title: Do multiple fires interact to affect vegetation structure in temperate eucalypt forests?
abstract: Fire plays an important role in structuring vegetation in fire-prone regions worldwide. Progress has been made towards documenting the effects of individual fire events and fire regimes on vegetation structure; less is known of how different fire history attributes (e.g., time since fire, fire frequency) interact to affect vegetation. Using the temperate eucalypt foothill forests of southeastern Australia as a case study system, we examine two hypotheses about such interactions: (1) post-fire vegetation succession (e.g., time-since-fire effects) is influenced by other fire regime attributes and (2) the severity of the most recent fire overrides the effect of preceding fires on vegetation structure. Empirical data on vegetation structure were collected from 540 sites distributed across central and eastern Victoria, Australia. Linear mixed models were used to examine these hypotheses and determine the relative influence of fire and environmental attributes on vegetation structure. Fire history measures, particularly time since fire, affected several vegetation attributes including ground and canopy strata; others such as low and sub-canopy vegetation were more strongly influenced by environmental characteristics like rainfall. There was little support for the hypothesis that post-fire succession is influenced by fire history attributes other than time since fire; only canopy regeneration was influenced by another variable (fire type, representing severity). Our capacity to detect an overriding effect of the severity of the most recent fire was limited by a consistently weak effect of preceding fires on vegetation structure. Overall, results suggest the primary way that fire affects vegetation structure in foothill forests is via attributes of the most recent fire, both its severity and time since its occurrence; other attributes of fire regimes (e.g., fire interval, frequency) have less influence. The strong effect of environmental drivers, such as rainfall and topography, on many structural features show that foothill forest vegetation is also influenced by factors outside human control. While fire is amenable to human management, results suggest that at broad scales, structural attributes of these forests are relatively resilient to the effects of current fire regimes. Nonetheless, the potential for more frequent severe fires at short intervals, associated with a changing climate and/or fire management, warrant further consideration.
authors.affiliation: Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, Victoria, 3086, Australia.
authors.forename: Angie
authors.initials: A
authors.lastname: Haslem
authors.affiliation: Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, Victoria, 3086, Australia.
authors.forename: Steve W J
authors.initials: SW
authors.lastname: Leonard
authors.affiliation: Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, 123 Brown Street, Heidelberg, Victoria, 3084, Australia.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Bruce
authors.affiliation: School of Ecosystem and Forest Sciences, University of Melbourne, Creswick, Victoria, 3363, Australia.
authors.forename: Fiona
authors.initials: F
authors.lastname: Christie
authors.affiliation: School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, 3125, Australia.
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Holland
authors.affiliation: School of BioSciences, ARC Centre of Excellence for Environmental Decisions, University of Melbourne, Parkville, Victoria, 3052, Australia.
authors.forename: Luke T
authors.initials: LT
authors.lastname: Kelly
authors.affiliation: Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, 123 Brown Street, Heidelberg, Victoria, 3084, Australia.
authors.forename: Josephine
authors.initials: J
authors.lastname: MacHunter
authors.affiliation: School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, 3125, Australia.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Bennett
authors.affiliation: Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, Victoria, 3086, Australia.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Clarke
authors.affiliation: School of Ecosystem and Forest Sciences, University of Melbourne, Creswick, Victoria, 3363, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: York
mesh_terms: D001315:Australia; D002980:Climate; D017753:Ecosystem; D005390:Fires; D065928:Forests
keywords: Australia; eucalypt forest; fire frequency; fire regime; fire severity; habitat change; inter-fire interval; post-fire chronosequence; time since fire; vegetation succession