Tree-Ring Talk

Stable isotopes of tree rings reveal seasonal-to-decadal patterns during the emergence of a megadrought in the Southwestern US

Recent evidence has revealed the emergence of a megadrought in southwestern North America since 2000. In this occasion I will talk about how we examined tree-ring growth and stable isotope ratios in Pinus ponderosa at its driest niche edge to investigate whether trees growing near their aridity limit were sensitive to the megadrought climatic conditions during or before the establishment of the current megadrought.

Multicentennial perspectives on extreme climate and natural disasters in the northeastern Pacific

Over the past decade, the northeastern Pacific has witnessed repeated and severe heatwaves that have profoundly impacted the functioning and productivity of marine and adjacent terrestrial ecosystems. However, there remains considerable and long-standing uncertainly regarding NE Pacific climate variability prior to 1900 CE and the extent to which recent extremes are atypical in a longer-term context.

RingdateR: A statistical and graphical tool for crossdating

Crossdating is the defining technique of dendrochronology, ensuring that all measurements in a dataset are annually resolved and absolutely dated. This level of accuracy allows for the development of high-resolution environmental reconstructions of climate, disturbance, and productivity not only in trees, but also in other ring-forming organisms including fish, corals, and bivalves. However, crossdating is a laborious process and can be a significant bottleneck in the development of new chronologies, especially when attempting to find matches among undated, dead-collected material.

How Mountain Topography Shaped Fire Use in the Southern Canadian Rocky Mountains

The Kootenai people of southern Canada historically traversed the Rocky Mountains, often several times annually, to hunt bison on the eastern front ranges. Some routes across this complex landscape were more energetically efficient than others, producing a tendency for archaeological and historical sites to be located along least-cost paths as strongly predicted by this project’s geographical computer models. Bison wallows also occurred across low travel cost areas from the eastern front well into the Rocky Mountain interior.

“Blue Rings" in paleoclimate reconstruction and beyond

'Blue Rings' are an anatomical anomaly found in conifers characterized by incomplete cell wall lignification, visible in safranin-Astrablue stained anatomical thin sections (Piermattei et al. 2015). This talk will guide you through a journey from the accidental discovery of 'Blue Rings', to the most recent application of their detection and enumeration in dendrochronology, forest ecology, and palaeoclimatology. The significance of the first millennium-long 'Blue Ring' chronology in detecting post-cooling volcanic eruptions will be discussed.

Dendrochronology in Motion: Visualizing Cottonwood Tree Growth across Space and Time

Cottonwood (Populus deltoides subsp. Monilifera) tree rings have been shown to faithfully record river discharge through time (Meko et al. 2015). What is less understood, however, is 1) how a tree's position on the floodplain influences its growth and its relationship to climate, and 2) how this influence changes through time. Taking advantage of the existing tree ring, hydrologic, and remote sensing datasets, we can watch the growth and development of a centuries-old riparian forest in a 10-minute video.

A hotter-drought fingerprint on Earth’s forest mortality sites – warming accelerates risks, especially for historical forests

Earth’s forests face grave challenges in the Anthropocene, including hotter droughts increasingly associated with widespread forest die-off. But despite the vital importance of forests to global ecosystem services, their fates in a warming world remain highly uncertain.

When the signal is the noise: Does aggregation impede prediction of forest response to climate?

Forest management aimed at promoting climate change resilience hinges on accurately quantifying the relationship between tree growth and climate. Aggregation is commonly used to upscale individual tree response (e.g., ring-width time series) to broader scales of inference, prediction, and decision-making. This approach assumes non-climatic drivers of tree growth vary randomly across a population such that their effects cancel out with replication and climate emerges as a strong predictor of aggregate tree growth.

Continental-scale tree ring-based projection of Douglas-fir growth - Testing the limits of space-for-time substitution

Nature-based solutions to the climate crisis increasingly focus on forests. In this research, we address the question “how much CO2 will trees remove from the atmosphere in the future?”, by projecting the future absolute growth of trees under future climate conditions. We confront the problem of extrapolation – i.e., that we must predict the response of trees to climate that is increasingly different from historical conditions.

The North American tree-ring fire-scar network

Fire activity is increasing across much of North America, driven by climate change and human land use. Instrumental records of fire are too short to quantify patterns and drivers of fire regimes to accurately model future fire.  Tree-ring fire scars are sub-annually resolved and span centuries to millennia.  We present the newly compiled North American tree-ring fire-scar network (n = 2,548 sites). It spans biomes from northern Alaska to southern Mexico and from California to northeastern Canada, including 104 different tree species.

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