TY - JOUR

T1 - Grazing effects on microbial community composition, growth and nutrient cycling in salt marsh and sand dune grasslands

AU - Ford, Hilary

AU - Rousk, Johannes

AU - Garbutt, Angus

AU - Jones, Laurence

AU - Jones, Davey L.

PY - 2013/1/1

Y1 - 2013/1/1

N2 - The effect of grazing by large herbivores on themicrobial community and the ecosystem functions theyprovide are relatively unknown in grassland systems. In thisstudy, the impact of grazing upon the size, composition andactivity of the soil microbial community was measured infield experiments in two coastal ecosystems: one salt marshand one sand dune grassland. Bacterial, fungal and totalmicrobial biomass were not systematically affected by grazingacross ecosystems, although, within an ecosystem, differencescould be detected. Fungal-to-bacterial ratio did notdiffer with grazing for either habitat. Redundancy analysisshowed that soil moisture, bulk density and root biomasssignificantly explained the composition of phospholipid fattyacid (PLFA) markers, dominated by the distinction betweenthe two grassland habitats, but where the grazing effect couldalso be resolved. PLFA markers for Gram-positive bacteriawere more proportionally abundant in un-grazed, and markersfor Gram-negative bacteria in grazed grasslands. Bacterialgrowth rate (leucine incorporation) was highest in un-grazedsalt marsh but did not vary with grazing intensity in the sanddune grassland. We conclude that grazing consistently affectsthe composition of the soil microbial community in seminaturalgrasslands but that its influence is small (7 % of thetotal variation in PLFA composition), compared with differencesbetween grassland types (89 %). The relatively smalleffect of grazing translated to small effects on measurementsof soil microbial functions, including N and C mineralisation.This study is an early step toward assessing consequences ofland-use change for global nutrient cycles driven by themicrobial community.

AB - The effect of grazing by large herbivores on themicrobial community and the ecosystem functions theyprovide are relatively unknown in grassland systems. In thisstudy, the impact of grazing upon the size, composition andactivity of the soil microbial community was measured infield experiments in two coastal ecosystems: one salt marshand one sand dune grassland. Bacterial, fungal and totalmicrobial biomass were not systematically affected by grazingacross ecosystems, although, within an ecosystem, differencescould be detected. Fungal-to-bacterial ratio did notdiffer with grazing for either habitat. Redundancy analysisshowed that soil moisture, bulk density and root biomasssignificantly explained the composition of phospholipid fattyacid (PLFA) markers, dominated by the distinction betweenthe two grassland habitats, but where the grazing effect couldalso be resolved. PLFA markers for Gram-positive bacteriawere more proportionally abundant in un-grazed, and markersfor Gram-negative bacteria in grazed grasslands. Bacterialgrowth rate (leucine incorporation) was highest in un-grazedsalt marsh but did not vary with grazing intensity in the sanddune grassland. We conclude that grazing consistently affectsthe composition of the soil microbial community in seminaturalgrasslands but that its influence is small (7 % of thetotal variation in PLFA composition), compared with differencesbetween grassland types (89 %). The relatively smalleffect of grazing translated to small effects on measurementsof soil microbial functions, including N and C mineralisation.This study is an early step toward assessing consequences ofland-use change for global nutrient cycles driven by themicrobial community.

U2 - 10.1007/s00374-012-0721-2

DO - 10.1007/s00374-012-0721-2

M3 - Article

VL - 49

SP - 89

EP - 98

JO - Biology and Fertility of Soils

JF - Biology and Fertility of Soils

SN - 0178-2762

IS - 1

ER -