Snow cover manipulations and passive warming affect post-winter seed germination: a case study of three cold-temperate tree species

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 Resale or republication not permitted without written consent of the publisher Editorial responsibility: Tim Sparks,

Seedling responses to decreased snow depend on canopy composition and small‐mammal herbivore presence

“…Understanding links between winter conditions and summer seedling performance could improve our ability to predict conditions that cause herbivores to limit plant establishment (Patankar et al 2013), helping to resolve the considerable variation often observed in plant-herbivore interactions (Agrawal 2011). While shallow snow and winter herbivory can be important causes of plant mortality (Howe and Brown 2000, Schaberg et al 2008, Martin and Maron 2012, Drescher and Thomas 2013, Drescher 2014, the potential for variation in winter climates to influence herbivory of surviving individuals is less understood (Connolly et al 2017). Here, we show that winter herbivory and variable winter soil temperatures may delay A. saccharum seedling leaf-out, and suggest that seedlings that survive harsh winter conditions could alter herbivory in the growing season.…”

Effects of climate warming and prolonged snow cover on phenology of the early life history stages of four alpine herbs on the southeastern Tibetan Plateau

“…In high latitude and alpine regions, changes in spatial distribution and amount of snow in winter are the most important landscape mesoscale variables controlling biological systems (Walker et al., ; Drescher, ). Thus, they will play a significant role in shifting temperature, water, and light conditions for seed germination and postgermination plant performance in spring.…”

“…Blumenthal et al. () reported that artificially increasing snow cover exacerbated invasion of exotic forbs in a mixed grass prairie; Galen and Stanton () argued that the delay in snowmelt and its effects on environmental cues for seed germination are more important than the length of total growing season; and Drescher and Thomas () and Drescher () found that sapling survival increased with increasing snow cover and that modest differences in snow cover and litter temperature could lead to big variation in postwinter seed germination. However, there are lots of unanswered questions.…”

Assessing tree germination resilience to global warming: a manipulative experiment using sugar maple (Acer saccharum)

“…Another concern with earlier snow melt is the potential for increased freeze-thaw events; which can expose seeds and seedlings to abrupt changes in colder temperatures that will increase early germinant mortality (Decker et al, 2003). Freeze-thaw events as a result of earlier springs have already been documented to severely impact other important processes, such as bud break, flower development and seed ripening, all of which could further reduce reproductive success (Chuine and Beaubien, 2001;Morin et al, 2008;Drescher, 2014).…”