American Ginseng (Panax quinquefolius L.)
Timber harvest is a common disturbance that is important due to its ongoing, cyclical nature and its direct effects on forest canopy structure. Most of the research regarding timbering has focused on the study of trees, with less emphasis placed on the incredibly diverse herbaceous understory. Due to the high demand for its root on the Asian market, ginseng is the premier medicinal, non-timber forest product in the United States. Historic accounts suggest that ginseng was once far more abundant than it is today, and while overharvesting of ginseng for its root is often described as the primary cause of reductions in population size, extensive changes in ginseng habitat caused by timbering likely played a role in ginseng decline. The purpose of this research is to determine if timbering events typical of the eastern deciduous forest have negative effects on the survival, growth, and reproduction of wild American ginseng. I found that the growth of American ginseng may benefit from the canopy gaps formed by timbering, but timbering needs to be performed in a manner that preserves the soil profile so that the initial chances of ginseng survival do not decrease substantially. I also found that seed production increases following timber harvest events. However, previous research indicates that germination rates may actually decrease due to the excess light availability in the understory, thus minimizing the importance of this reproductive stimulation. Some current silvicultural strategies such as single-tree selection and group selection mimic the structure of old-growth forests; environments to which American ginseng and perhaps other shade-species are adapted. These silvicultural strategies that mimic old growth forest dynamics are perhaps the best fit for land managers who have multi-dimensional goals involving continued production of valuable timber, maintained forest biodiversity, and conservation and stewardship of ecologically and economically valuable herbs like American ginseng. |
Cottongrass (Eriophorum vaginatum L.)
The northern hemisphere, and Alaska’s arctic tundra in particular, has experienced unprecedented climatic warming in recent centuries, and even in recent decades. Moist tussock tundra, dominated by cottongrass, covers large amounts of this arctic and subarctic land area. As warming in the northern hemisphere intensifies, ‘adaptational lag,’ which is a delayed evolutionary and migratory response of organisms to rapid climate change, may have far reaching negative effects on plant populations. The purpose of this research was to determine whether the observed shifts in northern latitude climate patterns have already resulted in adaptational lag for cottongrass ecotypes in northern Alaska. We found that, although plants were still growing in their home environments, populations of cottongrass are being affected by changing climate in a manner consistent with adaptational lag. This study may be an indication of the possible future effects of climate shifts in more southern latitudes. Please see the publication list below for more information about this research. |