Plant Ecology

, Volume 215, Issue 6, pp 613–624

Exploiting a window in time. Fate of recruiting populations of two rare fire-dependent Geranium species after forest fire

Article
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Abstract

Fire ephemerals are few in the boreal forest despite a long history of recurrent fires, which suggests such a life-history pose problems here. We analysed the fate of recruiting populations of two rare and fire-dependent annual Geranium species at burnt forest sites in South-eastern Sweden, to extract vital information on their life-history. Seedlings emerged from the soil seed bank only in the year of fire but spread over several weeks. At sites that burnt early in the season, some seedlings exhibited a summer-annual life-cycle, but those were less successful than plants at the same sites that delayed reproduction until the following year (winter-annuals). Herbivory was frequent in the fire year and until the following spring, but later almost absent, and thus hit seed production in summer-annuals badly. Winter mortality was highly variable for rosette-stage winter-annuals, with some populations nearly obliterated. Reproductive success varied greatly between populations mainly due to pre-reproductive mortality, with a return of 0.2–395 (average 79) seeds per seedling. The vast majority of seeds (92–100 %) were produced by the primary generation, emerging from the seed bank. Out of this first seed crop, 0.2–2.5 % germinated within the study period, resulting in secondary generations. Plants in these later generations were small and produced few seeds, showing that the opportunity for high reproductive success is essentially restricted to one year only. This makes populations highly vulnerable to local near-complete reproductive failure due to winter mortality and herbivory and may be the ultimate reason why strict fire ephemerals are so few in northern forests.

Keywords

Seed bank Annual plant Heat-triggered germination Reproductive output Winter survival Herbivory 

Supplementary material

11258_2014_327_MOESM1_ESM.doc (44 kb)
Supplementary material 1 (DOC 44 kb)

Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  1. 1.Department of Forest Ecology and ManagementSwedish University of Agricultural SciencesUmeåSweden

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