Tree-Ring Talk

Fire history and fire-climate relationships of Buryatia, Siberia

Wildfire activity in the boreal forests of Siberia has been increasing over the past 20 years in response to warming temperatures, with several extreme fire years in the past decade.  While extreme fire yeas have a strong association with temperature and drought conditions, smaller human-ignited fires occur almost every year, related to agriculture and logging.  To better understand the longer-term context of wildfires and fire-climate relationships of central Siberia, we developed a fire history for the Buryatia province, where we collected 25 sites of fire-scarred material throughout the

Combining tree-ring and forest plot data to infer climatic niche: a hierarchical Bayesian approach

The forest biome is expected to shift geographically with anthropogenic climate change. To build species-specific, process-based models for forecasting how trees' geographic distributions will change under future climate scenarios, we see a need to combine two major, complementary sources of information on individual tree performance in response to climate variation: tree-ring and forest plot data.

Forest Inventory and Analysis Tree-Ring Data

The National Forest Inventory and Analysis Program (FIA) conducts a congressionally mandated repeat forest inventory implemented on all lands in the conterminous United States. Forested plots (~125,000 nationwide) are revisited on a 5- or 10-year basis for data collection. As part of baseline protocols on initial visits increment cores were collected. Cores were used for aging stands, determining potential productivity in timber forest types and to quantify growth increment.

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.

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.

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