Abstract:
Ecosystem engineers directly or indirectly affect the availability of resources
through changing the physical state of biotic and/or abiotic materials. Fossorial
ecosystem engineers have been hypothesized as affecting fire behaviour through
altering litter accumulation and breakdown, however, little evidence of this has
been shown to date. Fire is one of the major ecological processes affecting biodiversity
globally. Australia has seen the extinction of 29 of 315 terrestrial mammal
species in the last 200 years and several of these species were ecosystem engineers
whose fossorial actions may increase the rate of leaf litter breakdown. Thus, their
extinction may have altered the rate of litter accumulation and therefore fire ignition
potential and rate of spread. We tested whether a reduction in leaf litter was
associated with sites where mammalian ecosystem engineers had been reintroduced
using a pair-wise, cross-fence comparison at sites spanning the Australian continent.
At Scotia (New South Wales), Karakamia (Western Australia) and Yookamurra
(South Australia) sanctuaries, leaf litter mass ( 24%) and percentage cover
of leaf litter ( 3%) were significantly lower where reintroduced ecosystem engineers
occurred compared to where they were absent, and fire behaviour modelling
illustrated this has substantial impacts on flame height and rate of spread. This
result has major implications for fire behaviour and management globally wherever
ecosystem engineers are now absent as the reduced leaf litter volumes where they
occur will lead to decreased flame height and rate of fire spread. This illustrates
the need to restore the full suite of biodiversity globally.
