Survival and Growth of Seedlings of 19 Native Tree and Shrub Species Planted in Degraded Forest as Part of a Forest Restoration Project in Madagascar's Highlands

background

This study compares the survival rates of 19 native tree and shrub species grown in a forest restoration project in Madagascar’s highlands. The study results are used to compare the survival of relatively short seedlings compared to relatively tall seedlings for all species combined in order to test the importance of seedling size for restoration.

Research Goals & Methods

3,500 seedlings-19 native trees and shrubs were collected from the surrounding forests, nursed and planted on upper slopes of a valley in the forest previously burned. Seedlings were planted at 8-20 months old, with heights ranging from 3-48 cm to assess the importance of seedling size on survival. Seedlings were planted early in the wet season in a large hole (40 x 40 x 40 cm3) mixed with well-rotted manure. 4 to 10 seedlings of each species were selected randomly for monitoring and marked with numbered stakes. The height of each seedling was measured at the time of planting and 10 months later.

Conclusions & Takeaways

Native species showed considerable variation in both survival and growth rates. Overall there was a 10% survival and relatively rapid growth observed for Macaranga alnifolia, Harungana madagascariensis, Filicium decipiens and Dodonaea madagascariensis. In contrast, low survival and and low growth or size reduction was observed for Ixora sp. (Rubiaceae), Trema orientalis (Celtidaceae) and Elaeocarpus hildebrandtii (Elaeocarpaceae). The results showed no significant differences in survival of short versus tall seedlings suggesting that seedlings need not sit in nurseries for long periods of time before transplanting to restoration sites. The preliminary results from this study show that Macaranga alnifolia, Harungana madagascariensis, Filicium decipiens and Dodonaea madagascariensis performed well in terms of early seedling survival and may be useful species in projects that aim to restore Madagascar highland forests. The authors recommend for large-scale restoration projects, planting trials to be run to investigate the growth and survival rates of candidate species rather than blindly investing resources into species that might have bad performance.