Techniques for restoring biodiversity: What works Techniques for restoring biodiversity: What works? What are the priorities? Not reinventing the wheel – building on the existing evidence base. Judy England, Environment Agency Martin Janes, River Restoration Centre Jenny Wheeldon, Natural England

REstoring rivers FOR effective catchment Management Although initially aimed at delivering the WFD the approach and conclusions are relevant to Floods Directive, restoration measures through improved retention, storage and discharge/ Natural Flood Management EU Biodiversity Strategy whose targets include restoring at least 15% of degraded ecosystems by 2020, by integrating green infrastructure into land-use planning. Restoration measures can play a significant role in the achievement of biodiversity protection objectives for specific habitats and species (according to the Birds and Habitats Directives). www.reformrivers.eu

REFORM hydromorphology framework Hydromorphological assessment should consider physical processes and appropriate temporal and spatial aspects beyond river restoration project boundaries and project life span.. Role of vegetation & floodplain ecosystems Findings suggest that direct measurements of hydromorphological processes and riparian vegetation are likely to be better in assessing hydromorphological degradation than in-stream biota. Vegetation and plants can play a cost-effective and significant role as physical ecosystem engineers for river restoration. www.reformrivers.eu

Improved coupling of hydromorphology to biotic response Hydromorphological impacts can take years to fully manifest themselves. Fish is the most sensitive biological quality element (BQE) with regard to hydromorphology. Macrophytes can be used for assessing hydromorphological degradation in lowland rivers, Current WFD sampling methods are not appropriate. There is a need to develop new biota sampling methods sensitive to HYMO impacts – include riparian habitats. www.reformrivers.eu

Restoration measure at a project scale Projects should have well-defined quantitative success criteria. Hydromorphological restoration has an overall positive effect on biota, but effects are highly variable and even negative. It is thus essential to monitor and adjust restoration projects. River restoration benefits not only aquatic biota. Terrestrial and semi-aquatic species benefit most (e.g. floodplain vegetation, ground beetles). No single “best measure” Widening of water courses to restore a more natural planform. Instream measures have the highest effect on fish and macroinvertebrates. Overall, measures should be selected taking consideration of the targeted organism group. www.reformrivers.eu

Restoration measure at a project scale It is important to select measures that restore specific limiting habitats at relevant scales. Restoration results in a higher number of individuals (abundance) but few new species (richness). Consider re-colonization potential. Restoration had positive effects even in small restoration projects. However, other studies indicate that exceptionally large projects have higher effects. www.reformrivers.eu

Key principles for river restoration Improve overall ecosystem integrity and biodiversity, rather than focusing on the status of single species, by using process- based techniques such as floodplain reconnection. Understand the connections between natural processes upstream and downstream: work beyond the scale of individual reaches to consider riparian areas, floodplains and the wider catchment. Target measures at the root causes of degradation – not the symptoms – and at the scale at which the pressures exist. Use minimal intervention wherever possible to reinstate natural processes so that rivers can recover by themselves. Addy et al. 2016 River Restoration and Biodiversity

REFORM fact sheets www.reformrivers.eu

Restoration measures to improve river habitats during low flows Slow flow refugia No refugia Why we need restoration Particular concern at extremes of flows Ecological resistance & resilience More natural channels have refugia at high & low flows Natural channels have increased ecological resilience & resistance Supports the need to link habitat restoration with flow restoration Flowing refugia No refugia

Environment Agency 2016

Environment Agency 2016 Explain table Highlights most of the published evidence focusses on active and passible single thread. Tells us some things we know – adding gravel to passive single-thread rivers is was considered inappropriate and the conclusion is supported by evidence with a high confidence. This measure is not sustainable where excess fine sediment is an issue and is not managed. Highlighted research priorities – considered low possibly of success and there was little evidence. This research into selected case studies to improve our knowledge. Environment Agency 2016

Mainstone draft (2017) : Review of ecological benefits of river restoration measures Impossible to made general statements about the ecological benefits of river restoration as schemes vary so widely in terms of the characteristics of the rivers involved. A conflicting and confusing evidence base is inevitable. Most uncertainty of restoration benefits exists around interventionist measures 1) Some of the most well-thought our practical schemes may yield no evidence because monitoring was either not considered or was too coarse to be of value. Schemes with poor strategic planning may generate monitoring data capable of analysis, but are unlikely to show significant ecological benefits.

Natural flood management- evidence base Headwater drainage Leaky barriers Catchment woodland Cross-slope woodland Runoff pathways Floodplain restoration Riparian woodland Here are the 14 interventions we can make Offline storage Soil and land management River restoration Salt marsh, mudflats and managed realignment Floodplain woodland Salt marsh, mudflats Sand dunes Beach management

Addy et al. 2016 River Restoration and Biodiversity

The benefits of wood Collins et al. 2012 Geomorphology

Some thoughts on gaps: Higher energy systems Assisted natural recovery/reduced maintenance Think wider – riparian, floodplain & catchment: Woodland creation/regeneration Natural flood management Catchment sensitive farming What can we learn from the recent floods (& future droughts)? What is popular? England CP’s work, faggot bundles, wood in rivers, weir removal/notching/etc, NFM Scotland Fisheries trusts and SEPA – morphology based restoring space and processes and green bank protection Wales – better ‘green’ bank protection & NFM related techniques NI – weir removal, green bank protection, mitigation for flood risk works Ireland… - enhancement based on reduced changed maintenance.

Do we need two lists? Complex/large scale: Simpler/smaller scale: where there is a need for good quality monitoring and scientific understanding to generate better quality evidence to help design and implementation, Simpler/smaller scale: where there is a need for greater assessment of the large numbers of simple projects implementing the same ‘common’ techniques – i.e. there is a large sample size already (multiple BACI).