Trophic cascades impact the biodiversity of ecosystems, and when examined from that perspective wolves appear to be having multiple, positive cascading impacts on the biodiversity of Yellowstone National Park. These impacts include: Scavengers, such as ravens (Corvus corax), bald eagles (Haliaeetus leucocephalus), and even grizzly bears (Ursus arctos horribilis), are likely subsidized by the carcasses of wolf kills. In the northern range, the relative abundance of six out of seven native songbirds which utilize willow was found to be greater in areas of willow recovery as opposed to those where willows remained suppressed. Bison (Bison bison) numbers in the northern range have been steadily increasing as elk numbers have declined, presumably due to a decrease in interspecific competition between the two species. Importantly, the number of beaver (Castor canadensis) colonies in the Park has increased from one in 1996 to twelve in 2009. The recovery is likely due to the increase in willow availability, as they have been feeding almost exclusively on it. As keystone species, the resurgence of beaver is a critical event for the region. The presence of beavers has been shown to positively impact streambank erosion, sediment retention, water tables, nutrient cycling, and both the diversity and abundance of plant and animal life among riparian communities.
Posted on: Wed, 19 Nov 2014 21:35:52 +0000
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