The Amazon Tall Tower Observatory in Brazil. The PIRE researchers used three cameras set up on different towers across the Amazon to photograph individual tree crowns, discovering a pattern of leaf growth and death that helps us understand the Amazon's seasonality.

Credit: Aline Lopes, M.S. student, National Institute of Amazon Research, Manaus

Tree crowns in the Amazon. The researchers found a synchronized pattern of leaf growth and death, which happens much more prevalently in the dry season, when photosynthesis is also increasing. But this pattern is seasonal and photosynthesis drops back down in the rainy season.

Credit: Aline Lopes, M.S. student, National Institute of Amazon Research, Manaus

A close-up of leaves in the Tapajos National Forest. Understanding the seasonal patterns of photosynthesis in the Amazon can help researchers build more accurate ecosystem and climate models.

Credit: Neill Prohaska, Ph.D. student, Ecology and Evolutionary Biology, University of Arizona

One full year of change in the Amazon upper forest canopy, seen from one of the research team's cameras on a tower north outside Manaus, Brazil. The letters on the bottom correspond to months of the year. New leaves are produced mostly in the five driest months, at the end of the year. This imposes a strong seasonality on the average leaf age of the canopy, with leaves being older and less photosynthetically efficient in the late wet to early dry season.

Credit: B. Nelson/INPA