"Timing of prescribed burns impacts plant diversity but not investment in pollinator recruitment in a tallgrass prairie" #GRASSLANDS #rxfire #seasonality #pollinators #insectthursday @darrenrebar @GPFIRESCIENCE @prairiefiresci @esaecosphere

"Timing of prescribed burns impacts plant diversity but not investment in pollinator recruitment in a tallgrass prairie"

This open access article was published Jan. 27 , 2022 in the journal Ecosphere. Access the article via the permanent web address (DOI). (https://doi.org/10.1002/ecs2.3914)

Abstract

Prescribed burns replicate the historic fires that played a key role in maintaining prairies. Spring-applied burns are commonly employed for grazing and brush control and, therefore, much is known about their effects. However, prairie plants may be sensitive to the historically variable timing of burns and thus differentially respond to when prescribed burns are applied, an aspect that remains poorly understood.

We performed three experimental seasonal burn treatments (summer, fall, or spring) in tallgrass prairie and examined (1) the response of the flowering forb community in terms of density and diversity, and (2) how individual milkweed plants (Asclepias spp.) invested in nectar to recruit pollinators.

We found that burn timing did not affect flowering forb density but did impact flowering forb diversity: It was lowest following spring burns, whereas summer- and fall-burned plots were more diverse. Nectar sucrose concentrations in milkweeds, however, were not affected by the timing of burns but rather seemed robust in their investment to recruit pollinators.

Therefore, while individual plant investment strategies may be more sensitive to other factors, the timing of prescribed burns seems important in promoting flowering forb diversity, which could have important downstream consequences on the diversity of pollinators and other animal communities.

Keywords: burn season; fire ecology; grassland; insect community; milkweed; nectar; sucrose concentration

Citation

Roberton, Bethany, and Darren Rebar. "Timing of prescribed burns impacts plant diversity but not investment in pollinator recruitment in a tallgrass prairie." Ecosphere 13, no. 1 (2022): e3914.

“Prescribed grass fire evolution mapping and rate of spread measurement using orthorectified thermal imagery from a fixed-wing UAS” #rxfire #grassland @IJRemoteSensing @USDA_NIFA @kuengineering @kufieldstation

“Prescribed grass fire evolution mapping and rate of spread measurement using orthorectified thermal imagery from a fixed-wing UAS”

This article was published online March 24, 2022, in the International Journal of Remote Sensing. Access the article via the permanent web address (DOI). (https://doi.org/10.1080/01431161.2022.2044538)

Abstract

Fire metrics such as fire front location and rate of spread (ROS) are critical to understanding the behavior of prescribed fires and wildfires. This paper proposes a new method for prescribed grass fire evolution mapping and ROS measurement using multitemporal thermal orthomosaics collected by a small fixed-wing Unmanned Aircraft System (UAS) at low altitudes. The proposed method provides a low-cost, safe, and effective solution for active grass fire monitoring and fire metric measurement in areas that may be challenging for a typical rotor-wing UAS to cover due to endurance and size constraints.

The proposed method is demonstrated using a prescribed grass fire data set collected by the KHawk fixed-wing UAS over a 13 ha. Kansas tallgrass prairie field on 8 October 2019. Repeat-pass thermal images collected by the KHawk UAS during about 10 min of the burning were grouped and processed to produce multitemporal orthomosaics with a spatial resolution of about 0˜.23 m and a horizontal position error of about 1.5 m. The resulting orthomosaics were further processed for fire front extraction and the measurement of fire front location and ROS.

The head fire ROS of this grass burn was observed to be between 0.2 and 0.4 ms−1 with a mean value of 0.27 ms−1.

Keywords: Unmanned aircraft system (UAS); grass fire monitoring; prescribed grass fire rate of spread; thermal remote sensing; thermal imagery; hazard monitoring

Citation

Gowravaram, Saket, Haiyang Chao, Tiebiao Zhao, Sheena Parsons, Xiaolin Hu, Ming Xin, Harold Flanagan, and Pengzhi Tian. "Prescribed grass fire evolution mapping and rate of spread measurement using orthorectified thermal imagery from a fixed-wing UAS." International Journal of Remote Sensing 43, no. 7 (2022): 2357-2376.

“Effects of 34 years of experimentally manipulated burn seasons and frequencies on prairie plant composition” #rxfire #grassland @rangelands @UNOmaha

“Effects of 34 years of experimentally manipulated burn seasons and frequencies on prairie plant composition”

This open access article was published in January 2019 in Rangeland Ecology and Management. Access the article via the permanent web address (DOI) (https://doi.org/10.1016/j.rama.2018.07.014)

Abstract

Historically, tallgrass prairie burns occurred at many seasons and frequencies. Currently, tallgrass prescribed burns often occur annually in the spring, usually for cattle forage production. Altering burning season and frequency is known to affect plant composition and biomass production, but researchers are still uncertain how burning season and frequency interact.

We present the long-term effects of a factorial combination of different burn seasons (spring, summer, autumn, or variable [rotated through seasons]) and frequencies (annual or quadrennial) on the plant composition and biomass production of an ungrazed, restored tallgrass prairie in eastern Nebraska, United States. The experimental plots were established in 1978 and visually surveyed for baseline data in 1979 and 1981. Experimental burn treatments were begun in 1982. Plots were visually surveyed until 2011 with the following results: 1) annual spring and summer burns increased C4 graminoid abundance; 2) annual autumn burns increased forb abundance; 3) burn season had little effect on plant composition for quadrennial burns; and 4) variable season burns generally led to plant composition that was intermediate between annual spring/summer and annual autumn burns. We also clipped biomass to estimate aboveground annual net primary production (ANPP) in 2015, a year in which both annual and quadrennial burns occurred.

Total ANPP did not differ significantly between burn frequencies nor between spring and autumn burns (772 g m− 2 average) but was lower in summer burns (541 g m− 2). ANPP results were similar to visual surveys, with significantly higher C4 graminoid ANPP in spring than autumn burns and significantly lower forb and C3 graminoid ANPP in spring than autumn burns.

Overall, these results suggest autumn burns can increase forb and C3 graminoid abundance, without strongly affecting total ANPP relative to spring burns. Future studies should compare plant and livestock production between spring and autumn burns in grazed fields.

Citation

Dickson, Timothy L., Barbara A. Hayes, and Thomas B. Bragg. "Effects of 34 years of experimentally manipulated burn seasons and frequencies on prairie plant composition." Rangeland Ecology & Management 72, no. 1 (2019): 82-91.

“Research gaps limit understanding of invasion-fire cycles” @lflory

“Research gaps limit understanding of invasion-fire cycles”

First published Nov. 1, 2022 in Biological Invasions. Access the article via the permanent web address (DOI) (https://doi.org/10.1007/s10530-022-02951-y)

Abstract

Invasive plants can alter fuels and fire regimes in ways that facilitate their spread and dominance through a process known as the invasion-fire cycle. This phenomenon can result in considerable fire and ecosystem impacts, but mechanisms, habitat susceptibility, and prevalence of invasion-fire cycles are poorly understood.

Here, we reviewed literature on invasion-fire cycles and describe how mechanisms by which and habitats in which invasion-fire cycles occur are influenced by invader growth form, including woody versus herbaceous and perennial versus annual species, among other factors, and highlight research needs to better understand invasion-fire cycles.

We found evidence that annual herbaceous species facilitated more continuous and frequent fires in shrublands and deserts by increasing fine fuel continuity, while perennial grasses and woody invaders more often facilitated intense and vertically continuous fires in forest habitats by increasing fuel loads. There was some evidence woody invaders can suppress fires by decreasing fine fuels, and both woody invaders and perennial grasses and forbs can inhibit fires due to high fuel moisture and low flammability, but effects of fire suppression by invaders on native communities were ambiguous.

Fire suppression and climate change may complicate effects of invasions on fire regimes directly, or indirectly through shifting abundances of fire prone or fire adapted native plant species. More research is needed to understand how propagule pressure, ignitions, climate, and resource availability affect invasion-fire cycles, and to determine relative importance of invasion-fire cycles in driving plant invasions and effects of invader driven changes to fire regimes on native communities.

Keywords: Climate; Facilitation; Fire behavior; Fire regime; Fire suppression; Fuels; Growth form; Ignitions

Citation

Tomat-Kelly, Giovanna, and S. Luke Flory. "Research gaps limit understanding of invasion-fire cycles." Biological Invasions (2022): 1-19.

About the "New Science Blog" @prairiefiresci

This description has been updated from the previous version published in December 2022.

The "New Science Blog" exists to increase the rate at which relevant science is shared with practitioners and researchers in the Upper Midwest.

Curating the blog:

The blog is curated to meet our major goal of sharing applied science with practitioners. The main goal is to have a place to easily share the latest publications. In between new publications, we are also sharing articles published between 2019-2022.

Papers shared via the blog are selected for their potential relevance to fire practitioners, land managers, ecologists, researchers, and policy makers in the region.

Your feedback about whether we were too narrow or too broad with our first selections will help us modify how we determine which papers to share.

How we find new publications:

The primary way we find new publications is through Google Scholar. Google Scholar alerts notify us when new fire science publications have been published for the tallgrass prairie and oak savanna ecosystems; for example, Google Scholar alerts notify us of papers that include both the phrase "tallgrass prairie" and "fire."

Google Scholar has tools you can use to easily create your own advanced searches and get updates in your inbox. Use the "Create alert" icon at the bottom of the left-hand menu on Google Scholar (scholar.google.com).

Other common ways we hear about new publications are through pre-publication presentations at conferences, updates on Twitter, and directly from authors.

The types of publications we tend to share:

Readers can expect to see an emphasis on papers that compare restoration and management techniques that incorporate prescribed fire (for example, research published in Restoration Ecology, Ecological Restoration, Fire Ecology, Conservation Biology, Ecosphere). Studies of fire effects on taxa and other natural history papers also provide valuable information to land stewards and wildlife biologists (journals such as American Midland Naturalist [RIP], Natural Areas Journal, and Biodiversity Conservation).

We will also share papers that provide examples of fire ecology research methods that can be applied to management challenges in the TPOS region even if the study was not conducted here.

Some or our readers have interest in papers that share interesting perspectives on fire ecology, wildfire, and prescribed fire, whether or not the information can be directly applied. You can expect to see about 5-10 percent of posts here sharing new peer-reviewed papers that address national policy, issues that affect public opinion about prescribed fire (like smoke), and fire science that is otherwise nationally or internationally notable.

There are multiple options to follow the New Science Blog:

There are a couple of ways to access the New Science Blog.

The blog is linked to the "Just New Papers" Twitter account (@strictlyfiresci), which posts automatically as this blog is updated.

An alternative way is to subscribe directly to this blog using RSS - http://www.tposfirescience.org/new-science/rss.xml

The third way, and the simplest for those who aren't interested in Twitter, is to watch for research round ups in the TPOS newsletter (join here).

Blog Article Titles

When new blog articles are posted, a social media management service posts a link to the article on @strictlyfiresci. The article title becomes the text of the tweet, along with a link back here to the article. To help boost visibility, blog article titles include the science publication's title as well as relevant hashtags (topics) and Twitter handles (depending on the article, the journal, one more authors on the publication, and the research funders may have accountes; we also often tag other outreach organizations).

“Forest landowner demand for prescribed fire as an ecological management tool in Pennsylvania, USA” #rxfire @PSUecosystems

"Forest landowner demand for prescribed fire as an ecological management tool in Pennsylvania, USA"

This article was published December 28, 2022, in Forest Policy and Economics. Access the article online at the permanent web address (DOI). (https://doi.org/10.1016/j.forpol.2022.102902)

Abstract

Prescribed burning is important for the ecological health of fire-dependent forests, however, there is little economic research examining landowner preferences for living with fire in the age of the Anthropocene.

To understand the value of reintroducing fire on the landscape we assessed forest owner willingness to pay (WTP) for various prescribed fire programs in Pennsylvania, where natural fire occurs infrequently. Survey responses were collected from 243 forest owners using Likert scales and choice experiment questions resulting in a 44% response rate.

Most respondents were classified as having limited experience with prescribed fire, but many also had low risk perceptions about prescribed fire and high trust in prescribed fire implementors. A majority (66%) elected to enroll in at least one of 16 proposed burn programs and almost a quarter of landowners were willing to pay up to $200 per acre. Using mixed logistic regression methods, mean WTP was estimated to range from $11 to $19 per acre, but varied significantly under different program alternatives. Respondents overall preferred programs that helped maintain ecosystem health and biodiversity, and offered cost-share, reduced liability, and access to burn bosses. Demographic characteristics were also important predictors of enrollment (i.e., income level, age, and involvement in assistance programs).

We conclude that forest owners in Pennsylvania see prescribed fire as potentially helping them meet priority management objectives and supporting cultural values about forest stewardship. Technical and financial assistance for forest owners will be important for expanding the use of prescribed fire in Pennsylvania.

Citation

Regmi, Arun, Melissa M. Kreye, and Jesse K. Kreye. "Forest landowner demand for prescribed fire as an ecological management tool in Pennsylvania, USA." Forest Policy and Economics 148 (2023): 102902.

"Adult Monarch (Danaus plexippus) Abundance Is Higher in Burned Sites Than in Grazed Sites" #rxfire #InsectThursday @julia_leone

Adult Monarch (Danaus plexippus) Abundance Is Higher in Burned Sites Than in Grazed Sites

This article was published Nov. 14, 2019 in the journal Frontiers in Ecology and the Environment. Access the article via the permanent web address (DOI). (https://doi.org/10.3389/fevo.2019.00435)

Abstract

Much of the remaining suitable habitat for monarchs (Danaus plexippus) in Minnesota is found in tallgrass prairies.

We studied the association of adult monarch abundance with use of fire or grazing to manage prairies. Sites (n = 20) ranged in size from 1 to 145 hectares and included land owned and managed by the Minnesota DNR, U.S. Fish and Wildlife Service, The Nature Conservancy, and private landowners. We measured Asclepias spp. (milkweeds, monarch host plants) and forb frequency in 0.5 × 2-m plots located along randomly-placed transects that were stratified to sample wet, mesic, and dry prairie types at each site. Adult butterfly surveys took place three times at each site during the summers of 2016 and 2017, using a standardized Pollard Walk (400 m). Data were analyzed using mixed effects models.

Monarchs were more abundant at sites managed with prescribed fire than with grazing. We found no difference in milkweed and forb frequency between burned and grazed prairies. There was no relationship between monarch abundance and the other predictor variables tested: milkweed frequency, site area, forb frequency, and percent prairie in a 1.5 km buffer area surrounding each site. Monarch abundance was lowest at grazed sites with high stocking rates.

Our findings suggest that milkweed and forb frequency do not vary between burned and grazed sites, although we only considered land management practices for the 12 years before the study and the most recent burns occurred in 2014, 2 years prior to the start of our study. They also suggest that heavy grazing may have negative impacts on monarchs.

Citation

Leone, Julia B., Diane L. Larson, Jennifer L. Larson, Nora Pennarola, and Karen Oberhauser. "Adult Monarch (Danaus plexippus) abundance is higher in burned sites than in grazed sites." Frontiers in Ecology and Evolution 7 (2019): 435.

"New Science" editor's note:

The authors state, “We chose a retrospective study design using sites with known management history instead of implementing our own experimental design because management can take many years to become apparent on the landscape and our study was constrained to 2 years.”

"The contribution of canopy samples to assessments of forestry effects on native bees"

"The contribution of canopy samples to assessments of forestry effects on native bees"

This open access article was published April 14, 2022, in Conservation Science and Practice. Access the article via the permanent web address (DOI). (https://doi.org/10.1111/csp2.12690)

Abstract

Forest management is often practiced to enhance conditions for wildlife, including native bees. Evaluations of the effects of forest management on bees have shown that abundance and diversity are higher in newly created early-successional conditions. To date, studies have restricted sampling to the forest understory; however, recent research finds that bee abundance is as high or higher in forest canopies than in understories, suggesting that previous observations of substantially greater bee abundance and diversity in recently managed areas could be an artifact of incomplete sampling of the vertical gradient within forests.

To examine the potential implications of sampling biases associated with the failure of previous studies to include canopy samples in comparisons of managed and unmanaged forests, we sampled bees within a recently harvested forest as well as the understory and canopy of adjacent unmanaged forest.

Bee abundance and diversity were an order of magnitude higher in managed areas compared to the unmanaged forest, even when understory and canopy samples were combined.

These results suggest that not sampling the canopy is inconsequential with respect to the broadly reported conclusion that managed areas support more abundant and diverse bee communities than surrounding forest cover.

Keywords: abundance; Apoidea; barrens; blue vane trap; canopy; forest; richness

Citation

Milam, Joan, Michael Cunningham‐Minnick, Henry Patrick Roberts, Christopher Buelow, and David I. King. "The contribution of canopy samples to assessments of forestry effects on native bees." Conservation Science and Practice (2022): e12690.

“Land management drives dynamic changes to microbial function through edaphic factors and soil biota” #rxfire @MicroSikes @JacobHopkinsOSU

Land management drives dynamic changes to microbial function through edaphic factors and soil biota

This article was published online Dec. 12, 2022, in Pedobiologia. Access the article through the permanent web address (DOI). (https://doi.org/10.1016/j.pedobi.2022.150859)

Abstract

Land management for conservation alters the abiotic and biotic components that underly belowground ecosystem health and function. We know that prescribed burning and grazing influence soil characteristics, nutrients, and biota individually, but rarely have these management effects been explored holistically, affecting an interacting belowground system. Since most belowground functions (e.g., nutrient cycling) arise from feedbacks among many soil factors, a better understanding of system-level responses to distinct management practices, rather than individual component responses, can help us better predict these ecosystem functions.

In a late successional tallgrass prairie ecosystem, we contrasted how prescribed fire and mowing altered nutrient cycles through changes to the abiotic soil environment, microbial community structure, and microbial enzyme functions.

Individual soil factors responded rapidly to both fire and mowing, and remained different from pre-treatment values. However, as a system, many relationships among soil factors that were present before management and lost directly after management, returned 1 month after management.

This shows the system-level resilience to management supported by the long evolutionary history between grasslands, fire, and grazing, and illustrates the importance of understanding management effects from a holistic perspective. Since global disturbance regimes and anthropological influence are predicted to change in the future, understanding how belowground components respond to change as a system can help land managers and ecologists alike conserve endangered ecosystems.

Keywords: Land management; Microbe; EnzymeSEM; Fire; Grazing; Belowground; System

Citation

Hopkins, Jacob R., Tatiana A. Semenova-Nelsen, and Benjamin A. Sikes. "Land management drives dynamic changes to microbial function through edaphic factors and soil biota." Pedobiologia 96 (2023): 150859.

Graphical Abstract

“Invasive grass and litter accumulation constrain bee and plant diversity in altered grasslands” #grasslands #bees @gpfirescience @NDSU_SNRS

“Invasive grass and litter accumulation constrain bee and plant diversity in altered grasslands”

This open access article was published Dec. 13, 2022, in the journal Global Ecology and Conservation. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.gecco.2022.e02352)

Abstract

Ecologists consider biological invasions one of the primary drivers of global change. Many remaining grasslands in North America have extensive invasions of exotic grass species that have replaced native plant species. In the Northern Great Plains, exotic cool-season grasses Kentucky bluegrass (Poa pratensis) and smooth brome (Bromus inermis), paired with human alterations to the landscape and historical disturbance regimes, have resulted in functionally and structurally altered grassland plant communities. These changes may extend to impact species that rely on these plant communities, such as bees. Bees are ecologically diverse and serve important pollinator roles but are at risk from the loss and change of floral and nesting resources in plant communities.

Our objectives were to determine whether Kentucky bluegrass and smooth brome alter the bee and forb species richness in invaded Northern Great Plains grasslands and how litter accumulation, grass cover, the amount of bare ground, and forb species richness interact with bee functional traits. To do this, we surveyed 67 grassland sites from 2017 to 2020 with two bee-sampling methods (268 netting and bee bowl surveys total) and vegetation cover surveys at each site. We collected 20,559 bees from 201 bee species and observed 249 forb and shrub species in vegetation surveys.

Bee richness and Shannon diversity were associated with greater forb richness while forb richness was significantly lower with thicker litter depths and higher with a greater coverage of all grasses other than Kentucky bluegrass and smooth brome. Bee trait analyses showed varying relationships with plant community variables. Of these, litter depth and Kentucky bluegrass cover were associated with lower ground-nesting bee abundance while small-bodied bee abundance was positively associated with increasing bare ground.

While our results support the close relationship between bee and plant diversity, we also found litter depth, in particular, contributed to the structure of these two communities. Specifically, Kentucky bluegrass and smooth brome are two exotic grass species associated with thatch-forming litter layers, especially under idle management that appear to simplify bee and forb communities. Our results make apparent the importance in maintaining structural and compositional diversity in invaded grasslands to support diverse bee communities.

Keywords: Invasive grass; Bee communities; Litter; Forb richness; Bee diversity; Kentucky bluegrass; Smooth brome; Northern Great Plains; Litter depth; Bee traits

Citation

Pei, C. K., Torre J. Hovick, Ryan F. Limb, Jason P. Harmon, and Benjamin A. Geaumont. "Invasive grass and litter accumulation constrain bee and plant diversity in altered grasslands." Global Ecology and Conservation 41 (2023): e02352.