Vegetation of the Olokemeji Forest Reserve, Nigeria: V. The Vegetation on the Savanna Site with Special Reference to Its Seasonal Changes

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Abstract
1. Following descriptions of the vegetation, climate, microclimates, litter and soil of the Olokemeji Forest Reserve (Hopkins 1962, 1965a, b, 1966) an account is given of seasonal changes in the herb stratum on the savanna site. 2. The wet season is the period when most growth (in dry weight and height) occurs, most species are present, and--at its end--most species flower. Although growth and development are dependent on water, rainfall is rarely responsible for the initiation or cessation of the various stages. Fire stimulates much growth and day-length probably initiates flowering in many species. 3. The maximum dry weight which the herb stratum attains during the year (a measure of its production) averaged 6.8 t/ha. The maximum leaf area index was about 6.0. 4. Four of a series of monthly photographs are presented to illustrate the main seasonal changes which are described. 5. The data from quadrats recorded monthly were ordinated by principal component analysis. The ordination of the sampling dates shows a distinct seasonal trend and between year difference. 6. A normal association-analysis (of the same data) gave thirteen common groups most of which changed their frequency seasonally. It is suggested that a fixed sample position is allocated to different groups at different times of the year.