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Regional demographic trends from long-term studies of saguaro (Carnegiea gigantea) across the northern Sonoran Desert

Journal of Arid Environments

By:
, , and
DOI: 10.1016/j.jaridenv.2012.08.008

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Abstract

Ten saguaro (Carnegiea gigantea) populations in the northern Sonoran Desert were monitored from 1959 to 2005 to discriminate how climate influences plant growth, abundance, reproductive potential, survivorship, age structure and regeneration trends. Thousands of saguaros were measured to determine site-specific growth rates and survivorship through time. Observed growth rates were used to predict the ages of saguaros and reconstruct local and regional regeneration patterns back to the late 18th century. Both growth rates and degree of branching generally tracked temperature and moisture gradients. Site-specific age-height models explained 89-97% of variance in observed ages, with a slope of nearly one. Regeneration was more consistent at sites in the western (hotter/drier) than eastern (cooler/wetter) sites, which exhibited clear multidecadal variability in regeneration rates. Averaged across the region, saguaro regeneration rates were highest from 1780 to 1860, coincident with wet conditions and high Pinus ponderosa recruitment in the highlands. Milder and wetter winters and protection from livestock grazing likely promoted late 20th century regeneration surges at some sites. Predictions of saguaro population dynamics in the 21st century likely will be confounded by the saguaro's episodic and asynchronous regeneration, continued urbanization, ongoing grass invasions and associated wildfires, and changing climate.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Regional demographic trends from long-term studies of saguaro (Carnegiea gigantea) across the northern Sonoran Desert
Series title:
Journal of Arid Environments
DOI:
10.1016/j.jaridenv.2012.08.008
Volume
88
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
Branch of Regional Research-Western Region
Description:
13 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Arid Environments
First page:
57
Last page:
69
Number of Pages:
13
Country:
Mexico;United States
State:
Arizona
Other Geospatial:
Sonora