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a)
1900
High
1920
1940
1960
1980
2000
2020
e)
f)
Wolves
extirpated
(1926)
Wolves
restored
(1995)
?
Low
b)
20000
15000
10000
5000
0
End of elk
culling
(1968)
?
c)
High
?
Low
d)
High
?
Low
1900
1920
1940
1960
Years
1980
2000
2020
Figure 3.6
(a-d) Historical trends in wolves, elk, tree recruitment and beavers for the northern range of Yellowstone National Park since 1900.
Uncertainty shown in grey. (e) Blacktail Creek in 1996, after 70 years of wolf extirpation and heav y browsing by elk and (f) in 2002, 7 years after the rein-
troduction of wolves (from Ripple and Beschta 2004).
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