SPECIES DIVERSITY, FLORISTIC COMPOSITION AND PHYSIOGNOMY CHANGES IN A RAINFOREST REMNANT IN SOUTHERN YUNNAN, CHINA AFTER 48 YEARS

Abstract

Zhu H, Wang H & Zhou SS . 2010. Species diversity, floristic composition and physiognomy changes in a rainforest remnant in southern Yunnan, China after 48 years. In order to investigate the effects of tropical forest fragmentation, a comparative study on floristic composition, plant life forms and ecological species groups in a 13.9 ha remnant tropical rainforest was conducted over 48 years (1959/1960–2008) in southern Yunnan, China. A total of 258, 292 and 332 native seed plant species were present in the remnant in 1959/60, 1997 and 2008 respectively. A total of 407 species were recorded in the remnant from the three inventories, of which 188 species were common. Species diversity did not reduce with diminution and further isolation of the remnant. Species could condense with the limited natural habitats of the remnant with the loss of surrounding natural vegetation. There was a significant shift in floristic composition with 27.1% species of the original forest absent in the inventory in 2008 and 43.4% of the present species were new migrants. The species shift was greatly accelerated in the recent 10 years in the remnant with changes of surrounding vegetation into rubber plantations. There was a conspicuous shift in the relative representation of mature-forest and light-demanding species: the former decreased. However, plant life forms did not show significant change in the remnant over 48 years. Species loss was balanced by new migrants across life forms. Although species diversity was maintained and physiognomy (life forms) of the remnant did not change significantly, the floristic composition and ecological species groups were conspicuously changed through time. This implies that the essential flora of the tropical rainforest could not be actually maintained in the remnant. It is suggested that the flora of tropical rainforest cannot be protected from impoverishment even if the fragmented forests are conserved.