Riparian soil and hydrological variations in Imbak Canyon and SFERA@UMS under contrasting tropical forest land-uses

Abstract

This study presents a comparative baseline assessment of soil characteristics and hydrological properties across three riparian forest types in Sabah, Malaysia: Primary Forest (PF), Old Regrowth Forest (ORF), and Logged Forest (LF). Conducted in the Imbak Canyon Conservation Area and SFERA@UMS, measurements focused on soil texture, bulk density, soil moisture, and unsaturated hydraulic conductivity. PF and ORF exhibited higher clay content, greater soil moisture retention, and moderate infiltration rates, indicating superior hydrological function. In contrast, LF plots, dominated by sandier textures and reduced canopy cover, showed lower moisture retention and markedly diminished hydraulic conductivity. While bulk density patterns did not strictly follow expected trends—PF and ORF had slightly higher mean values than LF—results may reflect natural variability and structural recovery stages. Relationships between soil texture and hydrological parameters highlight the influence of disturbance and forest regeneration on riparian ecohydrology. The study provides essential baseline data for future monitoring, reinforces the ecological value of undisturbed and recovering forests, and supports the prioritization of PF and ORF zones in riparian buffer planning and watershed conservation.