Trees make city streets more livable, provide shade, house wildlife, and reduce stormwater runoff that would otherwise pollute local waterways. Sounds obvious, but scientists have only recently begun to quantify such benefits so they can be more easily replicated in the urban environment.

Trees turn solar radiation into food through photosynthesis, thereby cooling their surroundings. Using newly released satellite data and images collected over the past three decades, Christopher Small, a researcher at Columbia University's Lamont-Doherty Earth Observatory, will correlate temperature with the abundance and position of trees, identifying patterns that could help city planners determine the most beneficial places to plant them. Small's work is a pilot project of the National Science Foundation's Urban Long-Term Research Area program, launched in 2009 to apply to man-made environments the sort of long-term monitoring often done in natural ecosystems. Small's collaborators in the New York City study will also examine the effects of urban plant life on native creatures: for instance, does caring for a neighborhood tree motivate Homo sapiens to engage in other civic activities?