Ann Milbau1, Bente Jessen Graae, Anna Shevtsova, Ivan Nijs. 1. Research Group of Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium. ann.milbau@emg.umu.se
Abstract
BACKGROUND AND AIMS: In a future warmer subarctic climate, the soil temperatures experienced by dispersed seeds are likely to increase during summer but may decrease during winter due to expected changes in snow depth, duration and quality. Because little is known about the dormancy-breaking and germination requirements of subarctic species, how warming may influence the timing and level of germination in these species was examined. METHODS: Under controlled conditions, how colder winter and warmer summer soil temperatures influenced germination was tested in 23 subarctic species. The cold stratification and warm incubation temperatures were derived from real soil temperature measurements in subarctic tundra and the temperatures were gradually changed over time to simulate different months of the year. KEY RESULTS: Moderate summer warming (+2.5 degrees C) substantially accelerated germination in all but four species but did not affect germination percentages. Optimum germination temperatures (20/10 degrees C) further decreased germination time and increased germination percentages in three species. Colder winter soil temperatures delayed the germination in ten species and decreased the germination percentage in four species, whereas the opposite was found in Silene acaulis. In most species, the combined effect of a reduced snow cover and summer warming resulted in earlier germination and thus a longer first growing season, which improves the chance of seedling survival. In particular the recruitment of (dwarf) shrubs (Vaccinium myrtillus, V. vitis-idaea, Betula nana), trees (Alnus incana, Betula pubescens) and grasses (Calamagrostis lapponica, C. purpurea) is likely to benefit from a warmer subarctic climate. CONCLUSIONS: Seedling establishment is expected to improve in a future warmer subarctic climate, mainly by considerably earlier germination. The magnitudes of the responses are species-specific, which should be taken into account when modelling population growth and migration of subarctic species.
BACKGROUND AND AIMS: In a future warmer subarctic climate, the soil temperatures experienced by dispersed seeds are likely to increase during summer but may decrease during winter due to expected changes in snow depth, duration and quality. Because little is known about the dormancy-breaking and germination requirements of subarctic species, how warming may influence the timing and level of germination in these species was examined. METHODS: Under controlled conditions, how colder winter and warmer summer soil temperatures influenced germination was tested in 23 subarctic species. The cold stratification and warm incubation temperatures were derived from real soil temperature measurements in subarctic tundra and the temperatures were gradually changed over time to simulate different months of the year. KEY RESULTS: Moderate summer warming (+2.5 degrees C) substantially accelerated germination in all but four species but did not affect germination percentages. Optimum germination temperatures (20/10 degrees C) further decreased germination time and increased germination percentages in three species. Colder winter soil temperatures delayed the germination in ten species and decreased the germination percentage in four species, whereas the opposite was found in Silene acaulis. In most species, the combined effect of a reduced snow cover and summer warming resulted in earlier germination and thus a longer first growing season, which improves the chance of seedling survival. In particular the recruitment of (dwarf) shrubs (Vaccinium myrtillus, V. vitis-idaea, Betula nana), trees (Alnus incana, Betula pubescens) and grasses (Calamagrostis lapponica, C. purpurea) is likely to benefit from a warmer subarctic climate. CONCLUSIONS: Seedling establishment is expected to improve in a future warmer subarctic climate, mainly by considerably earlier germination. The magnitudes of the responses are species-specific, which should be taken into account when modelling population growth and migration of subarctic species.
Authors: Marilyn D Walker; C Henrik Wahren; Robert D Hollister; Greg H R Henry; Lorraine E Ahlquist; Juha M Alatalo; M Syndonia Bret-Harte; Monika P Calef; Terry V Callaghan; Amy B Carroll; Howard E Epstein; Ingibjörg S Jónsdóttir; Julia A Klein; Borgthór Magnússon; Ulf Molau; Steven F Oberbauer; Steven P Rewa; Clare H Robinson; Gaius R Shaver; Katharine N Suding; Catharine C Thompson; Anne Tolvanen; Ørjan Totland; P Lee Turner; Craig E Tweedie; Patrick J Webber; Philip A Wookey Journal: Proc Natl Acad Sci U S A Date: 2006-01-20 Impact factor: 11.205
Authors: Elise S Gornish; Zachary T Aanderud; Roger L Sheley; Mathew J Rinella; Tony Svejcar; Suzanne D Englund; Jeremy J James Journal: Oecologia Date: 2014-12-25 Impact factor: 3.225
Authors: Pieter De Frenne; Bente J Graae; Jörg Brunet; Anna Shevtsova; An De Schrijver; Olivier Chabrerie; Sara A O Cousins; Guillaume Decocq; Martin Diekmann; Martin Hermy; Thilo Heinken; Annette Kolb; Christer Nilsson; Sharon Stanton; Kris Verheyen Journal: Ann Bot Date: 2012-02-16 Impact factor: 4.357