Long-term effects of snowmelt timing and climate warming on phenology, growth, and reproductive effort of Arctic tundra plant species

Esther R Frei,Gregory H.R Henry

doi:10.1139/as-2021-0028

Abstract

Arctic regions are particularly affected by rapidly rising temperatures and altered snow regimes. Snowmelt timing depends on spring temperatures and winter snow accumulation. Scenarios for the Arctic include both decreases and increases in snow accumulation. Predictions of future snowmelt timing are, thus, difficult and experimental evidence for ecological consequences is scarce. In 1995, a long-term factorial experiment was set up in a High Arctic evergreen shrub heath community on Ellesmere Island, Canada. We investigated how snow removal, snow addition, and passive warming affected phenology, growth and reproductive effort of the four common tundra plant species Cassiope tetragona (L.) D. Don, Dryas integrifolia Vahl, Luzula arctica Blytt, and Papaver radicatum Rottb. Timing of flowering and seed maturation as well as flower production were more strongly influenced by the combined effects of snowmelt timing and warming in the two shrub species than in the two herbaceous species. Warming effects persisted over the course of the growing season and resulted in increased shrub growth. Moreover, the long-term trend of increasing growth in two species suggests that ambient warming promotes tundra plant growth. Our results confirm the importance of complex interactions between temperature and snowmelt timing in driving species-specific plant responses to climate change in the Arctic.

Highlights

Snow is a characteristic seasonal feature of the Arctic land surface that influences the energy balance and the availability of resources such as water, light and nutrients essential for plant life, soil communities, and terrestrial animals (Callaghan et al 2011)
Snowmelt is considered to be the start of the growing season in tundra ecosystems, and the timing depends on both spring temperatures and the accumulation of snow during winter and its distribution, which is affected by factors such as wind and topography (Bjorkman et al 2015, Bokhorst et al 2016)
Growth and reproductive effort of two shrub and two herbaceous plant species in response to 21 years of experimental warming, snow removal and snow addition

Summary

Introduction

Snow is a characteristic seasonal feature of the Arctic land surface that influences the energy balance and the availability of resources such as water, light and nutrients essential for plant life, soil communities, and terrestrial animals (Callaghan et al 2011). Snowmelt is considered to be the start of the growing season in tundra ecosystems, and the timing depends on both spring temperatures and the accumulation of snow during winter and its distribution, which is affected by factors such as wind and topography (Bjorkman et al 2015, Bokhorst et al 2016). There is evidence that warming leads to a trend towards a later start of the snow season in many regions of the Arctic (Brown et al 2017) and in some regions to earlier snowmelt in spring (Derksen and Brown 2012, Hernández-Henríquez et al 2015). Arctic regions experienced up to three times greater warming and climate projections predict further substantial annual and winter warming for the region (IPCC 2018, Meredith et al 2019, AMAP 2021)

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