“Savanna fire regimes depend on grass trait diversity” @kim_1801 @SallyArchibald @sheffieldplants @prairiefiresci

“Savanna fire regimes depend on grass trait diversity”

Published September 2022 in Trends In Ecology and Evolution. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.tree.2022.04.010)

Highlights

Most fires on Earth occur in savannas, but vary considerably in their extent, frequency, and intensity. These patterns cannot fully be explained by climate or land management.

An important ‘missing-piece’ in explaining the variation in savanna fire regimes is the diversity of grasses that fuel fires and whose traits strongly influence fire behaviour. The major differences in savanna fire behaviour across continents may lie in the contrasting species and trait assemblages in savanna grass communities.

Fire regimes change significantly when savanna grass communities or traits are altered by the introduction of invasive species and climatic changes.

Improved representation of grass trait diversity in fire models will be essential for reliable forecasts of the behaviour and impacts of the majority of fires on Earth.

Grasses fuel most fires on Earth and strongly influence local fire behaviour through traits that determine how flammable they are. Therefore, grass communities that differ in their species and trait compositions give rise to significant spatial variation in savanna fire regimes across the world, which cannot be otherwise explained. Likewise, fire regimes are continuously modified by alterations to savanna grass community traits, through species introductions and climatic changes. However, current representation of grassy fuels in global fire models misses important variation and therefore limits predictive power. The inclusion of grass trait diversity in models, using remotely sensed trait proxies, for example, will greatly improve our ability to understand and project savanna fires and their roles in the Earth system.

Keywords: fire regimes; flammability; functional traits; grasses; Poaceae; savannas

Citation

Simpson, Kimberley J., Sally Archibald, and Colin P. Osborne. "Savanna fire regimes depend on grass trait diversity." Trends in Ecology & Evolution (2022).

“Fire effects on the persistence of soil organic matter and long-term carbon storage” @eco_pelle @prairiefiresci @gpfirescience @nafse @apfirescience @sefirescience

"Fire effects on the persistence of soil organic matter and long-term carbon storage"

This review article was published Dec. 23, 2021, in Nature Geoscience. Access the article via the permanent web address (DOI). (https://doi.org/10.1038/s41561-021-00867-1)

Abstract

One paradigm in biogeochemistry is that frequent disturbance tends to deplete carbon (C) in soil organic matter (SOM) by reducing biomass inputs and promoting losses. However, disturbance by fire has challenged this paradigm because soil C responses to frequent and/or intense fires are highly variable, despite observed declines in biomass inputs.

Here, we review recent advances to illustrate that fire-driven changes in decomposition, mediated by altered SOM stability, are an important compensatory process offsetting declines in aboveground biomass pools. Fire alters the stability of SOM by affecting both the physicochemical properties of the SOM and the environmental drivers of decomposition, potentially offsetting C lost via combustion, but the mechanisms affecting the SOM stability differ across ecosystems. Thus, shifting our focus from a top-down view of fire impacting C cycling via changes in plant biomass to a bottom-up view of changes in decomposition may help to elucidate counterintuitive trends in the response of SOM to burning.

Given that 70% of global topsoil C is in fire-prone regions, using fire to promote SOM stability may be an important nature-based climate solution to increase C storage.

Keywords: Carbon cycle; Fire ecology; Forest ecology; Natural hazards

Citation

Pellegrini, Adam FA, Jennifer Harden, Katerina Georgiou, Kyle S. Hemes, Avni Malhotra, Connor J. Nolan, and Robert B. Jackson. "Fire effects on the persistence of soil organic matter and long-term carbon storage." Nature Geoscience 15, no. 1 (2022): 5-13.

“Goat browse selectivity during conservation grazing in an invaded eastern oak-hickory forest” @prairiefiresci @oakfirescience @savannainst

“Goat browse selectivity during conservation grazing in an invaded eastern oak-hickory forest”

Published January 25, 2023, in Agroforestry Systems. Access the article via the permanent web address (DOI). (https://doi.org/10.1007/s10457-023-00810-w)

Abstract

Oak and hickory (Quercus spp. and Carya spp.) recruitment in forests of eastern North America is adversely impacted by woody invasive species. Conservation grazing, the use of livestock for restoration or biodiversity promotion, has been used to control invasive plants. The efficacy of such grazing and its ecological tradeoffs in oak-hickory forests, however, is unknown.

We aimed to fill this gap by investigating browsing intake and preference by goats. To support this, nineteen experimental plots were established in an invaded forest, and their species composition and biomass quantified. Twelve plots were browsed under high (1019 goat-days ha−1) and low (509 goat-days ha−1) browsing pressure regimes with direct observations of forage intake and selection. Leaves of commonly browsed species were assessed for nutritional composition.

Goats generally selected for native spicebush (Lindera benzoin) over invasive multiflora rose (Rosa multiflora), however, selection of the latter increased with time. Both species identity and browsing pressure were good predictors of browse intake. For greater biomass reduction of invasive species, the use of high browsing pressure is recommended.

This research showed that conservation grazing can be an effective tool to reduce biomass of invasive species such as multiflora rose, privet (Ligustrum spp.), and oriental bittersweet (Celastrus orbiculatus) in oak-hickory forests when high browsing pressure is implemented, nevertheless goats may initially target their preferred species (e.g., spicebush).

Keywords: Ecological restoration; Feeding behavior; Forest management; Browse quality; Invasive species; Deciduous forest

Citation

Novais, Wanderson, Benjamin A. Wenner, Jeremy A. Block, Simon C. Power, Elizabeth Porteus, and G. Matt Davies. "Goat browse selectivity during conservation grazing in an invaded eastern oak-hickory forest." Agroforestry Systems (2023): 1-12.

“Organizational capacity and ecological restoration” @SERestoration @UMNFWCB @prairiefiresci

“Organizational capacity and ecological restoration”

This open access review article was first published June 30, 2022, in Restoration Ecology. Access the article via the permanent web address (DOI). (https://doi.org/10.1111/rec.13757)

Abstract

Organizations entrusted with responsibilities and resources to repair ecosystems have for many decades pursued their defining purpose against long odds created by a host of inherent challenges, notably the long time frames required for ecological recovery and landscape-level stressors. Global change compounds these challenges, increasing shocks to the operating environments of these organizations. Interest in assessing organizational capacity to respond to system shocks (i.e. resilience) productively has been strong in many fields, though not in the restoration arena.

The objectives of this paper are to build awareness of the importance of organizations for achieving the aims of restoration and to spur organizational research to strengthen the restoration sector. I summarize research on organizations relevant to the restoration sector and with this foundation propose a framework for assessing the capacity of restoration organizations. The proposed framework is an adaptation of models used in other sectors, based on five critical capacities:

1. situation awareness
2. governance and leadership
3. internal resources
4. external relations, and
5. change readiness.

We can assess the extent to which an organization possesses each capacity by eliciting feedback about functions linked to each capacity. Devising assessment tools from this framework requires attention to key realities of the restoration sector including prevalence of short-term funding, effect of externalities on restoration outcomes, dependence on partnerships of multiple organizations for complex and large restorations.

Exploration into assessment approaches for restoration organizations highlights a major knowledge gap that, if addressed, could enhance the reliability of restoration as a global and local strategy for improving ecosystems services.

Implications for Practice

• The capacity of people (i.e. organization) undertaking a restoration greatly affects what can be accomplished with available resources and support. Yet, there has been little exploration of how to assess organizational deficiencies so these can be addressed, potentially improving outcomes of their restoration.
• Using precedents from other sectors, a framework to assess restoration organizations' capacity is proposed here. Assessments of organizational capacity can be undertaken for an individual organization or as an external assessment of multiple organizations.
• Because many restoration organizations depend on external support to pursue projects, expectations linked to funding decisions can accelerate the adoption of organizational capacity assessments.

Keywords: conservation organizations; ecosystem restoration; organizational functions; organizational resilience; strategic planning

Citation

Galatowitsch, Susan. "Organizational capacity and ecological restoration." Restoration Ecology (2022): e13757.

“Invasive species do not exploit early growing seasons in burned tallgrass prairies” #rxfire #grassland @gpfirescience @prairiefiresci @mahlering @nature_mn

“Invasive species do not exploit early growing seasons in burned tallgrass prairies”

This article was published April 19, 2022 in Ecological Applications. Access the article via the permanent web address (DOI). ( https://doi.org/10.1002/eap.2641)

Abstract

Invasive species management is key to conserving critically threatened native prairie ecosystems. While prescribed burning is widely demonstrated to increase native diversity and suppress invasive species, elucidating the conditions under which burning is most effective remains an ongoing focus of applied prairie ecology research. Understanding how conservation management interacts with climate is increasingly pressing, because climate change is altering weather conditions and seasonal timing around the world. Increasingly early growing seasons due to climate change are shifting the timing and availability of resources and niche space, which may disproportionately advantage invasive species and influence the outcome of burning.

We estimated the effects of burning, start time of the growing season, and their interaction on invasive species relative cover and frequency, two metrics for species abundance and dominance. We used 25 observed prairie sites and 853 observations of 267 transects spread throughout Minnesota, USA from 2010 to 2019 to conduct our analysis.

Here, we show that burning reduced the abundance of invasive cool-season grasses, leading to reduced abundance of invasive species as a whole. This reduction persisted over time for invasive cover but quickly waned for their frequency of occurrence. Additionally, and contrary to expectations that early growing season starts benefit invasive species, we found evidence that later growing season starts increased the abundance of some invasive species. However, the effects of burning on plant communities were largely unaltered by the timing of the growing season, although earlier growing season starts weakened the effectiveness of burning on Kentucky bluegrass (Poa pratensis) and smooth brome (Bromus inermis), two of the most dominant invasive species in the region.

Our results suggest that prescribed burning will likely continue to be a useful conservation tool in the context of earlier growing season starts, and that changes to growing season timing will not be a primary mechanism driving increased invasion due to climate change in these ecosystems.

We propose that future research seek to better understand abiotic controls on invasive species phenology in managed systems and how burning intensity and timing interact with spring conditions.

Keywords: climate adaptation; climate change; grassland management; growing season; phenology; prescribed burning; spring timing

Citation

Ratcliffe, Hugh, Marissa Ahlering, Daren Carlson, Sara Vacek, Andrew Allstadt, and Laura E. Dee. "Invasive species do not exploit early growing seasons in burned tallgrass prairies." Ecological Applications 32, no. 7 (2022): e2641.

“Exploring Opinions for Using Prescribed Fire to Control Eastern Redcedar (Juniperus virginiana) Encroachment in the Southern Great Plains, United States” #rxfire @prairiefiresci @gpfirescience @osu_research @rangelands

“Exploring Opinions for Using Prescribed Fire to Control Eastern Redcedar (Juniperus virginiana) Encroachment in the Southern Great Plains, United States”

Published December 5, 2022 in Rangeland Ecology and Management. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.rama.2022.10.002)

Abstract

Eastern redcedar (Juniperus virginiana) is rapidly encroaching on grasslands in the southern Great Plains. This has several adverse effects on the landscape including increased wildfire risk, decreased water runoff, and reduced forage available for cattle production. Several best management practices have been identified to reduce the spread of eastern redcedar, including the use of prescribed fire. However, numerous barriers exist against the use of prescribed fire such as societal acceptance or liability concerns.

The purpose of this study was to determine how stakeholders from government agencies, nongovernmental organizations, and landowners perceive the use of prescribed fire to control eastern redcedar encroachment. The strengths, weaknesses, opportunities, and threats−analytical hierarchical process method was used for data analysis.

The study showed that governmental and landowner stakeholders viewed that the negatives associated with prescribed fire outweigh the potential benefits. Nongovernmental organization stakeholders had differing opinions, and they were largely supportive of using prescribed fire.

The results suggest that there is a need for tailored outreach to alleviate the concerns associated with risks and liabilities, as escaped prescribed fires are highly uncommon.

Key Words: best management practices; encroachment; Great Plains; SWOT-AHP

Citation

Jeffries, Katelyn, Bijesh Mishra, Aaron Russell, and Omkar Joshi. "Exploring Opinions for Using Prescribed Fire to Control Eastern Redcedar (Juniperus virginiana) Encroachment in the Southern Great Plains, United States." Rangeland Ecology & Management 86 (2023): 73-79.

"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.