Large Wood in River Restoration and Management: Reintroducing the Eurasian Beaver Richard Brazier1, Mark Elliott2 and Alan Puttock1

Dr Alan Puttock and Professor Richard Brazier a.k.puttock@exeter.ac.uk [email protected] Homework Questions 1) How wood is being used in rivers for management purposes in your patch and elsewhere • Evidence primarily from North America of using beaver for river restoration • Growing interest in UK/Europe but very different landscapes 2) What the immediate and medium-term impacts have been on river geomorphology and habitats • Where damming doesn’t occur – very little • Where damming does occur - dramatic channel and riparian zone transformation 3) What the risks are that prevent wood from being used more, or in a more naturally- functioning way, for restoration and management • Live in a densely populated and heavily managed country, depleted of large wildlife. • ‘Rewilding’ and restoration of natural processes inevitably will cause conflict and management challenges. Beavers4) If there recognised are any asgood ‘ecological case studies engineers’ that illustrate and keystone these speciesimpacts, with benefits significant and/or risks hydrogeomorphological• Growing evidence base impacts: from Scottish and English projects 5) What added information/science do you need to incorporate wood more into restoration Gurnelland management. AM. 1998. The hydrogeomorphological effects of beaver dam-building activity. Progress• Understanding in Physical across Geography a range 22 of: 167–189. scales • Combination of empirical science and modelling approaches to understand implications at Naimana catchment et al., 1986. and landscapeEcosystem scale Alteration of Boreal Forest Streams by Beaver (Castor Canadensis).• Research designedEcology 67 in: conjunction1254–1269. with management objectives • Engagement and socio-economic research/understanding also required US Projects: Stream Restoration as an Ecosystem Process

Pollock et al., 2014. Using Beaver Dams to Restore Incised Stream Ecosystems. BioScience 64: Available from: http://bioscience.oxfordjournals.org/cgi/doi/10.1093/biosci/biu036 US Restoration Research and Projects US Restoration Research and Projects

Bouwes et al., 2016. Ecosystem experiment reveals benefits of natural and simulated beaver dams to a threatened population of steelhead (Oncorhynchus mykiss). Scientific Reports 6: Available from: http://www.nature.com/articles/srep28581 Context: Why we are interested in beaver reintroduction

• Recent extreme rainfall in the UK, caused major socio-economic and environmental damage: • Surface water flooding • Soil erosion • Diffuse pollution from agricultural land

• Solutions focussed on downstream palliative approaches i.e. building flood defences, dredging channels etc…

• Rewilding/Rewetting at landscape scales may offer alternative/complimentary solutions: • Enhancing resilience of downstream flood defences • Maintain elevated baseflows in rivers during droughts • Keeping soil and nutrients on the land

• Whilst also delivering much needed biodiversity and other benefits…

• Seeking to quantify the role that landscape restoration science might play as a ‘Nature Based Solution’ to the environmental problems that (for the most part) we have created… Should we be making a case for rewilding beyond biodiversity? Devon Beaver Project: Overview

• Fenced 1.8 ha site in North Devon • 1st order tributary draining from IMG • A pair of beavers introduced in 2011 • Changed site from small first order tributary running through woodland, to a diverse mosaicked wetland environment • 13 woody dams, ponds covering 1800 m2 • Site holding ca 1000 m3 of water within ponds • Frogspawn increased from 10 clumps in 2011 to 580 in 2016

Puttock et al., 2015. Aerial photography collected with a multirotor drone reveals impact of Eurasian beaver reintroduction on ecosystem structure. Journal of Unmanned Vehicle Systems. Devon Beaver Project: Results - Flow Attenuation Project has now been collecting continuous flow and rainfall data for 3 years, quantifying the rate and amount of water entering and leaving the site.

Results (from 70+ rainfall-runoff events) indicate that beaver activity, particularly the building of ponds and dams, moderates the channel response to rainfall following storm events, potentially reducing the risk of flooding downstream.

• Event Rain = 24 mm • Above Beaver (blue) Peak Discharge = 0.11 (mᶟ s¯¹) Storm event discharge = 2923 (m3) • Below Beaver (red) Peak Discharge = 0.04 (mᶟ s¯¹) Storm event discharge = 1493 (m3)

Puttock et al., 2017. Eurasian beaver activity increases water storage, attenuates flow and mitigates diffuse pollution from intensively-managed grasslands. Science of The Total Environment 576. Devon Beaver Project Results – water quality

Storm monitoring (17 events, 178 samples above, 119 below), suggests site may act as a sink or filter for diffuse water pollutants from agriculture (suspended sediment, nitrogen and phosphate).

However, more organic matter in the site, so potentially results in a greater loss of dissolved organic carbon than comparative agricultural land.

~100 T of Sediment ~15 T of Carbon Need for projects across different scales: Cornwall Beaver

• Site on one of 3 main tributaries of Tresillian entering Ladock (2nd order). • Total Catchment + 2300 ha • Site catchment 134 ha. • Dominated by Farmland. • 1+ year baseline monitoring • Beavers introduced summer 2017

http://www.cornwallwildlifetrust.org.uk/living-landscapes/cornwall-beaver-project Cornwall Beaver Project Pre-beaver

Post-beaver Catchment Scale: River Otter Beaver Trial

http://www.devonwildlifetrust.org/devons-wild-beavers/ Catchment Scale: River Otter Beaver Trial - Management Issues

http://www.devonwildlifetrust.org/devons-wild-beavers/ Catchment Scale: Behaviour, impact and risk modelling Summary and conclusions With Beavers present >500 years ago, we had a ‘nature-based solution’ to many of the water resource and indeed whole ecosystem management issues we now face.

Removing this keystone species may have dramatically affected the structure and function of many of our rivers… even more so when combined with intensification of agriculture and drainage of our uplands.

Research is demonstrating the value of more wild, wet, roughly structured landscapes: • Storing more water • Attenuating flooding (reduced and desynchronised flow) • Releasing more water in drought to elevate river baseflow • Mitigating diffuse pollution from agriculture • Storing carbon • Enhancing biodiversity

There will however, be management and conflict hurdles to be overcome... careful partnership working is crucial. Thanks to all colleagues, funders and associated partners

Devon Beaver Project Devon Beaver Project is led by Devon Wildlife Trust and the University of Exeter, and funded by Westland Countryside Stewards. Particular thanks go to John Morgan, the site owner, for hosting the reintroduction project and allowing site access for researchers. For site surveys the 3D Robotics Y6 was supplied by the University of Exeter’s Environment and Sustainability Institute (ESI) environmental monitoring drone lab.

River Otter Beaver Trial The River Otter Beaver Trial is led by Devon Wildlife Trust, working in partnership with the University of Exeter, Clinton Devon Estates and the Derek Gow Consultancy. Data has been provided by the Environment Agency. Expert independent advice is also provided by the Royal Zoological Society of Scotland (Roisin Campbell-Palmer and Simon Girling), Professor John Gurnell and Gerhard Schwab. The trial is licenced by Natural England. Additional funding is provided by the Wellcome Trust. Cornwall Beaver Project Cornwall Wildlife Trust and Chris Jones are leading the Cornwall Beaver Project on behalf of a wider partnership of individuals and organisations including; University of Exeter, University of Southampton, University of Plymouth, CoaST and Woodland Valley Farm.