Answers to Hone Your Problem-Solving Skills Questions

1. Scotch pine tree seedlings survive at much higher rates when growing under Salvia shrubs than when growing in open areas; thus, Salvia appear to serve as nurse plants for Scotch pine tree seedlings.

2. Scotch pine seedlings growing under Salvia shrubs experience lower light levels, lower soil temperatures, and higher soil moisture content than do Scotch pine seedlings growing in open areas. Any of these three (correlated) factors could contribute to the increased survival of pine seedlings that grow beneath Salvia; controlled experiments would be needed to separate their effects.

3. As a Scotch pine tree increased in size, it could begin to compete with (and hence harm) the Salvia shrub that once served as its nurse plant.