Biology Reference
In-Depth Information
Figure 2.5
Shrubland/chaparral-woodland-savanna formation: juniper (
Juniperus occidentalis
)
woodland, central Oregon, USA. Photograph courtesy of the National Archives, Washing-
ton, DC.
elevations, sharper peaks, and more dramatic scenery compared to the gen-
tler, older, more eroded, and lower Appalachian Mountains.
There is alpine tundra on the higher peaks, and a western montane conif-
erous forest below that includes
Abies
,
Picea
,
Pseudotsuga mensiesii
(Douglas
fi r), and
Pinus ponderosa
. Toward the south at lower elevations, the conifer-
ous forest grades into drier lowlands and woodlands of
Pinus edulis
(piñon
pine) and
Juniperus
(juniper; fi g. 2.5), and eventually into the western des-
erts (fi g. 2.6). In the southern Rocky Mountains,
Pinus aristata
(bristlecone
pine; I, fi g. 4.8) and related species grow from central Colorado to northern
New Mexico and northeastern Arizona. Some reach an age of nearly 5000
years and are the Earth's oldest organisms. When these ancient trees began
their life, the Greek city-states and the disparate political units that would
become Egypt were just assembling. The trees were already 3200 years old
when Hannibal and his unlikely entourage of elephants crossed the Alps in
218 BCE, and they were 3000 years old at the time of Christ. Throughout
