Tree species differ in their tolerance for shade and competition (Table 3-1). Trees often are classified as very tolerant, tolerant, intermediate, intolerant, and very intolerant to shade. Some species tolerate more shade as seedlings than as larger trees. Species that are very tolerant will reproduce and grow in deep shade beneath a dense canopy. Species that are very intolerant will survive only if their seeds sprout in wide openings that receive direct sunlight. The size of canopy openings, ranging from the loss of a single tree to removal of many acres, greatly influences which tree species will reproduce and survive. You must know the shade tolerance of a species to determine the light conditions necessary for reproducing it. Tree species that regenerate in openings may be different from species forming the original canopy, thus changing the species composition over time according to the size of canopy openings created.

Table 3-1. Tree species by shade tolerance classification.1
Very IntolerantIntolerantIntermediateTolerantVery Tolerant
Black Spruce
Black Willow
Eastern Cottonwood
Jack Pine
Quaking Aspen
Tamarack
Black Cherry
Black Walnut
Paper Birch
Red Maple
Red Pine
Silver Maple
Balsam Poplar
Bitternut Hickory
Black Ash
Bur Oak
Green Ash
Hackberry
Red Maple
Red Oak
Shagbark Hickory
White Ash
White Oak
White Pine
Yellow Birch
Balsam Fir
Basswood
Bigtooth Aspen
Black Ash
Green Ash
Hackberry
Northern White-Cedar
White Ash
White Spruce
Beech
Eastern Hemlock
Sugar Maple