1. Monthly archive

December 2021

Enhanced hydroclimatic variability over California

Most of the annual precipitation over California occurs in a short window between November and March and is highly dependent on the frequency of winter storms. Thus, the amount of precipitation can vary strongly from year to year, as demonstrated in the most recent decade (2012-2022), when year-to-year swings between high and low winter precipitation extremes resulted in drought, wildfires, and floods throughout California that caused billions of dollars in damage.

Double-header: (1) Sensitivity to hydrologic whiplash in the tree-ring record of the high Sierra Nevada; (2) The Cycloscope of Andrew Ellicott Douglass: Analog computing from early 20th century climate science resurrected

1) Sensitivity to hydrologic whiplash in the tree-ring record of the high Sierra Nevada

The North American Monsoon Rescues Forests From a Mega Drought While Others Are Left High and Dry

Drought conditions have been projected to increase globally as atmospheric CO2 (ca) and vapor pressure deficit (VPD) increase. Experimental and modelling studies have suggested that forest responses to drought may be bolstered by increased ca, but it remains unclear how prevalent this response is in natural forest ecosystems.

How do wood anatomical traits in Salix vary in response to flooding? A case study from the Yenisei River, Siberia

Recent, record-breaking discharge in the Yenisei River, Siberia, is part of a larger trend of increasing river flow in the Arctic driven by Arctic amplification. These changes in magnitude and timing of discharge can lead to increased risk of extreme flood events, with implications for infrastructure, ecosystems, and climate. To better understand the changes taking place, it is useful to have records that help place recent hydrological changes in context.

Dendroarchaeology in the Southeastern U. S.: The Quest to Develop New Regional Tree-Ring Networks Using Dendroarchaeological Data

The state of Kentucky and the North Carolina (NC) Piedmont represent large spatial gaps in public tree-ring datasets. For Kentucky, there are only four unique sites currently represented on the International Tree-Ring Data Bank. For North Carolina, only 26 unique sites are represented; less than 12 were collected from sites east of the Appalachian Mountains, and only seven are from Piedmont sites. Like other eastern states, Kentucky and North Carolina old-growth forests were removed for logging and agriculture during settler colonization of the states.

Prehistoric pile-dwellings: dendroarchaeology in the southwestern Balkans

A number of wetland archaeological sites have been identified around the lakes in the southwestern part of the Balkan Peninsula, however only a limited number have been excavated. The constantly wet, low-oxygen depositional environment on such sites provides excellent conditions for wood preservation. Since 2018, more than 1800 remains of construction woods have been sampled from these prehistoric sites, mostly from the Lakes of Ohrid and Kastoria.

Creating more culturally engaging and inclusive environments in STEM

The lack of diversity in STEM professions is an ongoing concern for the US both in terms of social justice and in having a globally competitive workforce. This session will present a framework for thinking about diversity and inclusion in STEM courses and in research environments, and provides research and information for faculty, graduate students, and campus leaders to be proactive in considering a wide array of identities to meet the needs of students beyond attending to structural forms of diversity.

The risks of xylem safety: when investing in cavitation resistance doesn't save trees from drought

As the earth’s climate warms, forest around the world – and particularly those in already arid climates – have been suffering increasing drought stress. During the “hot drought” of 2012-2016, over 1 million conifer trees across California’s Sierra Nevada mountains died. We investigated how trees that died differed from those that lived in how they built their wood. Surprisingly, pines that died tended to have narrower xylem tracheids (the water conducting cells in wood) with thicker walls – features that should have made them more resistant to hydraulic failure during drought.

Tailoring X-ray imaging techniques for dendrochronology of large wooden objects

X-ray computed tomography (CT) has been applied to visualize tree rings in a non-invasive way for dendrochronological research. For large objects such as chests or cabinets, it is often impossible or impractical to rotate fully within the scanner as is necessary for CT. As a solution to this challenge, we developed a line trajectory X-ray tomography technique, in which the object is moved only sideways. We show that this
method, although not yielding a full 3D image, is particularly well suited to reveal tree rings. Using this easily implementable scanning

Servingness in STEM: Meaning and Examples