DIVERSITY OF TREE SPECIES IN CULTIVATED AND FALLOW FIELDS WITHIN SHEA PARKLANDS OF GHANA

Abstract

Tree species diversity associated with shea in cultivated and fallow fields of shea parklands of Ghana was studied. The study was to assess tree species diversity in relation to land use type across a North – South gradient of shea growing sites in Ghana. The study was conducted in 2011/12 at Paga, Nyankpala and Kawampe. In addition to shea trees, other highly valued tree species are preserved in parkland systems because of their ability to improve soil fertility and increase crop yield In addition to reducing microclimatic extremes as well as wind and water erosion, parkland trees are important sources of income and nutritional security. There is the need to conserve other tree species so as to reduce the over reliance on shea tree as the sole economic tree in many areas of the savanna parkland. Fifty four (54) quadrats measuring 50 x 50 m (18 in each location) were used as experimental plots. Diversity of higher woody plants was analyzed using the Simpson Diversity Index (D). A total of 863 trees were studied. The total density of trees in cultivated and fallow fields was 64 and 355 for Paga, 39 and 130 for Nyankpala, 75 and 200 for Kawampe. Shea densities in all the study locations showed that there were more shea trees in fallow fields (469) than cultivated fields (298). The main species identified in the study were Diospyros mespiliformis Hochst, Annona senegalensis Pers, Azadirachta indica A.Juss, Terminalia albida Sc Elliot and Senna siamea Lam. The occurrence of these species amounted to 54.8% of all trees. Fallow fields were more species composed (33 species) than cultivated fields (21 species). The results showed differences in diversity based on locations with Paga and Nyankpala showing high species diversity of 0.95 each in cultivated and fallow fields. However, there were no significant differences (P >0.05) in species diversity of all three study locations within cultivated and fallow fields.