Effect of Fire Intensity and Depth of Burn on Lowbush Blueberry, Vaccinium angustifolium, and Velvet Leaf Blueberry, Vaccinium myrtilloides, Production in Eastern Ontario

The effects of prescribed fire intensity and depth of burn were investigated on Lowbush Blueberry (Vaccinium angustifolium) and Velvet Leaf Blueberry (Vaccinium myrtilloides) stem density, blueberry production and the number of blueberries/stem in a clear-cut Jack Pine, Pinus banksiana, ecosystem of eastern Ontario. Blueberry production and stem density were significantly (P < 0.001) increased by low intensity prescribed fires of 597 and 1268 kW/m. In contrast, prescribed fires of medium and high intensities did not affect blueberry production and stem density. The number of blueberries/stem was not affected (P = 0.056) by prescribed burning, two years after treatment. Pearson's multiple correlation analysis showed that blueberry production (R: -0.683, P < 0.01), stem density (R: 0.733, P < 0.01) and the number of blueberries/stem (R: 0.803, P < 0.01) correlated with depth of burn. As well, blueberry production (R: 0.507, P < 0.05) and stem density (R: -0.504, P < 0.05) correlated with fire intensity. Depth of burn was a better predictor of berry production and stem density than fire intensity. These results suggest that only low intensity fires with little penetrating effect in the ground should be used to manage blueberry crops.