Population Viability of Endemic Fauna in Fragmented Forests

Abstract

Forest fragmentation threatens endemic fauna through reduced habitat area, increased isolation, and disrupted metapopulation dynamics. This study assessed population viability of endemic vertebrate species across fragmented forest landscapes using demographic modeling, genetic analysis, and spatial population structure assessment. We conducted population surveys in 47 forest patches (0.5-850 ha) and employed stochastic population viability analysis (PVA) to project extinction probabilities over 100 years. Results indicate that populations in patches <20 ha face extinction probabilities exceeding 80% within 50 years, while patches >100 ha maintain viable populations (P(extinction) <5%). Genetic analysis revealed significant inbreeding depression (F = 0.18-0.34) in isolated small patches compared to large continuous populations (F = 0.02-0.06). Metapopulation modeling demonstrates that rescue effects from source populations can reduce extinction risk by 35-60% in sink patches when inter-patch distance <2 km. Demographic stochasticity, rather than environmental variation, emerged as the primary threat to small populations. Our findings emphasize critical thresholds for minimum viable population size (MVP ≈ 150 individuals) and maximum inter-patch distance (≤2 km) for maintaining metapopulation persistence. Conservation strategies should prioritize protection of large core habitats, establishment of habitat corridors to facilitate dispersal, and restoration of stepping-stone patches to enhance landscape connectivity.