Tree Shelters Accelerate Slow-growing Species in Nurseries

"Two experiments investigated the effects of tree shelters on height, caliper, and diameter growth of liners of 14 species and cultivars. In the first year at one nursery all nine varieties had greater height growth inside shelters, averaging 325% of controls without shelters, thus adding 1.1 feet (33 cm) to 2.3 feet (70 cm) to their height. After two years at the other nursery, the varieties had increased height growth inside shelters ranging from 111% to 484% of controls, or 0.3 feet (10 cm) to 4.2 feet (128 cm). Caliper growth either was adversely affected by shelters, as much as 0.4 inch (1 cm) in two years, or did not increase in proportion to height growth. Trees in shelters were less sturdy, but other studies indicate caliper growth in subsequent years may overcome this disadvantage." [Abstract]