•Exam #2 F 6/27 in class (bring cheat sheet)

Ecology: We are all connected and interdependent

CB 52.12Carrying Capacity

exponential growth

stationary phase

Carrying capacity can be limited by competition

CB 53.2

Competition limits where species can live

CB 53.2

niche- the specific environment where a species lives

CB 53.3

Tree species existing in different niches

SpeciesintroductionsHunting

HabitatDestructionOther

39%

23%

36%

2%Why are species going extinct?

Grizzly Bears

Historical Grizzly Bear range

Current Grizzly Bear range

CB 55.12

Yellowstone Grizzly Bear population increases

63 mi

54 mi

•466 mi of roads •950 mi of backcountry trails•97 trailheads•287 backcountry campsites

Yellowstone NP

CB 55.16

Artificial corridors allow animals to cross fragmented areas

CB 55.18

Where do grizzly bears fit?

Are they important?

How much of our resources should we share with grizzly bears?

CB 55.19

National park

Buffer zone

In Costa Rica they have a two tiered park system:

National Parks- very restricted human activities

Buffer zones- some restrictions on human activities

CB 55.19

National park

Buffer zone

Developed vs Developing nations:

Should/would the US designate such large areas as parks?

63 mi

54 mi

•466 mi of roads •950 mi of backcountry trails•97 trailheads•287 backcountry campsites

Yellowstone NP

Wolves in Yellowstone National Park

The last wolves in Yellowstone (1920’s)

Wolves commonly live in packs

Social vs Solo

Packs can kill larger prey

Packs give the ability to obtain more food, but also mean sharing food, reduced chance of reproduction, and increased chance of diseases.

Wolves are very territorial and will kill intruders

Wolves were re-introduced to Yellowstone in 1995

Wolf relocation

“hard” release:directly to new location

In Yellowstone used“soft” release:Kept in 1 acre pens to acclimate to new environment

Wolves were re-introduced to Yellowstone in 1995

http://www.forwolves.org/ralph/historical.html

Yellowstone area wolf packs 2004

Wolf deaths 1995-2005

38 deaths= 33%

Currently about 300 wolves 2003- 137 sheep and 66 cattle = $32,000

2004- 209 sheep, 57 cattle, and 6 other animals = $70,000

The cost of wolves in Yellowstone NP:

Estimate millions of dollars in increased visitors

Predator-predator interactions

Predator-predator interactions

CB 55.12

Yellowstone Grizzly Bear population increases

Wolves are decreasing the elk population

Benefits of decreasing herbivore populations

Increased Riparian Habitat

Fig 2

Increased Riparian Habitat

Fig 2

Increased Riparian Habitat

Fig 3

Increased Riparian Habitat

Fig 5

Are wolves responsible?

year1998 1999 2000 2001 1998 1999 2000 2001

Fig 6

Protection vs herbivory

gully depth vs browsing

Fig 6

The greatest difference has been in the deepest gullies, which are at the greatest risk to errosion.

The reintroduction of wolves to Yellowstone NP has had numerous positive benefits.

The reintroduction of wolves to Yellowstone NP has had numerous positive benefits:More food available for other carnivores

Fig 3

The reintroduction of wolves to Yellowstone NP has had numerous positive benefits:Increased Riparian Habitat

Bears (1993) Ian Stirling et al., Weldon Owen Pty Ltd pg 231

Animal behavior is unpredictable and inexplicable

CB 55.13

Not all habitats are equal

How do stable ecosystems develop?

Primary Succession- the first organisms to colonize bare rock

Secondary Succession- recovery from a disturbance