Plant community responses to thinning in densely regenerating Acacia harpophylla forest

Thinning is thought to be particularly effective at accelerating plant community recovery in some dense regenerating forests where one species dominates. However, longer‐term experimental data are required to confirm the efficacy of thinning for this purpose. We investigated plant community responses 8 years after thinning in densely resprouting brigalow (Acacia harpophylla) forests in Australia. We examined the abundance, diversity, composition, and size of all woody recruits, as well as the functional composition of woody plant assemblages using functional traits. The average prethinning density of A. harpophylla was 15,600 stems/ha. Four treatments were applied to 25 × 25 m plots in a randomized block design: control (no thinning) and random thinning (ringbarking) down to 4,000, 2,000, and 1,000 stems/ha. Reference plots were also established in a nearby mature forest. Thinning accelerated the recruitment of certain shrub species and increased some measures of diversity. However severe thinning led to an overabundance of exploitative shrub species (high‐specific leaf area and low stem‐specific density), akin to pioneer dominance during early stages of rainforest succession. Species with more conservative growth strategies have so far failed to recruit, potentially due to dispersal limitation. Longer‐term monitoring is required to determine if thinning does in fact accelerate compositional recovery in this endangered Australian ecosystem.