Seasonal dynamics of carabid beetles (Coleoptera: Carabidae) in areas with anthropogenic disturbances: The case of Uzungwa scarp nature forest reserve, Tanzania

Anthropogenic disturbance causes habitat destruction and thereby presents a serious threat to many forest species. Seasonal variation in diversity and community composition of carabid beetles was investigated in the Uzungwa Scarp Nature Forest Reserve (USNFR). Carabid beetles were collected using three methods, namely pitfall traps, active day search and active night search. Sampling of ground beetles was carried out in three seasons: end of dry season, end of wet season and wet season. Results showed that the diversity of ground beetles was high during the wet season (Shannon-Wiener H' = 2.19) and low at the end of the dry season (H' = 1.83). The difference was statistically significant when comparing the end of dry season against the wet season, likewise wet against end of wet season (t = 5.85 and 4.88, respectively, p < 0.05). Species richness was high during the wet season and the difference was statistically significant among the three seasons (χ2 = 13.46, p < 0.05). Kruskal-Wallis test revealed that the difference in abundance among the three seasons was statistically significant (H = 128.3, p < 0.05). In all the seasons, Galeritiola procera was the most abundant species and it was overrepresented during the wet season. Bray-Curtis similarity index showed low similarity in community composition among all three seasons. We conclude that communities of carabid beetles in disturbed areas vary with season, and therefore, to have a comprehensive sampling of carabid beetles, sampling should cover at least one-year involving different months in all seasons of the year.