Abstract
The aim with this study was to analyse the population dynamics ofSaxifraga cotyledon, a rare, long lived herb, withsemelparous rosettes. In Sweden, S. cotyledon grows infragmented habitats at high altitude and is classified as vulnerable accordingto the IUCN system. From a five year demographical study we estimatedpopulationgrowth rates and extinction risks for one small and one large subpopulation. Inthe small subpopulation deterministic matrix simulations showed largevariation,with two transitions projecting negative and two projecting positive populationgrowth. The large subpopulation also showed large variation, but all yearlytransitions projected positive population growth. In both subpopulationssurvival and growth contributed more than twice as much to population growthrates than did sexual reproduction, vegetative reproduction and the seed bankall taken together. In stochastic simulations the maximum likelihood growthestimator waslarger than 1 for both subpopulations. None of the two subpopulations sufferfrom high extinction rates and although the effect of demographic stochasticityincrease extinction risk in small populations it is enough with 70 individualsfor a viable population of S. cotyledon. Hence, for thestudied population of S. cotyledon, rareness per se is nota good indicator of vulnerability.
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Dinnétz, P., Nilsson, T. Population viability analysis of Saxifraga cotyledon, a perennial plant with semelparous rosettes. Plant Ecology 159, 61–71 (2002). https://doi.org/10.1023/A:1015593311183
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DOI: https://doi.org/10.1023/A:1015593311183