Tree-Ring Talk

Low-frequency streamflow signal from cottonwood tree rings

Tree-ring reconstructions from ring widths of upland trees are a longstanding source of information on variability of streamflow.  Such trees sense variations in net precipitation in runoff-producing parts of a watershed.  While riparian trees are much less commonly applied in streamflow reconstruction, large multi-aged populations of riparian trees offer the opportunity to improve reconstructions of streamflow through alternative standardization methods and a direct pathway of response of growth to changes in stream level.

Megafires, climate, and future forests

Wildfires of uncharacteristic severity interact with climate change and other disturbances to alter dry pine forests in western North America and the Mediterranean Basin. These fires present challenges for society and for the sustainability of ecosystems. While there are many differences between regions and nations, there are opportunities for comparative studies to assess current megafires and forecast future ecosystem change. 

Drought-Associated Tree Mortality: Global patterns and insights from tree-ring studies in the Southwestern U.S.A.

Forests play an important role in the earth system, regulating climate, maintaining biodiversity, and provisioning human communities with water, food and fuel. Interactions between climate and forest dynamics are not well constrained, and high uncertainty characterizes projections of global warming impacts on forests and associated ecosystem services. Recently observed tree mortality and forest die-off forewarn an acceleration of forest change with rising temperature and increased drought.

What can we learn from the arctic shrub (-rings)? Dendrochronological records of shrubs' annual growth in High and Low Arctic sites (Spitsbergen, Greenland, Alaska)

Recent changes in the thermal regime of the Arctic and related tundra expansion in higher latitudes resulted in an intense development of dendrochronological and dendroecological studies in the polar regions. In last decade we observed a significant increase in the use of tree-ring growth analysis in high latitudes where radial growth of woody plants, from shrubs to perennial herbs, is studied. Thermal limitations of cambial growth in the Arctic enable mainly dendroclimatological studies, which application requires a construction of reliable tree-ring chronologies.

Science at 9157': how the UA Sky School can help with your research and outreach needs

We provide year-round residential science programs (1-5 days) to Arizona K-12 students at our 25-acre Mt. Lemmon campus. Our philosophy is to provide place-basedinquiry-based, and outdoor science education. Programs include:

Scrambled or Poached? Modelling and Environmental Signals in Alluvial Systems

Recent numerical and physical modelling has claimed that environmental signals are entirely ‘shredded’ or ‘scrambled’ during fluvial sediment transfer processes, but landform and associated sedimentary records worldwide suggest otherwise. One probable reason for this apparent discrepancy is that many catchments contain depositional ‘niches’ , such as cutoffs, flood basins and identifiable deposits from single  large events (e.g.

Reconstructing Klamath River Flow with Uncertain Instrumental Records: a Mathematical Tale of Passion, Deception, and Desire

Tree-ring based reconstructions of streamflow variability are useful to water resource management. A challenge when developing reconstructions is assessing multiple uncertainties and how these uncertainties impact use in resource management. The skill of tree-ring reconstructions greatly depends on the quality and availability of tree-ring data and the instrument records used for reconstruction training and testing. This presentation will touch on the impact of potential uncertainty in instrumental records with an emphasis on streamflow reconstructions in the Upper Klamath River basin.

Tree-Ring View of “Nameless Oscillation” in California Streamflow

An ongoing severe drought in California highlights the importance of understanding and predicting multi-year swings in moisture availability on the scale of large watersheds.  The 20th and early 21st centuries have seen large oscillations with an average period of about 15 years in annual flows of the Sacramento and San Joaquin Rivers, two major sources of water supply for the state of California.  A meeting sponsored by the California Department of Water Resources (CADWR) was held in La Jolla, California, this past May specifically to address hydrologic and climatological aspects of the rh

From cell to continent: introducing our new cambial phenology project

Our aim is to fill important gaps both in the scientific basis for the use of tree rings as natural archives of past climate and in the scientific understanding of the rates and patterns of carbon storage in annual growth layers in relation to seasonal to inter-annual climate variation. These gaps concern the basic natural history of the tissue that forms annual rings in wood, the vascular cambium.

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