Synergistic fire and floodplain solutions

Lead Research Organisation: University of Nottingham
Department Name: Sch of Geography

Abstract

Wildfires, already a major concern in all continents, are forecast to increase in frequency and intensity, impacting parts of the world not previously affected (including the UK under future climate change). Indeed, 2020 was a record year for wildfires globally, and they are estimated to have cost $13 billion in the USA alone (Reuters December 15, 2020). Poor river management practices have contributed to the increased threat of wildfires by drying floodplains, creating a tinderbox effect. For centuries, humans have modified rivers, typically converting multi-channelled rivers into single, deeper channels. This drains and disconnects floodplains, lowers water tables, increases downstream flood risk, and reduces biodiversity by reducing the variety of riverine environments. Changing our approach to river management can therefore have multiple benefits: reduce fires, reduce flooding and increase biodiversity and ecosystem services.

Since 2010, floodplain restoration theory has begun to move towards reinstating multiple river channels and increasing wetted area to slow flow velocities and encourage groundwater recharge. This has become known as 'Stage 0' restoration because it aims to return rivers to their natural (pre-human intervention) state. Several sites have been set up to test the effectiveness of the approach, notably the South Fork McKenzie River restoration project in Oregon, USA, which started in 2017. One third of the floodplain has been restored to date. A $1.2 million data collection programme was established, running for 3 years so far, which includes monitoring of wildlife and vegetation, on the land and in the water, to assess the effectiveness of the restoration, relative to unrestored parts of the floodplain. The project's success has recently led to similar floodplain restoration trials in the UK, notably on National Trust land in Porlock Vale, Somerset.

Stage 0 restoration has many potential benefits, but until now it has not even been considered in terms of wildfire. However, this changed dramatically in Sept-Nov 2020, when a major wildfire (the 'Holiday Farm Fire') swept through the South Fork McKenzie area, at its peak burning >60,000 ha in 36 hours. The fire only ceased in late Nov 2020, but limited access to the site has recently been granted to the project team. Initial observations strongly suggest that while other parts of the landscape suffered a severe, uniform burn, the restored areas of the floodplain resulted in a diverse fire mosaic, with many parts suffering little or no fire damage. As well as reduced overall burn severity, the more diverse fire intensity in the restored area may actually have biodiversity benefits and build further ecological resilience, according to recent hypotheses in wildfire ecology. The Holiday Farm Fire therefore provides a unique and time-limited opportunity to investigate the ecological and environmental effects of the interaction between wildfire and Stage 0 floodplain restoration. The project site, with 33% of the floodplain restored and the rest as yet unimproved, combined with the detailed baseline data available and a large, very recent fire event, effectively presents us with a natural landscape-scale experiment. We intend to use this amazing opportunity to test the two hypotheses, and to develop both important new understanding of freshwater and terrestrial biodiversity on floodplains, and practical solutions for managing floodplains under both climate change and increasing wildfire risk.

Publications

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Description This one-year project is only part-way through at the moment. As explained in the 'Skills shortage' section of this form, we were granted a no-cost extension because one of the key project team members went on maternity leave shortly after the start of the project. It is therefore too early to meaningfully talk about key findings: we are in the process of analysing the data we have been collecting and assembling (some of the data are still coming in). We can report that our preliminary findings do seem to be in support of the hypotheses put forward in our application - essentially that floodplain re-wetting does indeed seem to reduce impact of wildfire, and create a mosaic of effects that may promote biodiversity. Accordingly, we have just submitted (on 15 March 2022) the first paper from the project, which is a Perspective paper that identifies a gap in our knowledge and understanding, outlines research priorities and illustrates the issues using our preliminary findings. (Not reported in the outputs section because it is only submitted, not published.)

Our next paper is underway, which will be based on a much deeper analysis of the full dataset. This will directly address the three award objectives:
Objective 1. Map burn severity immediately post-fire across restored and unrestored areas (data collected; maps currently being produced).
Objective 2. Compare biodiversity and recovery between restored and unrestored areas (data collected; currently being processed for analysis).
Objective 3. Test the pyrodiversity and fire-related shifting habitat mosaics hypotheses (data collected; currently being processed for analysis).

Given that the findings to date do seem to be as interesting and important as we suggested in our original application that they might be, we are also now starting to prepare a new grant application. For this, we are likely to target the new NERC scheme 'Exploring the frontiers of environmental science research 2022'. We will also be applying for a NERC-funded PhD studentship at the University of Nottingham (through the NERC Envision DTP). Finally, we have started discussing with our US colleagues the possibility of a NERC-NSF collaborative grant, though currently we expect that to follow the two applications stated above, rather than being concurrent with them.
Exploitation Route It is largely about joining up thinking, in terms of both theory and practical application, on key environmental issues facing the world today. Specifically, our work revolves around three major issues, all of which are of great current concern: wildfires, flooding and biodiversity. We have highlighted connections between these that have not been made before and the funding has allowed us to start to collect evidence. Thus it is forging a new area of interdisciplinary research, and that is what our recently submitted Perspective paper is promoting.

As the theory and evidence build with the further progress of our project, and given that we are working with the USDA Forest Service, we expect that on-the-ground management will start to change as a result of our work. It looks like we will find that land can be managed for the joint purpose of reducing flood risk, reducing fire risk and promoting biodiversity. That would be a step-change from the typical current situation of pursuing such aims in isolation, which often results in detriment to the others - for example, river straightening drying out floodplains, thus increasing fire risk and reducing biodiversity.
Sectors Environment

 
Title SFMR SFFS Avian data 
Description Bird point count data collected across 23 sites covering the restored and unrestored reaches of the South Fork McKenzie River. Observations carried out in June 2021, following method established in Ralph et al. (1993). Metadata comprises GPS coordinates and photos from each site, as well cloud cover, wind speed and air temperature. [Ralph, C. John; Geupel, Geoffrey R.; Pyle, Peter; Martin, Thomas E.; DeSante, David F. 1993. Handbook of field methods for monitoring landbirds. Gen. Tech. Rep. PSW-GTR-144-www. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; 41 p] 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
Impact N/a 
URL https://data.pointblue.org/apps/data_catalog/dataset/southforkmckenzie
 
Title SFMR SFFS Macroinvertebrate data 
Description Aquatic macroinvertebrate samples (Surber samples) taken at the restored and unrestored reaches of the South Fork McKenzie River during April 2021. Data comprises macroinvertebrate observations (currently undergoing identification) as well as supporting metadata (eg. GPS locationl, geomorphic context, vegetation cover, etc). 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? No  
Impact N/a 
 
Title SFMR SFFS Periphyton data 
Description Diatom samples collected concurrently (same sites) as aquatic macroinvertebrate samples. Data comprises 13 diatom scrubs collected in April 2021 and June 2021. Currently awaiting completing of identification and chlorophyll analysis of July 2020 dataset. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? No  
Impact N/a 
 
Title SFMR SFFS Remote sensing data 
Description Normalised Vegetation Difference Index (NDVI) and Normalised Burn Ratio (NBR) rasters generated from Sentinel 2A/2B imagery of South Fork McKenzie River site aquired in June 2020 and June 2021. NDVI generated from native 10 m resolution data (B08, B04), NBR generated from native 20 m resolution data (B08A and B12) subsequently upscaled to 10 m resolution using CNN-based super-resolution (following Lanaras et al. 2018) [Lanaras, C., Bioucas-Dias, J., Galliani, S., Baltsavias, E., & Schindler, K. (2018). Super-resolution of Sentinel-2 images: Learning a globally applicable deep neural network. ISPRS Journal of Photogrammetry and Remote Sensing, 146, 305-319] 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? No  
Impact N/a 
 
Title SFMR SFFS Soil data 
Description Soil samples collected at the restored and unrestored reaches of the South Fork McKenzie River during February (n = 27) and June (n = 33) 2021. Soils collected using T-bar, bulk samples taken at 0-30 cm, 30-60 cm and 60-90 cm (where deeper samples feasible). Samples subsequently processed for total carbon, total organic carbon, nitrate, total nitrogen, nitrite, texture, grain size analysis. BAER soil burn severity observation, infiltration tests and water repellency tests also carried out at each site. 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? No  
Impact N/a 
 
Title SFMR SFFS Vegetation data 
Description Vegetation surveys from 5 locations across the restored and unrestored reaches of the South Fork McKenzie River. Surveys carried out during July 2021, following Prior & Bowman (2020). Comprises species presence per quadrat, ground vegetation class, vegetation cover (%) and densiometer readings. [Prior, L. D., and D. M. J. S. Bowman. 2020. Classification of Post-Fire Responses of Woody Plants to include Pyrophobic Communities. Fire, 15] 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? No  
Impact N/a 
 
Description Collaboration with USDA Forest Service 
Organisation U.S. Department of Agriculture USDA
Department United States Forest Service
Country United States 
Sector Academic/University 
PI Contribution Our project team is working with the USDA Forest Service, jointly collecting data in the field, sharing data and working on joint publications. The datasets listed for this project result in part from the collaboration. The papers to result from this project (currently either submitted or in preparation, so not listed in this report) are co-authored by people from the USDA Forest Service.
Collaborator Contribution As stated above, the USDA Forest Service is working with our project team, sharing data and working on joint publications. They have helped us assemble the datasets, both by working with us in the field and sharing data from remote sensing and other sources. They are co-authoring the project's papers. Specifically, those involved are from the north-west of the USA (Washington and Oregon states), including the Pacific Northwest Research Station and Willamette Forest Department.
Impact Datasets are currently the tangible outputs to result from this collaboration. The first datasets from the collaboration have been released - details in the datasets section. More are to come as the project progresses. So far one paper has been submitted, with the next being drafted. With the project still ongoing and far from our end date (Sept 2022), none of the papers are yet published, so do not yet have entries in the publications section.
Start Year 2021