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

TY - JOUR

T1 - Cross-site comparison of herbivore impact on nitrogen availability in grasslands: the role of plant nitrogen concentration

AU - Bakker, E.S.

AU - Knops, J.M.H.

AU - Milchunas, D.G.

AU - Ritchie, M.E.

AU - Olff, H.

N1 - Reporting year: 2009 Metis note: 4561;CL; PDI ; AqE; file:///L:/Endnotedatabases/NIOOPUB/pdfs/PDFS2009\Bakker_ea_4561.pdf

PY - 2009

Y1 - 2009

N2 - 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

AB - 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

U2 - 10.1111/j.1600-0706.2009.17199.x

DO - 10.1111/j.1600-0706.2009.17199.x

M3 - Article

SN - 0030-1299

VL - 118

SP - 1613

EP - 1622

JO - Oikos

JF - Oikos

IS - 11

ER -