Tree-Ring Talk

Effects of climate on Colorado River flow: perspectives from the past, present and future

Mountain snowpack is a critical factor for determining annual streamflow in the upper Colorado River, but other climatic factors can play an important role as well.  In particular, spring temperatures appear to be increasingly important, but antecedent fall moisture and early summer rainfall may also influence flows.  In the Colorado River basis, where water demand increasingly exceeds supply, water managers are interested in gaining insights on these additional climatic influences.

Global Changes drivers in Mediterranean stress conditions: Drought, land use changes and forest decline

The southernmost European conifers forests are considered vulnerable areas to climate change. Recent climatic trends towards warmer and drier conditions across the Mediterranean Basin might render some of these populations more vulnerable to drought-induced growth decline at the southernmost limit of the species distribution and in relict forests. In addition to climate drivers, the land use changes and past management drive the growth response to climate change effects.

VS-Growth Evolution Neural Network (VS-GENN)

The tree-ring response to climate change is one of the most interesting problems in modern forest ecology. Despite the large number of papers on tree-ring response to environmental change (temperature increase, irrigation, drought, etc.) there is no reliable answer to how woody plants will respond to such change in different forest stands and biogeographic zones. The process-based tree-ring model developed by Vaganov & Shashkin ( VS-model) can be a key to answering this question.Two new principal approaches are described:

Tree-ring Dating the Llaves Valley Gallina

The 1970s were a period of intense activity in the Gallina heartland of north-central New Mexico. Excavations by James Mackey and Sally Holbrook and by Herb Dick documented dozens of Gallina sites and structures in the Llaves Valley alone. Unfortunately, analysis and publication did not always follow excavations, particularly in Herb Dick’s case.  His untimely death in 1993 left much of his excavated material in disarray.

Tree-Ring Talk, topic to be decided

A JOINT INSTITUTE OF THE ENVIRONMENT/LTRR SEMINAR: Volcanic Effects on Climate in the Late 20th and Early 21st Centuries

The relatively muted warming of the surface and lower troposphere since 1998 has attracted considerable attention. One contributory factor to this “warming hiatus” is an increase in volcanic cooling over the early 21st century. Our recent research has identified the signals of late 20th and early 21st century volcanic activity in multiple observed climate variables. Volcanic signals are statistically discernible in spatial averages of tropical and near-global sea-surface temperature, tropospheric temperature, net clear-sky short-wave radiation, and atmospheric water vapor.

Dendrochronology and middle Miocene petrified oak: Modern counterparts and interpretation

This study reports the first successful statistical ‘crossdating’ among ring width time series from many specimens of petrified wood, based samples of the genus Quercus from the Stinking Water (SW) site in Oregon, a Miocene-aged exposure associated with the Columbia River Basalts. Ring width time series from 26 radii, 17 different trees, show significant intercorrelation.

Tree-Ring Talk, topic to be decided

Probing (into) the memory of trees with dendrochronology

Communicating with trees through dendrochronology involve developing observational skills that goes beyond the usual year-to-year changes in ring width. Developing excellent observational skills is at the core of crossdating and dendrochronology. Understanding how tree-rings are affected by environmental factors also allows their use in reconstructing conditions prior to the onset of instrumental records. In this talk, I will briefly cover a few research projects being pursued at the University of Winnipeg DendroEcology Laboratory (UWDEL).

Asian Monsoon Variability over the Past Millennium Reconstructed from Long Tree-Ring Records: the Monsoon Asia Drought Atlas, version 2 (MADAv2)

The Monsoon Asia Drought Atlas, version 2 (MADAv2), is a substantially updated and improved year-to-year reconstruction of summer drought and wetness on a 1.0° grid over Monsoon Asia. It has been developed using the same basic methodology as that used in producing the previous version (MADAv1) published in 2010 and is now based on an improved target field of self-calibrating Palmer Drought Severity Indices (scPDSI) and a significantly larger network of 453 tree-ring chronologies compared to the previous effort.

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