Greenhouse and Field Growth of Northern Red Oak Seedlings Inside Different Types of Treeshelters

Greenhouse and field experiments were used to measure growth and survival of northern red oak seedlings (Quercus rubra L.) inside brown translucent, clear acrylic, and woven wire treeshelters compared to the growth and survival of unsheltered seedlings. In the greenhouse, seedlings grown in brown plastic and clear acrylic shelters had significantly reduced stem, leaf, and root development compared to unsheltered seedlings. Seedlings in clear shelters grew taller than control seedlings, but none were self-supporting after removal of the shelters. Reduced growth in the brown shelters was attributed to an 80% reduction in photosynthetically active radiation (PAR). In the field study, 2-year-old red oak seedlings grown in brown and clear shelters experienced lower mortality (55% and 40%, respectively) than unsheltered seedlings (60%), but most were unable to support themselves after removal of the shelters because of increased height growth and inadequate stem development. Half of the seedlings inside clear shelters experienced dieback of new growth during an unusually warm early growing season. Seedlings in the wire shelters were not supported or protected from mechanical stress (wind) and they were exposed to ambient temperatures. Wire-shelter seedlings had the lowest mortality (20%) and were self-supporting but significantly shorter than seedlings in the clear and brown shelters. Wire shelters show promise as an alternative to solid plastic shelters for producing self-supporting seedlings with comparable growth and greater survival at a similar overall cost.