CR 60:175-186 (2014)  -  DOI: https://doi.org/10.3354/cr01237

ABSTRACT: Climate change is leading to increased temperatures globally, which may be especially pronounced in cold-temperate regions. During winter, this may cause changes to thermal insulation provided by snow cover to the ground and lead to altered soil and litter layer temperature regimes, affecting plant regeneration and species’ ranges through frost damage. I investigated the effects of changing snow cover and litter temperature regimes on post-winter seed germination of 3 cold-temperate tree species, using snow manipulation and passive warming approaches. Snow manipulation and passive warming led to modest but complex changes in litter layer temperature regimes and caused responses in post-winter seed germination, increasing or remaining constant depending on species and treatment. Despite the modest differences in snow cover and litter temperature among treatments, post-winter seed germination varied up to 3-fold. The results suggest that tree seeds may be susceptible to modest changes in winter conditions as expected in the intermediate term under climate change and may be affecting future forest regeneration and species composition. The mechanisms underlying the observed seed germination response are currently unknown, but possible hypotheses are presented. If confirmed, these mechanisms may be involved in the re-assembly of future species-habitat relationships and control of species’ biogeographic ranges.

KEY WORDS: Climate change · Eastern white cedar · Forest composition · Green ash · Regeneration · Sugar maple