Influence of the landscape context on stand structure and spatial patterns of the doum palm (Hyphaene thebaica Mart.) in the Republic of Benin (West Africa)

摘要

Hyphaene thebaica Mart. (doum palm) is an agroforestry tree with high ecological and economic value, but currently its populations are harvested excessively, which is likely to increase in the future. This study assessed the current status of this species with regard to increasing landscape modification and human pressure in Benin. We compared the structure of adult palms in farmlands to those within the Biosphere Reserve of Pendjari (BRP). In addition, spatial patterns and sex ratio of the species were compared between both land use types. Results showed that mean diameter (adult palms) and density (adult palms and seedlings) were significantly higher (P 0.001) in BRP than in farmlands. However, no significant differences were noticed for doum palm height and density of juveniles (P > 0.05). The pair correlation function showed globally a random pattern for all palm life stages, albeit with a weak aggregation in farmlands. In the BRP, a strong aggregated pattern is observed for seedlings, whereas all other palm life stages showed globally a random pattern. Moreover, no spatial association was observed within palm life stages and between palm life stages and other tree species, but did exist between females and seedlings in the BRP. The sex ratio did not depart from 0.5 in both land use types. We conclude that in spite of the land use difference, the doum palm species is still well preserved. However, rapid land-use intensifications may lead to increasing pressure on the species populations in the future.