THE USE OF THE LAND SURVEY RECORD TO RECONSTRUCT PRE-EUROPEAN VEGETATION PATTERNS IN THE DARLING DOWNS, QUEENSLAND, AUSTRALIA

The Darling Downs is an extremely arable district in south eastern Que ensland that has lost the majority of its native vegetation cover to a griculture. Vegetation references from land survey charts produced dur ing the late 19th and early 20th century aided the reconstruction of t he original vegetation patterns in the Darling Downs. Nearly 5000 refe rences to vegetation were located for the study area and formed the ba sis of a vegetation map. The survey plans contain reference to seventy -three plant names which could generally be aligned to existing specie s, the majority of which are trees. The surveyors also referred to veg etation structure with terms such as 'open', 'shrubby' and 'dense'. Th e ambiguous use of some references and the lack of adequate coverage o f surveyor's charts for some sections of the study area did not allow for the production of an accurate and comprehensive map using the surv ey record in isolation. An iterative process evolved where (i) a worki ng map of the vegetation was produced from the survey record; (ii) the map was ground-truthed with existing remnants and ambiguities in surv eyors' terminology clarified; (iii) for gaps in the record, hypotheses concerning eradicated vegetation were erected from knowledge of the e nvironmental correlates of existing remnants; and (iv) these hypothese s were tested from areas where the survey record is comprehensive. Som e vegetation types cannot be distinguished reliably on the basis of th eir physical environment and the distinction between these types for m apping was reliant on either the evidence from the survey record or re maining paddock trees. These processes enabled relatively accurate map ping of the pre-European vegetation of the study area at 1:100,000 sca le. Comparison of the survey record and the vegetation of existing rem nants suggests that overstorey composition and understorey density hav e changed little during European management within remnants.