110 likes | 495 Views
Keystone Species in The Keystone State. By: Matthew Urmson For: AEE 440 Date: 6 October 2010. Trophic Cascades. Food Webs Trophic levels Top-down trophic cascades Bottom-up trophic cascades. Keystone Species. Keystone species defined Examples of keystones species Sea otter
E N D
Keystone Species in The Keystone State By: Matthew Urmson For: AEE 440 Date: 6 October 2010
Trophic Cascades • Food Webs • Trophic levels • Top-down trophic cascades • Bottom-up trophic cascades
Keystone Species • Keystone species defined • Examples of keystones species • Sea otter • Gray wolf
The Mountain Lion • Life history • Identification tips • Cougar tracks are asymmetrical • The status of cougars in Pennsylvania
Gray wolf • Life history • Identification tips • Wolf tracks are symmetrical • The status of wolves in Pennsylvania
The Problems of Extirpation • Extirpation is local extinction • Not to be confused with global extinction • Cause a change in local ecology • Result in dramatic loss of biodiversity
Ungulate irruptions • Ungulates in Pennsylvania • White-tailed deer & elk • Ungulate populations increase exponentially • Because there are no predators
Ungulate irruptions continued • Irruptions result in over-browsing of plants • Plant biodiversity is lost • Forests cannot regenerate • Bird species are negatively affected
Evidence of Over-browsing • Ungulate exclosures • Show regeneration after ungulates removed • Forests can regenerate
The Return of the Predator • Return of the keystone predator • Results in restoration of ecosystem • Forest regenerates and understory forms • Wolves in Yellowstone & Glacier National Parks
Benefits of Large Carnivores • Increase in plant biodiversity • Increase in bird biodiversity • Stronger and healthier ungulates • Overall improvement of the ecosystem