Multi-year salutary effects of windstorm and fire on river cane

Canebrakes are monodominant stands of cane (Arundinaria gigantea [Walter] Muhl.), a bamboo native to and once prominent in the southeastern USA. Canebrakes were important wildlife habitat within the bottomland hardwood forest ecosystem. They have been reduced in areal coverage by an estimated 98% since European settlement due to land conversion and the drastic alteration of disturbance regimes in their floodplain habitat. Ongoing canebrake restoration efforts are hampered by incomplete understanding of the role of natural disturbance in cane ecology. We used a large tornado blow down and multiple prescribed fires to quantify the response of cane to the sequential disturbances of windstorm and fire in the Tensas Watershed of northeastern Louisiana using number and condition of bamboo stems (culms) as response variables. We hypothesized that culms would be more abundant in burned than in unburned stands and that culm populations in burned stands would be younger than in unburned stands. In this study, conducted four years post fire, effects of both windstorm and burning were additive and beneficial. Results indicate that periodic aboveground disturbance has three salutary effects on cane ramet demography: 1) clonal growth following disturbances more than compensates for any culms killed; 2) the cohort of new culms is younger than the culms they replace; and 3) disturbance appears to inoculate some cane stands for several years against local die-offs. Fire is a valuable tool for canebrake management. By periodically resetting cane stands, fires and other disturbances may have played a key role in canebrake formation and persistence over time

Overdispersed Spatial Patterning of Dominant Bunchgrasses in Southeastern Pine Savannas

Spatial patterning is a key natural history attribute of sessile organisms that frequently emerges from and dictates potential for interactions among organisms. We tested whether bunchgrasses, the dominant plant functional group in longleaf pine savanna groundcover communities, are nonrandomly patterned by characterizing the spatial dispersion of three bunchgrass species across six sites in Louisiana and Florida. We mapped bunchgrass tussocks of \u3e5.0 cm basal diameter in three [Formula: see text] plots at each site. We modeled tussocks as two-dimensional objects to analyze their spatial relationships while preserving sizes and shapes of individual tussocks. Tussocks were overdispersed (more regularly spaced than random) for all species and sites at the local interaction scale (\u3c0.3 m). This general pattern likely arises from a tussock-centered, distance-dependent mechanism, for example, intertussock competition. Nonrandom spatial patterns of dominant species have implications for community assembly and ecosystem function in tussock-dominated grasslands and savannas, including those characterized by extreme biodiversity

Overdispersed Spatial Patterning of Dominant Bunchgrasses in Southeastern Pine Savannas

Spatial patterning is a key natural history attribute of sessile organisms that frequently emerges from and dictates potential for interactions among organisms. We tested whether bunchgrasses, the dominant plant functional group in longleaf pine savanna groundcover communities, are nonrandomly patterned by characterizing the spatial dispersion of three bunchgrass species across six sites in Louisiana and Florida. We mapped bunchgrass tussocks of \u3e5.0 cm basal diameter in three [Formula: see text] plots at each site. We modeled tussocks as two-dimensional objects to analyze their spatial relationships while preserving sizes and shapes of individual tussocks. Tussocks were overdispersed (more regularly spaced than random) for all species and sites at the local interaction scale (\u3c0.3 m). This general pattern likely arises from a tussock-centered, distance-dependent mechanism, for example, intertussock competition. Nonrandom spatial patterns of dominant species have implications for community assembly and ecosystem function in tussock-dominated grasslands and savannas, including those characterized by extreme biodiversity

Groundcover community assembly in high-diversity pine savannas: seed arrival and fire-generated environmental filtering

Environmental filtering—abiotic and biotic constraints on the demographic performance of individual organisms—is a widespread mechanism of selection in communities. A given individual is “filtered out” (i.e., selectively removed) when environmental conditions or disturbances like fires preclude its survival and reproduction. Although interactions between these filters and dispersal from the regional species pool are thought to determine much about species composition locally, there have been relatively few studies of dispersal × filtering interactions in species-rich communities and fewer still where fire is also a primary selective agent. We experimentally manipulated dispersal and filtering by fire (pre-fire fuel loads and post-fire ash) in species-rich groundcover communities of the longleaf pine ecosystem. We tested four predictions: (1) That species richness would increase with biologically realistic dispersal (seed addition); (2) that the immediate effect of increased fuels in burned communities would be to decrease species richness, whereas the longer-term effects of increased fuels would be to open recruitment opportunities in the groundcover, increase species richness, and increase individual performance (growth) of immigrating species; (3) that adding ash would increase species richness; and (4) that increased dispersal would generate larger increases in species richness in plots with increased fuels compared to plots with decreased fuels. We found that dispersal interacted with complex fire-generated filtering during and after fires. Dispersal increased species richness more in burned communities with increased and decreased fuels compared to burned controls. Moreover, individuals of immigrating species generally grew to larger sizes in burned communities with increased fuels compared to burned controls. In contrast to dispersal and fuels, ash had no effect on species richness directly or in combination with other treatments. We conclude that filtering occurs both during fires and in the post-fire environment and that these influences interact with dispersal such that the consequences are only fully revealed when all are considered in combination. Our experiment highlights the importance of considering the dynamic interplay of dispersal and selection in the assembly of species-rich communities

Nine years of comparative effectiveness research education and training: initiative supported by the PhRMA Foundation

The term comparative effectiveness research (CER) took center stage with passage of the American Recovery and Reinvestment Act (2009). The companion US$1.1 billion in funding prompted the launch of initiatives to train the scientific workforce capable of conducting and using CER. Passage of the Patient Protection and Affordable Care Act (2010) focused these initiatives on patients, coining the term ‘patient-centered outcomes research’ (PCOR). Educational and training initiatives were soon launched. This report describes the initiative of the Pharmaceutical Research and Manufacturers Association of America (PhRMA) Foundation. Through provision of grant funding to six academic Centers of Excellence, to spearheading and sponsoring three national conferences, the PhRMA Foundation has made significant contributions to creation of the scientific workforce that conducts and uses CER/PCOR

Does pyrogenicity protect burning plants?

Pyrogenic plants dominate many fire-prone ecosystems. Their prevalence suggests some advantage to their enhanced flammability, but researchers have had difficulty tying pyrogenicity to individual-level advantages. Based on our review, we propose that enhanced flammability in fire-prone ecosystems should protect the belowground organs and nearby propagules of certain individual plants during fires. We base this hypothesis on five points: (1) organs and propagules by which many fire-adapted plants survive fires are vulnerable to elevated soil temperatures during fires; (2) the degree to which burning plant fuels heat the soil depends mainly on residence times of fires and on fuel location relative to the soil; (3) fires and fire effects are locally heterogeneous, meaning that individual plants can affect local soil heating via their fuels; (4) how a plant burns can thus affect its fitness; and (5) in many cases, natural selection in fire-prone habitats should therefore favor plants that burn rapidly and retain fuels off the ground. We predict an advantage of enhanced flammability for plants whose fuels influence local fire characteristics and whose regenerative tissues or propagules are affected by local variation in fires. Our pyrogenicity as protection hypothesis has the potential to apply to a range of life histories. We discuss implications for ecological and evolutionary theory and suggest considerations for testing the hypothesis. © 2010 by the Ecological Society of America

Fuels and fires influence vegetation via above- and below-ground pathways in a high-diversity plant community

1. Fire strongly influences plant populations and communities around the world, making it an important agent of plant evolution. Fire influences vegetation through multiple pathways, both above- and belowground. Few studies have yet attempted to tie these pathways together in a mechanistic way through soil heating even though the importance of soil heating for plants in fire-prone ecosystems is increasingly recognized. 2. Here we combine an experimental approach with structural equation modelling (SEM) to simultaneously examine multiple pathways through which fire might influence herbaceous vegetation. In a high-diversity longleaf pine groundcover community in Louisiana, USA, we manipulated fine-fuel biomass and monitored the resulting fires with high-resolution thermocouples placed in vertical profile above- and belowground. 3. We predicted that vegetation response to burning would be inversely related to fuel load owing to relationships among fuels, fire temperature, duration and soil heating. 4. We found that fuel manipulations altered fire properties and vegetation responses, of which soil heating proved to be a highly accurate predictor. Fire duration acting through soil heating was important for vegetation response in our SEMs, whereas fire temperature was not. 5. Our results indicate that in this herbaceous plant community, fire duration is a good predictor of soil heating and therefore of vegetation response to fire. Soil heating may be the key determinant of vegetation response to fire in ecosystems wherein plants persist by resprouting or reseeding from soil-stored propagules. 6. Synthesis. Our SEMs demonstrate how the complex pathways through which fires influence plant community structure and dynamics can be examined simultaneously. Comparative studies of these pathways across different communities will provide important insights into the ecology, evolution and conservation of fire-prone ecosystems

F.A.R.O.G. FORUM, Vol. 5 No. 6

https://digitalcommons.library.umaine.edu/francoamericain_forum/1018/thumbnail.jp

Characterizations and comparison of low sulfur fuel oils compliant with 2020 global sulfur cap regulation for international shipping

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nelson, R. K., Scarlett, A. G., Gagnon, M. M., Holman, A. I., Reddy, C. M., Sutton, P. A., & Grice, K. Characterizations and comparison of low sulfur fuel oils compliant with 2020 global sulfur cap regulation for international shipping. Marine Pollution Bulletin, 180, (2022): 113791, https://doi.org/10.1016/j.marpolbul.2022.113791.The International Marine Organization 2020 Global Sulfur Cap requires ships to burn fuels with <0.50% S and some countries require <0.10% S in certain Sulfur Emission Control Areas but little is known about these new types of fuels. Using both traditional GC–MS and more advanced chromatographic and mass spectrometry techniques, plus stable isotopic, δ13C and δ2H, analyses of pristane, phytane and n-alkanes, the organic components of a suite of three 0.50% S and three 0.10% S compliant fuels were characterized. Two oils were found to be near identical but all of the remaining oils could be forensically distinguished by comparison of their molecular biomarkers and by the profiles of the heterocyclic parent and alkylated homologues. Oils could also be differentiated by their δ13C and δ2H of n-alkanes and isoprenoids. This study provides important forensic data that may prove invaluable in the event of future oil spills.This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. CMR and RKN were supported by the National Science Foundation (OCE-1634478 and OCE-1756242). GC × GC analysis support provided by WHOI's Investment in Science Fund