Unburned Control Sites Research Articles

SPECIES RESPONSES OF CARABID BEETLES (COLEOPTERA: CARABIDAE) DURING POST-FIRE REGENERATION OF BOREAL FOREST

AbstractBeginning 1 year after an intense forest fire in the Interlace region of Manitoba, carabid beetles were sampled by pitfall trapping in two burned sites and two unburned control sites. Before the tire, one burned site had been dominated by aspen, Populus tremuloides Michx,, and the other by conifers (mostly Picea spp.). During the 11-year study, burned sites became dominated by aspen saplings. Three carabid species were caught significantly more frequently in burned sites than in control sites. Two of these, Harpalus laticeps LeConte and H. egregius Casey, invaded soon after the fire and were caught in the burned sites for several years after the fire. Seventeen species were caught significantly less often in burned than in control sites; catches of another 13 common species were not significantly affected by burning of the site. Burning influenced the seasonal patterns of catches of Carabus taedatus F. and Pterostichus adstrictus Eschscholtz; this was attributed to higher litter and soil temperatures in burned sites. Seasonal patterns of other common species were not markedly affected by burning. In burned sites, the incidence of brachypterous species and the size of beetles increased with time after the fire. In control sites, the incidence of brachyptery was independent of time, but the percentage of brachypterous species was significantly higher in the conifer site than in the aspen site. Trends of brachyptery and size are those expected if early colonizers are super-tramp r-strategists and later invaders are K-strategists. Patterns of species occurrence during forest regeneration can be explained in terms of dispersal and competitive abilities, preference for physical attributes of the habitat, and responses to prey availability.

The influence of fire on the phenological behaviour of Mediterranean plant species in Bas-Languedoc (southern France)

Fire is an ancient ecological factor influencing the Mediterranean vegetation of southern France. The study was carried out on three areas to determine the phenological behaviour of plants with regard to fire. First we studied the flowering responses of perennials in relation to the time since fire: in a Quercus coccifera garrigue most species flower during the year following burning. In comparing species by species between burned and unburned areas most species did not show major differences in the phenological stages. However, fire did increase the number of inflorescences of grasses. A phenological synthesis showed that differences at the community level existed for the flowering stages between the burned areas and the unburned control sites during the first and second years following fire. The growth of some woody species was also studied; the elongation and growth of the plants were biggest during the first or second year after fire. The lack of differences in phenological response between burned and unburned plants may be an adaptive trait to fire.

Changes in Understory Production following a Wildfire in Southwestern Ponderosa Pine

An area burned by a May, 1972, wildfire and which had been previously sampled in 1972 and 1974 was remeasured in 1980 to determine changes in under-story production. The area was stratified into moderately and severely burned areas. By 1974 both herbage and forage production on the moderately burned area were approximately 3 times higher than unburned control sites and did not decline significantly by 1980. While increased herbage production on the severely burned site was similar to that of the moderately burned site in 1974, it declined to only half as much production by 1980. Furthermore, while over 95% of the total herbage production was in forage species for all 3 sampling years on the moderately burned study area, only 30 percent was forage on the severely burned study area by 1980. The decline in total production and shift to non-forage species on the severely burned study area is probably a consequence of heavy grazing which followed the bum. Since settlement in the late 1800’s forage production in southwestern ponderosa pine (Pinus ponderosul) has steadily declined.

Hydrologic and mineral budgets of New Jersey Pine Barrens upland forests following two intensities of fire

The hydrologic and mineral budgets of upland forest sites in the New Jersey Pine Barrens exposed to different fire intensities were determined. Inputs from bulk precipitation and outputs to groundwater were monitored in an unburned control site, two sites burned by severe wildfire, and two sites burned by light prescribed burning. Fluxes of water, calcium, magnesium, and potassium to groundwater were highest in wildfire sites, intermediate in prescribed burn sites, and lowest in the unburned control. At all sites, outputs were the greatest during late-winter snowmelt. In the unburned site, outputs were essentially absent during the growing season, whereas in the wildfire sites outputs to groundwater were present year round. Rates of mineral and water output were inversely proportional to biomass and forest floor mass, which in turn depended upon fire intensity. Relative increases in output were similar to those reported following fire in other ecosystems. However, absolute rates of mineral output both before and after fire were lower in these sandy soils than those reported elsewhere, probably due to the low total mineral storage and variety of fire adaptations present in the Pine Barrens ecosystem.