Deterministic and stochastic drivers of plant community reassembly in post-logging regrowth forests

Forests contain high levels of plant diversity and provide critical ecosystem services. Understanding mechanisms that drive post-disturbance recovery, especially for the understudied soil seedbank and the biodiverse understorey is useful for informing management decisions in an era of environmental change. We studied the temporal and spatial recovery of understorey extant vegetation and buried viable seed following harvesting operations which included tree removal and regeneration burns in temperate eucalypt forests. Using repeated surveys across a gradient of distance from forest edge, we combined taxonomic and functional trait approaches to partition deterministic (e.g., environmental filtering, competition) and stochastic (e.g., dispersal, colonisation) drivers of community recovery. We evaluated whether communities converged towards or diverged from pre-disturbance states and assessed the extent to which the soil seedbank acted as a reservoir promoting convergence or as a source of novel traits promoting divergence. Early post-disturbance trajectories were dominated by rapid recruitment of early seral species, indicative of strong stochastic influence, whereas longer-term reassembly was increasingly governed by life-history traits that determined persistence and turnover. Distance from forest edge and the occurrence of regeneration burns influenced these dynamics, altering the strength of stochastic processes and deterministic filtering across space. Our results highlight the complementary roles of soil seedbanks and trait-mediated persistence in the post-disturbance recovery period. Forest management practises that promote heterogeneity and reduce the areas outside of forest influence such as through maintaining remnant patches of mature forest and ensuring regeneration burns are heterogenous will provide greater benefits for functional and biological diversity.