Tree-Ring Talk

How long does a 15 year drought last? On the correlation of rare events

Recent tree ring analyses of the Colorado river flows over the past 500 years enable one to characterize the fluctuations on various timescales using Fourier analysis. We model these flows and calculate the clustering properties of droughts. These results are highly pertinent to the issue of water storage in the Mead and Powell reservoirs and the necessity to rethink how we use water in the southwestern US.

Climatic Changes and Their Effects on Rainfall in Hawai‘i

In the past three decades rainfall has been decreasing over many parts of the Hawaiian Islands, while temperatures have been rising. If these trends continued, severe deficit in the moisture availability could affect many parts of the Hawaiian Islands, with devastating impacts on Hawai‘i’s native ecosystem. In this presentation I will discuss how climate variability on the large-scale and rainfall variability on the small scale are related. Based on these empirical relations, statistical downscaling methods have been developed for the Hawaiian Islands.

Beyond chronology – a tale of tall trees

Barrels, as packaging for a range of traded goods, often ended up re-used in wells and latrines in towns. Tree-ring analysis of barrel finds not only supplies us with a precise chronology for their manufacture, and for the dating of the contexts in which they are found. The region of origin of the wood, through provenance determination, reveals connections between regions that might not necessarily be detected in the other finds from a site. In this talk, I will present some of the most recent provenance determination results that have emerged through my research in Northern Europe.

What I did this summer

The first Tree-Ring Talk of the semester will include multiple short summaries by lab members highlighting what they have been up to over the summer.  The talks will be followed by an informal social to give people the opportunity to catch up with each other.  Presenters will include:

  • Amy Hudson and Soumaya Belmecheri
  • Ben Bellorado
  • Charlotte Pearson
  • Dave Meko
  • Irina Panyushkina
  • Kit O'Connor
  • Paul Szejner
  • Peter Brewer
  • Ramzi Touchan
  • Ross Alexander
  • Valerie Trouet

Dendroarchaeology in Northwestern New Mexico: Results of Presession 2015 Research

Drought-associated tree mortality: Global patterns and insights from tree-ring studies in the Soutwestern U.S.A.

White fir as an invasive species in the Pinaleño Mountains

Proliferation of shade-tolerant species during the period of fire exclusion has been put forth as a major driver of increased severity of fire and insect outbreak regimes in mixed-conifer forests of the interior West.  Both fire regimes and insect defoliator outbreak regimes are responsive to closed and multi-storied canopies.  Douglas-fir tussock moth (Orgyia pseudotsugae) and western spruce budworm (Choristoneura occidentalis), both major pests in interior West forests, are particularly responsive to the presence of white fir (Abies concolor).  However, quantitative studies chara

A Tree-Ring Smorgasbord

A traditional Swedish smörgåsbord contains many dishes, where you usually sample a little of each. In this talk, I will serve a tree-ring based smorgasbord, based on my career as a tree-ring scientist over the last twenty years or so. I will guide you through various environments and research projects across the world, with some special focus on the long-term research conducted in the central Scandinavian Mountains.

The Influence and Interactions of Humans, Climate, and Fire on Mixed Conifer Forest Dynamics in the Sierra Nevada, USA

Fire is recognized as keystone process in Sierra Nevada dry mixed conifer forests and it has been drastically reduced by decades of fire exclusion. Frequent fire is thought have created a fire-grained mosaic of multi-aged forests that developed as a result of self-organizing processes where burn patterns and forest structure interact to maintain a fine-grained mosaic over time.

Tree-Rings and the Coupled Carbon Cycle Climate System

Forest ecosystems are one of Earth’s primary biomes: they provide a diverse suite of ecosystems goods and services crucial for societal well-being and play a crucial role in our planet’s carbon cycle. However, great uncertainties exist regarding the quantification, dynamics, and driving processes of terrestrial carbon cycling, and thus also the fate of forested regions. Dendrochronological methods are remarkably well suited to investigate forest carbon cycling on long and temporally precise time-scales and at tree-level to continental spatial scales.

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