Agroforestry technologies (AFTs) have the potential for improving productivity but little effort has been made to study their species composition and diversity in Tanzania. The study aims to determine the variations of useful plant species composition and diversity across five agroforestry technologies. A plot size of 10 x 10 m was used to assess plants from each agroforestry technology. The useful plant species were identified and grouped into four life forms (trees, shrubs, climbers and herbs). The variation in plant species diversity among different agroforestry technologies were statistically determined by ANOVA in R software while the correlation of species richness and diversity among plant life forms were statistically determined by Pearson product-moment analysis. We identified 61.6% trees, 21.3% shrubs, 10.5% climbers, and 6.6% useful herbs with many species in Fabaceae and Euphorbiaceae families. Percent cover of herbs, climbers, shrubs and trees differed significantly across all agroforestry technologies (p=0.034, p=0.016, p=0.002 and p=0.000), respectively. The highest mean tree (39) and shrub (19) species richness was recorded in Agrosilvopastoral Technology (ASPT) while the highest mean climber (10) species richness was recorded in Coffee Farming Agroforestry Technology (CFAFT). The highest mean tree species diversity was recorded in Mixed Intercropping Agroforestry Technology (MIAFT) while shrubs and climber species diversity was highly recorded in Wood Perennial Agroforestry Technology (WPAFT) and CFAFT, respectively. Tree, shrub, climber and herb species richness and diversity differed significantly (p<0.001) across all AFTs. However, relationships between trees, shrubs and climber species richness was found to be weak and significantly positively related to each other at P<0.05 indicating that the increase number of species of one life form in agroforestry systems (AFS) causes increase of plant species in another life form. This study suggest that, agroforestry systems should aim to encourage the use of ASPT and MIAFT that support high diversity of useful plant species.

Keywords: Plant life forms, agroforestry technologies, species composition, shrubs