Chalk and cheese or something in between: comparisons between remnant and regrowth Acacia harpophylla communities, western Darling Downs, Queensland

Abstract

Endangered Brigalow (Acacia harpophylla) dominated ecosystems have been extensively cleared and modified for agricultural production throughout the Brigalow Belt Bioregion. Intensification of agricultural land uses in the region has resulted in significant fragmentation and disturbance of remnants. Rehabilitating regrowth is an important conservation alternative to preservation that can effectively ensure the persistence of Brigalow communities throughout highly modified landscapes. While legislation is now in place to restrict clearing of remnant and Brigalow regrowth, little is known on the resilience of the range of regrowth types. This research investigates patterns in composition, structure and condition of Brigalow remnants and a range of regrowth communities in relation to surrounding land-use factors and past disturbance practices. Thirty-eight sites in the western Darling Downs, southern Queensland), were sampled encompassing both remnant (disturbed and 'reference') and regrowth (Old Regrowth > 35y; Intermediate Regrowth 26-35y; Recent Regrowth <25y). Multivariate analysis of composition data showed a broad gradient from recent regrowth through older stages of regrowth to remnant. Compositionally, remnant sites were significantly different to regrowth; while within regrowth communities, recent regrowth (<20y) was different to older stages (ANOSIM). The later stages of regrowth may represent an alternate stable state in these landscapes. The implications for broader landscape management are discussed.