The ecology of six Rhododendron species (Ericaceae) with contrasting local abundance and distribution patterns in Hong Kong, China

Abstract

Six native Rhododendron species grow in thedegraded, fire-prone landscape of Hong Kong: R. simsii andR. farrerae are common and widespread, R.moulmainense is relatively restricted, and R.championiae, R. hongkongense, and R.simiarum are rare. For all species except the rare R.simiarum, there was direct or indirect evidence of regrowth afterfire, but only the two smallest and commonest species grow in sites which arefrequently burned. Both flowered within 18 months of a fire. Most populationsofall species, except R. simiarum, had a deficiency ofindividuals in the smaller basal circumference classes. Seedlings were foundonly in three out of four plots of R. simiarum, and one ofR. farrerae. A few seedlings of the other rare specieswereseen in open, litter-free microsites outside the study plots, but no seedlingsof the most common species, R. simsii, were seen anywhere.In logistic regression models, one or more measures of plant size weresignificant positive predictors of flowering at least once in the three yearstudy period for all species, while percentage cover by surrounding vegetationhad a significant negative impact on all except R. simsiiand R. farrerae, for which no populations arestrongly-shaded. Although the absence of current recruitment is not necessarilya cause for concern in long-lived species that can resprout after fire, werecommend that active vegetation management should be tried to enhance thesurvival and reproduction of R. moulmainense, R.championiae and R. hongkongense, and that newpopulations of these species and R. simiarum should becreated.