2 research outputs found
Material spiraling in stream corridors: A telescoping ecosystem model
16 páginas ; 10 figurasStream ecosystems consist of several subsystems that
are spatially distributed concentrically, analogous to the
elements of a simple telescope. Subsystems include the
central surface stream, vertically and laterally arrayed
saturated sediments (hyporheic and parafluvial zones),
and the most distal element, the riparian zone. These
zones are hydrologically connected; thus water and its
dissolved and suspended load move through all of these
subsystems as it flows downstream. In any given subsystem,
chemical transformations result in a change in
the quantity of materials in transport. Processing length is
the length of subsystem required to ‘‘process’’ anamount
of substrate equal to advective input. Long processing
lengths reflect low rates of material cycling. Processing
length provides the length dimension of each cylindrical
element of the telescope and is specific to subsystem
(for example, the surface stream), substrate (for instance,
nitrate), and process (denitrification, for example).
Disturbance causes processing length to increase.
Processing length decreases during succession
following disturbance. The whole stream-corridor ecosystem
consists of several nested cylindrical elements
that extend and retract, much as would a telescope, in
response to disturbance regime. This telescoping ecosystem
model (TEM) can improve understanding of material
retention in running water systems; that is, their
‘‘nutrient filtration’’ capacity.We hypothesize that disturbance
by flooding alters this capacity in proportion to
both intensity of disturbance and to the relative effect of
disturbance on each subsystem.We would expect more
distal subsystems (for example, the riparian zone) to
show the highest resistance to floods. In contrast, we
predict that postflood recovery of functions such as
material processing (that is, resilience) will be highest in
central elements and decrease laterally. Resistance and
resilience of subsystems are thus both inversely correlated
and spatially separated. We further hypothesize
that cross-linkages between adjacent subsystems will
enhance resilience of the system as a whole. Wholeecosystem
retention, transformation, and transport are
thus viewed as a function of subsystem extent, lateral
and vertical linkage, and disturbance regime.National Science Foundation (NSF) grants DEB-
9306909 and DEB-9615358.Peer reviewe