Tree-Ring Talk

Probing the Error Term in Streamflow Reconstruction

Water balance models were first applied indirectly by tree-ring researchers in reconstructions of Palmer Drought Severity Index in the mid-1970s. Recent years have seen more direct and explicit use of water-balance models. This talk explores how a simple monthly water-balance model can be applied to diagnose possible causes of large errors in reconstructions of streamflow.

Drought in the rainforest? A shifting perspective on water scarcity in coastal British Columbia from tree-ring records

Summer streamflow droughts on British Columbia's rainforest coast have worsened dramatically over the last two decades, impacting human and ecological water supply. This region's unique hydroclimatology means that the "wettest part of Canada" is often the most water-scarce during summer, when demand is highest. The perception of being water-rich consistently undermines water conservation efforts in this densely populated area.

An exploratory study in wood anatomy, crossdating, climate-growth relationships, life history, and above-ground productivity

Velvet mesquite (Prosopis velutina Woot.) is a common tree in semi-arid, southwestern U.S. savanna ecosystems. While there are studies that examine some of the physiological and ecological aspects of this tree (response to fire, net ecosystem exchange, encroachment into grasslands, yearly growth through dendrometer bands, etc…), the wood anatomical features of a growth ring, suitability for dendrochronological research, life history, and above-ground productivity through time are knowledge gaps that can be filled.

Dendro Potential Along the John Muir Trail

I hiked the John Muir Trail this summer, noting lots of potential sites and projects for dendrochronology.

A process-based approach to understanding ecosystem-scale variation in n-alkane δD

Normal alkanes (n-alkanes) are long-chain fatty acids that are synthesized by terrestrial plants and then accumulate in soils and sediments. Since the hydrogen in the n-alkanes is derived from the hydrogen in plants’ water sources, the stable hydrogen isotopic composition (δD) of the n-alkanes includes information about the δD of environmental water.

Can extended monitoring data provide insight into controls on post fire tree growth?

Over the past two decades, the US government has been quietly collecting data on trees in our National Parks.  The Fire Effects Monitoring Program was established to measure ongoing effects of an active prescribed fire program on tree mortality, recruitment, fuel load, understory vegetation, and more.

Bark Beetle Outbreak Reconstructions from the Spruce Forest of the Tien Shan Mountains, Kazakhstan

Schrenk’s spruce has a relatively isolated distribution in central Asia and is only distantly related to other Eurasian spruces. Its primary bark beetle is Ips hauseri, a bark beetle capable of multiple generations per year. Neither tree nor insect species are well studied, and the outbreak dynamics in Kazakhstan are unknown. In spring of 2011 high-severity wind storms devastated portions of the Tien Shan spruce forest, events known to trigger bark beetle outbreaks in spruce forests.

A new spatiotemporal field reconstruction of last millennium Northern Hemisphere summer temperatures

Climate field reconstructions allow surface temperature variability to be estimated in both space and time from proxy paleoclimate data, providing targets for general circulation model comparisons and knowledge about the fingerprint of regional-scale climate variability in response to radiative forcing and internal climate system variability. Here, we use a network of 54 temperature-sensitive tree-ring width, density, and blue intensity chronologies at high latitudes to reconstruct the Northern Hemisphere summer temperature field back to 750 CE.

Calculating the flow of energy and water in complex terrain with high performance computing (HPC): Implications for dendroecology and dendroclimatology research.

High Performance Computing (HPC) is freely available to all University of Arizona researchers. However, understanding how to develop HPC applications and workflows that go beyond current desktop computing applications are not necessarily within the purview of most earth scientists. Collaboration between computer scientists and geoscientists is now a necessity to achieve cutting edge performance and results, e.g. in the life sciences the time to sequence DNA genomes are now counted in hours instead of years because of HPC and software developed specifically for research.

How long does a 15 year drought last? On the correlation of rare events

Recent tree ring analyses of the Colorado river flows over the past 500 years enable one to characterize the fluctuations on various timescales using Fourier analysis. We model these flows and calculate the clustering properties of droughts. These results are highly pertinent to the issue of water storage in the Mead and Powell reservoirs and the necessity to rethink how we use water in the southwestern US.

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