Competitive Interactions Across a Soil Fertility Gradient in a Multispecies Forest

** SUMMARY Report Description:**

This report investigates the impact of plant competition and soil fertility on the growth rates of four dominant tree species in British Columbia's sub-boreal spruce forests. It addresses the ongoing debate in plant ecology by assessing whether competition intensifies or weakens across a soil fertility gradient. Using soil nutrient indices, the study highlights strong support for nutrient-related soil fertility measures. Results reveal that competition and soil fertility significantly influence radial growth rates across all species, but the effects vary by species, neighborhood composition, and the type of competition (shading vs. crowding). Surprisingly, some species exhibit unique responses to crowding under low soil fertility conditions. Overall, this research underscores the complexity of tree competition in relation to soil fertility, challenging existing ecological theories and offering insights into forest ecosystems in British Columbia.