Department of Biological Sciences

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Browsing Department of Biological Sciences by Author "Adams, Byron J."

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    Biotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem
    Lee, Charles K.; Laughlin, Daniel C.; Bottos, Eric M.; Caruso, Tancredi; Joy, Kurt; Barrett, John E.; Brabyn, Lars; Nielsen, Uffe N.; Adams, Byron J.; Wall, Diana H.; Hopkins, David W.; Pointing, Stephen B.; McDonald, Ian R.; Cowan, Don A.; Banks, Jonathan C.; Stichbury, Glen A.; Jones, Irfon; Zawar-Reza, Peyman; Katurji, Marwan; Hogg, Ian D.; Sparrow, Ashley D.; Storey, Bryan C.; Green, T.G. Allan; Cary, S. Craig (Springer Nature, 2019-02-15)
    Abiotic and biotic factors control ecosystem biodiversity, but their relative contributions remain unclear. The ultraoligotrophic ecosystem of the Antarctic Dry Valleys, a simple yet highly heterogeneous ecosystem, is a natural laboratory well-suited for resolving the abiotic and biotic controls of community structure. We undertook a multidisciplinary investigation to capture ecologically relevant biotic and abiotic attributes of more than 500 sites in the Dry Valleys, encompassing observed landscape heterogeneities across more than 200 km2. Using richness of autotrophic and heterotrophic taxa as a proxy for functional complexity, we linked measured variables in a parsimonious yet comprehensive structural equation model that explained significant variations in biological complexity and identified landscape-scale and fine-scale abiotic factors as the primary drivers of diversity. However, the inclusion of linkages among functional groups was essential for constructing the best-fitting model. Our findings support the notion that biotic interactions make crucial contributions even in an extremely simple ecosystem.
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    Connectivity: insights from the US Long Term Ecological Research Network
    Iwaniec, David M.; Gooseff, Michael N.; Suding, Katharine N.; Samuel Johnson, David; Reed, Daniel C.; Peters, Debra P. C.; Adams, Byron J.; Barrett, John E.; Bestelmeyer, Brandon T.; Castorani, Max C. N.; Cook, Elizabeth M.; Davidson, Melissa J.; Groffman, Peter M.; Hanan, Niall P.; Huenneke, Laura F.; Johnson, Pieter T. J.; McKnight, Diane M.; Miller, Robert J.; Okin, Gregory S.; Preston, Daniel L.; Rassweiler, Andrew; Ray, Chris; Sala, Osvaldo E.; Schooley, Robert L.; Seastedt, Timothy; Spasojevic, Marko J.; Vivoni, Enrique R. (2021-05)
    Ecosystems across the United States are changing in complex and surprising ways. Ongoing demand for critical ecosystem services requires an understanding of the populations and communities in these ecosystems in the future. This paper represents a synthesis effort of the U.S. National Science Foundation-funded Long-Term Ecological Research (LTER) network addressing the core research area of "populations and communities." The objective of this effort was to show the importance of long-term data collection and experiments for addressing the hardest questions in scientific ecology that have significant implications for environmental policy and management. Each LTER site developed at least one compelling case study about what their site could look like in 50-100 yr as human and environmental drivers influencing specific ecosystems change. As the case studies were prepared, five themes emerged, and the studies were grouped into papers in this LTER Futures Special Feature addressing state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the "connectivity" theme and has examples from the Phoenix (urban), Niwot Ridge (alpine tundra), McMurdo Dry Valleys (polar desert), Plum Island (coastal), Santa Barbara Coastal (coastal), and Jornada (arid grassland and shrubland) sites. Connectivity has multiple dimensions, ranging from multi-scalar interactions in space to complex interactions over time that govern the transport of materials and the distribution and movement of organisms. The case studies presented here range widely, showing how land-use legacies interact with climate to alter the structure and function of arid ecosystems and flows of resources and organisms in Antarctic polar desert, alpine, urban, and coastal marine ecosystems. Long-term ecological research demonstrates that connectivity can, in some circumstances, sustain valuable ecosystem functions, such as the persistence of foundation species and their associated biodiversity or, it can be an agent of state change, as when it increases wind and water erosion. Increased connectivity due to warming can also lead to species range expansions or contractions and the introduction of undesirable species. Continued long-term studies are essential for addressing the complexities of connectivity. The diversity of ecosystems within the LTER network is a strong platform for these studies.
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    The Distribution of Surface Soil Moisture over Space and Time in Eastern Taylor Valley, Antarctica
    Salvatore, Mark R.; Barrett, John E.; Fackrell, Laura E.; Sokol, Eric R.; Levy, Joseph S.; Kuentz, Lily C.; Gooseff, Michael N.; Adams, Byron J.; Power, Sarah N.; Knightly, J. Paul; Matul, Haley M.; Szutu, Brian; Doran, Peter T. (MDPI, 2023-06-18)
    Available soil moisture is thought to be the limiting factor for most ecosystem processes in the cold polar desert of the McMurdo Dry Valleys (MDVs) of Antarctica. Previous studies have shown that microfauna throughout the MDVs are capable of biological activity when sufficient soil moisture is available (~2–10% gravimetric water content), but few studies have attempted to quantify the distribution, abundance, and frequency of soil moisture on scales beyond that of traditional field work or local field investigations. In this study, we present our work to quantify the soil moisture content of soils throughout the Fryxell basin using multispectral satellite remote sensing techniques. Our efforts demonstrate that ecologically relevant abundances of liquid water are common across the landscape throughout the austral summer. On average, the Fryxell basin of Taylor Valley is modeled as containing 1.5 ± 0.5% gravimetric water content (GWC) across its non-fluvial landscape with ~23% of the landscape experiencing an average GWC > 2% throughout the study period, which is the observed limit of soil nematode activity. These results indicate that liquid water in the soils of the MDVs may be more abundant than previously thought, and that the distribution and availability of liquid water is dependent on both soil properties and the distribution of water sources. These results can also help to identify ecological hotspots in the harsh polar Antarctic environment and serve as a baseline for detecting future changes in the soil hydrological regime.
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    Nematodes in a polar desert reveal the relative role of biotic interactions in the coexistence of soil animals
    Caruso, Tancredi; Hogg, Ian D.; Nielsen, Uffe N.; Bottos, Eric M.; Lee, Charles K.; Hopkins, David W.; Cary, S. Craig; Barrett, John E.; Green, T.G. Allan; Storey, Bryan C.; Wall, Diana H.; Adams, Byron J. (Springer Nature, 2019-02-15)
    Abiotic factors are major determinants of soil animal distributions and their dominant role is pronounced in extreme ecosystems, with biotic interactions seemingly playing a minor role. We modelled co-occurrence and distribution of the three nematode species that dominate the soil food web of the McMurdo Dry Valleys (Antarctica). Abiotic factors, other biotic groups, and autocorrelation all contributed to structuring nematode species distributions. However, after removing their effects, we found that the presence of the most abundant nematode species greatly, and negatively, affected the probability of detecting one of the other two species. We observed similar patterns in relative abundances for two out of three pairs of species. Harsh abiotic conditions alone are insufficient to explain contemporary nematode distributions whereas the role of negative biotic interactions has been largely underestimated in soil. The future challenge is to understand how the effects of global change on biotic interactions will alter species coexistence.
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    Response of a Terrestrial Polar Ecosystem to the March 2022 Antarctic Weather Anomaly
    Barrett, John E.; Adams, Byron J.; Doran, Peter T.; Dugan, Hilary A.; Myers, Krista F.; Salvatore, Mark R.; Power, Sarah N.; Snyder, Meredith D.; Wright, Anna T.; Gooseff, Michael N. (American Geophysical Union, 2024-07-31)
    Record high temperatures were documented in the McMurdo Dry Valleys, Antarctica, on 18 March 2022, exceeding average temperatures for that day by nearly 30°C. Satellite imagery and stream gage measurements indicate that surface wetting coincided with this warming more than 2 months after peak summer thaw and likely exceeded thresholds for rehydration and activation of resident organisms that typically survive the cold and dry conditions of the polar fall in a freeze‐dried state. This weather event is notable in both the timing and magnitude of the warming and wetting when temperatures exceeded 0°C at a time when biological communities and streams have typically entered a persistent frozen state. Such events may be a harbinger of future climate conditions characterized by warmer temperatures and greater thaw in this region of Antarctica, which could influence the distribution, activity, and abundance of sentinel taxa. Here we describe the ecosystem responses to this weather anomaly reporting on meteorological and hydrological measurements across the region and on later biological observations from Canada Stream, one of the most diverse and productive ecosystems within the McMurdo Dry Valleys.