Observations on Microclimate and Vegetation Interrelationships on the Accra Plains (Ghana)

Abstract

Measurements of microclimate and transpiration during a complete 24 hr. period were carried out on the Accra plains during the dry season (Dec. 1965 to April 1966). Seven microclimatological stations were set up in a characteristic tree and shrub clump (Elaeophorbia drupifera, Diospyros mespiliformis, Azadirachta indica, Securinega virosa, Capparis spp.) and the surrounding grassland (predominant grasses: Schizachyrium schweinfurthii, Vetiveria fulvibarbis, Heteropogon contorus). Hourly records of soil and air temperature, evaporative power of the air, relative humidity, wind speed and wind direction showed marked variations in space and time. The prevailing south-westerly wind effects an ecological differentiation around the clump. The grasses and the shrubs on the windward side show xerophytic features compared with the mesophytic condition of those in the lee of the clump. This is reflected both in the rate of transpiration of the plants and in the structure and floristic composition of the relevant areas. The well-known effects of fire and the microclimate exert considerable influence on vegetation pattern on the Accra plains.