Hyperspectral remote sensing links aspen genotype with belowground processes at landscape scales

Background/Question/Methods

It is becoming increasingly apparent that the genetic variation within species is important to ecosystem level processes.  Recent research demonstrates that plant genotype influences litter decomposition, soil microbial communities, and belowground nutrient cycling.  However, the extent to which plant genotypes create mosaics of genetically-mediated ecosystem processes across natural landscapes is unclear. Hyperspectral remote sensing technologies have great potential to estimate both biodiversity and ecosystem function over large spatial scales. To date, however, remote sensing techniques have yet to be applied to their full potential to address the genetic component of biodiversity. Here, we employ remote sensing techniques to assess the belowground consequence of fine-scale genetic diversity within Populus tremuloides (trembling aspen) forests, one of the most important and widespread forest types in North America.

We combine hyperspectral (AVIRIS) data with genetic, chemical, microbial, and biogeochemical data to determine how intraspecific plant genetic variation influences belowground processes at landscape scales.  Our study areas represented two ecoregions in which aspen dominates the forest canopy: western North American montane forests, where aspen forms large, expansive clones, and northern temperate forests of Wisconsin, Minnesota, and Michigan, where aspen forms smaller, patchy clones.  We ground-truthed AVIRIS data with 2000 paired canopy and soil samples for chemical and soil analyses.

Results/Conclusions

We demonstrate that both canopy chemistry and belowground processes vary over large and small spatial scales according to aspen genotype. Hyperspectral imagery can be used to distinguish aspen genotypes through variation in canopy spectral signature. In addition, hyperspectral estimates of variation in canopy chemistry correlate with wet-chemistry measurements. Variation in aspen canopy chemistry, in turn, is correlated with variation in belowground processes. Taken together, these findings indicate that forest tree species can create spatial mosaics of ecosystem functioning across large spatial scales.