Remotely Quantifying Aspen Genetic Variation

Biodiversity is important to ecosystem functioning. Diversity at all levels – of soil biota, plant and animal species and their behavior, and the genetics of those species –  provides ecosystems with the capacity to respond to changes in the environment. We are interested in characterizing multiple levels of biodiversity at broad spatial scales to help us better understand ecosystem processes and potential services.

Quaking aspen (Populus tremuloides) is the most widespread tree species in North America and among the most economically and ecologically important. Aspen is a clonal species, meaning that the “trees” you see in an aspen stand are actually just different “ramets” (sprouts) from the same organism. The heaviest and oldest single organism on Earth is actually an aspen clone in Utah.  Aspen shows significant phenotypic variation in its chemistry and phenology, which affects soil properties and forest physiological processes. This variation is largely driven by genetic differences in this clonal species, so we are testing whether we can use remote sensing imagery to distinguish among genotypes of aspen, and – as a consequence – their function. Our basic idea is that genetic differences may be expressed in leaf optical properties, which are highly variable among aspen clones and are a consequence of chemical differences.

We found that aspen genotypes (different clones) are better discriminated using single-date NASA AVIRIS hyperspectral images (an airborne imaging spectrometer) than in situ leaf and/or soil data. We also found that as genotypes diverge genetically, so do spectral properties. We believe that the power of AVIRIS to discriminate among aspen clones comes from its ability to “see” traits that, individually or combined, capture emergent differences in clones that are not readily detectable.

 

Collaborators:

Mike Madritch

Karen Mock

Rick Lindroth