Influence of climatic variability on local population dynamics of a Sonoran Desert platyopuntia

Journal of Arid Environments



Age-based population dynamics of Opuntia engelmannii, a shrubby cactus with flattened cladodes, were investigated at a Sonoran Desert site protected from grazing since 1907. Demographic statistics were determined from births and deaths on six permanent vegetation plots mapped four times between 1968 and 2001. Moderate longevity (13-56 years) and modest per capita annual survival (0.9298) were associated with fairly rapid turnover; cycles of population growth and decline were thus evident over relatively short periods. Age-frequency distribution, determined for subpopulations in two neighboring habitats in 1996 and 2003, was used to calculate residual regeneration, an index of the difference between observed cohort size and idealized survivorship. Establishment peaks occurred in the late 1970s, the mid-1980s, and the early to mid-1990s and coincided with increased winter moisture in the years before germination, ample summer rain in the year of germination, and decreased drought in the years after germination, reflecting favorable conditions for fruit production, seed germination, and seedling survival. Regionally, pulses and gaps in establishment coincide with the frequency and amplitude of large-scale climatic phenomena that affect cycles of moisture and drought on decadal and interdecadal scales. Because of local factors, however, subpopulations within a few km of one another can experience virtually identical climates yet differ strikingly in age structure and density. ?? 2004 Elsevier Ltd. All rights reserved.
Publication type Article
Publication Subtype Journal Article
Title Influence of climatic variability on local population dynamics of a Sonoran Desert platyopuntia
Series title Journal of Arid Environments
DOI 10.1016/j.jaridenv.2004.09.003
Volume 61
Issue 2
Year Published 2005
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Arid Environments
First page 193
Last page 210
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