Effects of annual burning on grassland in the aspen parkland of east-central Alberta

Abstract

Annual early spring burning has markedly altered the physiognomy and species composition of aspen parkland vegetation of east-central Alberta. Burning was conducted in April for at least 24 years when soil moisture was normally high. The number of herbaceous species per quadrat doubled while a number of woody species declined slightly. Forest cover declined while grassland increased. In the grass and shrublands, cover of the shrub Symphoricarpos occidentalis and the cool season grass Festuca scabrella declined greatly. Major increases in Calamovilfa longifolia, Carex obtusata, C. heliophylla, and Solidago missouriensis were noted. While the cover of Festuca scabrella and Stipa spartea var. curtiseta decreased; frequency of these species increased. Cover of all shrubs decreased, Populus tremuloides suckers excepted, while density of the fire adapted Elaeagnus commutata, Amelanchier alnifolia, Prunus virginiana, and Populus tremuloides suckers increased. Burning reduced the leaf blade length of all major grasses and sedges. Effect of burning on inflorescence production varied from species to species. Annual herbage production was reduced by burning with the grass and sedge component experiencing about a 50% reduction. Burning caused an increase in organic matter and phosphorus content of the Ah horizon. Burning did not appear to detrimentally affect the nitrogen status of the Ah horizon.