Water uptake of Alaskan tundra evergreens during the winter–spring transition

Abstract

Evergreen tundra plants take up water under snow cover, some via roots, but also likely by foliar uptake. The ability to take up water in the subnivean environment allows evergreen tundra plants to take advantage of mild spring conditions under the snow and replenish carbon lost by winter respiration.

Long‐term deepened snow promotes tundra evergreen shrub growth and summertime ecosystem net CO2 gain but reduces soil carbon and nutrient pools

“…Evergreen shrubs are particularly well adapted to the stresses of low‐nutrient tundra environments (Aerts & Chapin, ), while deciduous shrubs generally are more abundant in relatively fertile soils, and certainly rise to dominance in response to persistent high‐level nutrient additions (Chapin et al., ). However, unlike deciduous shrubs, evergreens can photosynthesize under snow (Starr & Oberbauer, ) and can take up and store available soil nutrients and water during the winter‐spring transition when soils are just starting to thaw (Larsen, Michelsen, Jonasson, Beier, & Grogan, ; Mckane et al., ; Moser et al., ). Therefore, evergreens should theoretically be favored when climate‐warming leads to increases in spring soil nutrient pools, even if complete snowmelt is delayed by ~1 week.…”

“…Year (Chapin et al, 1995). However, unlike deciduous shrubs, evergreens can photosynthesize under snow (Starr & Oberbauer, 2003) and can take up and store available soil nutrients and water during the winter-spring transition when soils are just starting to thaw (Larsen, Michelsen, Jonasson, Beier, & Grogan, 2012;Mckane et al, 2002;Moser et al, 2016). Therefore, evergreens should theoretically be favored when climate-warming leads to increases in spring soil nutrient pools, even if complete snowmelt is delayed by~1 week.…”

Insight into the physiological role of water absorption via the leaf surface from a rehydration kinetics perspective

“…Such dynamics have been studied by supplying water to intact leaves via the petiole (e.g., Boyer, ; Brodribb & Holbrook, ; Scoffoni, Pou, Aasamaa, & Sack, ; Trifilò et al, ) assuming that rehydration occurs entirely from soil recharge. However, several species, spanning rainforest to desert biomes, are known to absorb atmospheric water via their leaf surfaces (Burgess & Dawson, ; Martin & von Willert, ; Moser et al, ; Yates & Hutley, ). Thus, it is interesting to ask if the absorption of water by the leaf surface can significantly contribute to overall plant water status and, if so, whether it has biological relevance at the plant and ecosystem levels (Rundel, ; Stone, ).…”

Shortened duration and reduced area of frozen soil in the Northern Hemisphere

“…14 In addition, the changes in the transitional state that occur between predominantly frozen and thawed states have rarely been investigated despite their ecological significance. 15 Soil freeze-thaw processes are sensitive to the ambient environment, and the near-surface air temperature (T a ), snow cover, and surface soil moisture (SM) have proven to be the main factors controlling changes in FTCs. 12 Numerous investigations have found that an increasing T a is responsible for reductions in soil freezing timing, 14 duration, 16 and depth.…”

“… 14 In addition, the changes in the transitional state that occur between predominantly frozen and thawed states have rarely been investigated despite their ecological significance. 15 …”