Tree-Ring Talk

A four-century extension of the long BC conifer chronology in the eastern Mediterranean and other additions

Some 29 newly-reanalyzed data sets from Turkey, Greece, and Cyprus have allowed the extension of the long BC conifer chronology, which begins in the early 30th century BC and which has been stalled for years in the middle of the 8th century BC, down three and a half centuries to 307 BC. Our so-called “Roman Gap” is getting shorter.

Snapshots of a warmer North from ancient buried wood deposits in subarctic Canada and Alaska

Buried wood in arctic and subarctic North America, preserved in diverse depositional settings, provide glimpses of past landscapes and environmental change. In the Yukon and Alaska, ancient forest remains exposed in mining cuts and river bluffs help us understand how permafrost behaved during persistent warming of the last interglaciation ~125,000 years ago.

Ceci n’est pas un arbre: How to draw a functional tree.

Tree-ring growth is a daily scaled process, where endogenous and environmental components orchestrate wood formation through a series of developmental events that can be monitored studying plant phenology. Recent studies demonstrate that the temporal dynamics of wood formation inferred from phenology monitoring are excellent markers of tree sensitivity to weather and climate fluctuations. Encompassing for acclimation and adaptation components, wood developmental dynamics provide indeed for excellent metrics to predict tree-ring growth and productivity.

Linking science and policy: building bridges between research and decision making

In the face of current societal, public health, and environmental challenges, the use of science in public policy is more critical than ever. Understanding the process and practicalities of how environmental systems work is critical for predicting and managing systems in an ever-changing climate. Similarly, understanding the process and practicalities of local, state, and federal policy allows scientists and science-policy professionals to effectively engage in the policy process.

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.

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