Document: PHY-3-67-4

Disturbance and succession in interior Alaskan white spruce forests .

ADAMS, P.C.* and L.A.VIERECK

University of Alaska, Fairbanks, AK 99775 USA ¹

Abstract:
Models of ecosystem development on the Tanana River floodplain in interior Alaska portray succession as an orderly deterministic progression of biotic change. Variability in the successional process has been attributed to stochastic factors in early stages of succession, while autogenic processes such as facilitation become more important in middle and late succession. However, long-term monitoring of permanent plots at the Bonanza Creek Experimental Forest (BCEF), a Long-Term Ecological Research (LTER) site, shows that episodic environmental factors are important in later stages of succession as well. Changes in structure and composition of white spruce forests in interior Alaska may result from small-scale episodic exogenous disturbance. Repeated measurements of permanent plots at BCEF document changes in stand structure and species composition, and these measurements are linked with environmental measurements made at the same sites. Because canopy structure is an important factor controlling ecosystem processes in floodplain white spruce forests, small-scale disturbances that alter the stand structure, such as top breakage from heavy snowfall, influence the rate of transition from mature even-aged white spruce forests to old uneven-aged stands. This has important implications for climate change because the frequency of occurrence of these episodic events may change, thus changing the rate of succession in mature white spruce forests.

Keywords: succession, disturbance, riparian forest

This abstract is being presented at: 8:15 AM in session:
Oral Session #22: Multiple Disturbance Effects, Including Fire.