TY - JOUR
T1 - Soil nematode assemblage responds weakly to grazer exclusion on a nutrient-rich seabird island
AU - Andriuzzi, Walter S.
AU - Keith, Aidan M.
AU - Bardgett, Richard D.
AU - van der Wal, René
N1 - We thank SNH for permission to conduct this research and invaluable logistical support, David Pickett and Mark Newell for their help on the Isle of May, Dan Wright for clarifications on the experimental design, Alex Douglas for statistical advice and two anonymous reviewers for helpful comments on the manuscript.
PY - 2013/9
Y1 - 2013/9
N2 - The effects of aboveground herbivores on plant-soil interactions are highly context dependent and a key underlying factor controlling this is thought to be nutrient availability. Here, we tested whether the effects of vertebrate grazing on the soil food web varied with nutrient availability and hypothesised that soil food web structure would be driven more by the exclusion of vertebrate grazers than by nutrient enrichment. An 8-year long grazer exclusion experiment was performed in grasslands on a small Scottish island near soil nutrient-enriching seabird colonies at the coast and in less fertile conditions inland. We investigated the trophic structure of the soil nematode assemblage as a proxy for soil food web structure. Across all eight study sites the bacterial energy channel was predominant over the fungal channel. Grazer exclusion strongly enhanced plant biomass accumulation and although this tended to be associated with a somewhat lower abundance of bacterial-feeders, this effect was non-significant and surprisingly weak given the observed changes aboveground. Indeed, plant species identity, diversity and dominance were, just as any other vegetation descriptor, weak predictors of nematode trophic structure. Instead, site specific conditions were important, despite the small island area and apparently homogenous sampling conditions.
AB - The effects of aboveground herbivores on plant-soil interactions are highly context dependent and a key underlying factor controlling this is thought to be nutrient availability. Here, we tested whether the effects of vertebrate grazing on the soil food web varied with nutrient availability and hypothesised that soil food web structure would be driven more by the exclusion of vertebrate grazers than by nutrient enrichment. An 8-year long grazer exclusion experiment was performed in grasslands on a small Scottish island near soil nutrient-enriching seabird colonies at the coast and in less fertile conditions inland. We investigated the trophic structure of the soil nematode assemblage as a proxy for soil food web structure. Across all eight study sites the bacterial energy channel was predominant over the fungal channel. Grazer exclusion strongly enhanced plant biomass accumulation and although this tended to be associated with a somewhat lower abundance of bacterial-feeders, this effect was non-significant and surprisingly weak given the observed changes aboveground. Indeed, plant species identity, diversity and dominance were, just as any other vegetation descriptor, weak predictors of nematode trophic structure. Instead, site specific conditions were important, despite the small island area and apparently homogenous sampling conditions.
KW - Aboveground-belowground interaction
KW - Exclosure
KW - Grazing
KW - Nematode feeding groups
KW - Soil food web
KW - Trophic structure
UR - http://www.scopus.com/inward/record.url?scp=84879772597&partnerID=8YFLogxK
U2 - 10.1016/j.ejsobi.2013.05.009
DO - 10.1016/j.ejsobi.2013.05.009
M3 - Article
AN - SCOPUS:84879772597
VL - 58
SP - 38
EP - 41
JO - European Journal of Soil Biology
JF - European Journal of Soil Biology
SN - 1164-5563
ER -