Landscapes as gradients: The spatial structure of terrestrial ecosystem components in southern Ontario, Canada

Abstract

The conventional view of the environment – consisting of discrete patches that repeat themselves across the landscape – has seldom been tested. Across a wide spatial scope in southern Ontario, Canada, we investigated the spatial structure of physical and biological features of the environment: vegetation communities, moisture, pH, and organic content of soil at local scales (10–1250 m), and mammalian communities, mean annual temperature and precipitation at regional scales (10–650 km). Spatial structure was quantified using log–log regression of variance ( V) with distance ( D), according to the power formula, V = aD z . All these ecosystem components exhibited gradients. Slopes ( z) of log–log regressions were positive (0.065 < z < 0.703) and were significantly steeper at the regional scale than the local scale. Variance appeared to increase without bound as distance between sampling locations increased. The results support the view of landscapes as continua and gradients. These patterns represent a challenge to the conventional view of how the natural environment is organised.