Seasonal Nutrient Yield and Digestibility of Deer Forage from a Young Pine Plantation

Six classes of current herbaceous and woody forage were collected seasonally from a 5-yearold mixed loblolly (Pinus taeda) -shortleaf pine (Pinus echinata) plantation (in Texas) and subjected to nutrient analyses and nylon bag dry-matter digestion trials. Forages were most nutritious and digestible in the spring when tissues were succulent and growing rapidly. Browse leaves and twig tips were the most abundant forage from spring to autumn and the most nutritious and digestible forage throughout the year. Pine and the residual twigs of browse were low in quality and digestibility at all seasons. Forbs were more nutritious than grasses but both declined seasonally in nutrient quality and digestibility as their fiber content increased with maturation. A low level of phosphorus in forage tissues at all seasons appeared to be a major limiting factor for deer in the young plantation. For 3 to 5 years after a pine plantation is established, a wide assortment of grasses, forbs, and browse develops (Blair 1968). Between 5 and 8 years, crowns of the young pines are closing rapidly and forage growth declines with the diminishing light. Upon crown closure forage for deer remains sparse until trees are thinned or clearcut (Blair and Enghardt 1976). The capacity of a young plantation to support deer can be estimated by considering the amount of palatable vegetation available during different seasons, the yield of plant nutrients, the metabolic usefulness of forages, and the nutrient requirements of the animals. Although forage often is abundant during summer and fall (Blair 1967, 1968 ), tissues may be deficient in nutrient quality except in spring (Short 1969). This paper evaluates the dry-matter yield, nutrient content, and dry-matter digestibility of 1 Laboratory maintained in cooperation with the School of Forestry, Stephen F. Austin State University. 2 Present address: Western Energy and Land Use Team, Room 206 Federal Building, 301 South Howe St., Fort Collins, Colorado 80521. J. Wildl. Manage. 41 ( 4): 1977 J. WILDL. MANAGE. 41(4):667-676 forage in a 5-year-old plantation of mixed loblolly and shortleaf pine. Forages were sampled at several different phenological periods and evaluated by specific classes of plants and plant tissues.