Assessment of the success of active forest restoration in Mount Elgon National Park, Eastern Uganda

Abstract

Globally, active forest restoration involving the planting of native tree species has been used to reverse tropical forest degradation. Despite the substantial costs ($ 2500 per ha) in active forest restoration, there is limited scholarly information on the performance of active forest restoration projects world over. This study examined the performance of active forest restoration in Mount Elgon National Park, eastern Uganda. Specifically, the study assessed the following ecological attributes: (i) vegetation structure, (ii) ecosystem functions, (iii) tree species diversity, and (iv) tree species composition in 22- and 25-year old sites under active forest restoration and a reference forest. The study adopted a stratified sampling design where the survey areas were categorized into three strata (two strata in the sites under active restoration and one in the reference forest), based on similar environmental conditions such as topography, slope and aspect. Each stratum measured 12 hectares and was mapped using a GPS. A total of 10 plots of 40 x 30 m were randomly established in each stratum to measure vegetation structure, ecosystem functions, tree species diversity and tree species composition. To assess restoration success, the ecological attributes were compared among sites under active forest restoration and the reference forest using generalised linear models fitted in R version 3.3.1.The results showed that vegetation structure was less complex in sites under active forest restoration (22- and 25-year old) than in the reference forest. The ecosystem functions were lower in the sites under active forest restoration; (22- and 25-year old) than in the reference forest. Tree species diversity was lower in the sites under active forest restoration than in the reference forest. The sites under active forest restoration had different tree species compositions compared to the reference forest. Although the sites under active forest restoration have not yet recovered the vegetation structure, ecosystem functions and tree species diversity as in the reference forest, the results suggest a positive trend in the recovery of the restoration sites. The study recommends continued development and monitoring of the restoration sites by reducing or eliminating threats such as grazing and illegal pole cutting to accelerate converge to reference conditions. It recommends investigation to be done on the contribution of fauna on the speed and on the forest recovery trajectory. Further research is needed to examine the linkages between recovery of soil properties and vegetation attributes to further guide the implementation of active forest restoration.