Spatio-temporal gradients between ecosystems of the central Norwegian high mountains are analyzed. Complex landscape ecological site analyses combined with intensive pitfall trapping are carried out in four investigation areas in two regions. Key questions are addressed for the differences among ecosystems along a broad-scaled oceanic-continental gradient. The answers are based on ecological process analysis and mapping of zoocoenoses in small catchments of two alpine altitudinal belts. A comparison of four ridge sites is presented by analyzing water and temperature balance and activity of arthropods during the driest summer month. The results do not implicate summer drought and heat as limiting factors; summer wetness and cooling are most decisive. Landscape ecological processes, like the accumulation of snow during winter, snow melting, freeze-thaw action, percolation, soil moisture variation, and temperature regimes are exemplified by long-term measurements throughout the year in a small catchment in continental eastern Norway—the driest mountain region in Scandinavia. To learn about the organization and diversity of zoocoenoses, epigeic arthropods (Araneae, Carabidae) are investigated along spatial gradients. Interrelations between distribution patterns of animals and spatio-temporal dynamics of the environmental conditions are presented. The results are framed by gradient theory in landscape ecology. Finally, the complexity of spatio-temporal gradient determination between ecosystems is discussed and summarized by a scheme of gradient principles for the Norwegian mountains.