110 likes | 446 Views
3 Feb 2004 Biogeography Tour of Wisconsin III. Wildlife and People Generalizations about Euro-Americans, wildlife, and ecology: Broad stories Habitat loss, change, or fragmentation decline
E N D
3 Feb 2004 Biogeography Tour of Wisconsin III. Wildlife and People
Generalizations about Euro-Americans, wildlife, and ecology: Broad stories Habitat loss, change, or fragmentation decline Fragmentation: The reduction of ecological communities from large areas to small, disconnected patches Ex: prairie bird life; the Upland Sandpiper
Generalizations about Euro-Americans, wildlife, and ecology: Broad stories Habitat loss, change, or fragmentation decline A caveat: vegetation has always been patchy to some extent, especially under influence of any human group, but in the case of prairies what were thousands of acres are now dozens
Generalizations about Euro-Americans, wildlife, and ecology: Broad stories Habitat loss, change, or fragmentation decline A variation: the case of big cats; ex: mountain lions of river valley areas Habitat loss/fragmentation meant less room for hunting; but Euro-American settlers also killed deliberately to protect livestock.
Generalizations about Euro-Americans, wildlife, and ecology: Broad stories Habitat fragmentation population increases! “Edges” between fields and forests, for example, encourage deer populations because it provides them with the best food and cover. Adjacent forest stands of different ages encourage ruffed grouse because they prefer younger stands for breeding and older ones for feeding. Urban areas and the resources humans provide also encourage other animals.
Generalizations about Euro-Americans, wildlife, and ecology: Broad stories Exploitation decline ( protection/management recovery) Ex: beaver; white-tail deer
A brief history of WI deer Ecological characteristics combine with human economic, cultural, and political history Ecological characteristics: habitat and food requirements and preferences; reproductive behavior and timing
A brief history of WI deer Before European settlement: Abundant in the S; scarce in the N Euro-American settlement: Depleted deer in the S through subsistence and market hunting, displacement; encouraged deer in N with fragmentation of forests Late-19th century fires: Along with market hunting and agricultural expansion drove deer numbers to lowest on record; fear of total extirpation Management: New laws and better enforcement protected deer while vegetation encouraged by logging sparked population explosions in the N
A brief history of WI deer Logging slow-down: ideal food became less available and populations faced starvation each winter By this time, a variety of political constituencies were involved: sportspersons, farmers, foresters, wildlife managers Experiments with hunting season: 1943 as a model year; controlled populations considerably, reduced starvation Southern farms: In the 1960s, farmers in S WI allowed some areas to go to forest, creating new “edge” environments
Keystone species A species whose removal from an ecological community will cause greater change than the removal of the average species
Keystone species • White-tail deer in Wisconsin? • Studies use enclosures and islands to compare vegetation with and without deer • Deer prefer to browse hemlock, white cedar, and oak; remove shoots and greenery within their reach • Reduce diversity of canopy, understory, and ground layers; change species composition • Indirect impacts on insects, birds, other species dependent on vegetation • POPULATION DENSITY is key factor