surface-boundary-based delineation method provides a practical approach to defining mountain ecosystems, aligning spatial planning with land capacity and ecosystem service provisioning. By incorporating insights from river flow patterns and DTMs, this method captures the complexity of land surfaces shaped by past volcanic-tectonic activity and ongoing erosion-deposition processes. The resulting spatial boundaries reflect both current natural capital and dynamic limiting factors, demonstrating its potential for effective and detailed landscape management in complex mountainous regions. © 2025, Polskie Towarzystwo Inzynierii Ekologicznej (PTIE). All rights reserved.