Importance of landscape context for post‐restoration recovery of riparian vegetation

Abstract

Abstract We tested whether the recovery of riparian vegetation along rapids that have been restored after channelisation for timber floating can be predicted based on floristic and geomorphic characteristics of surrounding landscape units. Our study was located along tributary stream networks, naturally fragmented in rapids, slow‐flowing reaches, and lakes (i.e. process domains), in the Vindel River catchment in northern Sweden. We tested whether landscape characteristics, specifically to what extent the geomorphology (affecting local abiotic conditions), species richness, and species composition (representing the species pool for recolonisation), as well as the proximity to various upstream process domains (determining the dispersal potential), can predict post‐restoration recovery of riparian vegetation. Our results indicate that post‐restoration recovery of riparian vegetation richness or composition is not strongly related to landscape‐scale species pools in these streams. The restored rapids were most similar to upstream rapids, geomorphically and floristically, including plant traits. Species richness of adjacent landscape units (upstream process domains or lateral upland zone) did not correlate with that of restored rapids, and proximity of upstream rapids or other process domains was only weakly influential, thus diminishing support for the hypothesis that hydrochory or other means of propagule dispersal plays a strong role in riparian vegetation community organisation after restoration in this fragmented stream network. We conclude that, in these naturally fragmented stream systems with three discrete process domains (rapids, slow‐flowing reaches and lakes), hydrochory is probably not the main predictor for short‐term riparian vegetation recovery. Therefore, other factors than landscape context can serve in prioritising restoration and, in these systems, local factors are likely to outweigh landscape connectivity in the recovery of riparian vegetation.