EFFECTS OF HABITAT FRAGMENTATION ON SPECIES DIVERSITY USING BUTTEERFLY AS A-CASE STUDY IN OWERRI, IMO STATE NIGERIA

Abstract

This study assessed the effects of habitat fragmentation on  species diversity in Owerri, Imo State, Nigeria, using butterflies as ecological bio-indicators in an urbanizing landscape. The study area was classified into three habitat types based on fragmentation intensity: protected habitat (Old Zoo Reserve), semi-disturbed habitat (Nekede peri-urban green patch), and highly fragmented habitat (Nekede built-up mosaic). Butterfly data were collected through standardized line transect walks over a one-week sampling period, with species identified through direct observation supported by smartphone photography and reference identification materials. A total of 405 individual butterflies belonging to 24 species and 5 families were recorded across all habitats. Species richness and abundance declined with increasing habitat fragmentation, from 21 species and 176 individuals in the protected habitat to 12 species and 90 individuals in the highly fragmented habitat. Diversity analysis revealed a reduction in Shannon–Wiener index values from 2.68 in the protected habitat to 2.03 in the fragmented habitat, while Simpson’s diversity index declined from 0.91 to 0.82, accompanied by a decrease in evenness from 0.83 to 0.71. One-way ANOVA confirmed that differences in butterfly abundance among habitats were statistically significant (F(2,12) = 8.74, p < 0.01). Forest-dependent species such as Euphaedra medon and Charaxes varanes were restricted to the protected habitat, whereas disturbance-tolerant generalists such as Junonia oenone and Eurema hecabe dominated fragmented sites. The findings demonstrate that habitat fragmentation associated with urban development significantly reduces butterfly species diversity in Owerri and highlight the importance of conserving semi-natural and protected green spaces for sustaining urban biodiversity.