Tree-Ring Talk

Synchronism, causality and determinism in wood formation: a question of time

Trees synchronize the cycles of growth and dormancy with the seasonal variations in weather, an essential aspect in ecosystems characterized by wide differences between seasons favorable and unfavorable to the physiological activities. Wood formation, or xylogenesis, is a complex and fascinating example of an intermittent growth process sensitive to temperature that can be studied at several time scales. The period of wood formation is the time window during which the xylem is under differentiation.

Assessing the climate feedbacks of U.S. Southwestern dryland forests and woodlands.

Like other dryland regions around the world, the U.S. Southwest is on a steep trajectory towards a hotter and drier climate. Among the most conspicuous effects of this drying are large-scale vegetation transitions towards sparser systems and lower growth forms. Such structural transformations will have far-reaching consequences for ecosystem functioning and for the climate feedbacks of dryland vegetation. These feedbacks remain undervalued and understudied in a climate mitigation context, because drylands sequester less carbon per area compared to more mesic systems.

Tropical explorations: what tree rings can contribute to studying global change effects in the tropics

Tropical forests and woodlands are key components of the global carbon cycle, as illustrated by the strong contribution of tropical vegetation to the inter-annual variation in the global carbon sink. These strong fluctuations in the carbon land sink are associated with precipitation and temperature anomalies, suggesting a strong component of vegetation productivity. Yet, the extent to which such associations also exist for carbon storage in tree stems is poorly understood.

Stronger together: Asynchronous tree growth dampens the impacts of accelerated climate change in a temperate rainforest

In this talk, I will introduce the idea that ecosystems located near glaciers can serve as natural laboratories for global change biology and paleoclimate studies. This is because they have experienced climate changes that were amplified by nearby ice-margin fluctuations. I will report on results from one of these natural experiments in the old-growth temperate rainforest near La Perouse Glacier in Southeast Alaska. We used dendrochronology to observe how tree growth responded to a shift from “normal” to accentuated rates of summer temperature change that occurred in the mid 1800s.

Hacienda de Gila: dendroarchaeology, architecture, and history at the Lyons and Campbell Ranch, Gila, New Mexico.

Buildings have stories. The materials, architecture, design, decoration and other attributes reveal life histories of a structure and often show changes through time. Sometimes, however, the stories are hidden and must be coaxed out of the building. Such is the case of the original Lyons and Campbell Ranch headquarters in Gila, New Mexico. Known in the 1890s as headquarters of the largest cattle ranch west of the Mississippi, the Lyons and Campbell Ranch actually has a much longer and more intriguing story.

Applications of acanthochronlogy on the Altiplano cactus Echinopsis atacamensis...or how I learned to love the bomb (pulse).

Cactus on the Altiplano of South America contain an archive of useful climate, physiological and demographic information in the isotopes of their spines. As demonstrated on saguaro cactus in Tucson, Arizona, spines emerge from the apex of the cactus, cease growth, and then are retained in time-ordered sequence on the side of the cactus as the stem continues to grow upward. Thus, time ordered sequences of spines contain diurnal, seasonal, and annual information in the oxygen and carbon isotope ratios of the robust spine tissue.

Field Guide to a Hybrid Landscape: Nebraska’s hand-planted forest

Dana Fritz will speak about her new book and exhibition, Field Guide to a Hybrid Landscape. This fascinating and little-known story of the first federal tree nursery and what was once the world’s largest hand-planted forest reaches beyond Nebraska with relevance to our current challenges of climate chaos and biodiversity collapse.


Forests and global change: from tree ecophysiological mechanisms to ecosystem processes

Forest ecosystems are particularly threatened by global change components, such as increasing frequency and severity of climate extreme events, increasing atmospheric carbon dioxide (CO₂) and pollutants concentrations. All these factors strongly influence the capacity of forests to continue providing important ecosystem services we rely on, including climate regulation and mitigation.

The University of Arizona Campus Arboretum: weaving science into landscape

The University of Arizona Campus Arboretum is comprised of woody plants located on the nearly 400 acre main campus in the heart of Tucson, AZ. Many of those woody plants are the product of Land-Grant research addressing state needs: initially addressing the 19th century need for an agricultural base to the Arizona Territory and later, responding to the 20th century need for resource-conscious landscapes as a result of increased urbanization and environmental concern.

Human securities, sustainability, and migration in the ancient U.S. Southwest and Mexican Northwest

In the US Southwest and Mexican Northwest, tens of thousands of people were on the move in the 1200s through 1400s CE. By the end of the 1400s, regional-scale population levels had declined by about 50%. What conditions led to this pulse of migration and depopulation? Here we show, through a Southwest/Northwest scale meta-analysis of sub-regional archaeological studies, the spatial distribution, intensity, and variation in social and environmental conditions within eight culture areas, prior to depopulation.

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