Aspen Bibliography

Competition and succession in an aspen-white-pine forest

Document Type

Article

Journal/Book Title/Conference

Journal of Ecology

Volume

83

Issue

3

First Page

449

Last Page

457

Publication Date

1995

Abstract

  1. Changes in relative abundance, dominance, diversity, size inequality, and growth of trees was documented in a c. 60-year-old second-growth aspen-white-pine forest in northern Michigan, USA over a 10-year period. Abundance and dominance decreased for aspen but increased for white pine. Size inequalities, measured as coefficient of variation (CV) of diameter, of aspen decreased over the 10 years, while that of white pine increased. The decrease in CV for aspen appears to have been caused by mortality among small aspen stems.
  2. Few white pines grew close to aspens and their growth was unexpectedly greater than that of pines further away from aspens, suggesting a net facilitation of white pine growth. The mechanism of this interaction is unknown, although strong intraspecific competition was found among pines in areas where aspen ramets were less dense. This may have outweighed the competitive effect of aspen on pine growth, resulting in the net indirect facilitation.
  3. The asymmetry of intraspecific competitive effects on growth was substantially less at the local scale than that reported in other studies, which we attribute to greater relative importance of below-ground competition in this site of excessively drained, nutrient-poor sandy soil. For aspen, the amount of asymmetry which resulted in the best-fit model tended to decrease with increasing distance, suggesting that competition with immediate neighbours is likely to be more asymmetric than competition with more distant neighbours in closed-canopy plant communities such as forests. It is hypothesized that in closed-canopy vegetation, the contested resource may primarily be light at short distances, changing to entirely soil resources at greater distances.
  4. This study suggests that both population and, in turn, community dynamics may be governed by physiological senescence of connections within individual clones of the dominant aspens. As a result, the successional species turnover can be considered as a function of clone dynamics, which is an alternative to the more common, smaller-scale, gap dynamics that drive tree-by-tree replacement in many mature and primary forests.

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