Snow cover consistently affects growth and reproduction of Empetrum hermaphroditum across latitudinal and local climatic gradients

Changing seasonality of panarctic tundra vegetation in relationship to climatic variables

“…Weekly trends statistically significant at the 95% level or greater are marked with an asterisk on the x-axis. Temperature is in units of°C and trend is°C over time period of panel Torp 2010, Callaghan et al 2012, Bienau et al 2014, Bjerke et al 2014, Bjorkman et al 2015…”

Quantifying snow controls on vegetation greenness

“…Additionally, responses of vegetation growth to temperature gradients have been observed across multiple Arctic sites using standardized plots, where the different latitude and climate zones of each site act as surrogates for a gradient in temperature and snow conditions (Bienau et al. , Myers‐Smith et al. ).…”

“…For example, since winter precipitation is a key driver of Arctic vegetation phenology (e.g., Cooper 2014), the investigation of vegetation phenology and biomass responses can be conducted at a plot-scale and along experimental winter-precipitation gradients using snow fences (e.g., Leffler andWelker 2013, Semenchuk et al 2013). Additionally, responses of vegetation growth to temperature gradients have been observed across multiple Arctic sites using standardized plots, where the different latitude and climate zones of each site act as surrogates for a gradient in temperature and snow conditions (Bienau et al 2014, Myers-Smith et al 2015. Such plot-based studies are often used in space-for-time substitution approaches, where vegetation differences along environmental gradients are assumed to represent conditions in the past or future .…”

Clonality increases with snow depth in the arctic dwarf shrub Empetrum hermaphroditum

“…Two clonal growth forms can be distinguished; the guerilla form has longer internodes and more widely spaced ramets, which can infiltrate the surrounding vegetation, and the phalanx form has tightly packed ramets, which exclude other plants from their growing space (Doust, 1981). The growth habit of Empetrum varies between different habitats, with a more guerilla‐like growth on sites with intermediate and deep snow cover and a more phalanx‐like growth on sites with shallow snow cover (Bienau et al, 2014). Furthermore, we observed more berries per Empetrum shoot, which likely leads to higher local seed rain in the shallow snow cover habitat than in habitats with deep snow cover (Bienau et al, 2014).…”

“…The growth habit of Empetrum varies between different habitats, with a more guerilla‐like growth on sites with intermediate and deep snow cover and a more phalanx‐like growth on sites with shallow snow cover (Bienau et al, 2014). Furthermore, we observed more berries per Empetrum shoot, which likely leads to higher local seed rain in the shallow snow cover habitat than in habitats with deep snow cover (Bienau et al, 2014). The higher seed production might be an effect of the open habitat, where germination of Empetrum seeds might be promoted by soil disturbance (Graae et al, 2011), less competition from surrounding vegetation (Szmidt et al, 2002), and an earlier start of the growing season (Körner, 2003).…”