David Hsu is a graduate student studying urban ecology and economics at the University of Washington in Seattle. He blogs on cities at Complexcities.

Every day, we learn more about how we are changing the natural world - from the most intimate scales, such as the loss of unique species, to the most universal, such as climate change that will affect everyone, everything, and everywhere for hundreds of years. How can we possibly comprehend these changes in nature? As ecologists have written, we live in an invisible present, where natural processes and changes occur over generations; and within invisible places, such as broader landscapes, ecosystems, and regions.

One way that we're learning about the rhythms and scales of the natural world is through the Long-Term Ecological Research Network (LTER), funded by the U.S. National Science Foundation. Begun in the 1960s, the LTER network now comprises 26 research stations, each devoted to the long-term study of an ecologically-distinct area, such as lakes, deserts, cities, prairies, wetlands, and forests. An overview of the entire effort is here.

Each relatively large station, and coordination across the entire network, allows more than 1,800 scientists to study big ecosystems for long periods of time. Novel experiments include constructing over a hundred mini-prairies in central Minnesota to observe the importance of biodiversity to ecosystem health; monitoring one of the nation's fastest growing cities, Phoenix, and its surrounding desert ecosystem; finding connections between El Nino, plague, and prairie dog populations in New Mexico (plus prairie dog cam, here!); and observing lakes in Wisconsin to observe minute chemical changes over 25-year periods.

Part of the challenge of building a sustainable society will be to synchronize our perception - and our physical bodies - with the intrinsically different rhythms and scales that exist within nature. And what could be bigger than the LTER? As of November 2005, 32 countries on six continents have joined the International LTER network.