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Front 1

ESA 1973 purpose and limitations

Back 1

First federal statute to grant de factoexistence rights to species of plants and animals

Does not reflect advances in pop. biology and community ecology; criteria for endangered species ignores interspecies interactions

Front 2

proposals of authors and 2 issues to clarify

Back 2

Population densities of strongly interactivespecies cannot fall below threshold for ecological effectiveness; Geographic range for these species should be as large as possible

1. definition of strongly interactive species

2. achievement of ecologically effective densities of such spaces

Front 3

keystone species

Back 3

Paine (1969)

species whose activities maintain habitat diversity and whose presence affects the abundance of many other species

Front 4

3 keystone species

Back 4

ecological engineers: affect biological habitat structure

mutualist species: maintain species diversity

predators

Front 5

questions to determine if a species is a "strong interactor"

Back 5

1. Does its absence reduce local species diversity?

2. Does its absence reduce reproduction of other species?

3. Does its absence change habitat structure?

4. Does its absence change nutrient dynamics?

5. Does its absence change important ecological processes?

6. Does its absence reduce the resilience of the ecosystem to disturbances?

Front 6

why don't experiments work with determining key species

Back 6

would need to remove species for long periods of time, and without lots of protection for land this is unjustified

Front 7

predator-mediated cascades

Back 7

large carnivores (wolves) decrease, large consumers (elk) increase, vegetation (aspen, willow) decrease --> ecological degredation --> species extirpation (beavers)

large carnivores (coyotes) decrease, mesopredators (cats, foxes) increase, small consumers (birds, reptiles) decrease --> species extirpation (birds, reptiles)

marine mesopredator (sea otter) decrease, small consumers (urchins) increase, vegetation (kelp) decrease --> species extirpation (fish, invertebrates)

Front 8

ecologically effective density

Back 8

population level that prevents undesired changes in a defined ecological setting

Front 9

problem with estimating ecological effective density

Back 9

depends on locality, season, productivity, etc.

ex: wolves density lower where hunters are, where other large carnivores exist, etc.

Front 10

what must conservation practitioners do

Back 10

adopt an ecological view that ensures persistence of interactive species at ecologically effective densities and maximal spatial occurrence