Average length of time between fires is thought to limit shrub height of some Florida scrubs which has been found to exceed 3 m within 30 to 40 y, a height at which these scrubs no longer support the Florida scrub jay (Aphelocoma coerulescens) and possibly other rare species endemic to this vegetation type. We hypothesize, however, that stem lifespan, rather than the average fire return interval, limits the height attained by Quercus inopina, a dominant shrub oak endemic to scrubs on the Lake Wales Ridge in south-central Florida. To determine stem longevity and height growth, the perimeters of 56 stem clusters at nodes on the rhizomes of Q. inopina were outlined with wire flags in four scrub stands at Archbold Biological Station in south-central Florida and all stems in each cluster tagged. Height growth and survival of 448 stems were followed for 9–10 y, along with that of any new stem sprouts appearing within the perimeters of the marked clusters during this time. Between 80 and 90% of the initially tagged oak stems died within 10 y. New stem sprouts replaced these stems such that the total number of stems at the marked clusters either remained roughly the same or increased slightly. Median life span of stems was approximately 4 y, with maximum age estimated at 9 y. Rapid turnover limits the median height attained by stems of Q. inopina to <2 m, precluding the scrubs it dominates from reaching the 3–4 m height unfavorable to the Florida scrub jay, at least in the same 30–40 y time period as do scrubs dominated by its close relative Q. myrtifolia.
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1 April 2002
Stem Turnover in the Rhizomatous Scrub Oak, Quercus inopina, from South-central Florida
ANN F. JOHNSON,
WARREN G. ABRAHAMSON
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The American Midland Naturalist
Vol. 147 • No. 2
April 2002
Vol. 147 • No. 2
April 2002