Basic Life Science Research Associate, Biology
Witnessing history: comparison of a century of sedimentary and written records in a California protected area.
Regional environmental change
2023; 23 (2): 65
We use a combination of proxy records from a high-resolution analysis of sediments from Searsville Lake and adjacent Upper Lake Marsh and historical records to document over one and a half centuries of vegetation and socio-ecological change-relating to logging, agricultural land use change, dam construction, chemical applications, recreation, and other drivers-on the San Francisco Peninsula. A relatively open vegetation with minimal oak (Quercus) and coast redwood (Sequoia sempervirens) in the late 1850s reflects widespread logging and grazing during the nineteenth century. Forest and woodland expansion occurred in the early twentieth century, with forests composed of coast redwood and oak, among other taxa, as both logging and grazing declined. Invasive species include those associated with pasturage (Rume x, Plantago), landscape disturbance (Urtica, Amaranthaceae), planting for wood production and wind barriers (Eucalyptus), and agriculture. Agricultural species, including wheat, rye, and corn, were more common in the early twentieth century than subsequently. Wetland and aquatic pollen and fungal spores document a complex hydrological history, often associated with fluctuating water levels, application of algaecides, raising of Searsville Dam, and construction of a levee. By pairing the paleoecological and historical records of both lakes, we have been able to reconstruct the previously undocumented impacts of socio-ecological influences on this drainage, all of which overprinted known climate changes. Recognizing the ecological manifestations of these impacts puts into perspective the extent to which people have interacted with and transformed the environment in the transition into the Anthropocene.The online version contains supplementary material available at 10.1007/s10113-023-02056-9.
View details for DOI 10.1007/s10113-023-02056-9
View details for PubMedID 37125024
View details for PubMedCentralID PMC10116087
The Searsville Lake Site (California, USA) as a candidate Global boundary Stratotype Section and Point for the Anthropocene series.
The anthropocene review
2023; 10 (1): 116-145
Cores from Searsville Lake within Stanford University's Jasper Ridge Biological Preserve, California, USA, are examined to identify a potential GSSP for the Anthropocene: core JRBP2018-VC01B (944.5 cm-long) and tightly correlated JRBP2018-VC01A (852.5 cm-long). Spanning from 1900 CE ± 3 years to 2018 CE, a secure chronology resolved to the sub-annual level allows detailed exploration of the Holocene-Anthropocene transition. We identify the primary GSSP marker as first appearance of 239,240Pu (372-374 cm) in JRBP2018-VC01B and designate the GSSP depth as the distinct boundary between wet and dry season at 366 cm (6 cm above the first sample containing 239,240Pu) and corresponding to October-December 1948 CE. This is consistent with a lag of 1-2 years between ejection of 239,240Pu into the atmosphere and deposition. Auxiliary markers include: first appearance of 137Cs in 1958; late 20th-century decreases in δ15N; late 20th-century elevation in SCPs, Hg, Pb, and other heavy metals; and changes in abundance and presence of ostracod, algae, rotifer and protozoan microfossils. Fossil pollen document anthropogenic landscape changes related to logging and agriculture. As part of a major university, the Searsville site has long been used for research and education, serves users locally to internationally, and is protected yet accessible for future studies and communication about the Anthropocene.The Global boundary Stratotype Section and Point (GSSP) for the proposed Anthropocene Series/Epoch is suggested to lie in sediments accumulated over the last ~120 years in Searsville Lake, Woodside, California, USA. The site fulfills all of the ideal criteria for defining and placing a GSSP. In addition, the Searsville site is particularly appropriate to mark the onset of the Anthropocene, because it was anthropogenic activities-the damming of a watershed-that created a geologic record that now preserves the very signals that can be used to recognize the Anthropocene worldwide.
View details for DOI 10.1177/20530196221144098
View details for PubMedID 37213212
View details for PubMedCentralID PMC10193828
- The Searsville Lake Site (California, USA) as a candidate Global Boundary Stratotype Section and Point for the Anthropocene Series ANTHROPOCENE REVIEW 2023
- Lessons for conservation from beneath the pavement. Conservation biology : the journal of the Society for Conservation Biology 2022: e13983
Editorial Commentary: Recovery After Anterior Cruciate Ligament Reconstruction Is Optimal About 85% of the Time.
Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association
2022; 38 (8): 2491-2492
Recovery after anterior cruciate ligament reconstruction is optimal about 85% of the time. Revision surgery, psychiatric history, preoperative chronic knee pain, and subsequent knee injury are associated with suboptimal recovery patterns. Sophisticated growth models can analyze patient recovery trajectories. Growth mixture models (GMM) treat a whole cohort as a single group and characterize that group over time, for example, over the course of knee injury and subsequent recovery after surgical reconstruction. Latent class growth analysis is a subcategory of GMM that sorts the cohort into subgroups and allows analysis regarding groups having, for example, standard, delayed, and suboptimal recoveries. This theoretically allows a physician to anticipate which patients are likely to follow a suboptimal trajectory of recovery, to track that recovery based on the model, and to form a treatment plan accordingly.
View details for DOI 10.1016/j.arthro.2022.05.001
View details for PubMedID 35940743
Assessing the reliability of raptor pellets in recording local small mammal diversity
View details for DOI 10.1017/qua.2021.59
- Inferring critical transitions in paleoecological time series with irregular sampling and variable time-averaging QUATERNARY SCIENCE REVIEWS 2019; 207: 49–63
Post-fire vegetation and climate dynamics in low-elevation forests over the last three millennia in Yellowstone National Park.
View details for DOI 10.1111/ecog.00119
Abrupt Change in Ecological Systems: Inference and Diagnosis
TRENDS IN ECOLOGY & EVOLUTION
2018; 33 (7): 513–26
Abrupt ecological changes are, by definition, those that occur over short periods of time relative to typical rates of change for a given ecosystem. The potential for such changes is growing due to anthropogenic pressures, which challenges the resilience of societies and ecosystems. Abrupt ecological changes are difficult to diagnose because they can arise from a variety of circumstances, including rapid changes in external drivers (e.g., climate, or resource extraction), nonlinear responses to gradual changes in drivers, and interactions among multiple drivers and disturbances. We synthesize strategies for identifying causes of abrupt ecological change and highlight instances where abrupt changes are likely. Diagnosing abrupt changes and inferring causation are increasingly important as society seek to adapt to rapid, multifaceted environmental changes.
View details for DOI 10.1016/j.tree.2018.04.013
View details for Web of Science ID 000438464300010
View details for PubMedID 29784428
- Can protected areas really maintain mammalian diversity? Insights from a nestedness analysis of the Colorado Plateau BIOLOGICAL CONSERVATION 2017; 209: 546–53
Merging paleobiology with conservation biology to guide the future of terrestrial ecosystems
2017; 355 (6325): 594-?
Conservation of species and ecosystems is increasingly difficult because anthropogenic impacts are pervasive and accelerating. Under this rapid global change, maximizing conservation success requires a paradigm shift from maintaining ecosystems in idealized past states toward facilitating their adaptive and functional capacities, even as species ebb and flow individually. Developing effective strategies under this new paradigm will require deeper understanding of the long-term dynamics that govern ecosystem persistence and reconciliation of conflicts among approaches to conserving historical versus novel ecosystems. Integrating emerging information from conservation biology, paleobiology, and the Earth sciences is an important step forward on the path to success. Maintaining nature in all its aspects will also entail immediately addressing the overarching threats of growing human population, overconsumption, pollution, and climate change.
View details for DOI 10.1126/science.aah4787
View details for PubMedID 28183912
- Stasis and change in Holocene small mammal diversity during a period of aridification in southeastern Utah HOLOCENE 2016; 26 (7): 1005–19
PRELUDE TO THE ANTHROPOCENE: TWO NEWLY-DEFINED NORTH AMERICAN LAND-MAMMAL AGES
TAYLOR & FRANCIS INC. 2012: 60
View details for Web of Science ID 000313496400029