Ectomycorrhizal mats in forest soils have a wide global distribution and are apparently important to nutrient cycling. Since little known about the factors influencing their distribution we have conducted one of the first studies attempting to define the factors influencing mat distribution. We chose to study distribution patterns of mat-forming ectomycorrhizal fungi of the genera Hysterangium and Gautieria in coniferous forests of the Pacific northwestern United States by mapping ectomycorrhizal mats and other forest floor features in 2 x 10 meter plots and digitized into a Geographical Information System (GIS) for spatial pattern analysis.
Distribution was measured in terms of mat size, size variability and shape, total mat cover per stand age, nearest neighbor distances, and correlation with understory vegetation and tree age using the digitized plot mats. While GIS analysis indicated that Hysterangium and Gautieria did not physically overlap, there appears to be a tendency for clustering of mats. No apparent correlations were observed between forest floor features and mats located within the 2 x 10 meter grids. Mat distributions were found to vary temporally; total mat area, size and frequency differed for Hysterangium and Gautieria mats when comparing young, mature and old-growth stands. The GIS analysis has been reported by Griffiths et. al. 1996 (Pub 2251) and the digitized plot maps on which these analyses were based are available in this data set.
Barbara J. Marks, Gay A. Bradshaw, George W. Lienkaemper, Robert P. Griffiths, Theresa J. Valentine
Preservation of species diversity has been identified as a critical measure of forest ecosystem health. The data collected on ectomycorrhizal mats suggests that their presence may be a key component for preserving species diversity and normal ecosystem function by providing host trees with requisite nutrients from mineral soil and soil organic matter.
Because of the potential importance of these mats (Cromack et al., 1988, Griffiths et al.,1991b, 1994), we wanted to determine which factors on a scale of a few meters influenced their distribution patterns. These factors included both surface features and mats of different species and function. We also wanted to determine the effects of stand age on mat distribution to better understand how forest harvesting might influence the occurrence, size, shape and the physical relationships of mats.