Riparian vegetation metrics as tools for guiding ecological restoration in riverscapes

Abstract

Riparian woods are frequently fragmented and degraded, mainly as a consequence of land-cover related stresses, water diversion, regulation and invasive species. The need to enhance these systems towards their natural functioning has motivated numerous restoration efforts. However, river managers still need guidance on how to allocate scarce restoration resources, and to monitor and report the effectiveness of the restoration programmes. For this, the present work proposes a stepwise methodological procedure over spatial scales, using quantitative descriptors (metrics) of the ecological condition of the riparian vegetation. This evaluation is based on the composition and cover of plant assemblages, species attributes, and spatial patterns, which can reflect the deviation of the structure and condition of the riparian zone from the near-natural state to an impaired situation. Landscape metrics obtained from high spatial resolution imagery are used for the evaluation of the spatial features of the riparian zone, followed by the calculation of a riparian multimetric index, based on field observations. The integration of multi-spatial scale information provided by landscape metrics and biological metrics is essential and recommended for decision support of end-users and to evaluate the success of restoration measures. RÉSUMÉDescripteurs de la végétation rivulaire comme guide de la restauration écologique au sein des paysages de cours d'eau La dégradation et la fragmentation fréquentes des bois rivulaires sont principalement dues à des pressions d'usage du sol, à des modes de gestions des écoulements de l'eau et à la concurrence par des espèces invasives. C'est ce besoin de retour à des fonctionnements plus proches des conditions naturelles qui a motivé nombre d'efforts de restauration. Toutefois les gestionnaires de cours d'eau sont demandeurs d'outils d'évaluation des programmes de restauration et des manières de gérer des ressources qui se raréfient. Pour cela, notre travail propose une méthode hiérarchisée à des échelles spatiales variées, par des descripteurs quantitatifs (métriques) de l'état écologique de la végétation riparienne. Cette évaluation se fait à partir de la composition et du recouvrement des assemblages de plantes, des exigences spécifiques, et de leur répartition spatiale. Cette répartition spatiale est le reflet de l'écart de la structure et de l'état des

Fish and macroinvertebrate assemblages reveal extensive degradation of the world's rivers

“…The negative correlation of benthic macroinvertebrate condition with the decrease in forests is expected because many species depend on allochthonous organic matter (leaves, fruits, wood) provided by surrounding forests as energy sources (e.g., Boyero et al, 2020 ; Jonsson & Sponseller, 2021 ; Silva‐Araújo et al, 2020 ). Moreover, forests surrounding rivers constitute efficient buffers against pollution caused by other land uses, such as agriculture, because the filtering capacity of the vegetation improves water quality, which influences aquatic communities (Aguiar et al, 2011 ; Effert‐Fanta et al, 2019 ; Riis et al, 2020 ). In Japan, for example, the higher richness of red‐listed fish species was associated with high percentages of forest cover in the catchments (Lavergne et al, 2021 ).…”

“…These are driven by increased human populations and the pressures resulting from the increased consumption of goods and services (Díaz et al, 2019 ; IPBES, 2019 ; Reid et al, 2019 ). The result is excess of nutrients (Mekonnen & Hoekstra, 2017 ; USEPA, 2020 ), contaminants (Danner et al, 2019 ; Meng et al, 2020 ), altered flow regimes and connectivity (Belletti et al, 2020 ; Grill et al, 2019 ; Zarfl et al, 2015 ), impaired riparian vegetation and physical habitat structure (Aguiar et al, 2011 ; Kaufmann et al, 2022 ; Macfarlane et al, 2018 ), spread of invasive non‐native species (IPBES, 2019 ; Pereira & Ferreira, 2021 ; Seebens et al, 2017 ) and species overexploitation (Tickner et al, 2020 ).…”

Analytical solutions of velocity profile in flow through submerged vegetation with variable frontal width

“…Vegetation is widely used in river and wetland water ecological treatment and restoration (Constança Aguiar, F. et al, 2011;Stromberg, 2001) because it serves many eco-functions, such as fixation through roots for maintaining riverbed stability, water purification through the absorption capacity of the epidermis, and enriching biodiversity features by providing attachment matrices and habitats for organisms.…”

Determination of Riparian Vegetation Biomass from an Unmanned Aerial Vehicle (UAV)

“…Furthermore, their sensitivity and accuracy decrease with AGB and LAI [3,18]. All these limits are nowadays overcome by the recent developments in remote sensing (RS) platforms and geographic information systems (GISs), which have proven to be efficient tools to analyze the vegetation cover in different sectors [3,10,14,[19][20][21][22][23][24][25][26][27][28][29][30][31]. RS platforms, such as satellite systems, aircrafts, and unmanned aerial vehicles (UAVs), have different peculiarities exploited for different issues under investigation.…”