|Title||Successional changes in a mature aspen forest in northern lower Michigan: 1974-1981|
|Publication Type||Journal Article|
|Year of Publication||1985|
|Authors||Sakai AK, Roberts MRichard, Jolls CL|
|Journal||The American Midlands Naturalist|
The Wells Plot, a 1-ha area with over 1800 marked trees in northern lower Michigan, showed many changes from 1974 to 1981 anticipated for the succession from aspen to northern hardwoods. Early successional species (bigtooth aspen, trembling aspen and paper birch) became established immediately after logging and fire about 65 years ago because of rapid growth of root sprouts and stump sprouts and are now in the canopy. Since 1974 these species have experienced mortality with no recruitment. By 1981, there were large numbers of small white ash and red maple, and more shade-tolerant, late successional species such as beech, sugar maple, hop hornbeam and striped maple. The diameter distribution curve for aspen was bell-shaped, moving into larger size classes during this 7-year period because of continued diameter growth, no recruitment, and mortality in the smaller size classes. Red maple, sugar maple and beech had distributions skewed toward the smaller size classes. Red maple maintained its high importance value, although with increasing reliance on sexual reproduction, to maintain the population. Although a third of the current red maple population was presumably of stump sprout origin, almost all of the recent recruitment was of seed origin and over half of the red maple mortality occurred among sprout stems. Sugar maple recruitment was evenly divided between sprouts and seeds, and mortality occurred in both small sprouts and seedlings. Beech increased in density because of modest recruitment coupled with low mortality. Because the trees are mapped, and mortality, recruitment and growth of individual trees can be followed, these baseline data will be of value to future studies on the relative importance of seed vs. sprout reproduction, on spatial pattern and its effect on competition and reproduction, and on long-term tests of theories of plant succession and population dynamics.