Enhanced ecosystem functioning following stream restoration: The roles of habitat heterogeneity and invertebrate species traits

Abstract

Habitat restoration is increasingly undertaken in degraded streams and rivers to help improve biodiversity and ecosystem functioning. Follow‐up assessments focused on outcomes for biodiversity have often found scant evidence for recovery, raising concerns about the efficacy of habitat restoration for improving ecological integrity. However, responses of other ecological variables, such as ecosystem process rates and the functional trait composition of biological assemblages, have been little evaluated. We assessed how the restoration of habitat heterogeneity affected multiple functional parameters in 20 boreal stream reaches encompassing both more and less extensively restored sites, as well as channelised and natural reference sites. We further assessed relationships between our functional parameters and a fluvial geomorphic measure of habitat heterogeneity. Leaf decomposition was positively related to habitat heterogeneity. This was associated with shifts in the functional composition of detritivore assemblages, with the most obligate litter consumers more prominent in reaches showing higher habitat heterogeneity. The deposition of fine particulate organic matter was consistently higher in restored than channelised sites, and was positively related to the heterogeneity gradient. Algal biomass accrual per unit area did not vary either with restoration or the heterogeneity gradient. Synthesis and applications. Our findings demonstrate that restoration of river habitat heterogeneity can enhance retention and decomposition of organic matter, key ecosystem properties underpinning ecosystem functioning and service delivery. Significantly, enhanced litter decomposition was linked with a change in the functional composition rather than diversity of detritivore assemblages. Future evaluation of the success of habitat restorations should incorporate quantification of ecosystem processes and the functional traits of biota, in addition to measures of fluvial geomorphology and more traditional biotic metrics, to facilitate a more comprehensive and mechanistic assessment of ecological responses.

Species traits reveal effects of land use, season and habitat on the potential subsidy of stream invertebrates to terrestrial food webs

“…Accordingly, restoration of riffle habitats in agricultural streams, when linked with protection of riparian buffer zones, may have particular value in strengthening aquatic-terrestrial linkages (e.g. Kupilas et al 2016;Frainer et al 2018).…”

First signs of macroinvertebrate recovery following enhanced restoration of boreal streams used for timber floating

“…The use of intensive and targeted treatments, such as direct seeding and replanting in hardwood forests, may also increase the chance that a restoration program achieves at least some of its goals (Stanturf et al 2009). Similarly, Frainer et al (2017) found that ecosystem functioning was more likely to improve in projects restoring wood and boulders rather than smaller sized rocky substrates alone. Similarly, Frainer et al (2017) found that ecosystem functioning was more likely to improve in projects restoring wood and boulders rather than smaller sized rocky substrates alone.…”

“…Indeed, higher physical complexity has been related to higher biodiversity in near-natural systems, and losses of biodiversity have been documented for degraded systems with reduced physical complexity (Beisel et al 2000, Passy andBlanchet 2007). Similarly, follow-up studies of habitat restorations in streams and rivers have found that although physical complexity is frequently enhanced, this has often failed to generate the desired responses within target organism groups or ecosystem functions (Pretty et al 2003, Lepori et al 2005, Nilsson et al 2017, though examples of more successful outcomes exist (Miller et al 2010, Verdonschot et al 2016, Frainer et al 2017. Similarly, follow-up studies of habitat restorations in streams and rivers have found that although physical complexity is frequently enhanced, this has often failed to generate the desired responses within target organism groups or ecosystem functions (Pretty et al 2003, Lepori et al 2005, Nilsson et al 2017, though examples of more successful outcomes exist (Miller et al 2010, Verdonschot et al 2016, Frainer et al 2017.…”

Macroinvertebrados como bioindicadores em riacho tropical: uma avaliação de impactos por sedimentação, rompimento de barragem e de recuperação após medidas de restauração

“…Projetos de restauração ecológica tem tomado evidência e sua implantação tem crescido, principalmente em países Europeus e Estados Unidos onde a maioria dos projetos tem como objetivo principal recuperar o ambiente físico e fornecer uma heterogeneidade de habitats (FRAINER et al, 2017;GØRTZ, 1998;LOUHI et al, 2011;MUOTKA;LAASONEN, 2002;MUOTKA;SYRJÄNEN, 2007;PEDERSEN et al, 2007). Esses projetos baseiam-se na hipótese do "Campo dos Sonhos" que defende que "if you build, they will come" (se você construir eles virão), ou seja, ela pressupõe que a recriação da heterogeneidade de habitats irá automaticamente levar à restauração das comunidades biológicas (PALMER; AMBROSE; POFF, 1997).…”

“…FRAINER et al, 2017, JANUSCHKE et al, 2014LOUHI et al, 2011;LÜDERITZ et al, 2011;MUELLER;PANDER;GEIST, 2014;SUNDERMANN et al, 2011;TURUNEN et al, 2017) enquanto que para países da América do Sul esses projetos ainda são escassos. A sua aplicação pode ter diversos objetivos, destacando-se que a implantação de projetos que visem a restauração de habitats tem aumentado, buscando facilitar a recuperação da biodiversidade e do funcionamento dos ecossistemas dos ambientes degradados (FRAINER et al, 2017).…”