Author(s): Vladimir Krivtsov; Karen Allen; Tom Goss; Lauren Mork; Colin Thorne
Linked Author(s): Vladimir Krivtsov
Keywords: Nature-Based Solutions; Botanical survey; Ecosystem processes; Lotic environment; River planform; Soil moisture
Abstract: Here we briefly describe the outcome from a project designed to restore a reach of Whychus Creek near Sisters, Oregon by reconnecting the river to its floodplain. Monitoring involved comparing the floodplain vegetation assemblage before and after the restoration. ‘Stage Zero’ restoration has successfully replaced the degraded, single-threaded channel that was disconnected from its floodplain with a multi-threaded dynamic channel system, quickly achieving a substantial increase in the area covered by riparian vegetation. Reconnection of the channel to its floodplain has led to creation of patchy, shifting mosaics of habitats, which was reflected in the formal statistical analysis (Kruskal Wallis test). The approach of comparing only change in herbaceous and shrub riparian vegetation (as opposed to inclusion of all vegetation classes) reduces the error associated with inclusion of forest classes and any error likely over-represents pre-restoration riparian herbaceous and shrub vegetation. Herbaceous and shrub riparian cover classified from post-restoration imagery accounted for 12.3 acres of vegetation, a 2.7 times increase compared to the pre-restoration cover. Statistical analysis revealed substantial increases in vegetation cover and species richness of all plant functional groups. The increases in plant and habitat diversity have also undoubtedly benefitted other biological taxa. In summary, outcomes of the restoration are highly encouraging. Continued monitoring and evaluation are essential to establish the long-term consequences of this innovative type of restoration, recognise unintended impacts and responses, identify the need for maintenance or adaptive management, and substantiate the case for reconnecting rivers to their floodplains more widely.
DOI: https://doi.org/10.3850/IAHR-39WC2521711920221865
Year: 2022