Evaluating riparian solutions to multiple stressor problems in river ecosystems — A conceptual study

Abstract

Rivers are among the most sensitive of all ecosystems to the effects of global change, but options to prevent, mitigate or restore ecosystem damage are still inadequately understood. Riparian buffers are widely advocated as a cost-effective option to manage impacts, but empirical evidence is yet to identify ideal riparian features (e.g. width, length and density) which enhance ecological integrity and protect ecosystem services in the face of catchment-scale stressors. Here, we use an extensive literature review to synthesise evidence on riparian buffer and catchment management effects on instream environmental conditions (e.g. nutrients, fine sediments, organic matter), river organisms and ecosystem functions. We offer a conceptual model of the mechanisms through which catchment or riparian management might impact streams either positively or negatively. The model distinguishes scale-independent benefits (shade, thermal damping, organic matter and large wood inputs) that arise from riparian buffer management at any scale from scale-dependent benefits (nutrient or fine sediment retention) that reflect stressor conditions at broader (sub-catchment to catchment) scales. The latter require concerted management efforts over equally large domains of scale (e.g. riparian buffers combined with nutrient restrictions). The evidence of the relationships between riparian configuration (width, length, zonation, density) and scale-independent benefits is consistent, suggesting a high certainty of the effects. In contrast, scale-dependent effects as well as the biological responses to riparian management are more uncertain, suggesting that ongoing diffuse pollution (nutrients, sediments), but also sources of variability (e.g. hydrology, climate) at broader scales may interfere with the effects of local riparian management. Without concerted management across relevant scales, full biological recovery of damaged lotic ecosystems is unlikely. There is, nevertheless, sufficient evidence that the benefits of riparian buffers outweigh potential adverse effects, in particular if located in the upstream part of the stream network. This supports the use of riparian restoration as a no-regrets management option to improve and sustain lotic ecosystem functioning and biodiversity.

Inhibiting Effects of Vegetation on the Characteristics of Runoff and Sediment Yield on Riparian Slope along the Lower Yellow River

“…As an important transitional zone between rivers and terrestrial ecosystems, the riparian zone acts as a corridor, filter and barrier, and its effective management is an important guarantee for maintaining the stability and health of river and terrestrial ecosystems [1,2]. In recent years, due to natural environmental changes in climate, channel morphology, flood cycles and beach structures, and human activities such as urban expansion, large-scale engineering construction, and agricultural and livestock development, the structure and function of the riparian ecosystem has been severely impaired [3,4].…”

Agricultural impacts on streams near Nitrate Vulnerable Zones: a case study in the Ebro basin, northern Spain

“…Finally, it should be noted that the recovery of stream ecosystems in agricultural areas requires not only mitigation actions but also restoration to accelerate ecological recovery [64]. It is necessary to carry out restoration plans, at least in Ea, Zamaca and Tuerto Streams, which were the most hydromorphologically impacted.…”

“…It is necessary to carry out restoration plans, at least in Ea, Zamaca and Tuerto Streams, which were the most hydromorphologically impacted. Among the restoration strategies available to improve ecological status, the establishment of riparian buffers has been the most frequently and successfully used to improve stream habitat [64–68], which should try to include a minimum perimeter of 20-30 m along the impacted sites [64].…”

Aged streams: Time lags of nitrate, chloride and tritium assessed by Dynamic Groundwater Flow Tracking

“…In fact, the scenario 530 with the 200 m agricultural-free zone around the stream can be compared with a natural riparian zone, on which much research has been done (e.g. Anderson et al, 2014;Feld et al, 2018;Hefting and Klein, 1998;Hill, 1996;Ranalli and Macalady, 2010).…”