Effectiveness of conservation areas in protecting Shea trees against hemiparasitic plants (Loranthaceae) in Benin, West Africa

Abstract

Background and aims – The Shea tree (Vitellaria paradoxa), a multi-purpose species highly valued for the oil obtained from its seeds, is commonly maintained in the semi-arid parklands in West African Sudanian zone. However, most of the trees were reported to be infested with mistletoes – plant parasites that may lead to death of the Shea tree and these parasites are known to be directly dispersed on their host by birds. This study therefore aimed to assess the potential effectiveness of protected area on preventing mistletoes proliferation on Shea tree individuals. Methods – Infestations in two habitats: land use area (fields and fallows) and protected area of Pendjari hunting zone were compared. Overall 54 plots of 1 ha (100 m × 100 m) with 487 and 252 individuals of Shea tree in land use and protected area respectively were investigated. ANOVA was used to compare Shea tree infestation rate and infestation degree (with regard to diameter and height of infested Shea tree). Principal Component Analysis (PCA) was performed to correlate the habitats with infestation degree. Key results – The results showed that about 80% of Shea tree individuals were infested in the land use area, this rate was significantly higher than the one of 27.3% observed in the protected area. Overall, heavily infested Shea trees had significantly larger trunks and heights, mainly in land use areas. The land use area was shown to be correlated with high and very high Shea tree infestation degrees while the others infestations degrees (very weak, weak and moderate) were correlated with both areas. Conclusions – Shea trees growing in protected areas are better protected against mistletoe plant parasites than those on cultivated land. Various hypotheses to explain this result are discussed.