Importance of fire in alvar ecosystems - Evidence from the Burnt Lands, eastern Ontario

Abstract

Vascular plants recorded within 50 one metre square quadrats in 1997 in an area cut and burned 37 years earlier revealed an unusually high species diversity with 87 native vascular plant species, which is roughly twice as high as that recorded in various open areas of alvars that have not recently been burned. Site conditions appear to have favoured native species over weedy aliens, the latter accounting for 21% of species in quadrats, but having low cover values. The sampled area was dominated by graminoid plants and shrubs, and was transitional between alvar shrubland and alvar grassland. The saplings present were mostly Trembling Aspen, Populus tremuloides, and White Spruce, Picea glauca. The cut and burned area included 16 rare and/or restricted species. Some of the prominent vascular plants serve as larval foodplants for restricted butterflies, and the high species diversity and more mesic conditions in successional openings ensure adequate adult nectar sources. The burned site also provided habitat for rare birds. Considering these observations and because the vast majority of alvars have burned within the past few centuries, it is concluded that successional alvar burns deserve recognition as an important part of the alvar ecosystem and that burning of an alvar habitat is an appropriate management consideration. Management plans should account for certain fire-susceptible features such as ancient trees and arthropod populations.