The waterscape continuum concept: Rethinking boundaries in ecosystems

Continuity and discontinuity are fundamental concepts of ecosystem science. In reality, both continuities and discontinuities can exist; lentic and lotic systems can expand and contract as can soil/rock moisture and groundwater systems. Surface water, soil moisture, rock moisture, and groundwater, represent hydrological domains that are interconnected. Under a state of expansion each domain may be characterized by spatial continuity; for instance, a river may be entirely flow connected. However, under a state of contraction, discontinuities may appear, and the river may become fragmented. The rate of expansion and contraction in each domain, that is land‐, lentic‐, and lotic‐scapes, is a function of topography, geology, climate, and biota. In an effort to reconcile older, and sometimes incongruous, concepts of continuity and discontinuity we present a view of water‐connected ecosystems, such as riverscapes and catchments that are nested upon and within the uppermost layer of Earth. This layer is the key interface between the lithosphere, atmosphere, hydrosphere, and biosphere, and is known as the critical zone (CZ). We present the waterscape continuum and define it as the spatially and temporally dynamic water upon and within the CZ. To guide ecosystem research (across the land‐, lentic‐, and lotic‐scapes), we introduce the waterscape continuum template (WCT). We propose the waterscape continuum and the WCT can enhance our understanding of ecosystem processes and mechanisms.