Population Density and Diversity of Trees on Farmlands in Three Districts of the Upper East Region of Ghana: Implications for Food Security and Ecosystem Sustainability - Akpalu, Stephen Edem; Adeyiga, Gloria Kukurije; Amooh, Maurice Kwame; Kyereh, Dennis; Akpalu, Mercy Marilyn (New Perspectives in Agriculture and Crop Science Vol. 1, 2019)