Locally endangered tree species in a dry montane forest are enhanced by high woody species richness but affected by human disturbance

Understanding the relationship between biotic, abiotic and disturbance factors in dry degraded forests is crucial for effective conservation of endangered plant species. We studied the relationship between two locally endangered tree species, Olea europaea subsp. cuspidata and Juniperus procera, and environmental conditions in the Hugumburda dry Afromontane forest in Northern Ethiopia. We surveyed species richness of woody plants, herbaceous plant cover, soil and human disturbance factors from 70 plots (20 m × 20 m). The abundance of both species was positively correlated with each other, and with woody species richness and elevation. Moreover, the biomass of both species correlated positively with total tree biomass and number of O. europaea cut stumps. The positive relationship between O. europaea trees and cut stumps suggests that illegal selective logging is taking place in O. europaea-dominated areas. Based on the observed relationships we predict that conserving woody species may result in an increase in the abundance of both O. europaea and J. procera in the forest.