Small mammal succession is determined by vegetation density rather than time elapsed since disturbance

We examined post-fire responses of two sympatric Australian rodents, Pseudomys gracilicaudatusand Rattus lutreolus, as coastal wet heath regenerated following two high intensity wildfires. Pseudomys gracilicaudatus, an early serai-stage species, recolonized an area burnt in August 1974 after one year, but took only 3 months to recolonize another area following a wildfire in October 1994. Rattus lutreolus, a late serai-stage specialist, took approximately 3.6 years to recolonize following wildfire in August 1974, but had recolonized after only 4 months following wildfire in October 1994. We suggest that this apparent anomaly is associated with the rate of recovery of vegetation density. When the relative abundance of each species was plotted as a function of vegetation density, the trajectories following the two wildfires were concordant. An implicit relationship exists between time since wildfire and vegetation density. We make this relationship explicit by quantifying cover requirements for each species, and show that it is the resource continuum borne of regenerating vegetation ( rather than time per se ) that is important in determining the timing of small mammal successional sequences.