Title: Impacts of Arctic Shrubs on Root Traits and Belowground Nutrient Cycles Across a Northern Alaskan Climate Gradient

Abstract

Deciduous shrubs are expanding across the graminoid-dominated nutrient-poor arctic tundra. Absorptive root traits of shrubs are key determinants of nutrient acquisition strategy from tundra soils, but the variations of shrub root traits within and among common shrub genera across the arctic climatic gradient are not well resolved. Consequently, the impacts of arctic shrub expansion on belowground nutrient cycling remain largely unclear. Here, we collected roots from 170 plots of three commonly distributed shrub genera ( Alnus , Betula , and Salix ) and a widespread sedge ( Eriophorum vaginatum ) along a climatic gradient in northern Alaska. Absorptive root traits that are relevant to the strategy of plant nutrient acquisition were determined. The influence of aboveground dominant vegetation cover on the standing root biomass, root productivity, vertical rooting profile, as well as the soil nitrogen (N) pool in the active soil layer was examined. We found consistent root trait variation among arctic plant genera along the sampling transect. Alnus and Betula had relatively thicker and less branched, but more frequently ectomycorrhizal colonized absorptive roots than Salix , suggesting complementarity between root efficiency and ectomycorrhizal dependence among the co-existing shrubs. Shrub-dominated plots tended to have more productive absorptive roots than sedge-dominatedmore » plots. At the northern sites, deep absorptive roots (>20 cm depth) were more frequent in birch-dominated plots. We also found shrub roots extensively proliferated into the adjacent sedge-dominated plots. The soil N pool in the active layer generally decreased from south to north but did not vary among plots dominated by different shrub or sedge genera. Our results reveal diverse nutrient acquisition strategies and belowground impacts among different arctic shrubs, suggesting that further identifying the specific shrub genera in the tundra landscape will ultimately provide better predictions of belowground dynamics across the changing arctic.« less

Authors:

Chen, Weile; Tape, Ken D.; Euskirchen, Eugénie S.; Liang, Shuang; Matos, Adriano; Greenberg, Jonathan; Fraterrigo, Jennifer M.

Publication Date:

Fri Dec 11 00:00:00 EST 2020

Research Org.:

Univ. of Illinois at Urbana-Champaign, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1734953

Alternate Identifier(s):

OSTI ID: 1852127

Grant/Contract Number:  

SC0016219

Resource Type:

Published Article

Journal Name:

Frontiers in Plant Science

Additional Journal Information:

Journal Name: Frontiers in Plant Science Journal Volume: 11; Journal ID: ISSN 1664-462X

Publisher:

Frontiers Media SA

Country of Publication:

Switzerland

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; plant sciences; arctic shrub expansion; ectomycorrhizal fungi; plant-soil interactions; rooting depth; root economics spectrum; trait-based approach; soil nitrogen