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Cross-site comparison of herbivore impact on nitrogen availability in grasslands: the role of plant nitrogen concentration

Bakker, E.S. and Knops, J.M.H. and Milchunas, D.G. and Ritchie, M.E. and Olff, H. (2009) Cross-site comparison of herbivore impact on nitrogen availability in grasslands: the role of plant nitrogen concentration. Oikos, 118, 1613-1622. ISSN 0030-1299.

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Official URL: http://dx.doi.org/10.1111/j.1600-0706.2009.17199.x

Abstract

Herbivores may influence the nitrogen (N) recycling rates and consequently increase or decrease the productivity of grasslands. Plant N concentration emerged as a critical parameter to explain herbivore effects from several conceptual models, which predict that herbivores decrease soil N availability when plant N concentration is low whereas they increase it when plant N concentration is high (Hobbs 1996, Ritchie et al. 1998, Pastor et al. 2006). However, a broader cross-site comparison among published studies to test these predictions is hampered by the different methodologies used to measure soil N availability or a proxy thereof, and a lack of measurements of plant N concentration. Therefore it remains unclear whether these model predictions are generally valid across a range of grasslands. We tested whether there is a relationship between plant N concentration and herbivore impact on soil N availability (measured with resin bags) with a study of replicate 6–8 year old exclosures (with an unfenced control) of vertebrate herbivores (>1 kg) established at each of seven grassland sites in North America and Europe. Contrary to model predictions, we found a negative relationship between the effect of herbivores on resin bag soil N availability and plant N concentration. Our study confir

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:6192
Deposited On:23 Mar 2010 01:00
Last Modified:24 Apr 2012 16:45

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