Boundary dynamics at the aquatic-terrestrial interface: The influence of beaver and geomorphology

Abstract

Beaver (Castor canadensis) impoundments are used to illustrate the effect of large animals on the boundary dynamics of 'patch bodies', volumetric landscape units which have surficial boundaries with upper and lower strata, and lateral boundaries with adjacent patches within the same stratum. Patch bodies created by beaver impoundments include the beaver pond, the aerobic soil beneath the pond, and thee underlying anaerobic soil. Beaver herbivory in the riparian zone creates an additional patch body concentric to the pond. Beaver and water are the primary biotic and abiotic vectors mediating fluxes across lateral patctt body boundaries; vegetation and microbes are the primary biotic vectors mediating fluxes across surficial patch body boundaries.Basin geomorphology affects the permeability of pond boundaries (i.e., their ability to transmit, energy and materials) by affecting the kinetic energy of water, the surface-to-volume ratio of the impoundment, and the movement of beaver between the pond and the riparian l'oraging zone. We suggest that: (1) permeability of lateral boundaries to abiotic vectors is a function of kinetic energy; (2) within-patch retention of particulate matter transferred by abiotic vectors across lateral boundaries is maximized by a decrease in kinetic energy; (3) lateral patch boundaries between safe refuge and a resource used by an animal vector are most permeable when they are narrow; and (4) total amount ol ~ energy and materials transferred across surficial boundaries is maximized by increasing surface area.

Shellfish Reefs Increase Water Storage Capacity on Intertidal Flats Over Extensive Spatial Scales

“…The beaver builds dams, which impound water upstream. The size of the water reservoir depends on the size of the dam, but also on the underlying landscape topography; in a steep canyon valley the reservoir can only extend to a moderate surface area before the dam overflows, but on flat wetlands the reservoir can be much larger (Johnston and Naiman 1987). The effects of these reservoirs on fish communities are generally beneficial because they provide extreme flow refuge, breeding sites and habitats (Kemp and others 2012).…”

Importance of floodplain waters for the conservation of chironomid (Diptera) biodiversity in a 6thorder section of the Garonne river (France)

“…This dimension includes the whole alluvial plain, defined as a mosaic of homoge neous patches on the physico-chemical and biological plan (Johnston & Naiman 1987, Pringle et al 1988, as well as the transverse bi-directional exchanges control ling interactions within this mosaic (Amoros & Roux 1988, Junk et al 1989, Bayley 1995.…”

Resource Transitions and Energy Gain: Contexts of Organization

“…The food available in such a territory should be accessible by water and high in quality. In response to this high-quality resource, the beaver construct a dam and lodge, forming an impoundment (Johnston and Naiman 1987). Hypotheses 1, 2, 5, and 11 are illustrated by this organization.…”