Carbon and water relations of contrasting Arctic plants: implications for shrub expansion in West Greenland

The recent expansion of deciduous shrubs is a common observation throughout the Arctic. However, we lack a complete understanding of how physiological differences between deciduous shrubs and coexisting species may confer competitive advantages to shrubs. We combined leaf gas exchange and stable iso...

Full description

Saved in:
Bibliographic Details
Published in:Ecosphere (Washington, D.C) D.C), 2016-04, Vol.7 (4), p.n/a
Main Authors: Cahoon, Sean M. P., Sullivan, Patrick F., Post, Eric, Peters, D. P. C.
Format: Article
Language:English
Subjects:
13C
18O
Arctic
Betula nana
Canopies
Carbon
Drought
dual isotope model
Gas exchange
Photosynthesis
Physiology
Poa pratensis
Polar environments
Precipitation
Researchers
Seasons
Sensitivity
Shrubs
Soils
Stable isotopes
Terrestrial ecosystems
Vegetation
Water relations
water stress
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The recent expansion of deciduous shrubs is a common observation throughout the Arctic. However, we lack a complete understanding of how physiological differences between deciduous shrubs and coexisting species may confer competitive advantages to shrubs. We combined leaf gas exchange and stable isotope analyses of two important species, Betula nana and Poa pratensis, to elucidate the processes governing seasonal carbon (C) gain in West Greenland. We tested two competing hypotheses. On one hand, we anticipated the cooler, drier soils beneath the Betula canopy could result in greater drought sensitivity in this species. Alternatively, because Poa tends to occupy sites with wetter soils, we hypothesized that it may be more sensitive to drought. Our results revealed greater drought sensitivity in Poa, which displayed reductions in Amax and gs during periods of high atmospheric demand and dry soils. Additionally, leaf Δ13C and Δ18O were negatively correlated in Poa, suggesting strong stomatal influence on Δ13C. Conversely, there was no relationship between gs and canopy or soil microclimates and no correlation between leaf Δ13C and Δ18O in Betula, indicating that variation in Δ13C may have been driven by variation in photosynthesis. Our results suggest that Poa is more susceptible to drought than Betula, whereas Betula was able to maintain steady, yet conservative, C gain. These differences in C‐H2O relations may confer a competitive advantage to Betula in a warmer, drier climate.
ISSN:2150-8925
2150-8925
DOI:10.1002/ecs2.1245