Reproduction of salal (Gaultheriashallon) under forest canopy

Abstract

Sexual and vegetative reproduction of salal (Gaultheriashallon Pursh) was measured under forest canopies of different closure. Sexual reproduction occurred only at ≤33% closure; vegetative reproduction occurred under sparse and dense closure. Crown closure influenced sexual reproduction primarily through interception of radiation and associated reductions in salal vigour. Irradiance had a greater influence on the mode of reproduction than did shoot density, and allocation of total reproductive effort (sexual plus vegetative) was contrary to optimality models, but consistent with resource limitation. No shoot <5 years old flowered; shared costs of flowering indicated physiological integration among salal shoots. Vegetative reproduction was negatively associated with age (r2 = 0.95), and 85% of the space occupied after 9 years of growth was occupied during the first 3 years. Under canopy the spatial pattern of salal shoots was better adapted to maintain plant persistence than to colonize new areas. Implications of salal's rates and modes of reproduction to forest and wildlife management are noted.