Callaham, M. A., Butt, K. R. and Lowe, C. N.
Stable isotope evidence for marine-derived avian inputs of nitrogen into soil, vegetation, and earthworms on the isle of Rum, Scotland, UK.
European Journal of Soil Biology, 52
Official URL: http://dx.doi.org/10.1016/j.ejsobi.2012.07.004
The largest breeding colony of Manx shearwaters (Puffinus puffinus) in the world is found on the Isle of Rum in the inner Hebrides of Scotland. We collected a feather, guano, soil, vegetation, and earthworms near shearwater burrows to determine whether inputs of nitrogen (N) from guano were incorporated into belowground foodwebs. For comparison, similar samples were collected from a nearby plot that was experimentally fertilised 40 years prior. The shearwater feather had the highest level of 15N enrichment (+18‰), followed by guano (+12‰). Soil (+7.5‰) and vegetation (+5.7‰) collected at the burrow entrance were enriched with 15N relative to those collected at 2 m or more away (+0.5 to +3.1‰ for soil, and −2.5 to −4.6‰ for vegetation). In contrast, soil inside the fertilised plot had δ15N ≈ 0, but was enriched with 15N away from the plot edge. Earthworms collected from shearwater greens had enriched 15N signatures relative to earthworms from the fertilised plot (+3.8 and −0.9‰, respectively). Our data suggest that available N is tightly cycled in vegetation and soil for decades, and that shearwater derived N is substantially assimilated by earthworms. Therefore, because earthworms do not occur outside areas of shearwater influence, the birds should be viewed as ecosystem engineers of soil invertebrate foodwebs on Rum.
|Uncontrolled Keywords (separate with ;):|| Guano;
|Subjects:||Q Science > QL Zoology|
|Schools:||School of Built & Natural Environment|
Kevin Richard Butt
|Deposited On:||05 Sep 2012 14:41|
|Last Modified:||06 Mar 2013 17:01|
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