Assessment of growth and survival rate of native tree species in COMBIO Project areas in Eastern Province Rwanda

Abstract

The restoration practices of degraded land or deforested forest landscapes using native tree species are increasingly important in addressing global environmental challenges. In Rwanda, COMBIO is among the project that are restoring degraded land and deforested forest in Eastern province using native tree species to enhance ecological resilience and supports community livelihoods. This study assessed the growth and survival rates of one year-old native tree species planted in six sanctuaries with under the COMBIO project areas in Eastern province of Rwanda. Data collection was done by measuring tree height, base-diameter and counting living, dead and missing trees with spatial locations captured using Differential Global Positioning System (DGPS). The study also used interviews and observations to identify factors influencing tree performance and propose best practices. Collected spatial data and physical and environmental variables such as topography, rainfall and temperature related to the project intervention areas were analysed in ArcGIS Pro. Tree growth performance data including average height, base diameter and survival rate were analysed using Ms excel and R software, while the data from both interviews and observation were quoted and interpreted. Results showed significant variation in growth and survival rates across species and sites whereby fast-growing species reached average heights between 1m- 4.8m with base-diameter of 3 cm-8.6 cm, while slow-growing species remained below 1m in the height and 3cm in base-diameter. Survival rates ranged from 60-100% for resilient species, 20 to 60% for less resistant species and below 20% for species introduced from other spatial location, indicating poor adaptation of montane species to the eastern region, which is a lowland and savannah. Key factors influencing growth survival of species included site-species matching, rainfall, temperature, pest and diseases, competition with unwanted trees, topography, livestock grazing, Indirect planting system and lack knowledge among labourers. The study suggests that proper species selection, implementation of Taungya system, protection of plantation against the reach of livestock, application of organic manure, high maintenance practices, use of quality seedlings use of termite resistant trees and enhanced community awareness of tree management are the best practices to ensure successful growth and survival not only in the current sancta but also in further future COMBIO project areas