Importance of Marine-Derived Nutrients Supplied by Planktivorous Seabirds to High Arctic Tundra Plant Communities.

Adrian Zwolicki,Katarzyna Zmudczyńska-Skarbek,Lech Stempniewicz,Pierre Richard,Andy J Green

doi:10.1371/journal.pone.0154950

Abstract

We studied the relative importance of several environmental factors for tundra plant communities in five locations across Svalbard (High Arctic) that differed in geographical location, oceanographic and climatic influence, and soil characteristics. The amount of marine-derived nitrogen in the soil supplied by seabirds was locally the most important of the studied environmental factors influencing the tundra plant community. We found a strong positive correlation between δ15N isotopic values and total N content in the soil, confirming the fundamental role of marine-derived matter to the generally nutrient-poor Arctic tundra ecosystem. We also recorded a strong correlation between the δ15N values of soil and of the tissues of vascular plants and mosses, but not of lichens. The relationship between soil δ15N values and vascular plant cover was linear. In the case of mosses, the percentage ground cover reached maximum around a soil δ 15N value of 8‰, as did plant community diversity. This soil δ15N value clearly separated the occurrence of plants with low nitrogen tolerance (e.g. Salix polaris) from those predominating on high N content soils (e.g. Cerastium arcticum, Poa alpina). Large colonies of planktivorous little auks have a great influence on Arctic tundra vegetation, either through enhancing plant abundance or in shaping plant community composition at a local scale.

Highlights

Polar terrestrial ecosystems are distinctive, as they develop and function under very harsh conditions [1]
One of the most important general features of polar terrestrial ecosystems is their chronically low nutrient availability to plants, through the poor quality of the soil which spends much of the year frozen [34]
This study presents direct evidence of a strong relation between the proportion of nitrogen stable isotopes in soil and the level of seabird guano deposition, and confirms previous studies proposing that δ15N signature is a reliable measure of maritime nitrogen supply by seabirds [36,37,38,39,40]

Summary

Introduction

Polar terrestrial ecosystems are distinctive, as they develop and function under very harsh conditions [1]. Among the main recognized ecological factors affecting the development and dynamics of terrestrial vegetation in polar regions are: air temperature [2,3], soil moisture [4,5], soil pH [5], nutrient availability [6], snow cover [7], proglacial chronosequences [8], dispersal limitations [9] and natural disturbances [4]. These factors are modulated at the macroclimatic scale, e.g. resulting from geographical separation, as well as by microclimatic features.

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Conclusion