Much of Arizona was still experiencing tremendous drought-related ecosystem impacts in August due to long-term soil moisture deficits. As noted by the CLIMAS/Institute for the Study of Planet Earth (Gregg Garfin):
- In southeastern Arizona, which comprises an ecotone between Sonoran Desert vegetation and Chihuahuan desert vegetation, it seems that Chihuahuan Desert indicator species are mostly dead. Sonoran Desert shrubs are exceedingly stressed. Ranchers in this part of the state claim that this drought is worse than the 1950s drought.
- Throughout the state, there has been severe die back in Arizona's extensive conifer forests. There is severe die back in the spruce-fir forests of the sky island mountain ranges (> 10,000 ft.) in southeastern Arizona -- a surprising occurrence, and an indicator of extreme drought. This is mostly due to bark beetle and spruce budworm outbreaks as a result of drought-related vegetation stress and increased vulnerability to pests.
- Ponderosa and pinyon pine mortality is exceedingly high in Northern Arizona. Pinyon mortality is higher on the Mogollon Rim (Colorado Plateau), whereas Ponderosa pine mortality is exceedingly high below The Rim (e.g., in Prescott, Arizona). The latest USFS aerial surveys indicate that Ponderosa pine mortality is about 10 times greater than noted last year -- a lag effect of severe drought and drought-related insect outbreaks, as well as a result of the fact that last year's aerial survey was conducted at the beginning of the summer. In a region of Mohave County, north of Kingman Arizona, there is a tremendous amount of pinyon pine mortality.
- In the Tonto Basin of Central Arizona, saguaro "forests" on south-facing slopes are still in pretty good shape; however juniper forests on North-facing slopes are displaying high mortality. (Junipers are the "shrub" species likely to takeover where pinyon pine mortality is high.) Paleo-pollen analyses indicate that much of Southern Arizona's desert landscape was populated by juniper woodlands (not saguaro cactus) during the last pluvial period (several thousand years ago). Moreover, in this same region, there is high mortality among riparian species such as cottonwoods and willows.
As noted by the High Plains Regional Climate Center (Kenneth F Dewey), lake levels in Lake Mead (in northwest Arizona) have been dropping steadily during the last five years.
A detailed report of drought conditions for the Lake Mead and Las Vegas, NV, area can be found at:
http://www.hprcc.unl.edu/nebraska/sw-drought-2003.html
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