V. Nuutinen et al., SPATIAL VARIATION OF AN EARTHWORM COMMUNITY RELATED TO SOIL PROPERTIES AND YIELD IN A GRASS-CLOVER FIELD, Agriculture, ecosystems & environment. Applied soil ecology, 8(1-3), 1998, pp. 85-94
Spatial variation in abundance of earthworms, soil properties and herb
age yield were surveyed on a 1.4 ha grass-clover field. Sampling and m
easurements were made in a regular grid (25 m x 25 m) of 32 sampling s
ites during the first and second years after the establishment of the
ley. Five earthworm species were present in the field. The total abund
ance and biomass of earthworms varied from zero to 218 individuals and
18 g dry-weight per m(2). The soil properties and herbage mass also v
aried widely. The majority of variables showed discernible spatial dep
endence in the first separation distance between the sampling sites. I
t was usually difficult to model the spatial continuity satisfactorily
, because much of the small scale variation was evidently not captured
by the sample spacing. Soil clay percentage displayed a particularly
clear and continuous spatial gradient. The distributions of Lumbricus
terrestris and Dendrodrilus rubidus were distinctly aggregated. For L.
terrestris there was some evidence for association with silty soil, w
hile D. rubidus was found only in the area with the lowest clay conten
t. An alternative explanation for the uneven distribution of the two s
pecies is the recently started dispersal into the ley. Non-parametric
correlation suggested a positive relationships between earthworm activ
ity and both infiltration of water and clover production. When geograp
hical distance between sampling sites was controlled for in the analys
es, these correlations were not statistically discernible, but a posit
ive relationship between total numbers of earthworms and soluble soil
phosphorus content emerged. (C) 1998 Elsevier Science B.V. All rights
reserved.