Carbon count

To those with a deep yearning for warm places fueled by long, cold winters, Jennifer Powers’ research sounds suspiciously like a vacation. She spends several weeks two or three times a year in the dry tropical forest of Costa Rica’s Santa Rosa National Park (Guanacaste). A kilometer-long white sand beach is a mere 20 minutes away. Pineapple, papaya and watermelon are her daily staples. She even brings her family with her on occasion. But Powers is hardly on holiday. Her packing list? A soil sampler, rubber boots, a laptop, DVDs and plastic bags. “I dig a lot of holes,” she explains with a laugh.

Powers works at the crossroads of geography and ecology using tools such as remote sensing and geographic information systems (GIS) to understand how tropical forests differ in terms of their carbon cycle—the amount of carbon stored in the soil and released into the atmosphere—and what that variation means for big-picture processes such as climate change. “There’s a real variable response of ecosystems to land-use change and deforestation [in tropical forests]. Sometimes soil carbon stores increase, sometimes they decrease. Global-scale models average over all this variation,” Powers says. “We need to upscale the information we’ve collected at a plot scale … to understand the regional and continental drivers and the implications.”

Powers’ current project in the province of Guanacaste in the northwest corner of Costa Rica, funded by a three-year NASA New Investigator Award, involves taking soil samples, identifying and measuring trees and logging coordinates for well over 50 plots around Santa Rosa National Park and Palo Verde National Park, another dry tropic forest to the south. The data will be matched up with satellite imagery in an effort to document changes in carbon storage and biodiversity on a regional scale as dry tropical forests return after years as pasture or following more recent deforestation.

Her research has implications for everything from better understanding the dynamics of climate change and the carbon cycle to public policy and even economics in the form of carbon trading. The arduous work of collecting detailed field data, down to the contents of the soil, to feed regional-scale analysis of carbon cycling and storage means Powers must make connections between the micro and macro. “My work spans everything from microbial ecology to continental-scale field studies,” she notes. “There are big questions of whether tropical forests are sources or sinks of atmospheric carbon dioxide,” Powers says. “Understanding carbon cycling processes at both field and regional scales fits right into this context.”