Ex situ conservation of oak (Quercus l.) in botanic gardens : a North American perspective
Date
2012
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Publisher
University of Delaware
Abstract
Oaks have significant ecological, economic and aesthetic importance, but are threatened by habitat loss, invasive species, shifting climates, and pests and pathogens like sudden oak death. Recalcitrant acorns lose viability when dried, rendering long-term seed bank storage futile. Conservation through living collections is currently the only ex situ conservation option. This research investigated the representation of North American threatened oaks in living collections. Using BGCI’s PlantSearch database a survey of ex situ living collections of North American native oak taxa was conducted to determine their prevalence in botanic gardens. A detailed survey of four oak taxa, Quercus acerifolia (E. J. Palmer) Stoynoff & W. J. Hess, Q. arkansana Sarg., Q. boyntonii Beadle and Q. georgiana M.A. Curtis, was conducted to gain insight into the ex situ conservation of wild-collected plants of known provenance in living collections. Botanic gardens growing the four taxa were contacted individually to gain information about the number of accessions, number of individuals and provenance. Among the 97 North American oak taxa presently recognized by the Flora of North America (north of Mexico), six were not represented in botanic gardens and only 2% of records represent the most threatened taxa. However, the four oaks studied here were relatively well represented in collections, and the most threatened oaks (Q. acerifolia and Q. boyntonii) had a higher percent representation of wild collections than less threatened oaks (Q. arkansana and Q. georgiana). Q. georgiana is highlighted as a case study by asking whether oak genetic diversity in living collections represents genetic diversity in the wild through use of DNA fingerprinting techniques. Twenty-four individuals from living collections were compared to 224 individuals from nine populations across the range of the species using microsatellite markers developed for Q. rubra. Genetic diversity was high in wild populations, while less than 63% the genetic variation identified in wild populations was present in known ex situ collections. Results from this study can be used to assist in making management decisions about ex situ conservation of oaks such that genetic diversity within species is maximized in living collections, which has long-term implications for restoration and reintroduction efforts.