Tree-Ring Talk

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.

The tracks of my floods: tree-ring memoirs of an Arctic river

The shortness of gaged river flows limits our understanding of the variability of the river component of heat and fresh water inflow to the Arctic Ocean. This talk describes a tree-ring approach to addressing the uncertainty of Arctic river flows using a combination of non-riparian and riparian  trees growing in the floodplain of the lower Ob River, in western Siberia. The talk focuses specifically on the tree-ring signal for inter-annual variability of flooding, which happens on a massive spatial scale each year along the Ob with spring ice break.

Revisiting the response of the Asian monsoon system to volcanic eruptions over the last millennium

Volcanic eruptions are the most important natural climate forcing over the last millennium.  Reductions in top of the atmosphere incoming shortwave radiation and the concomitant declines in global temperatures are expected to cause a weaker hydrological cycle, a reduction in precipitable water, and a drier monsoon.  The putative response of the ENSO system to volcanic eruptions should likewise result in drought of south and southeast Asia, enhancing this effect.

Assimilation of tree ring and forest inventory data to forecast future growth responses of Pinus ponderosa

Forest responses to future climate changes are highly uncertain, but critical for forecasting and managing for forest carbon dynamics. To improve ecological forecasts of forest responses, we harness the strengths of two large ecological datasets: tree-ring time series data that provide annually resolved growth responses, and repeated measurements of tree size measurements from spatially extensive forest inventory (FIA) data.

A review of the 2020 North American Monsoon season

After a relatively weak monsoon across the southwestern U.S. in 2019, expectations were high for an active 2020 monsoon season. Unfortunately, the opposite happened and June through September precipitation totals were record low for many stations across the region. The summer was also the hottest on record for many locations. This presentation will provide a basic background of the climatology of the North American Monsoon System with respect to shifts in circulation patterns, moisture sources, and patterns of precipitation.

Art and the Ecology of Time

Standard time is measured on atomic clocks, providing a technical basis for business and personal activities. Might trees be more meaningful timekeepers? Might a clock paced by their natural growth encourage us to nurture our environment and the relationships that matter most? Over the past several years, conceptual artist and experimental philosopher Jonathon Keats has been collaborating with the Long Now Foundation and the Nevada Museum of Art on a monumental clock calibrated by bristlecone pine trees.

dfoliatR empowers analyses of forest defoliator outbreak chronologies

Further extending the functional capacity of classic DPL programs, we developed “dfoliatR”, an R package based on the program OUTBREAK developed by Richard Holmes and Thomas Swetnam in the 1980s. dfoliatR uses dplR to access standardized tree-ring series from insect defoliator host species and chronologies from non-host species. It infers defoliation events with an indexing procedure that removes the climatic signal (represented in a non-host chronology) from individual host-tree series.

The Dendroarchaeology of Navajo Sites on Northern Black Mesa, Northeastern Arizona

From 1967 to 1986, scholars from, first, Prescott College and, subsequently, Southern Illinois University at Carbondale undertook one of the largest contract archaeological projects in Arizona.  The Black Mesa Archaeological Project (BMAP) was designed to mitigate the damage to the cultural resources of the Mesa caused by the construction of an open pit coal mine to provide fuel for the Navajo Generating Station near Page, Arizona.  Documentation of nearly 2,000 prehistoric (Ancestral Puebloan) and historic (Navajo) sites produced more than 8,000 archaeologic

This summer: what I did, what I didn't do, and what I wanted to do

The long-standing tradition of a round up of activities over the summer continues with a series of five-minute lightning talks by the following people:

  1. David Frank
  2. Margaret Evans
  3. Charlotte Pearson
  4. Paul Sheppard
  5. Peter Brewer
  6. David Meko
  7. Brandon Strange
  8. Ann Lynch
  9. Ramzi Touchan
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