Early warning of declining forest health matters for interventions, particularly in wildfire-prone regions. Traditional field sampling is too slow for whole forests, and scaling up genomic analysis is costly. Remote sensing from aircraft or satellites offers broad coverage, but existing methods often lack the early, gene-level detail needed for rapid response.
A new study led by Nathan Swenson, Gillen Director of the University of Notre Dame Environmental Research Center (UNDERC), and funded by NASA, shows a clear link between leaf spectral reflectance and gene activity. Spectral reflectance is the ratio of reflected to incoming light at visible and near-infrared wavelengths. The team measured reflectance on leaf surfaces and then analysed gene expression from the same leaves collected at UNDERC sites in northern Wisconsin and the Upper Peninsula of Michigan. They sampled sugar maple and red maple and focused on genes related to water response, drought, photosynthesis and plant–pest or plant–pathogen interactions.
For more than half of the genes analysed, specific reflectance wavelengths correlated strongly with gene expression, suggesting it may be possible to predict hundreds to thousands of ecologically important genes from reflectance alone. To scale up, Swenson points to a 2024 PLOS Biology study that used satellite images and AI to create tree species maps for the National Ecological Observatory Network. Layering species maps with reflectance–gene models could let researchers map gene activity across whole forests from aircraft, satellites or sensors on the International Space Station, enabling rapid genomic-scale assessment of tree stress and earlier interventions before forest health reaches a crisis point.
Difficult words
- spectral reflectance — ratio of reflected to incoming light at wavelengths
- gene expression — level of gene activity measured as RNA production
- remote sensing — observing Earth from air or space sensors
- scale up — increase size or reach of a methodscaling up
- correlate — show a relationship or pattern with anothercorrelated
- intervention — action taken to improve or prevent problemsinterventions
- photosynthesis — process plants use to make energy from light
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Discussion questions
- What are the main advantages and possible limitations of using satellite reflectance to monitor forest gene activity?
- How might earlier genomic-scale assessment change wildfire prevention and forest management in vulnerable regions?
- What practical challenges do you think researchers would face when combining species maps with reflectance–gene models?
