Survival and Growth Response of Four Agroforestry Species to Post Planting Management Regimes

Abstract Post planting seedling management activities are important factors that determinegrowth and survivalof tree species. A study was conducted to evaluate the effect of management regimes on growth and survival ofCordia africana, Croton macrostachyus, Vachelliaabyssinica, and Grevillea robustatree species. The management regimes (treatments)were with and without application of fertilizer, irrigation and weeding. Management regimeswere arranged in split-split-split plot design replicated three times with tree species as main plot factor and other treatments randomized totheir assigned sub plots. Plant height, root collar diameter and survivaldata were collectedfor statistical analysis. The nonparametrictestKaplan-Meierwas used to estimatesurvival probabilities. Besides, multivariate analysis and Tukey HSD for post hoc testswereemployed for assessing management effects on growth parameters of the tree species. Accordingly, time and management regimes significantly affected growth and survival of tree species. Seedlings with one and four months after planting had better survival and growth rates than twenty months after planting. Apart from main effects fertilizer and weeding, management regimes revealed no interaction effects.Vachelliaabyssinica and Cordia africanahadhigher survival rates, whileVachelliaabyssinica revealed least in growth rate. Height and diameter of Cordia africana and Croton macrostachyushad significant and strong correlations with fertilizerand so does weeding withGrevillea robusta.Generally, management regimes improved growth and survival of the tree species. However, effect of irrigation and fertilizer rates on growth and survival of agroforestry tree speciesrequires further systematic study for packaging management recommendation.