Detecting vegetation change in Kenai Fjords National Park: a revisit of 15-year-old inventory plots

Boucher, Tina; Miller, Amy; Boggs, Keith

In 2008 we revisited 22 sites along the coast of Kenai Fjords National Park initially sampled in1993. Our goal was to conduct a pilot study to assess vegetation change on early and latesuccessional plant communities, and to assess the feasibility of relocating plots that had not beenpermanently marked. We sampled 10 plots that were glaciated during the maximum extent of theLittle Ice Age (LIA, ca. 1850), and 12 plots that were beyond the maximum glacial extent. Plotswere grouped into the following categories: forest, tall shrub, dwarf shrub-forb, and coastalherbaceous meadow.Because plots were not permanently marked in 1993, we were not able to accurately relocate 13out of 22 plots. Where we could not relocate the exact plot center, we sampled in homogeneousvegetation in the general area of the original plot. We took repeat photographs where possible todocument vegetation change within the plots and in the surrounding landscape. While we wereable to identify some consistent trends, other changes could have been due to relocation error.Where the plot data may have fallen short, the repeat landscape photos provide a valuableindication of the scale of vegetation change across the landscape.Observed trends in the plot data included increased species richness in early successional shrubplots and increased salmonberry (Rubus spectabilis) cover on disturbance slopes outside the LIAmaximum. Landscape photos corroborated the increase in Rubus spectabilis observed in severalplots, possibly indicating a change in frequency or severity of the disturbance regime on activeside slopes. In coastal herbaceous meadows we saw a decrease in beach rye (Leymus mollis)cover and increase in forb cover likely due to natural successional processes and isostaticrebound. Late seral forests appeared fairly stable, while young spruce forests showed trendssimilar to those in the early successional shrub plots.This study provides an indication of the nature of change in vegetation over a 15-year window onrecently deglaciated terrain and on older landscapes, and provides insight into possible futureresearch efforts. However, this study was not designed to replace a monitoring program, and wedo not advocate using this plot design for future long-term monitoring efforts.

Detecting vegetation change in Kenai Fjords National Park: a revisit of 15-year-old inventory plots

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