Conservation of long-lived perennial forest herbs in an urban context: <Emphasis Type="Italic">Primula elatior</Emphasis> as study case |
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Authors: | Fabienne Van Rossum |
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Institution: | (1) Plant Biology and Nature Management, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium;(2) Present address: Department of Vascular Plants, National Botanic Garden of Belgium, Domein van Bouchout, 1860 Meise, Belgium |
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Abstract: | Urban forests are generally fragmented in small isolated remnants, embedded in an inhospitable human-used matrix, and incur
strong anthropogenic pressures (recreational activities, artificialization, pollution and eutrophication). These lead to particularly
high constraints even for common forest herbs, whose genetic response may depend on life-history traits and population demographic
status. This study investigated genetic variation and structure for 20 allozyme loci in 14 populations of Primula elatior, a self-incompatible long-lived perennial herb, occurring in forest fragments of Brussels urban zone (Belgium), in relation
to population size and young plants recruitment rate. Urban populations of P. elatior were not genetically depauperate, but the small populations showed reduced allelic richness. Small populations showing high
recruitment rates—and therefore potential rejuvenation—revealed lower genetic diversity (H
o and H
e) than those with low or no recruitment. No such pattern was observed for the large populations. There was a significant genetic
differentiation among populations within forest fragments (F
SC = 0.052, P < 0.001), but not between fragments (F
CT = 0.002, P > 0.10). These findings suggest restricted gene flow among populations within fragments and local processes (genetic drift,
inbreeding) affecting small populations, strengthened when there is recruitment. Urban forest populations of long-lived perennial
herbs can be of conservation value. However, restoration of small populations by increasing population size through regeneration
by seedling recruitment may lead to negative genetic consequences. Additional management, aiming to restore gene flow among
populations, may need to be applied to compensate the loss of genetic diversity and to reduce inbreeding. |
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Keywords: | Allozymes Genetic erosion Urban habitat fragmentation Population size Recruitment rate |
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