60-Second Science

Forest Canopy Color Reveals CO2 Uptake

Tree leaf color provides a good proxy for photosynthetic productivity, indicating how much carbon dioxide a tree is sequestering. Karen Hopkin reports

When autumn rolls around, the leaf peepers come out in force. Armed with digital cameras, they record the most spectacular displays of fall foliage. Well according to a study in the journal Functional Ecology [Toshie Mizunuma et al., The relationship between carbon dioxide uptake and canopy colour from two camera systems in a deciduous forest in southern England], those images may be more than just pretty pictures. They may represent a new way to monitor climate change.

Trees take carbon dioxide, or CO2, from the atmosphere and convert it into biomass. By sopping up CO2 they help to stabilize the climate. But at the same time, they’re also affected by climate, for example, budding earlier in the season as global temperatures rise.

To understand how all this balances out, ecologists monitor how forests take up CO2. It’s a costly business that involves using a network of 500 instrument towers worldwide. So researchers got to wondering whether there might be an easier way to keep an eye on photosynthesis. And they found that digital cameras do the trick.

Analyzing two years’ worth of snaps taken every half hour in a forest in southern England, the researchers discovered that a tree’s leafy colors provide a good proxy for its photosynthetic productivity. So next time you go for a walk in the woods, take only photos. And leave only data points.

—Karen Hopkin

[The above text is a transcript of this podcast.]

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