Human impacts on Persoonia falcata. Perspectives on post-contact vegetation change in the Keep River region, Australia, from contemporary vegetation surveys

Persoonia falcata R. Br. and Buchanania obovata Engl. seeds are consistently preserved in abundance from archaeological sites across the Keep River region from 3500 b.p. up until the contact period. Although artefacts continued to be deposited after establishment of the pastoral industry, remains of these two plant species disappear in the upper levels of all excavated deposits. The contemporary vegetation in the vicinity of these sites appears to lack P. falcata, although B. obovata remains in abundance. These observations raise questions regarding (1) the impact of changing land-use and fire regimes, (2) the impact of Aboriginal land management on particular plant species and (3) the reorientation of Aboriginal site use across the region after settlement. These issues are explored in this paper using a comparative analysis of stand structure of the contemporary vegetation around previously excavated sites, as well as from published information on recent regional fire history. Results show improved recruitment of P. falcata (that is, seedlings are recruited into adult life stages) in the only site where Aboriginal people have re-introduced customary management. Both the timing of burning and significant unburnt periods appear important to the post-contact decline and also in the future success of populations of P. falcata in the region.