Canopy gaps and dead tree dynamics: poking holes in the forest.

Abstract

When large trees die, individually or in clumps, gaps are opened in the forest canopy. A shifting mosaic of patches, from small single-tree gaps to very large gaps caused by wildlife, is a natural part of the development of composition and structure in mature forests. Gaps increase the diversity of forests across the landscape and present local environments that encourage the establishment and growth of new species.

The role, however, of small gaps is not yet well understood. A long-term study established in 1990 seeks to uncover the role of gaps in creating forest diversity, their different effects on multilayered old-growth forests and single-layer mature forests, and their effects on belowground ecosystem attributes such as root density, soil moisture, and nutrient cycling.

Management questions are numerous and important: Do gaps facilitate the development of late-successional forests? If so, what kinds of management treatments can mimic that process? Are gaps "hot spots" for biological diversity, nutrient cycling, and forest productivity?

The value of the long-term study lies in its efforts to continue tracking forest responses to gaps through time. As with so many other areas of forest research, changes through time tell a more complete story than does initial response.

Citation

Duncan, Sally. 2002. Canopy gaps and dead tree dynamics: poking holes in the forest. Science Findings. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. April (43): 1-5