Large Wood in River Restoration and Management:

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1 Large Wood in River Restoration and Management: Reintroducing the Eurasian Beaver Richard Brazier, Mark Elliott and Alan Puttock Dr Alan Puttock and Professor Richard Brazier a.k.puttock@exeter.ac.uk r.e.brazier@exeter.ac.uk

2 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 naturallyfunctioning 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. Beavers 4) If there recognised are any as good ecological case studies engineers that illustrate and keystone these species impacts, 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 Gurnell and management. AM The hydrogeomorphological effects of beaver dam-building activity. Progress Understanding Physical across Geography a range 22: of scales Combination of empirical science and modelling approaches to understand implications at Naiman a catchment et al., and landscape Ecosystem scale Alteration of Boreal Forest Streams by Beaver (Castor Canadensis). Research designed Ecology 67: in conjunction with management objectives Engagement and socio-economic research/understanding also required

3 US Projects: Stream Restoration as an Ecosystem Process Pollock et al., Using Beaver Dams to Restore Incised Stream Ecosystems. BioScience 64: Available from:

4 US Restoration Research and Projects

5 US Restoration Research and Projects Bouwes et al., Ecosystem experiment reveals benefits of natural and simulated beaver dams to a threatened population of steelhead (Oncorhynchus mykiss). Scientific Reports 6: Available from:

6 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?

7 Devon Beaver Project: Overview Fenced 1.8 ha site in North Devon 1 st 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 m 2 Site holding ca 1000 m 3 of water within ponds Frogspawn increased from 10 clumps in 2011 to 580 in 2016 Puttock et al., Aerial photography collected with a multirotor drone reveals impact of Eurasian beaver reintroduction on ecosystem structure. Journal of Unmanned Vehicle Systems.

8 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 (m 3 ) Below Beaver (red) Peak Discharge = 0.04 (mᶟ s ¹) Storm event discharge = 1493 (m 3 ) Puttock et al., Eurasian beaver activity increases water storage, attenuates flow and mitigates diffuse pollution from intensively-managed grasslands. Science of The Total Environment 576.

9 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. Puttock et al., Eurasian beaver activity increases water storage, attenuates flow and mitigates diffuse pollution from intensively-managed grasslands. Science of The Total Environment 576.

10 Devon Beaver Project Results Sediment/Nutrient Storage ~100 T of Sediment ~15 T of Carbon

11 Need for projects across different scales: Cornwall Beaver Site on one of 3 main tributaries of Tresillian entering Ladock (2nd order). Total Catchment ha Site catchment 134 ha. Dominated by Farmland. 1+ year baseline monitoring Beavers introduced summer

12 Pre-beaver Cornwall Beaver Project Post-beaver

13 Catchment Scale: River Otter Beaver Trial

14 Catchment Scale: River Otter Beaver Trial - Management Issues

15 Catchment Scale: Behaviour, impact and risk modelling

16 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.

17 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.