Using a model based fourth-corner analysis to explain vegetation change following an extraordinary fire disturbance
In ecosystems where large-scale disturbances are infrequent, the mode of succession may be difficult to discern and floristic surveys alone cannot be used determine the underlying processes causing vegetation change. To determine the causes of vegetation change in response to a large-scale fire event, we combined traditional floristic survey data, plant functional traits and environmental variables in a model-based solution to the fourth-corner problem. This approach allowed us to describe the trait-environment relationship and provides an intuitive matrix of environment by trait interaction coefficients. We could then quantify the strength and direction of associations between plant traits, species life-forms and environmental factors in two alpine plant communities over nine years post-fire. Initially, the fire drastically reduced vegetation cover and species density to very low levels. The fourth-corner analysis interaction coefficients indicated that over the course of the nine-year study a high abundance of graminoids, a low abundance of shrubs, tall species and those with high leaf dry matter content had the strongest associations with the two plant communities. We also found evidence for functional homogenisation between these two communities using this novel technique. Analysing plant traits and species responses post-fire in this manner can be used to infer the ecological processes driving shifts in vegetation.
KeywordsPlant functional traits Fire Succession Climate change Alpine
We thank the Cooperative Research Centre for Sustainable Tourism, the National Climate Change Adaptation Research Facility and New South Wales National Parks and Wildlife Service for funding and logistical support. We thank Wendy Hill, Andrew Bryant, Andrew Growcock, Daniel Guitart, Daryl Robinson, Jeremy Carrington, Rachel Hill, Sebastian Rossi, Tanya Fountain and Zarni Bear for assistance with the fieldwork. We thank John Morgan for useful comments on an early draft of the manuscript and David Warton for guidance in fitting the fourth-corner models.
Author contribution statement
CMP conceived and designed the study and conducted a large proportion of the fieldwork, SAB conducted fieldwork and did the initial analyses, SEV wrote the manuscript and developed the analytical ideas in conjunction with ADL, who also conducted and generated the final analyses. SEV, CMP and ADL edited the manuscript.
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