VEGETATION CHANGE ALONG AN ALTITUDINAL GRADIENT ON MT-HERMON, ISRAEL - NO EVIDENCE FOR DISCRETE COMMUNITIES

1. Distribution of vascular plant species on Mt Hermon, Israel, was analysed to determine if plant species occurred in discrete communities or if vegetation change was continuous along the altitudinal gradient (300-2810m a.s.l.). 2. Numbers of species beginning and ending their ranges in 50- and 100-m elevational bands were compared to those expected if species were arranged randomly along the mountainside. A Monte Carlo simulation was used to determine expected distributions of range borders. 3. There were no significant differences between cumulative frequency distributions of observed and expected downslope boundaries at either the 50- or 100-m spatial scale, although distributions of upslope boundaries differed from expected. 4. While species borders were occasionally aggregated within individual altitudinal bands at both spatial scales, coincidence of aggregated downslope and upslope termini, indicating an abrupt ecotone, occurred only around 1200 m a.s.l. This elevation marks a transition from maquis vegetation to an open deciduous forest. However, the opposite border of neither community was aggregated. 5. Although there were some vegetation discontinuities along the mountainside, there was no evidence of discrete plant communities.