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Distribution and persistence of epiphyte metapopulations in dynamic landscapes

Johansson, Victor (2012). Distribution and persistence of epiphyte metapopulations in dynamic landscapes. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2012:17
ISBN 978-91-576-7653-5
[Doctoral thesis]

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Habitat loss is a major cause of species extinction. Old trees have declined, and this continues because of poor management. Examples are development of secondary woodland in semi-open grasslands, and lack of natural tree regeneration. We therefore can expect that species associated with old tree are declining. The aim of this thesis is to increase the understanding about the habitat requirements, colonization-extinction dynamics and persistence of oak-associated epiphytic lichens with different traits. For species with slow dynamics, data on colonization and extinction events are time consuming to collect. We instead fitted Bayesian incidence function models extended to dynamic landscapes to snapshot data of our study species. The results show that all species were restricted to old trees, but the lower age limit when oaks become suitable differed among species. Colonization rates were generally low and explained by connectivity to surrounding occupied trees, in accordance with metapopulation theory. The colonization rates were higher for species with wide niches (colonizing relatively young trees) and small dispersal propagules than for species with narrow niches (only colonizing old trees) or large dispersal propagules. Stochastic extinctions from intact trees were negligible in all study species, and thus, the extinction rate is set by the tree fall rate, which is low, as oaks become old. By using oak surveys from 1830 and 2009 from a landscape where oaks have declined drastically short after 1830, we show that epiphyte occurrence patterns are better explained by the historical configuration of oaks compared to the present configuration. This indicate non-equilibrium occurrence patterns 180 years after habitat decline, and simulations using the fitted metapopulation models suggest even longer time-lags before new equilibriums are reached. The metapopulation extinction risk increased with decreasing habitat amount, and was highest for species with narrow niches or large dispersal propagules (i.e. low colonization rates). Conservation actions in landscapes with a low density of old oaks had only minor effects on epiphyte persistence, while actions in landscapes with many old but few young trees may increase species persistence. The best conservation approach for the long-term persistence of all species is to assure a constant tree regeneration in landscapes with currently high densities of old oaks.

Authors/Creators:Johansson, Victor
Title:Distribution and persistence of epiphyte metapopulations in dynamic landscapes
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2012
Number of Pages:57
I.Victor Johansson, Tord Snäll, Per Johansson and Thomas Ranius (2010). Detection probability and abundance estimation of epiphytic lichens based on height-limited surveys. Journal of Vegetation Science 21, 332-341.
II.Victor Johansson, Thomas Ranius and Tord Snäll (2012). Epiphyte metapopulation dynamics are explained by species traits, connectivity, and patch dynamics. Ecology (in press). http://www.esajournals.org/doi/pdf/10.1890/11-0760.1
III.Victor Johansson, Tord Snäll and Thomas Ranius. Estimates of connectivity reveal non-equilibrium epiphyte occurrence patterns almost 180 years after habitat decline (submitted manuscript)
IV.Victor Johansson, Thomas Ranius and Tord Snäll. Epiphyte metapopulation persistence after drastic habitat decline and low tree regeneration: time-lags and effects of conservation actions (manuscript).
Place of Publication:Uppsala
Publisher:Institutionen för ekologi, Sveriges lantbruksuniversitet
ISBN for printed version:978-91-576-7653-5
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F40 Plant ecology
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
Obsolete subject words > NATURAL SCIENCES > Biology > Terrestrial, freshwater and marine ecology > Terrestrial ecology
Agrovoc terms:lichenes, epiphytes, habitats, quercus, age, plant population, population dynamics, species extinction, colonizing ability, landscape, nature conservation, sweden
Keywords:Colonization-extinction dynamics, Connectivity, Extinction debt, Historical landscape, Lichens, Oak, Tree age
Permanent URL:
ID Code:8652
Department:(NL, NJ) > Dept. of Ecology
(S) > Dept. of Ecology
External funders:FORMAS
Deposited By: Mr Victor Johansson
Deposited On:27 Mar 2012 13:42
Metadata Last Modified:02 Dec 2014 10:49

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