Making the Most of Your Mast
What is Mast?
The term "mast" is a general term that refers to the reproductive bodies of plants and is often associated with wildlife food sources. Mast is often divided into categories of "hard mast" and "soft mast". "Hard mast" is the production of hard-shelled seeds, such as acorns and hickory nuts. "Soft mast" describes seeds that are covered with fleshy fruit, as in apples and berries. Mast may also include seeds and fruits of all other plants such as grasses, herbs (forbs), pines, hardwoods, and fungi.
Natural forest stands are composed of a variety of overstory tree species and understory shrub species. Species diversity protects forests from insect damage and disease. It also improves soil fertility, and is essential for providing wildlife with food and shelter. By understanding the importance of managing for a variety of plants, you are taking the first step towards maximizing your mast production.
Wildlife management has a rich history that traditionally focused mainly on game species. Original food habit studies were conducted on hunter-harvested individuals. Although these data were quite informative, they represented the diets of animals in just the fall and winter seasons. Modern scientific wildlife studies have identified year-round food habits of not only important game animals, but of many non-game wildlife species as well. Mast has been found to be consumed in all seasons, but not necessarily from the same plant species. Therefore, it is essential to manage a diversity of vegetation so that different types of mast will be available throughout the year. Examples of mast producers in different seasons are listed in Table 1. Mast producers for each season should include an array of vegetation ranging from ground-cover plants such as grasses, forbs and low shrubs, to large shrubs, mid-story trees, and overstory trees. Managing for several mast producers each season ensures that a variety of nutrients will be available to wildlife, and provides alternative food sources should one plant species have a year of low seed production. For example, white oaks produce few acorns during years in which acorn production is high in red oaks, demonstrating how the presence of both oak groups is complementary.
Artist unknown; illustration courtesy of the University
of Florida Herbarium
Nutritional needs of wildlife change from season to season (See Table 1), depending on whether they are preparing for reproduction, growth, migration, or hibernation. A diversity of mast producers can fulfill the changing needs of wildlife species. Nuts are very high in carbohydrates, making them an important energy source especially in the colder months. Mushrooms and other fungi, legumes, grasses and forbs are very high in protein. These plants are especially important to reproducing animals and their young during spring and summer. An example of seasonal variation of nutrients is evident in berry-producing plants. Berries of summer-bearing plants are high in sugar and carbohydrates, while the berries of fall and winter-bearing plants are high in lipids (fats). This seasonal difference meets the changing nutritional needs of wildlife through the year.
Mast diversity and increased mast production can be achieved by creating a varied landscape. In a pasture you may disc strips for planting forbs and legumes, or for providing a seed bed for establishment of local species. Leaving snags and logs to rot will provide fungi, a valuable protein source in spring and summer. Crowded stands of overstory trees produce poor mast yields and varieties. By opening the canopy you will allow light to reach more of each tree's crown, where it will stimulate more mast production. The canopy should also be open enough to allow light to reach the ground, where it will encourage the growth of desirable understory vegetation. Similarly, a dense midstory provides little mast, and suppresses the development of understory growth. A diverse vertical structure (vegetation growth from understory to canopy) supports more species than if most of the vegetation is in one stratum (e.g., a dense canopy). This can be achieved by thinning, prescribed burning, and mechanical or chemical treatments.
Mast Production Strategies
First, evaluate your land. Make a list of all plants and categorize them by season of mast production. What percent of your mast is produced in the spring, summer, fall, and winter? Ideally you want to have equal amounts of mast in every season, or only slightly more in the colder months when wildlife energy demands are higher. Is your seasonal mast production reliant on one type of plant? If that plant has a low mast year, what other species will provide mast? After reviewing your list, consider what you can do to increase desirable mast producers.
Now that you have identified some mast production goals, you are ready to achieve them. The following land management tools can be applied toward maximizing mast production:
Prescribed burning is the most effective tool available to the landowner, and can be used to achieve most management objectives. Growing season fires stimulate mast production of grasses, forbs, blueberries, and runner oaks. After a summer burn, protein content and palatability of grasses are higher, and the amount of mast produced by herbaceous and shrubby vegetation is increased. Summer burns are also effective at reducing midstory shrubs and vines, and promoting growth of herbaceous vegetation. Properly used, prescribed fires can be applied to site preparation prior to planting of overstory trees, range forage improvement, restoration and maintenance of natural vegetation, and control of undesired vegetation. The Florida Division of Forestry will help you plan and implement a burn program that is best for your land management objectives.
Through fire or mechanical means such as discing, scarification can be used to create openings for understory vegetation, or for planting or seeding native forbs in plantations or pastures. Fire is preferable to discing, as it retains root crowns of perennial plants.
Thinning and partial harvests are important operations for gradually increasing community diversity. Selection cutting of overstory and midstory trees allows an uneven-aged stand to develop if a variety of species already exist in the stand. Uneven-aged, multi-species forests will promote mast diversity, and thinning should increase mast yields on the remaining trees. Patch cutting provides larger openings for the growth of herbaceous vegetation and establishment of young trees and shrubs. For rapid vegetation regrowth follow these removals with a prescribed growing-season fire. Crown thinning (removal of large overstory trees) creates an open canopy that promotes development of understory and midstory trees and shrubs. Thinning by any of these methods on a 5 to 8 year cycle is recommended for increasing mast production. Alternatively, if different sections of a forest are thinned at staggered intervals of 3 to 5 years new mast production will be encouraged in different parts of the stand on a regular basis.
Byrd, N.A. 1981. A forester's guide to observing wildlife use of forest habitat in the south. USDA/U. S. Forest Service. SA-FR 15. 36 pp.
Byrd, N.A. & H.L. Holbrook. 1974. How to improve forest game habitat. Forest Management Bulletin.
Cerulean, S., Botha, C. & D. Legare. 1986. Planting a refuge for wildlife: How to create a backyard habitat for Florida's birds and beasts. Florida Game & Freshwater Fish Comm.
Collins, J.O. 1961. Ten year acorn mast production study. LA Wildl. & Fish. Comm. W-29R-8.
Grelen, H.E. & V.L. Duvall. 1966. Common plants of longleaf pine-bluestem range. Southern Forest Exp. Sta., 96 pp.
Halls, L.K. & T.H. Ripley. 1961. Deer browse plants of southern forests. Southeastern Forest Exp. Sta. 78 pp.
Hunter, M.L. 1990. Wildlife, Forests, and Forestry: Principles of Managing Forests for Biological Diversity. Prentice-Hall Inc. 370 pp.
Miller, H.A. & L.K. Halls. 1969. Fleshy fungi commonly eaten by southern wildlife. South. Forest Exp. Sta. SO-49.
Robbins L.E. & R.L. Meyers. 1992. Seasonal effects of prescribed burning in Florida: A review. Tall Timbers Research, Inc., Miscellaneous Publication No. 8.
Shaw, S.P. 1971. Wildlife and oak management. In Oak Symp. Proc. Northeastern Forest Exp. Sta.
Stiles, E.W. 1984. Fruit for all seasons. Natural History. v:8/84. pp.43-54.
1Graduate Research Assistant and Associate Professor, Dept. of Wildlife and Range Sciences, University of Florida,
Gainesville. Florida Cooperative Extension Service * Institute of Food and Agricultural Sciences * University of Florida, Gainesville * John T. Woeste, Dean