Invasion by Austroeupatorium inulifolium (Asteraceae) arrests succession following tea cultivation in the highlands of Sri Lanka

Abstract

An understanding of floral succession is vital in planning the restoration of native vegetation in abandoned agricultural landscapes. Although such restoration is essential for the establishment of habitat corridors between the fragments of tropical montane cloud forest in the Sri Lankan highlands, in which > 90% of the land has been converted to tea plantations, no studies of succession have hitherto been possible because of the near-total absence of secondary forest in this region. In a pioneering restoration initiative in 1998, however, tea cultivation was abandoned on a 25 ha site (elevation 1540–1780 m) at Agrapatana, ~500 m from a natural forest. Succession was allowed to proceed without intervention, except that tea was removed from 10 ha. By 2009, the invasive Neotropical shrub Austroeupatorium inulifolium and Australian tree Acacia decurrens dominated the vegetation (0.43±0.14 and 0.03±0.04 stems m-2, respectively), to the total exclusion of native woody species. There was no significant difference in the density of Austroeupatorium (82±12%) and Acacia (14±9%) between quadrats with and without tea. Methods to suppress these two aggressive invasive species are urgently needed, especially given that Austroeupatorium has recently become established within pristine montane forests such as Horton Plains National Park (2,100 m elevation).   Key words: Acacia decurrens; Eupatorium; montane cloud forest; invasive species DOI: http://dx.doi.org/10.4038/cjsbs.v40i2.3934 CJSBS 2011; 40(2): 175-181