Relating species density to environmental variables in presence of spatial autocorrelation: a study case on soil nematodes distribution

The relationships between soil nematodes and soil texture, carbon content and depth were assessed in both a cultivated and uncultivated plots. Simple correlation coefficient analyses indicated a negative linear correlation between the plant-parasitic species Helicotylenchus retnsus Siddiqui and Brown and soil clay content in the uncultivated site. However, Mantel Lests showed this correlation to be spurious and only due to the presence of a common spatial pattern in the variables distribution. Both H. retusus density and soil clay content appeared to be independently driven by a common, unknown cause. The use of suitable statistical methods to analyse spatially dependent variables proved to be particularly fruitful in that they prevent spurious correlations and allow us to test different causal models involving the set of variables at hand.

[1]  F. James Rohlf,et al.  Biometry: The Principles and Practice of Statistics in Biological Research , 1969 .

[2]  R. Sokal,et al.  Spatial autocorrelation in biology: 1. Methodology , 1978 .

[3]  G. Robertson.  The impact of soil and crop management practices on soil spatial heterogeneity , 1994 .

[4]  H. Ferris,et al.  Stability and characteristics of spatial description parameters for nematode populations. , 1990, Journal of nematology.

[5]  D. Freckman.  Bacterivorous nematodes and organic matter decomposition , 1988 .

[6]  J. Chotte,et al.  Distribution of nematodes in vertisol aggregates under a permanent pasture in Martinique , 1996 .

[7]  A. F. Robinson,et al.  Meloidogyne incognita and Rotylenchulus reniformis and Associated Soil Textures from Some Cotton Production Areas of Texas. , 1993, Journal of nematology.

[8]  J. Goodey.  Laboratory methods for work with plant and soil nematodes. , 1949 .

[9]  P. Legendre.  Spatial Autocorrelation: Trouble or New Paradigm? , 1993 .

[10]  G. Yeates.  Soil nematodes in terrestrial ecosystems. , 1979, Journal of nematology.

[11]  D. Coleman,et al.  Let the soil work for us , 1988 .

[12]  J. A. Trofymow,et al.  Carbon and energy flow through microflora and microfauna in the soil subsystem of terrestrial ecosystems. , 1984 .

[13]  D. Hawkins,et al.  Correlation of Edaphic Factors with Plant-parasitic Nematode Population Densities in a Forage Field. , 1993, Journal of nematology.

[14]  N. Mantel.  The detection of disease clustering and a generalized regression approach. , 1967, Cancer research.

[15]  J. Rossi,et al.  Microspatial structure of a plant-parasitic nematode community in a sugarcane field in Martinique , 1996 .

[16]  A. C. Campbell,et al.  The Spatial Analysis of Soilborne Pathogens and Root Diseases , 1985 .

[17]  P. Moran.  Notes on continuous stochastic phenomena. , 1950, Biometrika.

[18]  Pierre Legendre,et al.  Aquatic heterotrophic bacteria: Modeling in the presence of spatial autocorrelation , 1988 .

[19]  Richard Webster,et al.  Quantitative spatial analysis of soil in the field , 1985 .

[20]  R. Webster,et al.  Statistical Methods in Soil and Land Resource Survey. , 1990 .

[21]  J. Seinhorst,et al.  Modifications of the Elutriation Method for Extracting Nematodes From Soil , 1962 .

[22]  J. Southey.  Laboratory methods for work with plant and soil nematodes , 1970 .

[23]  J. Rossi,et al.  Plant row and soil factors influencing the microspatial patterns of plant-parasitic nematodes on sugarcane in Martinique(l) , 1996 .

[24]  R. Sokal,et al.  Multiple regression and correlation extensions of the mantel test of matrix correspondence , 1986 .

[25]  S. Koenning,et al.  Impact of Soil Texture on the Reproductive and Damage Potentials of Rotylenchulus reniformis and Meloidogyne incognita on Cotton. , 1996, Journal of nematology.

[26]  J. Ord,et al.  Spatial Processes. Models and Applications , 1982 .

[27]  M. Fortin,et al.  Spatial pattern and ecological analysis , 1989, Vegetatio.

[28]  G. Robertson,et al.  The spatial distribution of nematode trophic groups across a cultivated ecosystem , 1995 .

[29]  D. Hawkins,et al.  Applications of geostatistics in plant nematology. , 1994, Journal of nematology.