SHRUB INVASION AND BACTERIAL COMMUNITY PATTERN IN SWEDISH PASTURE SOIL

In arid environments, soil resources accumulate around shrubs to form resource islands. These islands are accompanied by increased bacterial counts and/or increases in microbe mediated processes. The present st udy investigates the universality of resource islands by measuring bac terial numbers and soil nutrients under and between shrubs invading a Swedish pasture. Substrate utilization patterns were also compared. Ne ither bacterial count patterns nor soil nutrient measurements supporte d resource island formation. Analysis of the substrate utilization pat terns indicated metabolic differences comparing under-and between-plan t communities. The results of this study suggest that resource island formation is not an intrinsic property of shrub invasions but rather m ay be related to the water harvesting or hydraulic lift associated wit h shrubs in arid environments.