Ecology of relict tertiary deciduous trees in subtropical China

Abstract

How relict Tertiary deciduous trees survive and persist under current climate and frequent human activity becomes an important topic for conservation of rare and endangered species. The southeastern China-Himalaya region is one of the most important refugia for Tertiary relict flora in East Asia and harbors extraordinarily abundant relict Tertiary deciduous trees. This is also a moist subtropical region covered by evergreen broad-leaved forests in mountainous and hilly areas. The geographic distributions of these relict trees are isolated and disjunct. They occur always on unstable terrain such as valleys, ravines, steep slopes, and stream banks and form a topographic climax forest. These species are dispersed by minute wind-dispersed seeds and also reproduce vegetatively. The floristic composition of the relict-dominated communities is complex and ancient. The communities occupy particular landforms and form a mosaic pattern with the zonal vegetation. Hence, as pioneer species, relict deciduous trees can be regarded not only as ‘filler species’ for habitat space where zonal vegetation failed to colonize, but also as ‘gap-repairing species’ on gentle habitats.