IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Absence of large soil predators lead to a decline of lower trophic levels and slower decomposition in temperate beech forests of northwest Spain
Autor/es:
MELGUIZO-RUIZ, N.; JIMÉNEZ, G.; DE MAS, E.; SCHEU, S.; WISE, D.H.; AUSTIN, A.T.; MOYA-LARAÑO, J.
Lugar:
Dijon
Reunión:
Congreso; Global Soil Biodiversity Congress; 2014
Institución organizadora:
Global Soil Biodiversity Initiative
Resumen:
Soil food webs are the result of complex interactions with variable controls from different trophic levels, which often has consequences for ecosystem processes. Bottom-up control occurs when higher productivity from lower trophic levels affects the density and biomass of top predators, whereas top-down control arises when generalist predators indirectly affect carbon and nutrient turnover through their impact on prey abundance. This study focused on the potential of top predators to structure the soil food web and leaf-litter decomposition in eight temperate beech forests sites of varying rainfall (1000-1500 mm) in northwest Spain. We tested if changes in the density of large predators affect prey density of different trophic levels, potentially cascading down to decomposition rates. We conducted a field experiment where we manipulated the presence of top-predators by removing or adding large arthropod predators in experimental plots, with simultaneous evaluation of leaf litter decomposition. After one year, predator removal had a surprisingly negative effect on the total abundance of soil fauna, particularly fungivore abundance, suggesting that the overexploitation of resources due to reduced predation, as well as the reduction of intermediate predators may have caused a strong decline in these prey populations. Springtails were significantly larger in predator removal plots, suggesting either a plastic response mediated by a growth-reproduction trade-off or that larger springtail species were favoured in the absence of predators. Finally, we found a significant reduction in litter decomposition with predator removal, which is consistent with the result that predator removal decreased fungivore populations and thus slowed decomposition rates and nutrient turnover. There was no interaction with site precipitation, suggesting that the effects of predators were similar and independent of rainfall. This study suggests a strong top-down control on the structure of the soil faunal community with important consequences for carbon and nutrient turnover in these forest ecosystems.