THE INFLUENCE OF LANDSCAPE POSITION ON TEMPORAL VARIABILITY IN 4 NORTH-AMERICAN ECOSYSTEMS

The spatial setting of an ecosystem within a landscape influences many of the ecosystem's properties. Here, we ask whether there is a relation between the spatial positioning of different locations in a landscape and the annual variability exhibited at each location. We include data from four biome types represented in the Long-Term Ecological Research (LTER) network: northern Wisconsin lakes, Hubbard Brook Experimental Forest, the Jornada Desert, and the North Inlet estuary. At each LTER site, data on 26-68 ecological parameters have been collected at three to seven locations along an elevational gradient for at least 5 yr. We tested whether at each LTER site the annual variability exhibited by parameters at each location within the landscape was related to the location's relative elevation, that is, landscape position. Specific mechanisms relating spatial positioning to variability differed at the four LTER sites, but at each LTER site, (1) locations differed in the annual variability exhibited by ecological parameters, (2) for at least a subset of the parameters, this variability was related to the locations' spatial positions, and (3) water movement across the landscape was the important underlying factor determining variability patterns. We conclude that landscape position influences the annual variability that ecosystems exhibit.