Forest Fruit and Nut Production

Acorn Production

Acorn traps set up under trees

These acorn traps placed under oaks sample acorns as they fall from the trees in autumn.

Acorns are considered a keystone resource in upland hardwood ecosystems. Acorn abundance influences rodent populations and the populations of their predators. Populations of many game species including squirrels, bear and deer are also affected by annual acorn production. Even forest structure and hardwood regeneration are indirectly affected by acorn production by influencing densities of deer – which in turn browse heavily on woody vegetation. And, of course, oak regeneration comes from their seeds – acorns!

Our research shows:

  • Acorn production varies among years, species, and individual oak trees.
  • Acorn production among individual oak trees is not “all or none.”
  • A good crop = more trees with acorns + more acorns per tree.
  • Acorn density is correlated with the proportion of fruiting trees.
  • Good producers produce more acorns more frequently.
  • Good producers constitute <50% of population, but produce most of the acorns.
  • Good producers are hard to identify because a similar proportion of good and poor producers produce in all years.
  • The proportion of trees bearing acorns is a good predictor of crop size.
  • A simple estimate of the proportion of trees bearing acorns in any given year can be substituted for many current labor-intensive hard mast indexing techniques.
  • A lot of trees must be sampled to get good estimates of acorn crop sizes.

Forest Fruit Production

Acorn chestnut oak

Acorn chestnut oak.

Blueberries

Blueberries.

Fleshy fruit is a key food resource for both game and nongame wildlife. Land managers need to know how land uses affect fruit production, and how it changes over time. We quantified fleshy fruit abundance for 5 years in both young, recently harvested and mature forest stands of 2 forest types - drier upland hardwoods and moister cove hardwood forest types.

Our research shows:

  • Over the 5-year study period total dry pulp biomass production was low and relatively constant in both mature forest types.
  • Fruit production was higher in young stands than mature forest beginning about 2 years post-harvest (2000).
  • About 5 years after harvesting, about 0.6 kg of dry edible fruit pulp was produced per hectare in the mature cove hardwood forest, and about 16 kg/ha was produced in the young upland hardwood stands.
  • A few species dominated fruit production, but dominant species differed among treatments and years.
  • Pokeberry and blackberry dominated fruit production in young stands.
  • Many herbaceous and tree species also produced more fruit in young stands than in mature forest.
  • Fruit availability was highest during summer and early fall.
  • American holly, sumac, and greenbriar retained fruit during winter.
  • Fruit availability varied spatially and temporally due to differences in species distribution and fruiting phenology.
  • In the southern Appalachians, young, recently regenerated stands provide abundant fruit compared to mature forest stands and represent an important source of food for wildlife for several years after harvest.