“Identifying trade-offs and opportunities for forest carbon and wildlife using a climate change adaptation lens”

“Identifying trade-offs and opportunities for forest carbon and wildlife using a climate change adaptation lens”

This open access essay was published February 21, 2022 in Conservation Science and Practice. Access the article via the permanent web address (DOI). (https://doi.org/10.1111/csp2.12631)

Abstract

On a warming planet, a key challenge natural resource managers face is protecting wildlife while mitigating climate change—as through forest carbon storage—to the greatest extent possible. But in some ecosystems, habitat restoration for imperiled species may be incompatible with maximizing carbon storage. For example, promoting early successional forest conditions does not maximize stand-level carbon storage, whereas uniformly promoting high stocking or mature forest conditions in the name of carbon storage excludes species that require open or young stands. Here, we briefly review the literature regarding carbon and wildlife trade-offs and then explore four case studies from the Northern Forest region of the United States. In each case, human activities have largely dampened the influence of natural disturbances; restoring or emulating these disturbances is typically required for habitat restoration even when doing so equates to less carbon storage at the stand level. We propose that applying a climate adaptation lens can help managers and planners navigate these trade-offs and steer away from maladaptive practices that may ultimately reduce adaptive capacity. Instead, critically evaluating the consequences of stand-level management actions on both carbon and wildlife can then facilitate landscape-scale climate adaptation planning that supports a diversity of habitats alongside opportunities to invest in maximizing forest carbon.

Keywords: carbon storage; climate change mitigation; disturbance; early successional habitat restoration; woodlands

Citation

Littlefield, Caitlin E., and Anthony W. D'Amato. "Identifying trade‐offs and opportunities for forest carbon and wildlife using a climate change adaptation lens." Conservation Science and Practice 4, no. 4 (2022): e12631.

Endangered Myotis bats forage in regeneration openings in a managed forest

“Endangered Myotis bats forage in regeneration openings in a managed forest”

Available online October 15, 2021, in Forest Ecology and Management. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.foreco.2021.119757)

Abstract

Bat populations face numerous threats, including the loss of forests in which they roost and forage. Present-day forests are commonly managed for timber harvesting, recreation, and wildlife. Understanding bat responses to forest management is crucial for balancing the conservation of endangered bats and forest restoration. We used radio telemetry to study nocturnal movements and habitat selection patterns of female and juvenile bats of two forest-dependent, federally listed bat species in an oak-dominated managed forest. We estimated foraging space use and assessed habitat selection for 33 northern long-eared bats (Myotis septentrionalis) and 25 Indiana bats (Myotis sodalis) from May to August 2014–2017 in south-central Indiana, USA. Myotis septentrionalis space use averaged 176 ha and bats selected water, historic thinning, and patch cuts (≤4 ha) over other habitats, with all but one bat avoiding larger openings (≥4-ha clearcuts). Myotis sodalis space use averaged 343 ha and bats selected 4-ha patch cuts, historic openings, and historic thinning over other habitats. In contrast to M. septentrionalis, one-third of the M. sodalis foraged over larger clearcuts, while two-thirds foraged over smaller openings and thinnings. We showed that bats were attracted to small regeneration harvests of varying structural ages. Forests maintained for a mix of mature stands, thinned stands, shelterwoods, small regenerative cuts (<7 ha), and small water sources should provide suitable foraging habitat for these endangered Myotis species, while also promoting forest regeneration.

Citation

Divoll, Timothy J., Stephen P. Aldrich, G. Scott Haulton, and Joy M. O'Keefe. "Endangered Myotis bats forage in regeneration openings in a managed forest." Forest Ecology and Management 503 (2022): 119757.

Fire as a driver and mediator of predator–prey interactions

“Fire as a driver and mediator of predator–prey interactions”

This open access article was published March 23, 2022 in Biological Reviews. Access the article via the permanent web address (DOI). (https://doi.org/10.1111/brv.12853)

Abstract

Both fire and predators have strong influences on the population dynamics and behaviour of animals, and the effects of predators may either be strengthened or weakened by fire. However, knowledge of how fire drives or mediates predator–prey interactions is fragmented and has not been synthesised. Here, we review and synthesise knowledge of how fire influences predator and prey behaviour and interactions. We develop a conceptual model based on predator–prey theory and empirical examples to address four key questions: (i) how and why do predators respond to fire; (ii) how and why does prey vulnerability change post-fire; (iii) what mechanisms do prey use to reduce predation risk post-fire; and (iv) what are the outcomes of predator–fire interactions for prey populations? We then discuss these findings in the context of wildlife conservation and ecosystem management before outlining priorities for future research. Fire-induced changes in vegetation structure, resource availability, and animal behaviour influence predator–prey encounter rates, the amount of time prey are vulnerable during an encounter, and the conditional probability of prey death given an encounter. How a predator responds to fire depends on fire characteristics (e.g. season, severity), their hunting behaviour (ambush or pursuit predator), movement behaviour, territoriality, and intra-guild dynamics. Prey species that rely on habitat structure for avoiding predation often experience increased predation rates and lower survival in recently burnt areas. By contrast, some prey species benefit from the opening up of habitat after fire because it makes it easier to detect predators and to modify their behaviour appropriately. Reduced prey body condition after fire can increase predation risk either through impaired ability to escape predators, or increased need to forage in risky areas due to being energetically stressed. To reduce risk of predation in the post-fire environment, prey may change their habitat use, increase sheltering behaviour, change their movement behaviour, or use camouflage through cryptic colouring and background matching. Field experiments and population viability modelling show instances where fire either amplifies or does not amplify the impacts of predators on prey populations, and vice versa. In some instances, intense and sustained post-fire predation may lead to local extinctions of prey populations. Human disruption of fire regimes is impacting faunal communities, with consequences for predator and prey behaviour and population dynamics. Key areas for future research include: capturing data continuously before, during and after fires; teasing out the relative importance of changes in visibility and shelter availability in different contexts; documenting changes in acoustic and olfactory cues for both predators and prey; addressing taxonomic and geographic biases in the literature; and predicting and testing how changes in fire-regime characteristics reshape predator–prey interactions. Understanding and managing the consequences for predator–prey communities will be critical for effective ecosystem management and species conservation in this era of global change.

Keywords: carnivore; foraging behavior; hunting behavior; interaction; landscape of fear; mega-fire; multiple threats; predation rates; prescribed burning; wildfire

Citation

Doherty, Tim S., William L. Geary, Chris J. Jolly, Kristina J. Macdonald, Vivianna Miritis, Darcy J. Watchorn, Michael J. Cherry et al. "Fire as a driver and mediator of predator–prey interactions." Biological Reviews 97, no. 4 (2022): 1539-1558.

Exposure to fire affects acorn removal by altering consumer preference

“Exposure to fire affects acorn removal by altering consumer preference”

Available online February 3, 2022, in Forest Ecology and Management. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.foreco.2022.120044)

Abstract

Prescribed fire has been encouraged as a management tool to increase oak regeneration across the southeastern United States. The least utilized part of the burn window in this region is during fall, but burning in this season with the objective of oak regeneration has been discouraged because of the potential negative consequences on subsequent germination. While exposure to fire decreases acorn viability, acorns cached in recently burned areas increases their survival. By following the fate of unburned acorns added to those areas, previous studies identified post-fire habitat characteristics (e.g., altering vegetation structure, decreased leaf litter, etc.) as a cause of increased acorn establishment success. However, exposing acorns to fire may also contribute to fate of surviving acorns by changing consumer removal rates. We exposed acorns to fire and established cafeteria-style experiments in unburned forests to compare burned and unburned acorn selection and removal rate of eight oak species by caching and non-caching consumers (i.e., predator type). Exposing acorns to fire did not appear to affect selection of oak species but affected overall removal risk for acorns differently by species of consumers. For example, while one important non-caching consumer (white-tailed deer, Odocoileus virginianus) and caching consumer (southern flying squirrel, Glaucomys Volans) showed strong selection of burned acorns, other important consumers in each predator type showed little discrimination or strong selection of unburned acorns (e.g., southern fox squirrel Sciurus niger). Exposure to fire reduced the overall rate of removal of acorns and when an acorn was removed, fire significantly reduced the probability that it would be removed by a caching consumer. Overall, our experiment demonstrates that shifts in consumer removal for exposed acorns may play an important role in the net effects of fall burning on oak regeneration.

Citation

Boggess, C. Moriah, Carolina Baruzzi, Heather D. Alexander, Bronson K. Strickland, and Marcus A. Lashley. "Exposure to fire affects acorn removal by altering consumer preference." Forest Ecology and Management 508 (2022): 120044.

Measuring flammability of crops, pastures, fruit trees, and weeds: A novel tool to fight wildfires in agricultural landscapes

"Measuring flammability of crops, pastures, fruit trees, and weeds: A novel tool to fight wildfires in agricultural landscapes"

This open access article was published October 5, 2023, in Science of the Total Environment . Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.scitotenv.2023.167489)

Abstract

Fires on agricultural land account for 8–11 % of the total number of fires that occur globally. These fires burn through various crops, pastures, and native vegetation on farms, causing economic and environmental losses. Fire management on farms will be aided by understanding the flammability of plant species as this would allow the design of low-flammability agricultural landscapes, but flammability data on large numbers of agricultural species are lacking. Many crop and vegetable species are assumed to be low in flammability, but this has rarely been tested. Therefore, we examined the shoot and whole-plant flammability of 47 plant taxa commonly grown on farms in Canterbury, New Zealand, which included many globally common temperate agricultural crops. We demonstrated that most of the agricultural species were low to very low in flammability, with many of them (24 taxa; 51 %) not igniting in the experimental burning. Among different crop types, fruit crops and cereals had significantly higher flammability, while taxa categorized as vegetable crops, grazing herbs, pasture grasses, pasture legumes, and weeds were lower in flammability. We further showed that taxa with lower moisture content, higher retention of dead material and faster moisture loss rates were higher in flammability. The strong variation of flammability between the studied taxa suggests that the selection of suitable low flammability species and strategic redesign of agricultural landscapes with fire-retardant planting can be a useful tool to reduce fire hazards and impacts of wildfires in agricultural landscapes.

Conclusion

Our study has compared the flammability of plant species commonly found in a temperate agricultural landscape and shows how knowledge of plant flammability can be applied to assess fire hazards and used to design landscapes to combat wildfire. By categorising the flammability of agricultural plant species, this study will enable farmers and landholders to redesign their farms, wherein they may be able to plant any low-flammability species, in areas they deem as high fire hazards. Overall, this knowledge will improve our understanding of the temporal and spatial variation of fire spread and intensity in agricultural landscapes and help prepare for wildfires in the age of rapid global climate change.

Citation

Tanmayi Pagadala, Md Azharul Alam, Thomas M.R. Maxwell, Timothy J. Curran, Measuring flammability of crops, pastures, fruit trees, and weeds: A novel tool to fight wildfires in agricultural landscapes, Science of The Total Environment, Volume 906, 2024, 167489, ISSN 0048-9697

Escaping the fire trap: Does frequent, landscape-scale burning inhibit tree recruitment in a temperate broadleaf ecosystem?

“Escaping the fire trap: Does frequent, landscape-scale burning inhibit tree recruitment in a temperate broadleaf ecosystem?” 

Available online April 2, 2022, in Forest Ecology and Management. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.foreco.2022.120191) 

Abstract 

Frequent prescribed burning is commonly used to restore and maintain open forest ecosystems in temperate broadleaf regions of the eastern United States. Repeated surface fires reduce the abundance of small woody stems through top-kill or mortality, with implications for age structure and ecosystem development. In this study, we quantified tree recruitment patterns over two decades across two landscape-scale studies in Missouri: the Missouri Ozark Forest Ecosystem Project (a control, with no burning) and the Chilton Creek Management Area (burned on 2–3 year fire return interval). Through time, frequent burning reduced the rate of ingrowth (i.e., new trees entering the overstory size class, defined as ≥11.4 cm diameter at breast height (DBH)), and the effect of burning on the ingrowth rate was consistent across site types (summits, exposed backslopes, protected backslopes, or upland waterways). Two decades of frequent burning reduced the abundance of scarlet oak (Quercus coccinea) in the ingrowth population. In the unburned control, the proportional abundance of mesic species such as red maple (Acer rubrum) and blackgum (Nyssa sylvatica) increased during the study period; frequent fire controlled the population of red maple but resulted in a similar increase in blackgum abundance in the ingrowth population of the burned area. Our results indicate that frequent burning affects the tree recruitment process in multiple ways: 1) reducing the source population for recruitment by reducing midstory abundance; 2) increasing probability of mortality or top-kill during the recruitment period. Fire-free periods may be necessary to allow eventual replacement of canopy trees in temperate broadleaf open forest ecosystems. 

Citation 

Knapp, Benjamin O., Calvin J. Maginel, Bradley Graham, John M. Kabrick, and Daniel C. Dey. "Escaping the fire trap: Does frequent, landscape-scale burning inhibit tree recruitment in a temperate broadleaf ecosystem?." Forest Ecology and Management 513 (2022): 120191. 

Impacts of Riparian and Non-riparian Woody Encroachment on Tallgrass Prairie Ecohydrology

"Impacts of Riparian and Non-riparian Woody Encroachment on Tallgrass Prairie Ecohydrology"

This open access article was published April 13, 2022, in Ecosystems. Access the article via the permanent web address (DOI). (https://doi.org/10.1007/s10021-022-00756-7)

Abstract

Woody encroachment has impacted grassland ecohydrology worldwide, prompting management strategies aimed at woody vegetation removal to prevent or mitigate loss of water yield. We measured stream discharge following sustained cutting of riparian trees (2010–2020) in a native tallgrass prairie (northeastern Kansas, USA). Discharge has declined at this site since the 1980’s despite a concurrent increase in precipitation. This decline has been previously attributed to increased transpiration of stream water by riparian vegetation. We used water stable isotopes (δ¹⁸O and δ²H) to determine whether riparian grasses, shrubs, and trees primarily used stream/groundwater or soil water. Additionally, we quantified the increase in riparian and non-riparian woody cover (1978–2020) and combined it with sap-flux data to estimate changes in transpirative water loss. Sustained cutting of riparian trees did not result in increased discharge. Rather than stream/groundwater, the largest proportion of water used by riparian trees (Quercus spp.) was deep soil water. Cornus drummondii (clonal woody shrub) used a higher proportion of stream water and had greater overall variability in water-use. Riparian shrub cover increased about 57% from 1978 to 2020. Over the same time period, shrub cover increased about 20% in areas outside the riparian zone, resulting in an estimated 25% increase in daily transpirative water loss. Although stream water use was less than 50% for all riparian zone species, the total increase in shrub cover on this watershed, coupled with higher transpiration rates of shrubs, suggests that these woody species—within and outside the riparian zone—are key contributors to observed declines in stream flow in this system.

Citation

Keen, R.M., Nippert, J.B., Sullivan, P.L. et al. "Impacts of Riparian and Non-riparian Woody Encroachment on Tallgrass Prairie Ecohydrology." Ecosystems 26, 290–301 (2023). 

Estimated Mortality and Morbidity Attributable to Smoke Plumes in the United States: Not Just a Western US Problem

"Estimated Mortality and Morbidity Attributable to Smoke Plumes in the United States: Not Just a Western US Problem"

This open access article was published August 21, 2021, in GeoHealth. Access the article via the permanent web address (DOI).  (https://doi.org/10.1029/2021GH000457)

Abstract

As anthropogenic emissions continue to decline and emissions from landscape (wild, prescribed, and agricultural) fires increase across the coming century, the relative importance of landscape-fire smoke on air quality and health in the United States (US) will increase. Landscape fires are a large source of fine particulate matter (PM2.5), which has known negative impacts on human health. The seasonal and spatial distribution, particle composition, and co-emitted species in landscape-fire emissions are different from anthropogenic sources of PM2.5. The implications of landscape-fire emissions on the sub-national temporal and spatial distribution of health events and the relative health importance of specific pollutants within smoke are not well understood. We use a health impact assessment with observation-based smoke PM2.5 to determine the sub-national distribution of mortality and the sub-national and sub-annual distribution of asthma morbidity attributable to US smoke PM2.5 from 2006 to 2018. We estimate disability-adjusted life years (DALYs) for PM2.5 and 18 gas-phase hazardous air pollutants (HAPs) in smoke. Although the majority of large landscape fires occur in the western US, we find the majority of mortality (74%) and asthma morbidity (on average 75% across 2006–2018) attributable to smoke PM2.5 occurs outside the West, due to higher population density in the East. Across the US, smoke-attributable asthma morbidity predominantly occurs in spring and summer. The number of DALYs associated with smoke PM2.5 is approximately three orders of magnitude higher than DALYs associated with gas-phase smoke HAPs. Our results indicate awareness and mitigation of landscape-fire smoke exposure is important across the US.

Plain Language Summary

The pollutants from landscape (wild, prescribed, and agricultural) fires are expected to have an increasing impact on air quality and health in the United States (US) across the current century. The implications of landscape-fire smoke on the regional and seasonal distribution of health events and the relative health importance of specific pollutants within smoke are not well understood. In the present study, we assess the seasonal and regional distribution of the health impacts from US smoke exposure from 2006 to 2018. We also estimate the long-term health impacts for both fine particles (PM2.5) and gas-phase hazardous air pollutants (HAPs) in smoke. Although the majority of large landscape fires occur in the western US, we find the majority of deaths (74%) and asthma emergency department visits and hospital admissions (on average 75% across 2006–2018) attributable to smoke occur outside the West. Across the US, smoke-attributable asthma emergency department visits predominantly occur in spring and summer. The long-term health impacts associated with smoke PM2.5 are much higher than the estimated long-term health impacts of gas-phase smoke HAPs. Our results indicate awareness and mitigation of landscape-fire smoke exposure is important across the US, not just in regions in proximity to large wildfires.

Keywords: air quality; wildfire smoke; PM2.5; hazardous air pollutants; health impact assessment

Citation

O’Dell, K., Bilsback, K., Ford, B., Martenies, S. E., Magzamen, S., Fischer, E. V., & Pierce, J. R. (2021). "Estimated mortality and morbidity attributable to smoke plumes in the United States: Not just a western US problem." GeoHealth,  5, e2021GH000457.

Wildfire, Smoke Exposure, Human Health, and Environmental Justice Need to be Integrated into Forest Restoration and Management

"Wildfire, Smoke Exposure, Human Health, and Environmental Justice Need to be Integrated into Forest Restoration and Management"

This open access article was published May 7th, 2022, in Current Environmental Health Reports. Access the article via the permanent web address (DOI). (https://doi.org/10.1007/s40572-022-00355-7)

Abstract

Purpose of Review

Increasing wildfire size and severity across the western United States has created an environmental and social crisis that must be approached from a transdisciplinary perspective. Climate change and more than a century of fire exclusion and wildfire suppression have led to contemporary wildfires with more severe environmental impacts and human smoke exposure. Wildfires increase smoke exposure for broad swaths of the US population, though outdoor workers and socially disadvantaged groups with limited adaptive capacity can be disproportionally exposed. Exposure to wildfire smoke is associated with a range of health impacts in children and adults, including exacerbation of existing respiratory diseases such as asthma and chronic obstructive pulmonary disease, worse birth outcomes, and cardiovascular events. Seasonally dry forests in Washington, Oregon, and California can benefit from ecological restoration as a way to adapt forests to climate change and reduce smoke impacts on affected communities.

Recent Findings

Each wildfire season, large smoke events, and their adverse impacts on human health receive considerable attention from both the public and policymakers. The severity of recent wildfire seasons has state and federal governments outlining budgets and prioritizing policies to combat the worsening crisis. This surging attention provides an opportunity to outline the actions needed now to advance research and practice on conservation, economic, environmental justice, and public health interests, as well as the trade-offs that must be considered.

Summary

Scientists, planners, foresters and fire managers, fire safety, air quality, and public health practitioners must collaboratively work together. This article is the result of a series of transdisciplinary conversations to find common ground and subsequently provide a holistic view of how forest and fire management intersect with human health through the impacts of smoke and articulate the need for an integrated approach to both planning and practice.

Citation

D’Evelyn, S.M., Jung, J., Alvarado, E. et al. Wildfire, Smoke Exposure, Human Health, and Environmental Justice Need to be Integrated into Forest Restoration and Management.Curr Envir Health Rpt 9, 366–385 (2022).

Functional consequences of animal community changes in managed grasslands: An application of the CAFE approach

"Functional consequences of animal community changes in managed grasslands: An application of the CAFE approach"

This open access article was published October 25, 2023, in Ecology. Access the article via the permanent web address (DOI). (https://doi.org/10.1002/ecy.4192)

Abstract

In the midst of an ongoing biodiversity crisis, much research has focused on species losses and their impacts on ecosystem functioning. The functional consequences (ecosystem response) of shifts in communities are shaped not only by changes in species richness, but also by compositional shifts that result from species losses and gains. Species differ in their contribution to ecosystem functioning, so species identity underlies the consequences of species losses and gains on ecosystem functions. Such research is critical to better predict the impact of disturbances on communities and ecosystems. We used the “Community Assembly and the Functioning of Ecosystems” (CAFE) approach, a modification of the Price equation to understand the functional consequences and relative effects of richness and composition changes in small nonvolant mammal and dung beetle communities as a result of two common disturbances in North American prairie restorations, prescribed fire and the reintroduction of large grazing mammals. Previous research in this system has shown dung beetles are critically important decomposers, while small mammals modulate much energy in prairie food webs. We found that dung beetle communities were more responsive to bison reintroduction and prescribed fires than small nonvolant mammals. Dung beetle richness increased after bison reintroduction, with higher dung beetle community biomass resulting from changes in remaining species (context-dependent component) rather than species turnover (richness components); prescribed fire caused a minor increase in dung beetle biomass for the same reason. For small mammals, bison reintroduction reduced energy transfer through the loss of species, while prescribed fire had little impact on either small mammal richness or energy transfer. The CAFE approach demonstrates how bison reintroduction controls small nonvolant mammal communities by increasing prairie food web complexity, and increases dung beetle populations with possible benefits for soil health through dung mineralization and soil bioturbation. Prescribed fires, however, have little effect on small mammals and dung beetles, suggesting a resilience to fire. These findings illustrate the key role of re-establishing historical disturbance regimes when restoring endangered prairie ecosystems and their ecological function.

Keywords: bison; community assembly; dung beetle; ecosystem function; prescribed fire; Price equation; small mammal; species richness; tallgrass prairie restoration

Citation

Hogan, Katharine FE, Holly P. Jones, Kirstie Savage, Angela M. Burke, Peter W. Guiden, Sheryl C. Hosler, Erin Rowland‐Schaefer, and Nicholas A. Barber. "Functional consequences of animal community changes in managed grasslands: An application of the CAFE approach." Ecology (2023): e4192.