Wind dispersal and subsequent establishment of VA mycorrhizal fungi across a successional arid landscape

Abstract

Wind is an important vector in the dispersal of microorganisms to new habitats. However, wind dispersal is generally assumed to be random or logarithmically related to distance. We assessed the wind dispersal and subsequent establishment of an important group of plant symbionts, VA mycorrhizal fungi, across a 74 Ha recontoured surface mine. Winds were predominantly westerly aloft, but due to complex north-south ridges, up-valley, thermally-driven air flows developed. Patterns of spore dispersal were tested by a combination of released spore mimics from the potential source areas and by assessing the composition of species deposited across the site and in the putative source areas. Survival of the fungi was assessed two years after the dispersal patterns were monitored.

The spore mimics moved in predictable but complex patterns across the site depending on the interactions of surface and upper winds. Mimics from the valley sources moved up the valleys in the lower flows and occasionally over the ridges in the upper winds. Those from the ridge approximately 2 km distant were entrained in the upper air flows and deposited all across the site. The VA mycorrhizal fungal species compositions from the soils correlated with the deposition patterns measured with the mimics.

Fungal survival showed a pattern similar to dispersal; the fungi often survived in habitats not resembling the habitat of origin although some selection in both more favorable and less favorable sites occurred. These data suggest that microbial dispersal even by wind is predictable if the wind characteristics are known, that the VA mycorrhizal fungi from the site can survive in habitats different from their habitats of origin, but that some selection among species may occur after deposition.