Investigating the climate-growth relationships of red fir Abies magnifica in the Sierra Nevada using a multi-proxy approach

Keywords: Blue light intensity, Climate variables, Isotope, Tree ring
Session Type: Virtual Paper
Day: Friday
Session Start / End Time: 4/9/2021 04:40 PM (Pacific Time (US & Canada)) - 4/9/2021 05:55 PM (Pacific Time (US & Canada))
Room: Virtual 30

Abstract

One of the challenges in developing proxy reconstructions of snow in the Sierra Nevada is that it is difficult to separate the response of tree growth to lack of snow from the simple response to lower precipitation. the strongest correlations with cool season precipitation in the Sierra Nevada have traditionally been derived from low to mid elevation trees where the snow pack can be ephemeral. Abies magnifica grows at elevations (1500-2700 m) coincident with the elevations that receive some of the most significant snowpack of any forest type in the Sierra Nevada. However, it has not been extensively used as a dendroclimatic proxy due to its complex climate-growth relationships. In order to investigate these complex-relationships here we take a multi-proxy approach including ring width, blue intensity (BI), and stable isotope measurements (oxygen and carbon) to evaluate whether tree-ring records of Abies magnifica could be a valuable new source of climatic information for the Sierra Nevada. We sampled trees from two sites along an elevation gradient in the Sagehen Creek watershed in eastern California and measured tree-ring widths, early and late wood blue light intensity, and oxygen and carbon isotopes. Our preliminary results show that blue light intensity has shown much stronger correlation with climate variables including temperature and April 1 SWE compared to ring width from the same trees. These results show that Abies magnifica may turn out to be an important new species to use for developing climate reconstructions.