Sessions in which Steven Voelker participates
Wednesday 29 June, 2022
To determine how trees of a temperate to boreal ecotone forest have responded to climate change and nitrogen deposition we investigated tree-ring growth and stable carbon isotope responses of sugar maple and white spruce at Turkey Lakes Watershed (TLW), in Ontario, Canada. Trees at TLW underwent a dramatic surge in age-adjusted tree basal area increment (ΔBAI) between 1900 and 1970 and have declined thereafter. The early ΔBAI pulse was acutely expressed in sugar maples and white spruce whe...
Trees do not grow during winter where freezing temperatures occur regularly. Therefore, much of what has been learned from tree-ring data about variability in Earth’s climate is driven by summer conditions. To investigate winter climate and atmospheric circulation over North America, we employ a multi-proxy approach. First, we use earlywood carbon and oxygen stable isotopes of trees growing adjacent to Lake Superior to capture the climate memory embodied by this inland sea. Indeed, previou...
Here we report shrub-ring isotope records for big sagebrush (Artemisia tridentata) from below the “reverse treeline” in central Utah, USA. Despite sectorial growth, ring-widths of mature plants (age range 9 to 54 years) cross-dated well. Plants were sampled in upland locations (controls) as well as adjacent to mounds (circular patches of denuded soil approximately five m diameter) made by harvester ants (Pogonomyrmex occidentalis) and in swale locations where water drains during monsoon ra...
Thursday 30 June, 2022
In their book chapter in 2011 Gagen et al. (2011) highlighted the need for stable isotope dendroclimatology to move beyond studies that simply demonstrate ‘potential’. This symposium, more than a decade since this publication, will focus on dendrogeochemical studies that demonstrate that the field has moved beyond studies focused on ‘potential’. In particular, this session will strive to identify compelling new insights into unique aspect...
The interpretation of stable isotopes in a dendroecological framework can provide powerful insights into how trees adjust physiologically in response to the environment. This symposium aims to bring together researchers who use stable isotopes in tree rings to address ecophysiological responses to environmental changes from intra-annual to multi-decadal resolution. We hope this symposium will enable fruitful discussions and new ideas a...