Sam Davis is a staff scientist at the Partnership for Policy Integrity (PFPI), a nonprofit that uses science, litigation, policy analysis, and strategic communications to promote policies that protect climate, ecosystems, and people.
With a unique blend of academic excellence and unyielding passion for the environment, Dr. Sam Davis, a lifelong treehugger, has made a significant impact in the world of conservation. They have dedicated their life to protecting our planet and its diverse ecosystems. Sam’s personal mission to “connect people to their wild hearts” is at the forefront of their work.
Davis is a staff scientist at the Partnership for Policy Integrity (PFPI), a nonprofit that uses science, litigation, policy analysis, and strategic communications to promote policies that protect climate, ecosystems, and people. They previously served as a conservation scientist with the Dogwood Alliance, a leading organization in forest advocacy. Through innovative research and content development, Sam has been instrumental in raising awareness about the importance of preserving our natural habitats for the next generation.
Beyond their professional accomplishments, Davis’s self-expression and creativity shine through in various aspects of their life. Their love for nature, culture, art, and writing is a testament to their multifaceted personality. Sam owns and runs a small business, Nonbeenary Designs, teaches biology at a nearby university, and has published fiction, art, and many other creative projects.
Sam’s unique voice and passion are what set them apart as an environmental activist. Their dedication to their craft, combined with their artistic sensibilities, allows them to connect with people from all walks of life, inspiring new generations of forest advocates. Sam is not only an expert in environmental science but also a powerful force for change.
Sam has been featured and quoted in print media, podcast, radio, and as a keynote speaker—usually on topics of the forests, environment, and justice. In their free time, Sam works on a number of digital media projects, including graphic design and content development. Sam consults with other mission-focused small businesses to provide SEO, graphics, marketing, and web support.
Sam earned a PhD in environmental science in 2015 at Wright State University and completed a postdoc at University of California Merced. Their work has been published by NOLA.com, Pressenza, Countercurrents, CounterPunch, NationofChange, LA Progressive, and the Good Men Project, among others.
Garlic mustard is an invasive Eurasian biennial that has spread throughout the eastern United States and southern Canada. Populations of this plant vary in their susceptibility to Erysiphe cruciferarum, a causal agent of powdery mildew disease in Brassicaceous plants. We examined whether there were biogeographic patterns in the distribution of resistance in invasive North American and native European populations of this plant. We grew plants from 78 invasive and 20 native populations and screened them for powdery mildew resistance in the greenhouse.
We found that populations were mostly monomorphic for either resistance or susceptibility but that some polymorphic populations were found from both continents. The proportion of populations showing resistance versus susceptibility was similar in both Europe and North America. Within continents, the spatial distribution of resistant and susceptible populations did not deviate significantly from random.
We also examined whether the possession of the resistance trait alter intraspecific competitive dynamics. In two trials, we competed plants from resistant and susceptible populations in a target-neighbor design in the presence and absence of powdery mildew inoculum and examined the growth of the target plant. Target plants from resistant populations were overall larger than target plants from susceptible populations.
Target plants were overall larger when grown in competition with susceptible neighbors. Further, resistant target plants showed a greater degree of release from competition when grown with a susceptible neighbor versus a resistant neighbor than the degree of release shown by susceptible target plants. This suggests a benefit of possessing the resistance trait with little apparent costs which should promote selection for this trait within plant populations.
Biological Invasions volume 22, pages 1657–1668 (2020)
As the world seeks solutions to climate change, and in light of the 2015 Paris Climate Agreement, attempts to decarbonize the electric power sector by 2050, a primitive form of energy generation has reemerged as a possible environmentally friendly solution to fossil fuels. Bioenergy, defined here as the process of turning woody plant based matter into a combustible fuel used in the electric power generation sector, is perhaps the oldest source of energy that humans have known. While bioenergy has been branded as an environmentally sound solution to the problems of power sector decarbonization and climate change, there are a number of issues with an increased global dependence on bioenergy as a replacement for fossil fuels.
Published as a reference module in Earth Systems and Environmental Sciences.
As efforts to decarbonize the electric sector take on increased urgency, governments are turning to wood pellets as a potential renewable energy resource. However, the production of pellets from woody biomass has immediate community-wide impacts on air and water quality. This article investigates the siting of wood pellet production facilities in the southeastern United States and finds that they are 50 percent more likely to be located in environmental justice (EJ)-designated communities.
We define an EJ community as a county where the poverty level is above the state median and at least 25 percent of the population is nonwhite. In addition, we find that all biomass pellet mills in North Carolina and South Carolina are in EJ communities. There is a longstanding history of EJ communities being disproportionately targeted for the siting of coal and natural gas power plants, in addition to waste-to-energy plants and landfills.
Wood pellet production facilities are similar to these plants in their emissions of harmful particulate matter, airborne pollutants such as carbon monoxide, carbon dioxide, nitrogen oxides, sulfur oxides, and their degradation of local water quality. Wood pellet production is increasing rapidly in the southeastern United States. These data add to growing evidence that biomass pellet mills in the southeastern United States place an undue burden on economically depressed areas of color.
Pieris rapae L., an invasive crop pest, may have recently begun using Alliaria petiolata Bieb. (Cavara & Grande), a European invasive biennial. We investigated how P. rapae uses forest habitats for nectar and oviposition and examined larval performance on A. petiolata in the field and laboratory.
Being known primarily to occupy open habitats, we found that P. rapae regularly uses forest edge habitats, most surveyed A. petiolata plants had P. rapae damage, and P. rapae successfully used both stages of A. petiolata for larval development.
As it pertains to insect herbivores, the preference-performance hypothesis posits that females will choose oviposition sites that maximize their offspring's fitness. However, both genetic and environmental cues contribute to oviposition preference, and occasionally “oviposition mistakes” occur, where insects oviposit on hosts unsuitable for larval development.
Pieris virginiensis is a pierine butterfly native to North America that regularly oviposits on an invasive plant, Alliaria petiolata, but the caterpillars are unable to survive. Alliaria petiolata has high concentrations of the glucosinolate sinigrin in its tissues, as well as a hydroxynitrile glucoside, alliarinoside.
We investigated sinigrin as a possible cause of mistake oviposition, and sinigrin and alliarinoside as possible causes of larval mortality. We found that sinigrin applied to leaves of Cardamine diphylla, a major host of P. virginiensis that does not produce sinigrin, had no effect on oviposition rates. We tested the effect of sinigrin on larval performance using two host plants, one lacking sinigrin (C. diphylla) and one with sinigrin naturally present (Brassica juncea).
We found no effect of sinigrin application on survival of caterpillars fed C. diphylla, but sinigrin delayed pupation and decreased pupal weight. On B. juncea, sinigrin decreased survival, consumption, and caterpillar growth. We also tested the response of P. virginiensis caterpillars to alliarinoside, a compound unique to A. petiolata, which was applied to B. oleracea. We found a significant reduction in survival, leaf consumption, and caterpillar size when alliarinoside was consumed.
The ‘novel weapon’ alliarinoside likely is largely responsible for larval failure on the novel host A. petiolata. Sinigrin most likely contributes to the larval mortality observed, however, we did not observe any effect of sinigrin on oviposition by P. virginiensis females. Further research needs to be done on non-glucosinolate contact cues, and volatile signals that may induce P. virginiensis oviposition.
Specialized metabolites in plants influence their interactions with other species, including herbivorous insects, which may adapt to tolerate defensive phytochemicals. The chemical arsenal of Alliaria petiolata (garlic mustard, Brassicaceae) includes the glucosinolate sinigrin and alliarinoside, a hydroxynitrile glucoside with defensive properties to glucosinolate-adapted specialists.
To further our understanding of the chemical ecology of A. petiolata, which is spreading invasively in North America, we investigated the metabolite profile and here report a novel natural product, petiolatamide, which is structurally related to sinigrin.
In an extensive study of North American populations of A. petiolata, we demonstrate that genetic population differences as well as developmental regulation contribute to variation in the leaf content of petiolatamide, alliarinoside, sinigrin, and a related glycoside.
We furthermore demonstrate widely different metabolic fates of these metabolites after ingestion in the glucosinolate-adapted herbivore Pieris rapae, ranging from simple passage over metabolic conversion to sequestration. The differences in metabolic fate were influenced by plant β-glucosidases, insect-mediated degradation, and the specificity of the larval gut transport system mediating sequestration.
Alliaria petiolata is a European biennial herb that invades North American forests and has direct negative effects on associated flora and fauna. In some places, A. petiolata has invaded the habitat of Pieris virginiensis, a rare, univoltine butterfly that normally uses native spring ephemeral crucifer hosts. There are occasional observations of P. virginiensis laying eggs on A. petiolata, but the frequency and effects of these “mistake oviposition events” are not yet known.
We investigated P. virginiensis oviposition preference through field observations in three locations (NY, OH, PA), and also through laboratory experiments measuring egg deposition of adult females on either a native or invasive crucifer. In addition, we examined neonate larval performance through no-choice feeding assays on both A. petiolata leaves and cabbage leaves painted with A. petiolata leaf extracts.
We found that P. virginiensis lays significantly more eggs on the exotic A. petiolata than on its native host Cardamine diphylla in both field and laboratory experiments. Caterpillars fed either A. petiolata leaf tissue or its ethanol extract did not survive to pupation, and most died after only a few days. Continual invasion and persistence of A. petiolata in P. virginiensis habitats may lead to genetic bottlenecking and possibly local extinctions without human intervention.
Pieris virginiensis Edwards, the West Virginia White butterfly, is a rare, univoltine butterfly native to riparian areas of mature forests in North America, from Wisconsin to Vermont, and as far south as northern Georgia and Alabama (Finnell & Lehn 2007). Pieris virginiensis has been considered in decline due to forest disturbance via logging, fragmentation, deer grazing pressure, and plant invasion (Finnell & Lehn 2007).
It is considered rare, but has not yet been evaluated by the International Union for Conservation of Nature’s Red List, and there are no long-term studies of P. virginiensis populations to confirm anecdotal observations of continual decline (IUCN 2012). Although there are butterfly monitoring organizations, P. virginiensis is frequently overlooked as it flies early in the spring in forested areas, which are not major sources of butterfly diversity and are not often regularly monitored.
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Old-growth forests are put into perspective in the world, in regions of the United States, and in the southern Blue Ridge Mountains, which are highlighted as a case of having significant pockets of old-growth that were missed in a broad-scale remote sensing assessment published in 1999.
Published in Imperiled: The Encyclopedia of Conservation.