Distribution ranges and spring phenology explain late frost sensitivity in 170 woody plants from the Northern Hemisphere

• Published in: Global ecology and biogeography 2016-09, Vol.25 (9), p.1061-1071
• Main Authors: Muffler, Lena, Beierkuhnlein, Carl, Aas, Gregor, Jentsch, Anke, Schweiger, Andreas H., Zohner, Constantin, Kreyling, Juergen
• Format: Article
• Language: English
• Subjects: Assisted colonization; assisted migration; common garden experiment; distribution limit; extreme events; frost damage; leaf unfolding; leaf-out; spring freeze
• ISSN: 1466-822X; 1466-8238
• DOI: 10.1111/geb.12466

Aim: Cold events determine the distributional range limits of woody species. Despite global warming, the magnitude of late frost events in boreal and temperate regions is not expected to change. Hence, the risk for late spring frost damage of woody species may increase with an earlier onset of the growing season. Here, we investigated biogeographical, phenological and phylogenetic effects on late frost sensitivity. Location: Ecological-Botanical Gardens Bayreuth, Germany (49°55'45"N,11°35'10"E). Methods: We inspected 170 woody species in the Ecological-Botanical Gardens from across the entire Northern Hemisphere for frost damage after an extreme late frost event in May 2011 (air temperature —4.3°C after leaf unfolding of all species). Distribution range characteristics, climatic parameters of place of origin and phenological strategy were linked to sensitivity to the late frost event. Results: The northern distribution limit and the range in continentality across the distributional ranges correlated negatively with a taxor's late frost sensitivity (pseudo-R² = 0.42, pseudo-R² = 0.33, respectively). Sensitivity to the late frost event was well explained by the climatic conditions within species' native ranges (boosted regression trees; receiver operating characteristic 0.737). Average (1950–2000) May minimum temperature in species' native ranges was the main explanatory variable of late frost sensitivity (51.7% of explained variance). Phylogenetic relatedness explained additional variance in sensitivity to the late frost event Sensitivity to the late frost event further correlates well with species phenological strategy. Frosttolerant species flushed on average 2 weeks earlier than frost-sensitive species. Main conclusions: Range characteristics and the prevalent climatic parameters across species native ranges are strongly related to their susceptibility to late spring frost damage. Further, more late frost-sensitive species unfolded their leaves later than more tolerant species and late frost tolerance is phylogenetically conserved. Thus, late frost sensitivity may challenge natural and human-assisted migration of woody species under global warming.