Niche Partitioning of Three Sympatric Mammals Based on Tree Dimensions and Understory Vegetation in Alas Pinggan Forest, Prigen Partisi Relung Tiga Mamalia Simpatrik Berdasarkan Dimensi Pohon dan Vegetasi Tumbuhan Bawah di Hutan Alas Pinggan, Prigen

Abstract

Ecological niche partitioning is a fundamental mechanism enabling the coexistence of sympatric species. This study examines resource partitioning among three mammalian taxa Macaca fascicularis, Tupaia sp., and Muntiacus muntjak at Alas Pinggan Forest, East Java, Indonesia. Surveys were conducted on 27–29 April 2026 across 11 plots (0.5 ha each) using direct observation, camera trapping, and vegetation analysis. Total sampling effort comprised three days of direct observation and four camera-trap nights, recording M. fascicularis (six direct observations), Tupaia sp. (detections across nine plots), and M. muntjak (one plot). Vegetation surveys documented 255 trees (24 species; mean DBH 31.7 cm). Canonical Correspondence Analysis revealed significant associations between species distributions and habitat variables (p = 0.014). M. fascicularis occupied mid-canopy strata (10–20 m) with large trees (DBH 30–50 cm; niche breadth: 0.62). Tupaia sp. specialized in dense understory (height <2 m, coverage >60%; niche breadth: 0.38). M. muntjak inhabited the forest floor with intermediate understory (40–60%; niche breadth: 0.54). Low pairwise niche overlap indices (Cλ < 0.50) indicated substantial resource partitioning. Environmental parameters varied significantly: temperature 22.5–26.3°C, humidity 71–88%, light 850–1,950 lux, and wind 0.7–2.5 m/s. These results demonstrate that vertical stratification and understory complexity create distinct microhabitats supporting mammal coexistence. Conserving tropical mammal diversity requires maintaining structural complexity across forest strata.