Vegetation such as shrubs and grass tussocks is usually considered to present a competitive barrier for seedlings planted in reforestation programs. However, shrubs also have the ability to facilitate the establishment of seedlings of woody species under their canopy, especially in
ecosystems under high abiotic stress. In 2003, an experiment was set up in exclosures in northern Ethiopia to test the use of shrubs as nurse plants for reforestation. Seedlings of African wild olive Olea europaea ssp. cuspidata were planted in three microhabitats: (1) bare soil
between shrubs, (2) under individuals of the dominant thorn shrub Acacia etbaica, and (3) under individuals of Euclea racemosa, a fruit-bearing evergreen shrub which supports the majority of naturally established olive seedlings. Experimental seedlings were planted during the short spring rains (March–April) and long summer rains (June–September). The present study reports early seedling survival, i.e. until the end of the first winter (February 2004). Olive survival was significantly higher when planted under shrub cover as compared to open areas, especially under Euclea canopies, but spring rain enrichment planting showed high mortality in all three microhabitats due to drought stress soon after planting. Reduction of solar radiation by shrub canopies and thus control of soil-water evaporation and seedling transpiration most likely controlled the observed facilitation. We conclude that planting under shrubs during above average summer rains, as occuring during La Niña episodes, may have important advantages in assisting natural regeneration of dry Afromontane vegetation, and that conserving the pre-existing shrubs at the same time reduces the risk of erosion and keeps levels of indigenous biodiversity high.