COMPETITION BETWEEN CALAMAGROSTIS-CANADENSIS AND EPILOBIUM-ANGUSTIFOLIUM UNDER DIFFERENT SOIL-TEMPERATURE AND NUTRIENT REGIMES

The relative competitive abilities of Calamagrostis canadensis (Michx. ) Beauv. and Epilobium angustifolium L. were tested in two sets of rep lacement series experiments. Both species were grown in monocultures a nd a range of mixtures in 25-cm pots. In the first set, substrates wer e held at either 9 or 21 degrees C; in the second set the pots were fe rtilized at high or low rates. In the 21 degrees C treatment C. canade nsis was more competitive than E. angustifolium (relative crowding coe fficient for C. canadensis towards E. angustifolium was 2.88), while t here were little competition differences in the cool soil conditions. Under the cool soil temperatures, however, E. angustifolium showed hig her vegetative reproduction than under the warm soil conditions. In th e high nutrient conditions, C. canadensis was more competitive than E. angustifolium (relative crowding coefficient for C. canadensis toward s E. angustifolium was 5.84). There was little competition in the low nutrient experiment. These experiments indicate that if both species c olonize a site simultaneously, C. canadensis will outcompete E. angust ifolium under most conditions, as suggested from field observations of earlier researchers.