By the numbers, Denali National Park and Preserve is home to an abundant diversity of species, including 39 mammals, 169 birds, 14 fish, 1 amphibian, 758 vascular plants, over 1000 mosses and lichens, and thousands of other life forms including insects, spiders, fungi, algae, and more! As these species intertwine upon the landscape, how will the change trends affect them? Is there reason to be concerned for their health, or the health of the ecosystem as a whole? While park staff and visiting researchers cannot answer all these questions with 100% certainty, they do have some ideas. Do you?
Many aspects of ecology link closely, so if one ecosystem attribute drastically changes, other changes will certainly follow. Vegetation communities are one of the most important components of subarctic ecosystems because they:
- Stabilize the soil, improving productivity and protecting water resources
- Improve air quality by producing oxygen through respiration
- Moderate temperature within their canopies
- Provide food and suitable micro and macro habitats for most organisms
As an example, let’s look at the invasion of wetlands by woody vegetation (trees and shrubs). The addition of shrubs to a wetland system will first affect the plants already there, which now must compete for light, nutrients, and water. The presence of shrubs will alter site microclimate, slowing wind and causing greater accumulation of snow. Animals that browse shrubs, such as snowshoe hare, will be attracted to the area, as will their predators, lynx and wolves. On the other hand, birds that nest in open wet meadows, such as rusty blackbirds, may be forced to move elsewhere or eventually be excluded completely. The invasion of shrubs into the wetland will also increase the chance of wildfire, which, if severe, may cause the site to undergo an additional change toward yet another ecological community type.
Although successional changes often have profound effects on the flora and fauna of a given ecological community, species that make their home in those communities often have adaptations to account for those predictable effects. Reordering of vegetation communities however, results in completely new ecological conditions that are outside the normal range of variation for those species. Moreover, due to recent unprecedented climate warming, the pace of these changes may be beyond the capacity of certain species to adapt.
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