Vascular Plant Diversity in Burned and Unburned Alvar Woodland: More Evidence of the Importance of Disturbance to Biodiversity and Conservation

Paul Catling


Vascular plant biodiversity was compared in an unburned semi-open alvar woodland dominated by conifers and an equivalent woodland that had burned nine years previously and had developed into a long-lasting successional shrubland. The comparison, based on 30 quadrats 1 m2 at each of two sites, revealed less than 25% similarity in the vegetation cover of the two sites. The successional alvar shrubland that developed following fire had twice as many species and more regionally rare species than the corresponding woodland site. The shrubland also had higher values for various biodiversity measures that take heterogeneity and evenness into account. These data provide additional evidence for the importance of fire and disturbance in the creation of successional habitat upon which biodiversity depends. A cautious use of fire in management of alvars is supported.


vascular plant; alvar; biodiversity; rare species; disturbance; fire; succession; Simpson's Index; Shannon-Wiener function; Brillouin’s Index; Smith and Wilson evenness; Ontario

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