Tree regeneration in church forests of Ethiopia: effects of microsites and management

Background

Tree regeneration is severely hampered in the fragmented afromontane forests of northern Ethiopia. Pressures of harvesting and grazing and climactic conditions present challenges to regeneration. This study explores how trees regenerate in remnant forests along the gradient from open field, forest edge to closed sites and canopy gaps inside the forest.

Research goals & methods

The authors investigated the effects of seed sowing, litter removal, and weeding on the regeneration success of four indigenous tree species along the gradient from open field, forest edge to closed sites and canopy gaps inside the forest. Within the forest, local canopy openings facilitated seedling growth (for all species except Olea) and survival (Ekebergia and Olea), suggesting that all species benefited from local high light conditions in forest gap sites. Outside the forest, germination and growth rates were lower in the open field for all species, most probably due to water stress in the dry season. Outer edge conditions favored growth for three of the four species. Natural seed germination was, however, zero at any site for Juniperus and Olea and low for Ekbergia and Prunus in the open field. Soil scarification influenced germination positively, while weeding did not have a positive effect.

Conclusions & takeaways

These results suggest that simple measures may improve seedling establishment, and that, for some species, forest edges are particularly useful for growth and survival after successful establishment. Together with erecting fences, needed to protect seedlings against grazing, seed sowing, planting seedling, and soil scarification may contribute to maintain and restore church forests in the fragmented landscapes of northern Ethiopia.