Biology Reference
In-Depth Information
Figure 2.6
Desert formation: Sonoran Desert association of saguaro (
Carnegiea gigantea
) with
creosote bush (
Larrea tridentata
), Arizona.
these millennia the width of the less-dense and lighter-colored spring wood
(fi g. 2.7), forming part of the annual growth ring, refl ects precipitation and
water availability (stream fl ow, water table fl uctuations) and, to a lesser
extent, temperature, length of the growing season, and nutrient levels. The
ring patterns from living trees have been fi tted into sequences from older
