DEEP in the rolling hills and arid landscape of the Arizona desert, construction of what has been called ``a modern-day Noah's ark'' is almost complete. Under construction for four years, it is already filled with thousands of species of plants and animals. The only remaining task for its builders is to finish the habitat for a special group: eight humans who will be enclosed in Biosphere 2 for the next two years. The privately funded project is an unprecedented attempt to create a closed environment capable of sustaining life for a long period of time. Once its doors are closed sometime early this spring, it will become a self-supporting system similar to the Earth itself (Biosphere 1 to project organizers). The air the humans breathe will be provided by the plants they grow; the carbon dioxide they exhale will be used by the plants. The air itself will be purified by forcing it through soil that carpets the 2.5-acre structure. If the project is successful, it will yield new information not only on how life processes work on Earth, but also on how life could be transported to other planets.
From outside, the 85-foot-high, 539-foot-long building that houses the project looks as though it could have been transported from the future. The greenhouse-like structure even has its own mission-control center, where more than 30 computers, hooked up to thousands of sensors, monitor changes in temperature, humidity, light, and other conditions in all the ecosystems created for the project.
Inside Biosphere 2, the environment is about as low tech as the supporting structure is high tech. In every direction lush green plants crowd the glass walls and rise toward the cathedral ceiling. Plants have been transplanted from around the world to recreate a rain forest, a marshland, a savanna, and a desert. Adjacent to this wilderness area, a half-acre garden has been planted to grow, without the use of chemicals, more than 100 different types of agricultural plants - including rice, potatoes, and soy - which the ``biosphereans'' will live on. To complete the project, a 25-foot-deep ocean has been built. It will contain 1,000 of the more than 3,800 species of plants and animals included in the project.
``We're bringing together ecology and technology in a new and exciting way,'' says Abigail Alling, a marine ecologist who is director of marine ecological systems in Biosphere 2, and one of the eight people chosen for the two-year experiment.
The ocean Ms. Alling will oversee contains a lagoon, a beach, and a wave machine to simulate tides and waves and to circulate nutrients. The 800,000-gallon tank is home to parrotfish, starfish, anemones, and a Caribbean coral reef that includes 50 species of hard coral and many soft corals. Alling says one of her jobs is to keep a coral reef ``alive'' while living next door to a stream and saltwater marsh, both of which have a high nutrient content that can be deadly to coral.
``If we can succeed in having such a complex system in such a very short space, then it can be applied to cleaning up rivers and the ocean,'' she says. This type of research can be applied to stressed coral systems around the world, such as those found in the Florida Keys.
Although some of Biosphere 2's research, such as its water recycling methods, may be applicable in creating the support systems needed to colonize space, the research focus is on how environmental processes work and humanity's impact on them.
``Within Biosphere 2 we will be able to monitor the consequences of what we do,'' says Linda Leigh, a botanist who is also one of the four women and four men who will live in the project. ``In the real world it's hard for people to see the effects of their individual actions. Inside the biosphere, I expect if we cut down a tree we are going to see a blip on one of the computer monitors. We will be able to measure the effect of one action on the rest of the ecosystems we are living in.''
Ms. Leigh, who is the scientific director for Biosphere 2, says much of the research could be important in restoring environments that have already been damaged. ``How do you make a soil? How do you reclaim a soil?'' she asks. ``We have quite a research program on soils in there; we are working with 30 different types.'' She also says other research projects conducted around the world have helped in the creation of Biosphere 2 ecosystems, especially those dealing with the size of habitats.
``One project I'm very interested in is the minimum size biome or environment you can have that still functions as a biome,'' Leigh says. She cites research conducted by Thomas Lovejoy, assistant secretary for external affairs at the Smithsonian Institution and a biologist who has received worldwide attention for his work in the rain forest of Brazil. His ``minimum-critical-size-habitat'' focuses on what happens to the patches or ``islands'' of rain forest that remain after an area is deforested.
``What we've learned from Dr. Lovejoy is that one of the most devastating effects on the small reserves in the rain forest is the sunlight coming in from the side and destroying the understory,'' she says.
``Using this information we planted a very thick belt of ginger-order plants like the banana and bird of paradise to stop the sunlight from getting to the base of the rain forest we created inside Biosphere 2.'' Leigh says this tactic has proved successful so far. ``This is something that might be readapted to Biosphere 1,'' she adds.
Lovejoy's contribution to Biosphere 2 will not be limited to his research in the rain forest; he also serves as a scientific adviser to the project. To this end he brings not only his experience as a biologist but also insight he has gained as chairman of the United States Man and Biosphere Program (MAB), a scientific project that studies ecosystems throughout the world. Though different in scope, he says both programs offer something unique and of value.
``Biosphere 2 is a `model' of the real thing. It's a scaled-down, closed system, and much of what will be learned will be learned from observing how things adjust over time,'' he says. ``On the other hand, the Man and Biosphere program focuses on specific ecosystems and how they respond to manipulation and use by people on an everyday basis. It is a special attempt to link the social and biological sciences, something which is too often overlooked and very hard to do.''
Unlike the Biosphere 2, which is a condensed experiment, the MAB program involves hundreds of ``biosphere reserves,'' with tens of thousands of species and millions of acres of land scattered around the globe. The key to the MAB program is to study human impacts on different environments and create a global information network to share the scientific research and discoveries.
At the heart of the MAB program is the biosphere reserve, a designated area of the Earth divided into three separate areas, each of which represents a typical terrestrial or marine environment. Each reserve has a minimally disturbed, legally protected core area that is surrounded by a buffer zone with boundaries designated by a national park or wildlife refuge. The outer edge is a transition area where people conduct their everyday activities.
ONE current MAB project in progress compares land use in the Olympic Biosphere in the Pacific Northwest with that in the Southern Appalachian Biosphere Reserve in Tennessee. University of Washington professors Bob Lee and Robert Neiman say these areas, with their diverse habitat and development, offer an excellent opportunity to study how surrounding land ownership and land use affect landscape patterns.
``It's our hypothesis that the large blocks of managed private and public forest land in the Olympic Peninsula have resulted in landscapes with less ecological diversity, habitat abundance, and resource stability than the smaller-parcel ownership in the Appalachia area,'' says Dr. Lee.
The effort to understand the ``minimum critical size'' of an ecosystem links the two biosphere projects.
Though the projects vary in scale and complexity, Lovejoy says they share two important features. ``Both are looking at mankind's influence on the environment; both are efforts to understand how this planet really works.''