Research and Publications
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We asked how the soil-microbiome responded to the bioherbicide Pseudomonas fluorescens strain ACK55 in comparison to the separate and combined effects of a conventional pre-emergent chemical herbicide, imazapic, in two cheatgrass-invaded sagebrush-steppe sites. First-year microbial responses were evaluated using targeted sequencing of the 16S and LSU rRNA genes for bacteria+archaea and fungi, respectively, and were related to plant-community responses. A strong cheatgrass reduction with imazapic at one site was accompanied by a small shift in bacteria+archaea (16S) community composition with no effect on microbial alpha diversity, and this shift was small in comparison to natural microbiome variation between sites. ACK55 was not detected in soil a year after application, and it caused only transient and marginally significant reductions in annual grass cover accompanied by small reductions in soil fungi species richness. Full-length sequencing of the ACK55 16S rRNA gene and phylogenetic analyses revealed that ACK55 is more likely P. salmonii than P. fluorescens. Knowledge gaps remain on the duration and consequences of microbial-community shifts with imazapic and why molecular analyses showed ACK55 did not persist in soils. Confusion regarding microbial biopesticides can result where isolation, effectiveness testing, commercial release, and regulation are not guided by molecular taxonomic analyses.
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In a factorial design replicated across four common garden locations in Idaho and Wyoming, USA, we tested for the effect of current environment (i.e., density treatment, temperature treatment, and common garden location), source environment (i.e., genotype source climate), and their interaction on each plant’s flowering phenology. Flowering timing was strongly influenced by a plant’s current environment, with plants that experienced warmer current climates and higher densities flowering earlier than those that experienced cooler current climates and lower densities. Genotypes from hot and dry source climates flowered consistently earlier than those from cool and wet source climates, even after accounting for genotype relatedness, suggesting that this genetically based climate cline is a product of natural selection. We found minimal evidence of interactions between current and source environments or genotype-by-environment interactions. Phenology was more sensitive to variation in the current climate than to variation in source climate. These results indicate that cheatgrass phenology reflects high levels of plasticity as well as rapid local adaptation. Both processes likely contribute to its current success as a biological invader and its capacity to respond to future environmental change.
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The dimensions of specialization, personal experience, and transmission of Indigenous Knowledges and Sciences (IKS) are diverse and complex. Researchers and professionals need to recognize this diversity and understand that the information gathered by Indigenous Peoples is collected and communicated in different ways. Immense variation is present among Indigenous cultural roles, languages, and oral histories, as well as in methods of obtaining information. In order for IKS to maintain its accuracy, reliability, and relevance, users must dedicate time and resources to its interpretation and contextualization. Western thought and reasoning does not inherently align with the complexities of Indigenous knowledge transmission; thus, working with tribal experts to gain well-rounded understanding and avoid bias is recommended.
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Wildfires can produce health impacts that persist for years in affected communities. This article describes an Extension-led study of health impacts in rural Oregon communities one year after a destructive wildfire. Data collection included key informant interviews (n=36), an online survey (n=80), and three focus group interviews with survivors (n=23). Mental health, exposure to contaminants, physical stress, food insecurity, and other issues were frequently identified health concerns. Survivors’ difficulties in dealing with housing displacement significantly exacerbated health challenges. We describe potential roles for Extension in addressing wildfire risk and mitigating health impacts, including a description of the Oregon Fire Program.
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The area burned in the western United States during the 2020 fire season was the greatest in the modern era. Here we show that the number of human‐caused fires in 2020 also was elevated, nearly 20% higher than the 1992-2019 average. Although anomalously dry conditions enabled ignitions to spread and contributed to record area burned, these conditions alone do not explain the surge in the number of human‐caused ignitions. We argue that behavioral shifts aimed at curtailing the spread of COVID‐19 altered human‐environment interactions to favor increased ignitions. For example, the number of recreation‐caused wildfires during summer was 36% greater than the 1992-2019 average; this increase was likely a function of increased outdoor recreational activity in response to social distancing measures. We hypothesize that the combination of anomalously dry conditions and COVID‐19 social disruptions contributed to widespread increases in human-caused ignitions, adding complexity to fire management efforts during the 2020 western US fire season. Knowledge of how social behavior changes indirectly contributed to the increased number of ignitions in the 2020 wildfire season can help inform resource management in an increasingly flammable world.
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Ecological restoration is vital for sustaining healthy habitats supporting human and wildlife populations in the United States. With limited intact natural ecosystems remaining, restoration plays a crucial role in reversing environmental degradation by halting harmful activities and implementing proactive management strategies. Beyond benefiting wildlife, restoring degraded lands and waters provides essential services to human communities, including clean water filtration, carbon sequestration, soil erosion prevention, and building resilience to catastrophic weather events. Restoration efforts help mitigate drought, curb the spread of invasive species, and enhance wildfire resilience and flood control. In addition, land and water restoration fosters economic opportunities for local communities through sustainable land management and thriving working landscapes.
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This paper examines the substitutability or complementarity of these proactive risk-reducing actions. If mitigation and evacuation preparedness are substitutes, wildfire education programs may take a life-over-property approach. However, if proactive risk-reducing efforts are complements, wildfire education programs can confidently encourage residents to prepare for evacuation while also mitigating wildfire risk on their properties. This complementarity may also demonstrate that poorly mitigated households are less prepared to evacuate, compounding their risks. Using household survey data from 25 wildland-urban interface (WUI) communities across five Western states, we explore how wildfire risk mitigation actions affect evacuation preparedness. We find that improving household wildfire mitigation is associated with an improvement in wildfire evacuation preparedness. This complementary relationship between wildfire mitigation and evacuation preparedness actions highlights the potential benefits of a wildfire education approach that encourages residents to simultaneously prepare for evacuation and reduce wildfire risk on their properties before they are threatened by a wildfire.
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Two studies found that planting site climate, post-planting weather, planting season, tree seed lot sources, and tree species had particularly meaningful impacts on planted tree seedling performance after fire. Although the survival monitoring data used in both studies were limited to tree seedling survival after the first growing season, survival rates for this vulnerable period were linked to longer-term survival trends.
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We investigated the spread of “Snowstorm” forage kochia at 11 invasive annual grass-dominated plant communities in southeastern Oregon a decade after they had been seeded. The seeding boundary was permanently marked at the time of seeding to ensure accurate measurements of forage kochia spread. Forage kochia established beyond the seeding boundary at two of the 11 seeded sites. The maximum distance that forage kochia spread from the seeding boundary was 65 cm. These results suggest that forage kochia does not readily spread in annual grass-dominated sagebrush steppe and what little spread it exhibited was over a relatively short distance. The risk of forage kochia spreading and dominating annual grass-invaded rangelands, at least in this region, appears minimal. Additional investigations of forage kochia spread in different environments and across various plant communities is warranted to inform land managers of any potential risks. Multiple decades evaluations of its potential to spread would also be important. Even though additional research would be valuable, our results that forage kochia does not readily spread suggest it may be a relatively safe option to seed to diversify nonnative grasslands.
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Increasing presence of woody plants in dryland ecosystems, also known as “woody encroachment,” is commonly attributed to anthropogenic land-use changes such as livestock grazing and wildfire suppression. However, empirical evidence to support these external drivers has not uncovered a unifying mechanism. We test whether plant demographic processes could be responsible for woody encroachment using tree-ring data from pinyon and juniper woodland populations in the western United States. Our results indicate that woody encroachment patterns can largely be predicted by a null model based only on steady tree population growth. Modern increases in woodland density, which are typically viewed as a natural resource management problem, may therefore be a result of long-term population expansion and recovery.