Soil ecosystem services depend on water regulation both to retain soil moisture and to eliminate water excess without harmful loss of particles and nutrients. As such the combination of soil physical properties that support soil hydrological functioning is a well-recognized service delivered by soil. There is widespread recognition of soil biodiversity and biological activities that are needed to sustain soil structural properties. The detrimental consequences of a weakened functionality have been stressed in the EU Soil Strategy and hydrology in particular is related to all soil threats. Biopores and soil aggregate formation have been shown to be crucial results of soil macroorganism activities contributing to soil hydrology. In collaboration between the French “Observatoire de Recherche en Environnement – Agro-écosystèmes, Cycles Biogéochimiques et Biodiversité” (ORE-ACBB) and the FP7 EU project EcoFINDERS we investigated the relationsship between earthworm biodiversity, macropores and three agricultural landuse types. A field campaign was conducted in October-November 2011. Earthworm burrow distribution was quantified at 10, 20, 30, 50 and 100 20 cm horizontal layer intervals down the soil profile to 1 meter depth and correlated with the earthworm community consisting of 12 species dominated by the endogeics Aporrectodea caliginosa and Aporrectodea chlorotica and the anecics Aporrectodea longa and Lumbricus centralis. Medium-small macropores in the ploughing layer with diameters (Ø) less than 5 mm were significantly more abundant in permanent grassland compared to conventional rotation system with annual crops. An intermediate system with 3 year grass and 3 years with annuals was also intermediate between the two other systems. At 30 cm's depth we found no large macropores, Ø >7 mm, in the system with annuals, but increasingly more in rotations with grass. Addition of frequencies of macropores with Ø>7 mm retains the significant difference between annual and the permanent grass system. Moreover, all the large burrows, >5 mm Ø, follow this pattern and are significantly more numerous in permanent grass to annuals (P<3%). At depth 100 cm total number of macropores were more abundant in the annual crops compared with permanent grass (P=5%), due to a larger number of macropores <7 mm. We present an interpretation of the macropore patterns in relation to the anecic and endogeic lifeforms and their established role in creating burrows of different spatial distribution and density.
Main Research Area:
XVI International Colloquium on Soil Zoology and Biology, 2012