Application of the diminishing returns concept in the hydroecologic restoration of riverscapes

The density of restoration projects can produce space-crowding effects through ecosystem processes such as water flow.

“There are theoretical limits on the maximum restoration benefit for a given geographic area, and the density of restoration projects can produce space-crowding effects through ecosystem processes (eg water flow; Diefenderfer et al. 2012).”

Detection of time- or space-crowding effects requires robust statistical modeling and experimental designs.

“The detection of time-or space-crowding effects requires robust statistical modeling and experimental designs (Diefenderfer et al. 2012; Pennino et al. 2016).”

The incremental return of wetted area per dike breach diminished with additional breaches once a peak of 28 ha wetted area per breach was reached when 26% (11 of 42) of channels were breached.

“(2) the incremental return of wetted area per breach diminished with additional breaches once a peak at 28 ha wetted area per breach was reached when 26% (11 of 42) of the channels were breached;”

Multiple dike breaches produced a synergistic increase in wetted floodplain area with low numbers of breaches, evidenced by a slope greater than 1 between proportion of area wetted and proportion of channels opened.

“It also revealed three effects of multiple dike breaches: (1) the slope greater than 1 between the proportion of area wetted and the proportion of channels opened evidenced a synergistic increase in wetted floodplain area with low numbers of breaches;”

The spatial configuration of dike breaches affected wetted floodplain area: upstream breaches yielded 2% and midstream breaches 63% of the wetted area produced by downstream breaches.

“(3) the spatial configuration of dike breaches affected the amount of wetted floodplain area producedupstream breaches yielded 2% and midstream breaches 63% of the wetted area produced by downstream breaches (Diefenderfer et al. 2012).”

In some cases, synergistic and nonlinear hydrologic effects are associated with effects of space crowding.

“these synergistic and nonlinear hydrologic effects are associated with effects of space crowding”

Practical constraints have limited implementation of statistical sampling designs to only one, space crowding, for which modeling was used.

“In our experience, although we proposed several statistical sampling designs to ascertain cumulative effects (Diefenderfer et al. 2011), practical constraints have limited implementation to only one, space crowding, for which we used modeling (Diefenderfer et al. 2012).”