TABLE CONTENTS

SESSION TWO – ECOLOGY AND BIODIVERSITY OF SOIL
NEMATODES IN SUSTAINABLE SOIL CONSERVATION
CONVENORS: GREGOR YEATES & NIGEL BELL
Nematode Assemblages and Soil Properties Are Closely Linked
Sánchez-Moreno, S. (1) & H. Ferris (2)
(1) Departamento de Protección Vegetal, Instituto Nacional de Investigación y Tecnología Agraria y
Alimentaria, Madrid, Spain 28040; (2) Department of Nematology, University of California Davis, CA, USA
95616.
Nematode faunal composition is closely linked to the soil chemical and physical properties
that define the microenvironments in which nematodes interact with each other and with
other organisms. Nematodes play relevant functions in the soil food web, in which keystone
species and interaction forces have a dominant role determining system stability. Nematode
species and their interactions respond to environmental drivers, and such relationships result
in reciprocal causal associations in which nematodes affect and reflect soil properties.
Relationships between nematodes and soil properties depend on soil management and scale
of observation, both of which affect the interpretation of these relationships. Thus, it may be
difficult to extract general patterns between nematode assemblages and soil properties, and
such associations must be evaluated through case-specific inferences.
At a microcosm level, soil texture, soil nitrogen, microbial organic carbon, microbial
diversity, bulk density and the presence of food sources and natural enemies play roles in
determining nematode assemblage composition. For example, abundance of many bacterial
feeders, such as Acrobeloides and Mesorhabditis, are often correlated with soil N measures,
and some nematode species may be used as enrichment indicators. Other soil properties, such
as soil texture, may be a limiting factor in fitness of plant-feeding nematodes like
Meloidogyne. On the other hand, nematodes affect plant and microbial growth, carbon
allocation in the rhizosphere, microbial diversity, organic matter decomposition and nitrogen
mineralization. While some relationships appear at diverse scales, other common findings
may reflect spurious correlations due to common spatial patterns in distribution variables.
At landscape level, longitude, elevation, temperature, pH, vegetation and land use may
determine the composition of nematode assemblages. Introducing computational tools as GIS
or geostatistical analysis into data analysis may help improve our understanding of nematode
ecological relationships.
5 th International Congress of Nematology, 2008 3