CONSTRAINTS ON FLOWERING PHENOLOGY IN A PHRYGANIC (EAST MEDITERRANEANSHRUB) COMMUNITY

The phenological pattern of flowering at the community level was studi ed in a Greek phryganic ecosystem near Athens for 4 consecutive years. Flowering is strongly seasonal: 80% of the insect-pollinated flora, w hich consists of 133 species, blooms between February and June. There is a variably expressed secondary flowering period in autumn. The poll inating fauna follows a strongly correlated pattern of abundance. Two types of plants were distinguished: pauciflorous species bearing <10 f lowers that are large compared to the plant body, and multiflorous spe cies with many small flowers. Pauciflorous species flower in the winte r half of the year, while multiflorous species flower mainly in the su mmer half. The mean flower life spans are 9 and 3 days, respectively. The duration of flowering (DF) for each species is 55 days on average, which is long compared to other communities. The DF shows year-to-yea r variations, concomitant with the vicissitudes of the climate. The st art of flowering of a species is statistically correlated with the tem perature in the previous month, not with rainfall; its end date of flo wering only partly compensates for the time gained or lost. DF is maxi mal in winter. The average flower life span of species flowering at an y given date varies strongly and independently of the average DF. We t ested the hypothesis that flowering phenology is set by phylogenetic a nd life form constraints. This could not be corroborated for phylogeny , evidently because of the overriding influence of the mediterranean c limate, and probably also for biogeographical reasons. In contrast, li fe forms and multiflorous and pauciflorous species show strong differe nces. Many (51) of the species are therophytes; we tested the hypothes is that because of their annual habit they would be more dependent on pollination than perennials. Thus we anticipated that therophytic spec ies would be differentiated from perennials in their flowering phenolo gies. This is not corroborated. We therefore conclude that the seed ba nk plays a role that is analogous to that of a perennial plant body.