, Volume 301, Issue 1-2, pp 65-76
Date: 03 Oct 2007

Shift in soil–plant nitrogen dynamics of an alpine–nival ecotone

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Abstract

We investigated the nitrogen (N) dynamics of an alpine–nival ecotone on Mt. Schrankogel, Tyrol, Austria, in relation to temperature. Natural abundance of 15N was used as a tool to elucidate differences in N cycling along an altitudinal transect ranging from 2,906 to 3,079 m, corresponding to a gradient in mean annual temperature of 2.4 °C. The amount of total soil N, of plant available N and soil C/N ratio decreased significantly with increasing altitude, whereas soil pH increased. Soil δ 15N decreased with increasing altitude from +2.2 to −2.1‰ and δ 15N of plant tissues (roots and leaves) decreased from −3.7 to −5.5‰. The large shift in soil δ 15N of 4.3‰ from the lowest to the highest site suggested substantial differences in N cycling in alpine and nival ecosystems in the alpine nival ecotone investigated. We concluded that N cycling at the alpine–nival ecotone is likely to be controlled by various factors: temperature, soil age and development, atmospheric N deposition and plant competition. Our results furthermore demonstrate that the alpine–nival ecotone may serve as a sensitive indicator of global change.

Responsible Editor: Euan James