Protecting woody plantings from wildlife, for wildlife
Successful forest conservation starts with a detailed knowledge of the land, its history, and its capabilities and limitations.
Such information is the basis of forest planning. While winter in northern Michigan is a wonderful time for planning, spring is a good time for planting vegetation that enhances composition (plant species on a property) and structure (the vertical and horizontal arrangement of vegetation). The type and abundance of wildlife in a forest are largely determined by vegetation composition and structure.
Site capabilities and limitations are based on soil type, water availability, and light levels. After those factors are known, and preferably documented, the next step is to identify wildlife species or communities of interest and whether woody plantings are to provide food, cover, or both.
Although some plants benefit many species of wildlife, plantings will be most successful if they are customized according to the food preferences and cover requirements of the target species or community.
Browsing is defined as the eating of leaves and twigs of woody vegetation. Browsing differs from grazing, which is the eating of herbaceous vegetation. Browsing can be a significant impediment to forest regeneration and is a reason why some forests are not as compositionally or structurally complex as they should be. The park-like conditions that we see around us are often the result of browsers limiting age classes of trees and other woody plants.
Rodents, lagomorphs (rabbits and hares), and cervids (deer and elk) are all browsers, but different species of browsers impact plants differently. Rabbits and hares, as well as deer and elk, work from above and browse the terminal end of young stems at different heights. Rodents often eat woody plants below the snowline in the winter and tend to girdle plants.
Young woody plants (seedlings and saplings) need to be protected from browsers. For large plantings, fencing the entire area may be required. Where fewer plants are involved, such as apple trees, fences can be constructed around each tree with stakes and welded wire fencing.
Seedlings need protection for five years or more. To protect woody plantings from deer, tree shelters should be 6 feet tall. To protect from elk, tree shelters should be 8 feet tall. Barriers 2 feet high may deter rabbits and hares. The best protection against rodent browsing is the elimination of taller vegetation near the planting. That reduces food and shelter for the animals and has the additional benefit of suppressing competing vegetation. Alternatively, tree guards can be put around the main stem of the planting.
Several sizes and types of tree shelters, including cone-shaped models for conifers, are also available. Homemade models can be constructed with stakes, staples, and construction-grade plastic.
In addition to protecting seedlings, tree shelters can, under certain circumstances, serve several other functions: increase seedling survival and growth rate through moisture retention and a greenhouse effect, improve growth form of seedling planted for timber production, protect seedlings from herbicide drift and mowing machinery, and help managers locate seedlings. It is important to note, however, that shelters do not eliminate the need for weed management.
Problems that are encountered with tree shelter include trapping of other wildlife (now preventable with netted tops), possible attraction of insect pests, winter die-back of terminal shoots, and the continued need to support stems for one to two years after they grow above the shelter. Regardless of the type of shelter used, frequent inspection is needed to detect possible problems and to repair or replace damaged parts.
Because they have grown here for thousands of years, native woody plant species have two main advantages over non-native species.
First, native species are well-adapted to our site conditions.
Second, non-native plants can become weedy (invasive) and crowd out native species. Autumn olive, glossy buckthorn, Scots pine, and other non-native woody plants can be a serious threat to the ecological integrity of forests. Because of the costs and time involved, it is generally wise to consider plantings as a small part of a broader habitat management program that focuses on existing vegetation.
Greg Corace is the forester for the Alpena-Montmorency Conservation District. For more information, including sources used in this article, Greg can be reached at firstname.lastname@example.org or 989-356-3596, ext. 102.