Article
Geochemistry & Geophysics
Benjamin Z. Klein, Oliver Jagoutz
Summary: The Bear Valley Intrusive Suite (BVIS) in the Southernmost Sierra Nevada represents a unique snapshot of magmatic processes within continental arc crust, with a fundamental dichotomy found between the lower crust composed of mafic cumulates and the middle/upper crust composed of tonalites. Modeling results suggest that BVIS magmas must have cooled below 900 degrees C near 7 kbars depth before rapidly emplacing in the upper crust along near-isothermal paths. The Sierra Nevada Arc magmas are thought to have cooled and differentiated at greater depths than the BVIS magmas, based on seismic velocity observations.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Biodiversity Conservation
Laura C. Streib, Jeffery R. Stone, Eva C. Lyon, Hung H. Quang, Kevin M. Yeager, Susan R. H. Zimmerman, Michael M. McGlue
Summary: This study analyzed lake sediment records from the eastern Sierra Nevada over the past three millennia to reveal ecological changes driven by hydroclimate oscillations. Results showed that hot-dry conditions of the Industrial Era altered lake state, leading to profound impacts on high-elevation lakes and the ecosystem services they provide.
GLOBAL CHANGE BIOLOGY
(2021)
Article
Engineering, Civil
Mohammad Safeeq, Aliva Nanda, Joseph W. Wagenbrenner, Jack Lewis, Carolyn T. Hunsaker
Summary: The sediment yield from headwater catchments is controlled by hydrology, geomorphology, and soil disturbance. The role of snow on modulating spatial and temporal variation of sediment yield remains unclear. This study in the southern Sierra Nevada found that snowmelt is a strong driver of sediment yield, and rainfall events have higher erosion severity and power than snowmelt events. A shift from snow to rain under a warming climate is likely to increase sediment yield.
JOURNAL OF HYDROLOGY
(2022)
Article
Ecology
James W. Roche, Kristen N. Wilson, Qin Ma, Roger C. Bales
Summary: This study evaluates the uncertainties in water balances across 52 watersheds in the Central Sierra Nevada and highlights the importance of evapotranspiration as a central metric of water-balance change and variability.
FRONTIERS IN FORESTS AND GLOBAL CHANGE
(2022)
Article
Geochemistry & Geophysics
Herve Rezeau, Benjamin Z. Klein, Oliver Jagoutz
Summary: Exposures of arc crustal sections provide rare opportunities to study lower crustal magmatic processes in connection with middle and upper crustal arc products. Through detailed petrography and mineral chemistry of the Bear Valley Intrusive Suite, this study reveals the crystallization processes of mafic and tonalitic rocks in the lower crust of the Sierran arc. The research proposes a model involving mixing of dry and wet magmas with similar viscosities and crystallization-differentiation processes in the deep crust to explain the formation of SiO2-rich melts in the Bear Valley Intrusive Suite.
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
(2021)
Article
Environmental Sciences
Ryan M. Ferrell, Scott Devine, Anthony T. T. O'Geen
Summary: The deep root system of forests allows them to withstand insufficient precipitation. However, there is limited documentation regarding the spatial distribution of regolith thickness in forest ecosystems. A study in the southern Sierra Nevada estimated regolith thickness using hand auger measurements across a 543-ha watershed and found that more than 55% of the area had a depth greater than 5 m. The study also revealed a correlation between topography and spatial trends in regolith thickness.
VADOSE ZONE JOURNAL
(2023)
Article
Geosciences, Multidisciplinary
Helen W. Beeson, Scott W. Mccoy
Summary: The timing, rates, and spatial patterns of elevation change in the Sierra Nevada are analyzed in this study using fluvial geomorphology measures and landscape evolution modeling. The results suggest that westward-draining rivers in the Sierra Nevada are in a disequilibrium state due to significant down-to-the-west tilting in the last 11 million years. The study also finds that surface uplift from late Cenozoic tilting appears to have been similar along strike and heavily modulated by lithology and drainage area exchange.
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
(2022)
Article
Microbiology
Mia R. Maltz, Chelsea J. Carey, Hannah L. Freund, Jon K. Botthoff, Stephen C. Hart, Jason E. Stajich, Sarah M. Aarons, Sarah M. Aciego, Molly Blakowski, Nicholas C. Dove, Morgan E. Barnes, Nuttapon Pombubpa, Emma L. Aronson
Summary: Dust provides significant input of nutrients in ecosystems, and is also a vector for dispersing microorganisms. This study found that the composition and diversity of dust-associated microorganisms differ by elevation and are influenced by landscape topography and droughts in source areas.
FRONTIERS IN MICROBIOLOGY
(2022)
Article
Environmental Sciences
Steven Pestana, Jessica D. Lundquist
Summary: Thermal infrared imagery from GOES satellites provides an opportunity to observe mountain surface temperatures. Orthorectification is necessary to correct for the parallax effect in off-nadir imagery. ABI brightness temperatures closely match those of forest canopy temperatures.
REMOTE SENSING OF ENVIRONMENT
(2022)
Article
Geosciences, Multidisciplinary
H. W. Beeson, S. W. McCoy
Summary: The author responded to Gabet's criticisms and defended their interpretation of migrating knickpoints in the Sierra and their estimates of surface uplift. They used systematic topographic analysis and various methods to identify consistent trends of uplift timing and magnitude along the length of the range. Although pinpointing the timing of the most recent tectonic event is challenging, they argue that the uncertain estimate is valuable for understanding the tectonic history of the Sierra.
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
(2023)
Article
Biochemistry & Molecular Biology
Yi-Ming Weng, David H. Kavanaugh, Sean D. Schoville
Summary: The evolutionary histories of alpine species are closely related to their response to glaciation, with population structure influenced by drainage basins. Taking into account species' ecological preferences is crucial for understanding their response to climate fluctuations.
Article
Forestry
Marissa J. Goodwin, Lucy P. Kerhoulas, Harold S. J. Zald, Malcolm P. North, Matthew D. Hurteau
Summary: Climate change is causing more severe and prolonged droughts in forest ecosystems, affecting the ability of trees to survive. The research investigated the water-use patterns of Sierra Nevada conifers during a recent drought using tree ring analysis. The study found no significant changes in water-use patterns during the drought period and identified species-specific variations in water sources. The lack of plasticity in water-use patterns may make Sierra Nevada conifers vulnerable to drought mortality in the future.
Article
Ecology
Margarita Huesca, Susan L. Ustin, Kristen D. Shapiro, Ryan Boynton, James H. Thorne
Summary: This study used airborne hyperspectral imagery to identify the most important wavelength regions predicting drought-induced tree mortality in blue oak woodlands. The best metric for predicting canopy stress was found to be a normalized ratio using specific spectral bands, with a correlation of R-2 = 0.83. The study also revealed that tree mortality prediction accuracy was highest between 1% and 10% mortality rates.
Article
Environmental Studies
Bryant C. Baker, Chad T. Hanson
Summary: There is debate about the effectiveness of commercial thinning as a wildfire management strategy, with conflicting studies on the severity of thinned forests during wildfires. Our study in the Caldor Fire of 2021 found significantly higher cumulative severity in commercially thinned areas compared to unthinned forests. Further research is needed to determine if this pattern holds true for other large wildfires in the western US.
Article
Geography, Physical
Gonzalo Jimenez-Moreno, Oliver Heiri, Antonio Garcia-Alix, R. Scott Anderson, Francisco J. Jimenez-Espejo, Charo Lopez-Blanco, Laura Jimenez, Carmen Perez-Martinez, Marta Rodrigo-Gamiz, Alejandro Lopez-Aviles, Jon Camuera
Summary: Obtaining accurate temperature reconstructions from the past is crucial in understanding natural temperature changes and evaluating anthropogenic global warming. This study presents a detailed Holocene temperature reconstruction based on chironomid assemblages, revealing significant cooling during the Middle and Late Holocene. The current climate warming exceeds future projections, posing a threat to alpine environments and biodiversity.
QUATERNARY SCIENCE REVIEWS
(2023)
Article
Geochemistry & Geophysics
Summer J. Brown, J. Ryan Thigpen, James A. Spotila, William C. Krugh, Lisa M. Tranel, Devon A. Orme
Article
Geology
Alexander L. Densmore, Ralf Hetzel, Susan Ivy-Ochs, William C. Krugh, Nancye Dawers, Peter Kubik
Article
Environmental Sciences
Junhua Guo, Christine Pyles, William Krugh, Rob Negrini
INTERNATIONAL JOURNAL OF SEDIMENT RESEARCH
(2019)
Article
Geography, Physical
Andrew Meigs, William C. Krugh, Kelsay Davis, Greg Bank