A possible role for river restoration enhancing biodiversity through interaction with wildfire

Abstract

Background: Historically, wildfire regimes produced important landscape-scale disturbances in many regions globally. The "pyrodiversity begets biodiversity" hypothesis suggests that wildfires that generate temporally and spatially heterogeneous mosaics of wildfire severity and post-burn recovery enhance biodiversity at landscape scales.However, river management has often led to channel incision that disconnects rivers from their floodplains, desiccating floodplain habitats and depleting groundwater. In conjunction with predicted increases in frequency, intensity and extent of wildfires under climate change, this increases the likelihood of deep, uniform burns that reduce biodiversity. Predicted synergy of river restoration and biodiversity increase:Recent focus on floodplain re-wetting and restoration of successional floodplain habitat mosaics, developed for river management and flood prevention, could reduce wildfire intensity in restored floodplains and make the burns less uniform, increasing climate-change resilience; an important synergy. According to theory, this would also enhance biodiversity. However, this possibility is yet to be tested empirically. We suggest potential research avenues. Illustration and future directions:We illustrate the interaction between wildfire and river restoration using a restoration project in Oregon, USA. A project to reconnect the South Fork McKenzie River and its floodplain suffered a major burn ("Holiday Farm" wildfire, 2020), offering a rare opportunity to study the interaction between this type of river restoration and wildfire; specifically, the predicted increases in pyrodiversity and biodiversity. Given the importance of river and wetland ecosystems for biodiversity globally, a research priority should be to increase our understanding of potential mechanisms for a "triple win" of flood reduction, wildfire alleviation and biodiversity promotion.

Increasing threat of wildfires: the year 2020 in perspective: A Global Ecology and Biogeography special issue

“…Alterations to landscape hydrology that result in floodplain dehydration, for example draining and homogenization of wetlands, can increase wildfire risk (Ferreira Barbosa et al, 2022;Pugh et al, 2022).…”

“…Alterations to landscape hydrology that result in floodplain dehydration, for example draining and homogenization of wetlands, can increase wildfire risk (Ferreira Barbosa et al, 2022; Pugh et al, 2022). Altered hydrology was identified by Ferreira Barbosa et al (2022) as one of the factors linked to the large burn area in the Brazilian Pantanal, one of the world's largest wetlands (Garcia et al, 2021).…”

“…The authors found that fire refugia were largely affected by microsite hydrological conditions, controlled by topography. The rewetting mechanism put forward byPugh et al (2022) in this special issue is similarly likely to provide such refugia. As landscapes around the globe are subjected to changing fire regimes, the characteristics that promote or imperil unburned refugia will be critical to understand vegetation and faunal recovery.…”

“…Since 1985, the Pantanal has lost 68% of its water mass, with the 2020 flooded area 83% lower compared to average (FerreiraBarbosa et al, 2022). In the western United States, altered hydrology may also be affecting fire regimes, asPugh et al (2022) describe in this special issue. The authors argue that floodplain restoration resulting in re-wetting could result in wildfires that are less severe and less homogeneous.…”

EEAGER: A Neural Network Model for Finding Beaver Complexes in Satellite and Aerial Imagery

“…There are no systematic or widespread beaver population monitoring programs in the United States, however, it is estimated that the current population of beavers in North America is roughly 15–30 million (Naiman et al., 1988). The conversation around beavers has shifted in recent decades, with more emphasis placed on the idea of beavers as river restoration partners rather than as pests or commodities (Johnson et al., 2019; Jordan & Fairfax, 2022; Pollock et al., 2015; Pugh et al., 2022; Skidmore & Wheaton, 2022). Recent research highlights the ability for beaver activity to sequester carbon (Laurel & Wohl, 2019; Wohl, 2013), support sensitive, threatened, and endangered species (Anderson et al., 2015; Bouwes et al., 2016; Dittbrenner et al., 2022; Romansic et al., 2020), attenuate flood waves (A. Puttock et al., 2017, 2021; C. J. Westbrook et al., 2020), keep vegetation green and maintain baseflow during droughts (Fairfax & Small, 2018; Silverman et al., 2019), and create patches of wildfire refugia (Fairfax & Whittle, 2020; Foster et al., 2020; Whipple, 2019; Wohl et al., 2022).…”