unseen iceberg: plant roots in arctic tundra

• Published in: The New phytologist 2015-01, Vol.205 (1), p.34-58
• Main Authors: Iversen, Colleen M, Sloan, Victoria L, Sullivan, Patrick F, Euskirchen, Eugenie S, McGuire, A. David, Norby, Richard J, Walker, Anthony P, Warren, Jeffrey M, Wullschleger, Stan D
• Format: Article
• Language: English
• Subjects: aboveground biomass; arctic; Arctic Regions; Atmosphere; Biomass; Biosphere; Carbon; Climate change; Climatic conditions; climatic factors; Distribution; Dynamics; Ecosystem models; Ecosystems; Environment models; Environmental changes; Environmental conditions; ENVIRONMENTAL SCIENCES; fine roots; Fluxes; GEOSCIENCES; Ice Cover; Icebergs; Marine ecosystems; Mineral nutrients; Model testing; Models, Biological; mortality; Nutrient dynamics; organic horizons; Organic soils; Permafrost; Plant biomass; Plant roots; Plant Roots - physiology; Plant species; Plants; plant–soil; Polar environments; Representations; Resource partitioning; root biomass; root production; root turnover; Roots; Soil; Soil ecology; Soil horizons; Soil layers; Soils; Species; Taiga & tundra; Tansley reviews; Terrestrial ecosystems; Terrestrial environments; thawing; Tundra; Tundra soils; Tundras
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.13003

CONTENTS: 34 I. 35 II. 35 III. 41 IV. 43 V. 49 VI. 50 VII. 51 VIII. 52 53 References 53 SUMMARY: Plant roots play a critical role in ecosystem function in arctic tundra, but root dynamics in these ecosystems are poorly understood. To address this knowledge gap, we synthesized available literature on tundra roots, including their distribution, dynamics and contribution to ecosystem carbon and nutrient fluxes, and highlighted key aspects of their representation in terrestrial biosphere models. Across all tundra ecosystems, belowground plant biomass exceeded aboveground biomass, with the exception of polar desert tundra. Roots were shallowly distributed in the thin layer of soil that thaws annually, and were often found in surface organic soil horizons. Root traits – including distribution, chemistry, anatomy and resource partitioning – play an important role in controlling plant species competition, and therefore ecosystem carbon and nutrient fluxes, under changing climatic conditions, but have only been quantified for a small fraction of tundra plants. Further, the annual production and mortality of fine roots are key components of ecosystem processes in tundra, but extant data are sparse. Tundra root traits and dynamics should be the focus of future research efforts. Better representation of the dynamics and characteristics of tundra roots will improve the utility of models for the evaluation of the responses of tundra ecosystems to changing environmental conditions.