Using a Closed Ecological System to Study Earth's Author(s): Mark Nelson, Tony L. Burgess, Abigail Alling, Norberto Alvarez-Romo, William F. Dempster, Roy L. Walford, John P. Allen Source: BioScience, Vol. 43, No. 4 (Apr., 1993), pp. 225-236 Published by: University of California Press on behalf of the American Institute of Biological Sciences Stable URL: http://www.jstor.org/stable/1312123 . Accessed: 13/08/2011 02:01

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected].

University of California Press and American Institute of Biological Sciences are collaborating with JSTOR to digitize, preserve and extend access to BioScience.

http://www.jstor.org Using a Closed EcologicalSystem to Study Earth's Biosphere Initial results from

Mark Nelson, Tony L. Burgess,Abigail Ailing, Norberto Alvarez-Romo,William F. Dempster, Roy L. Walford, and John P. Allen

T he idea of creatingmaterially ber 1991. Initial results indicate that closed microbiospheres, in- the in Biosphere 2 are cludinghumans, to study eco- Syntheticbiospheres maturing rapidly and functioning to logical processeshad its roots in sev- open the prospectfor maintain most introduced species. The eral branches of research. One was humans are healthy and producing the sealed microcosmsand open, but nearly all their nutritional require- mesocosms that comparativebiospherics II i ments from the boundary-defined, I~~~~~i i ~i ~ ~~~~~iii i . i i i i i i iiiiiiiiii agricultural area. The ecologists developedto study ecosys- cycling of nutrients such as carbon tem processes. Another source was interest in the study of the vital bal- dioxide through the vegetation is op- the experimentallife-support systems ances that keep our biosphere opera- erating with shorter periods and designedfor use in spacecraftand as tional. Therefore, future efforts to greater fluxes than in the global envi- prototypesfor space habitations. construct a life-support system by ronment, atmospheric oxygen has During the 1960s, H. T. Odum miniaturizing the biosphere and de- shown an unanticipated decline, and beganadvocating life-support research termining the minimum for some shifts in community dominance in sealed greenhousesthat would rely man is a goal that is as important for of the ecosystems are occurring. on the ecologicalself-organizing prop- the quality of human life on Earth as ertiesof the enclosed soils, plants, and it is for the successful exploration of Previousresearch in closed animals(Odum 1963). In 1971, Den- the planets" (Cooke 1971). nis Cooke wrote, "The fact that we Biosphere 2 (so named to ecological systems are empha- not now able to engineera com- size that previously we have had only The science of closed laboratory materially pletely ecosystem that would Earth's biosphere, "Biosphere 1," to closed ecosystems with the work be reliable for a existence in began long study) was designed by Space Bio- of Clair Folsome at the University of space...is striking evidence of our ig- spheres Ventures (SBV),a private com- Hawaii. Folsome closed 1-5 norance and materially of, contemptfor, lack of pany started in 1984 to study pro- liter flasks filled with ocean , cesses and and air. These MarkNelson is chairmanof the ecosystem dynamics sand, microbes, , Institute to those of the bio- flasks have to be viable for of Ecotechnics,London, UK, and direc- analogous global proved tor of environmental sphere (Allen 1991). Biosphere 2 also prolonged periods if they contain suf- applications,Space was BiospheresVentures (SBV), Oracle, AZ planned to be an entrepreneurial ficient metabolic diversity at closure 85623.Tony L. Burgessis programcoor- venture to market closed life-system and are provided with an adequate dinatorof the DesertLaboratory, Uni- facilities, data management systems, energy flow (Folsome and Hanson versityof Arizona,Tucson, AZ 85621. and spin-off products such as air puri- 1986). Some, closed as long ago as AbigailAiling is directorof researchand fiers. Visitors and educational materi- 1968, are still functional today. Other marineecosystems, Biosphere 2, SBV. als also generate income. early researchers of materially closed NorbertoAlvarez-Romo is directorof Biosphere 2 differs from previous include Frieda Mission SBV. William F. systems (ecospheres) Center, laboratory microcosms and meso- Taub of the University of Washing- Dempsteris directorof systemsengineer- cosms in of SBV. L. Walfordis chief of size, diversity ecosystems, ton, Joe Hanson of the Jet Propulsion ing, Roy and of material closure. It is medicaloperations, Biosphere 2, SBV. degree Laboratory in Pasadena, California, John P. Allen is vice presidentof bio- virtually materially sealed (currently and Basset Maguire of the University spheric development, SBV. Nelson, less than 10% air exchange per year) of Texas (Hanson 1982). Alling,and Walford are also crew mem- and open to energy of sunlight, elec- Previous closed ecological system bers insideBiosphere 2 for the initial tricity, heat transfer, and information facilities developed for space applica- closureexperiment, 1991-1993. ? 1993 flow. The first closure experiment, of tion focused on providing human life AmericanInstitute of BiologicalSciences. two years' duration, began in Septem- support and included either algae or

April 1993 225 Inside Biosphere 2. (Clockwise from upper left) Ocean biome. Photo: C. Allan Morgan. Lower thornscrub eco- tone of savannah biome. Photo: Gill Kenny. Rainforest biome. Photo: Tom Lamb. Desert biome. Photo: C. Allan Morgan. Photos taken before closure. bacteria and sometimes agricultural Russian work on algae-basedsys- plantsin the closed systemsthat could crops as well. Researchefforts in the tems proceeded at IBMPin Moscow produce grains and vegetables for 1950s and 1960s focused on systems and at the Institute of Biophysics, human nutrition (Galston 1992). based on green algae (Chlorella ,Siberia, culminating in This step was taken at the Institute vulgaris).In 1961, Yevgeny Shepelev human closures of 15 and 30 days in of Biophysics in the Bios-3 experi- at the Institute of Biomedical Prob- the late 1960s and early 1970s. In the ment.The test facilityhad a volumeof lems (IBMP)in Moscow became the United States, early NASA-fundedre- more than 300 cubic meters divided first human to survive one day in a search conducted by scientists with among a chamber for algae tanks, a bioregenerativelife-support system, Boeing Corporation also achieved hydroponiccropping area, and a hu- which included some 30 liters of human-occupied closures. But the man living area that included Chlorellathat supplied all of his re- early hopes of a completelyregenera- processing, medical, and control quiredair and water (Shepelev1972). tive systemusing only one companion rooms, kitchen and dining areas, and Jack Myersat the Universityof Texas species to support humans began to separateapartments for the threecrew was among earlyUS experimentersto fade when it became apparent that members. The research, first led by develop systems coupling mice with Chlorellawas not palatable as a hu- Boris Kovrov, and, after Kovrov's Chlorella (Eley and Myers 1964, man food. It became clear that the death, by Josef Gitelson, used lettuce, Myers 1963). next step would be to include higher wheat, potatoes, radishes, and beets

226 BioScience Vol. 43 No. 4 grown hydroponically under artificial scaling up from previous research pro- eventually can be incorporated into lighting to provide approximately half totypes to include the integration of systems for long-term habitation on the nutrition for crews of two or three food production, water recycling, and the moon, Mars, and other space bases. people. Experiments lasted as long as atmospheric gas control in its biomass The design of Biosphere 2 employs six months. Almost all air was regen- production chamber. Support labora- the tendency of biological systems to erated, although catalytic burnerswere tories are investigating associated self-organize: "the process by which needed to oxidize trace gas buildups. questions of waste recycling, food ecosystems develop structure and pro- More than 90% of water was re- preparation, and overall data man- cesses from available energies... [to] cycled, the main mechanism being agement. From this first phase it is improve the system's adaptation to purification by plant transpiration and anticipated that designs for further external changes and variations" then condensation to provide drink- ground-based and ultimately space (Odum 1983). and water. Human will ing irrigation systems emerge (Knott 1990). In the costs aside from a of the and appraising potential wastes, portion Japanese European programs of closed one has urine, were not inside the in closed for life system design processed ecological systems the alternative of for a facility, but were exported; some food, support, although smaller, also are paying complex with self including dried meat for needed pro- under way. The Japanese efforts, un- ecosystem was health of der the of Nitta of the maintenance, respiration and tein, imported. Overall, leadership Keiji in the crew of Bios-3 was National in controls the form of multiple good, although Aerospace Laboratory as some simplification of their intestinal Tokyo, have concentrated on gas re- species ecological engineer- ing, or in restricting the produc- microbiota occurred (Lebedev and cycling systems involving oxygen and Petrov Terskov et al. and con- tion to some reduced system like 1971, 1979). separation an artificial turbidistat and In the United States, funding for centration, water recycling systems, algal the structure, mainte- bioregenerative life support experi- plant and algae physiology and culti- supplying nance, controls and the rest of ments was drastically reduced when a vation techniques, and animal physi- 1966 conference to review the field and Eu- the functions as metallic-hard- ology breeding (Nitta 1987). ware Where the made it apparent that simple systems ropean efforts have focused on engineering. one or two of effects on de- natural combinations of circuits using only species algae microgravity biological and "biohardware" have and bacteria would not be feasible. velopment essential for the successful already The also dramatized two radi- translation of controlled been selected for power and min- meeting ground-based of different for further life into iaturization for millions years cally strategies ecological support systems at lim- development: those who favored com- space, and on basic re- probably thermodynamic physiological its, it is plex, multispecies systems modeled sponses of plants (Andre et. al. 1989, exceedingly question- on natural communities and those able that better utilization of Skoog 1987). can be for main- who favored a more reductionist, engi- energy arranged neered with a few that tenance and control purposes approach species Biospheric research facility with could be manipulated for maximal bulky, non-reproducing, (Cooke NASA 2 differs from other re- non-selfmaintaining engineering. productivity 1971, 1968). Biosphere -Odum 1963 In 1978, NASA reinstituted a pro- search programs in that it is a system gram for the development of bio re- with diverse components that provide These hypotheses, as well as the generative systems called CELSS(Con- not only human life support but also theory that ecological systems have trolled Ecological Life Support maintain resilient, persistent, complex, greater resilience to perturbations than Systems). CELSS has funded research and evolving ecosystems. This design monocultural systems, have not been at a variety of universities and within philosophy contrasts with CELSS-type tested extensively. In particular, such NASA, principally at Ames Research systems, which seek to integrate sepa- studies are pertinent to the question of Center, Johnson Space Center, and rate components into a tailored sys- determining how biodiversity affects Kennedy Space Center to conduct basic tem. Such CELSSsystems are focused stability of ecosystems and of our investigation and explore engineering on minimizing weights and volumes global . applications of the various compo- for launch. Biosphere 2, although To foster its diversity, Biosphere 2 nents necessary for life support. Much employing specialist knowledge, has includes many microhabitats within work has focused on high-yield sys- incorporated an approach that seeks each ecosystem type. It was deliber- tems for biomass and food produc- to promote and ensure the self-orga- ately over-packed with species to pro- tion. University work has included nizing capabilities of living systems by vide maximal diversity for self-orga- intensive hydroponic systems for deliberately replicating a typical range nization and to compensate for growing some of the principal tar- of tropical and subtropical environ- unknown and potentially large initial geted food crops, including wheat, ments with their associated diversity species losses. Environmental tech- white and sweet potatoes, and soy- of life forms and metabolic pathways. nologies provide thermal control, beans (Bubenheim 1990, Bugbee and Research using Biosphere 2 has fo- water and wind flows, and substitutes Monje 1992, Corey and Wheeler 1992, cused on studies relevant to Earth's for natural functions like waves and MacElroy et. al. 1987, Salisbury et. ecosystem and biospheric processes. rain. But the facility would not func- al. 1987, Schwartzkopf 1992). Such studies also are expected to pro- tion unless the biota fulfills its essen- In 1986, the CELSS Breadboard vide baseline data on the dynamics of tial role of using energyflow for bio- Project was started with a goal of complex life-support systems that massproduction (including food from

April 1993 227 ... and humans. The Vil..... w i.ll .....vcgc"iitioi roor. l', s oii materials, plants, Fan coil unit for temperaturecontrol condensation apparatus reactors operate by forcing air through Space frame with tempered glazing a plenum at the base of a soil con- tainer so that it diffuses through the Lungweather cover biologically active soil, exposing trace ...~~~~~~~~\X .t'f^ X..^~ ..7 /Air-tight \ elastomermembrane gases to the wide range of metabolic ....Air-li....lt vcsli.u10i974 . t. ,. \Floating lungpan Air light vestibulc 10,974cubic cetl /Food and oxygen producing plants pathways of a diverse suite of soil ff-W~r~-l0~ * /F that also utilize CO microbiota (Hodges and Frye 1990). J Patents have been issued on new de- di^rri?" &Recycling marsh \ 4480 cubic feet (variable voltnume) velopments of this air purification 100cubic feet A lytical sensors aiid \ \ \ 100cubic feet / \ technology. data collection equipment Shower, sink, and toilet 89/ b The test program for the soil-bed cubc ee \lus i h t q connected to water recycling system / included habitat / - reactors laboratory bench- tluman quarters, . . . tunnel with..,, and video Undergroundlung bed, desk, computer, tot connectcnnect testtet moduledue tot lungung tankt top replicate systems and trials in the test module. Potential problem gases such as carbon Figure 1. Schematicof Biosphere2 test module showing its configurationduring a ethylene, monoxide, series of human enclosure experiments conducted from 1988 to 1990. Its main and methane could be effectively con- structureis approximately7 m on a side by 8 m tall, with a variable volume of trolled in this manner. The field crop approximately 480 m3. area for Biosphere 2 was designed as a soil-bed reactor. The agricultural crops) and ensuring clo- objectives have been accomplished entire volume of air in Biosphere 2 can sure of essential biogeochemical cycles using the Biospheric Research and be pumped upward through the soil in through diverse metabolisms. The Development Center (BRDC) facili- approximately one day if trace gas design of Biosphere 2, which attempts ties at the project site near Oracle, levels in the atmosphere require its to harmonize living systems with sup- Arizona. Experiments were conducted operation (Glenn and Frye 1990, porting environmental technologies, with the 480-cubic-meter Biosphere 2 Nelson 1989). Throughout the first unites two historical approaches to test module (Figure 1) to test sealing year of operation, the air has not life-support systems: the engineered technologies, as well as many other required purification by means of the and the ecological. In the Russian component technologies developed for soil-bed reactor system. Individual terminology from V. I. Vernadsky, Biosphere 2. Like Biosphere 2, the test food crops and cropping systems were this integration of "biosphere" and module admits ambient sunlight tested for productivity, disease and "technosphere" by man is called the through a laminated glass and steel pest resistance, and ease of harvest in "noosphere" (Vernadsky 1986). spaceframe superstructure, and is BRDC and at the Environmental Re- A biosphere was defined in the sealed underground with a stainless search Laboratory (ERL) of the Uni- design of Biosphere 2 as "an evolving, steel liner. To avoid dangerous pres- versity of Arizona. Techniques of in- stable, complex, self-regulating sys- sures from expansion or contraction tegrated pest management for tem containing more than one ecosys- of the air inside the tightly sealed biological control of pests and dis- tem as well as all five kingdoms of structure, a variable volume chamber eases were developed. The small buff- life" (protoctists, prokaryotes, fungi, (lung) with a flexible membrane ab- ering capacity and rapid cycling of air plants, and animals), capable of sup- sorbs the volume changes. Inclusion and water of Biosphere 2 precludes porting humans and their technolo- of selected plant species from tropical use of toxic pesticides and herbicides gies, open to energy and information ecosystems in test module experiments and demands that nutrients be re- flow, and essentially materially closed verified their ability to thrive in close turned to the soil to maintain inten- (Allen and Nelson 1988). Parameters proximity in a small, tightly sealed sive agricultural productivity (Leigh for the life systems, engineering and environment. The test module et al. 1987). mechanical systems, and information achieved air-exchange rates (leakage) Aquatic plant and microbial sys- and analytical systems all have been as low as 24% per year. tems for recycling human and animal developed to satisfy requirements Starting in 1988, there were test wastes and domestic wastewater were flowing from this definition of a bio- module experiments that included hu- developed and tested in experiments sphere. The research program, which mans. These experiments were the in which humans and other animals included four years of experiments in first to seal a human into a system were enclosed for up to 21 days in the a closed ecosystem test facility, was designed for bioregeneration of wa- Biosphere 2 test module (Nelson et. developed to test how well these de- ter, wastes, food, and air driven by al. 1991b). These waste treatment sign parameters would succeed in cre- natural sunlight for an extended pe- systems, developed with the consulta- ating a biosphere and to investigate riod of time (Alling et al. 1990, in tion of B. C. Wolverton of the NASA mechanisms of biosphere operation. press, Nelson et. al. 1991a). Stennis Space Center, demonstrated An air-purification system using the ability of human-made wetlands Research and development in soil bed reactors (Bohn 1972, Bohn to process waste products and isolate and Bohn Carlson and Leiser chemical preparation for Biosphere 2 1986, potential pollutants (Ham- 1966) was developed to metabolize mer 1989, Wolverton 1987). Since the commencement of the project and thus remove trace gas contami- An analytic laboratory system was in 1984, research and development nants from outgassing of structural designed to minimize outside con-

228 BioScience Vol. 43 No. 4 sumable materials and to be suffi- ing species were developed by terres- and biomass, soils installed in Bio- ciently pollution-freeso it can be in- trialand marinesystem designers. The sphere2 were inoculatedwith natural corporatedinside a materiallyclosed terrestrialteam favored a strategythat soil coresand mycorrhiza, from facility. A gas chromatograph-mass targeted particularspecies for inclu- naturalecosystems were imported, and spectrometer (GCMS) system was de- sion. This iterative process, for ex- flying insects attractedto lights were veloped that uses as a carrier gas ample,integrated pollinators with host collected and introduced. Species hydrogen produced inside Biosphere plant requirementsand canopy struc- survyes, except for soil microbiota, 2. Also required was an apparatus for ture as total species lists were evalu- were conducted before closure and producing liquid nitrogen to be used ated. Selectioncriteria for Biosphere2 indicated that approximately 3000 in air and water analyses. A set of plant assemblagestook into account species were included. nearly reagent-free laboratory ana- life support for animal consumers, The otherdesign approach, used to lytic techniques was devised in which taxonomic diversity, life-form spec- create the marsh, ocean, and streams the few chemical reagents required tra, envelopesof physicalparameters inside Biosphere2, favoredthe diver- for analysis are neutralized or con- within Biosphere2, as well as ethno- sity of crucialmicrobiota by bringing tained. Automated systems were de- botanical utility and aesthetic inter- intactchunks (extracted homologues) veloped for continuous air and water est. from the natural ecosystems and, in quality determinations as well as Animal food requirementsintro- addition to the collection of particu- GCMS, ion chromatography, and duced severalbiases into the selection lar species, installing community atomic absorption techniques for more of plantspecies. The African bushbaby samplesin Biosphere2. For example, extensive analysis of soil, plant tissue, (Galago garnetii) needed fruits and the marsh biome was constructedof water, and air samples. acacia gum. Bees would be most reli- 3.5-cubic-metermarsh modules con- A five-level cybernetic system (nerve ably supportedby Compositaeflow- sistingof boxed soil with plantstrans- system) was developed by SBV and ers. Becausemany plant species would portedintact from FloridaEverglades Hewlett-Packard to automate much take severalyears to reachpeak flow- wetlands. The strategy taken in the of the technical interface with the life ering capacity, fast-growing support design and developmentof the marsh systems and to archive and process specieswere introduced to allow rapid was to replicateas closely as possible information from approximately 1900 production of animal during the natural environment (Finn and data points distributed throughout initial stages of closure. Adey 1991). Mechanicalsystems were Biosphere 2. The nerve system is dis- Duringconstruction, tight controls designed to generate tides, currents, tributed both inside Biosphere 2 and were not maintainedto preventlocal waves, and rain, as well as to help in the nearby Mission Center build- organisms from entering the struc- control salinity gradients and nutrient ing, and it is linked together by a ture, becauseit was felt that rigorous cycling. Inoculation of the ocean in- computer network. sterilizationand biocide applications side Biosphere 2 to ensure a diversity In preparation for building the Bio- would be more likely to induceexplo- of ocean plankton was accomplished sphere 2 marsh ecosystem, SBV and sive reproductionof undesirableor- by transporting 20% of the approxi- the Marine Systems Laboratory at the ganismsthan would accidentalinclu- mately 900,000-gallon ocean volume Smithsonian Institution created two sion of local species. To build up from Scripps Institution in La Jolla, small estuarine systems, ecological invertebrateand microbiotadiversity California, as well as a small amount mesocosms, in Washington, DC. The of sea water that accompanied the first was modeled on the Chesapeake 1The team of ecological designers of Biosphere shipment of corals from the Carib- Estuary, a temperate system; the sec- 2, given specifications and coordinated by the bean and the Yucatan Peninsula. The ond was an SBV research staff, included staff from the Everglades system (Adey Botanical Gardens at Kew and New remainder was made up of local well and Loveland Finn and Royal 1991, Adey York Botanical Gardens on rainforest design water mixed with aquarium salt. 1991). These mesocosms were able to and operation; the Environmental Research Agricultural regulations governing establish a gradient of environmental Laboratory at the University of Arizona on imports into Arizona necessitated the conditions to the natural intensive agriculture and some of the environ- use of soil materials analagous mental Smithsonian's Marine predominately such as and tidal engineering; Sys- from southern Arizona. Soil ones, salinity flow, tems Laboratory for marsh and ocean design; horizons and they have thus far maintained a Tony Burgess of the Desert Laboratory, Tuc- with appropriate physical and chemi- high level of biodiversity. son, AZ, for desert and thornscrub; Peter cal characteristics were installed as Warshall, an independent consultant working as 5 meters to with the Office of Arid Land deep permit adequate Studies, University for root maturation over an Creation of Biosphere 2 of Arizona, for savannah and vertebrate species space selections; and Scott Miller of the Bishop Mu- extended time. For the marine sys- During the design phase, from 1984 seum in Honolulu, HI, to coordinate a team of tems, local limestone was used as the to 1988, there was close collaboration entomological consultants. The Institute of base of both the marsh and reef sys- and ar- Ecotechnics (UK), a small, private research whereas additional among ecologists, engineers, that has worked on the tems, aragonite chitects1 as company developing Bahamian reef ecological requirements theory and practice of integrating appropriate sand, rock, aragonite were translated into construction technology with ecological restoration projects, clam shell, oyster shell, and silica sand plans, and technologies were employed was the consultant on management of the de- were included to supply required to ensure maintenance of appropriate signed ecosystems. SARBID, now Biospheric chemical constituents. water and other Design, Inc., coordinated overall physical de- temperatures, flows, to the number of After closure, it was anticipated Two contrast- sign provide required habitats, ecological parameters. as well as temperature, humidity, wind, wave, that there would be species losses that ing ecological approachesfor select- tide, and rain controls. would decline as food webs became

April 1993 229 Table 1. Dimensions and volumes of Biosphere 2. Dimensions (meters) Areas Volumes Soil Water Air Section N-S E-W height (square meters) (cubic meters) (cubic meters) (cubic meters) (cubic meters) Agriculture 41 54 24 2000 38,000 2720 60 35,220 Habitat 22 74 23 1000 11,000 2 1 10,997 Rainforest 44 44 28 2000 35,000 6000 100 28,900 Savannah/ocean 84 30 27 2500 49,000 4000 3400 41,600 Desert 37 37 23 1400 22,000 4000 400 17,600 West lung 48 48 15 1800 15,000 0 0 15,000 South lung 48 48 15 1800 15,750 0 750 15,000 Lungs were measured at one-half inflation. more integrated and canopy structure lation between leak rate and pressure peltata, white popinac (Leuceana matured. To allow for the Darwinian that extrapolates to an estimated leak glauca), and horseradish tree (Moringa process to operate and to compensate rate of 6% per year at the currently oleifera). These trees probably will for extinctions, communities were ini- maintained operating pressure. In ad- gradually be replaced by the slower- tially stocked with a greater diversity dition, measurement of the progres- growing trees more characteristic of of plant species than would probably sive dilution of a marker trace gas the mature rainforest such as ma- be supportable. In most habitats, plants (SF6)confirms that the leak rate is not hogany (Swietenia macrophylla), rub- were installed in fairly equal abun- larger than 10% per year. During the ber trees (Hevea brasiliensis), kapok dances to allow a hierarchy of domi- initial four-month experimental pe- (Ceiba pentandra), tree ferns, and nance to emerge and to evaluate how riod, approximately 10% of the air palms. There are more than 300 spe- species thrived relative to one an- was lost and a corresponding 10% cies of higher plants in the Biosphere other. To allow tracking of plant com- was injected during a one-time opera- 2 rainforest, with initial biomass less munity changes, each perennial in the tion in December 1991. Previous sys- than 10% of that expected at full terrestrial and marsh biomes was tems, such as Bios-3 and the Bread- growth. Thus, the succession can be mapped and its canopy diameter mea- board Facility, have had leak rates in studied. sured before closure. Subsamples are the range of 1-10% per day (Knott Biomass increased approximately remeasured periodically, and a com- 1990). 50% in the rainforest from the time it plete resurvey is scheduled in Septem- The ecosystems of Biosphere 2 are was planted in November 1990 until ber 1993 after the initial two-year housed in two wings (Figure 2) that it was resurveyed in July 1991 closure period. share water and air circulation. Screens (Petersen et al. 1992). Since closure, prevent flying insects and other ani- the canopy structure has continued to Ecosystem changes mals from moving between the an- develop rapidly, with some Leuceana since closure thropogenic biome wing (agricultural trees now 12-18 meters tall requiring and human habitat) and the wilder- pruning back from the frame. Occa- Biosphere 2 is designed to be as mate- ness biome wing (rainforest, savan- sional treefall occurs, allowing faster rially closed as engineering could en- nah, desert, marsh, and ocean). Like growth of previously shaded trees, sure to prevent exchanges with the the global biosphere, Biosphere 2 is analogous to what occurs under natu- outside atmosphere and underlying composed of various biomes with dif- ral rainforest conditions. The ginger soil. It is energetically open, allowing fering soils, climate regimes, and veg- belt also has developed vigorously, both incident sunlight through its glass etation. Five areas patterned on a performing its role of sidelight screen. spaceframe and the import of electric- tropical to subtropical climatic gradi- The crew has replaced understory ity in addition to heat transfer by ent are housed in the eastern wing, plantings to overcome soil trampling means of heated or chilled water, which which is 165 meters long and 30-44 and plant loss occasioned by con- regulates internal temperature. It also meters wide. struction activities. is informationally open, connected A tropical rainforest with neotrop- A savannah with species from Aus- with the outside for exchange of data ical, predominantly Amazonian spe- tralia, South America, Africa, and and communications via computer cies, occupies the humid end of the Florida occupies the central terrestrial systems, telephone, video, and televi- gradient. Rainforest habitats include corridor. Habitats within the savan- sion. cloud forest, flood plain, stream, and nah include a gallery forest (with Af- The 1.28-hectare airtight area, ap- lowland rainforest. Along three sides rican acacia trees), two seasonally proximately 180,000 m3 in volume of the rainforest, a dense growth of flooded ponds (billabongs), a small (Table 1), is sealed above ground with plants in the order Zingiberales (the stream (modeled on a Florida Ever- laminated glass mounted on a ginger belt) protects the inner rainfor- glades stream), and a grassland with spaceframe and below ground with a est from strong lateral sunlight; a bam- 35 grass species, as well as associated stainless steel liner. Two variable vol- boo planting between the rainforest legumes and shrubs. The major grass ume chambers are connected to the and the ocean is intended to reduce herbivore is the leopard tortoise main structure. Experimentation with salt aerosol intrusion. The lowland (Geochelone pardalis). An ecotone various pressures during September rainforest has a quick-growing canopy modeled on the thornscrub areas of 1991-January 1992 established a re- of light-loving trees such as Cecropia Sonora, Mexico, and Malagasy sepa-

230 BioScience Vol. 43 No. 4 -- .. . - ... rates the savannah from the desert ???.:;B:'i'18,,:?:1!61:!'Y:,:i' ?s:???isii:aii?nsi7E:..??:?????3 ???;l;sr??? - '76::?:?? .. ;L_ila r biome. Since closure, a number of r*:;?;r? ,,?:8p""r"; RSi'i' have stoloniferous '::''??;dil.ii. grasses spread by "' growth, especiallypara grass (Brach- ?:+ - *~~~~~4i iaria mutica), Rhodes grass (Chloris :61: :I-- guyana), and Paspalumconjugatum, Z:1 whereas Vasey grass (Paspalum 4 .n. ?:::" . 'W:sbii.111 -.". urvillei) has increasedthrough seed- -ok~~~~I~::;~?~:..::~r;~j~iiii~i: ''~i ling establishment. These are C4 i II.?I':?iin domi- plants, and their accelerating Li: ?i;i? nance within Biosphere2 in the first ten monthscontrasts with predictions jir:? ifijin:? made on the basis of the previously It?r measured, competitive disadvantage of C4 photosynthesisunder low light and elevated carbon dioxide levels

(Ehleringer1978). ?iiIii; A coastal fog desertarea patterned on those found in the Vizcaino region of Baja California and similar cli- matesin othercontinents occupies the lowerelevation, south end of the east- ern wing. Its habitats include bajada, sanddune, granite boulders and slope, clay pan, and salt flat. The vegetation includes columnar species such as boojumtree (Fouquieriacolumnaris), cardoncactus (Pachycereuspringlei), and datil (Yucca valida) and shrubs such as cholla cactus (Opuntia molesta, Opuntia prolifera),century plants (Agave spp.), creosote bush (Larrea tridentata), and lavender (Lavandulapubescens). 2 The Biosphere desert was de- Figure2. a. The areas within Biosphere2. Isometricdrawing by ElizabethDawson. signedto simulatea communitytran- b. Biosphere2, human habitat in foreground.Photo by Gill Kenney. sitional between open desert scrub with a diverselife-form spectrum and general tendency for sandy soils to light (there is 40-50% of ambient a denser,more uniformcoastal scrub, favor perennial grasses in arid cli- light after transmission through the approximatingan ecotone between mates (Shmidaand Burgess1988). glass and structuralshading) and re- Vizcaino desert scrub (Turner and A salt- and freshwatermarsh mod- duced wind (the air handling system Brown 1982) and Vizcaino coastal eled on the wetlands of the Florida generallyproduces only mildair move- succulentscrub (Westman 1983). Since Evergladeshas six habitatson a gradi- ments),the mangrovesand some other closure, dense canopies have formed ent from freshwaterto progressively plants have become somewhat leggy in some sites, suppressing smaller more saline water. The freshwater and etiolated, with markedlygreater plants, especiallysucculents, to form marsh includes Everglades cattails internode lengths than occur in na- a vegetationmore closely resembling (Typhaspp.) and other tall emergent ture. Observationsof the marsh bi- coastal sage scrub, drought-decidu- plants (Canna spp.); the oligohaline ome phenology and biomass are as- ous thicket, or batha (Zohary 1962). marsh is dominated by a variety of sistedby Matt Finnof the Smithsonian This change was associated with the grassspecies such as wildmillet (Setaria Institution. managementstrategy of wateringthe geniculata) and large ferns such as A coral reef ecosystemmodeled on desertbiome to keep it activelygrow- Acroftichumspp.); the salt marshhas the Caribbeancoral reef biome is part ing for an extended period (Novem- Spartinagrasses and fiddler crabs (Uca of the ocean biome. There are four ber 1991 through March 1992) to spp.); the black mangrove area has habitats: beach with edible coconut assist in loweringatmospheric carbon Avicennia germinans;an oyster bay palms(Cocos nucifera) and Everglades dioxideconcentrations during the first area;and a redmangrove (Rhizophora beach community grasses and other winter.Unlike other parts of the desert mangle)marsh area adjoinsthe ocean halophytes;a shallowlagoon area with biome, the sand dune has shown a ecosystem. The mangroves have sea grasses (Thallasia testudinum), dramaticincrease in perennial grass grown rapidly,with many individuals conch (Strombus gigas), and red- cover, dominated by Eragrostis now more than 5 meters tall, and bandedshrimp (Stenopus hispidus); a lehmanniana and Sporobolus con- there has been new seedlingestablish- coral reef collected off the Yucatan tractus.This increaseconforms with a ment since closure. Under the lower Peninsulaand from the Bahamaswith

April 1993 231 soft and hard corals, including sea Table 2. Energetics of Biosphere 2. fans and brain corals (Gorgonia spp.) Energy Peak Average and a bottomed (Diploria spp.); sandy Electrical ocean. More than 1000 KW 800 KW eight-meter-deep 2000 KW 1200 KW 40 of coral and a similar num- (External support) species Heating 11 x 106 kj/hr 5 x 106 kj/hr ber of fish species were introduced. Cooling 35 x 106 kj/hr 20 x 106 kj/hr Since closure, overall reef system Solar flux 27 x 106 kj/hr 6 x 106 kj/hr health has been good, with only one Photosynthetic active 30 e *m-2 ' day-1 20 e *m-2 . day-1 known loss of a coral species, repre- radiation sented by one individual. Tissue death of some individuals and a few cases of Cactus wrens (Campylorhynchus etable and grain systems) that pro- white band disease were noted in some brunneicapillus) and rock wrens vides a complete diet for the eight- brain corals commencing in early (Salpinctes obsoletus) were evicted person crew (Glenn et al. 1990) and spring of 1992. Algae scrubbers de- before full closure, but a single curve- supports the recycling systems for the signed for maintenance of required billed thrasher (Toxostoma curviro- human and domestic animal waste low nutrient levels in the ocean (Adey stre) and several English sparrows products and inedible biomass. The and Loveland 1991) have been supple- (Passer domesticus) eluded capture. agricultural system operates without mented and eventually may be re- The thrasher has since died, but En- biocides, and it employs a host of placed by protein-skimmers fabricated glish sparrows are still resident in beneficial insects as well as sprays from fiberglass tubing inside Biosphere both wilderness and agriculture areas. (e.g., soap, sulfur, and Bacillus 2, which remove dissolved organic A baby galago was born, and fighting thuringensis) for controlling pests and molecules and acids by aeration. Coral between the dominant and subordi- diseases. health and vitality is being tracked nate adult female galago has required The Biosphere 2 agricultural sys- through analysis of underwater vid- caging of the latter to avoid serious tem is soil-based to minimize eos by Phil Dustan of the College of injury. consumables (e.g., chemical fertiliz- Charleston in Charleston, South Caro- Viability of small plant and animal ers or hydroponic nutrient chemicals) lina, who has developed color photo- populations is being studied through and make return of nutrients more graphic techniques for long-term several genetic assays. The assays were feasible than in a hydroponic system. monitoring of natural coral reefs developed after a workshop in Sep- Moreover, the soil was designed to (Dustan 1985, Dustan and Halas tember 1991, convened by Stephen function as a soilbed reactor to reduce 1987). Studies conducted by Donald O'Brien of the National Cancer In- trace gas buildups. Spoon of Georgetown University in stitute and Michael Clegg of the Uni- At closure, there was an initial the year between creation of the ocean versity of California-Riverside, to supply of some three months' food system and closure indicated that a explore the research potential of Bio- previously grown in Biosphere 2. The high diversity of microbiota was be- sphere 2. Biosphere 2 offers an oppor- goal is to supply the crew's nutrition ing maintained (Spoon and Ailing tunity to examine in detail founder during this initial two-year closure 1991). Robert Howarth of Cornell effects on small populations. With and leave a similar amount for the University is collaborating on studies limited breeding pools, to what extent next crew. Waste recycling is accom- of Biosphere 2 ocean chemistry. will genetic bottlenecks develop and plished by composting animal wastes Vertebrates in Biosphere 2 include what strategies can be used to increase and inedible crop residues and through the prosimian bushbaby (G. garnetii) genetic variation to mitigate the prob- use of an aquatic plant lagoon system from Africa, Australian blue-tongued lem? A few initial studies are under for human wastewater treatment. The skink (Tiliqua scindoides), prehensile way and longer-term studies are being remaining nutrients in the water in skink (Corucia zebrata), and more developed. these lagoons go back into the fields than a dozen frog and lizard species. Since initial installation of the eco- during crop irrigation. A separate sys- There are approximately 150 insect systems, humans have intervened, as- tem that condenses water from the species, including several dozen spe- suming the role of keystone predators atmosphere supplies potable water. cies raised in the Biosphere 2 insec- (Paine 1966) to control weed and pest Since closure, the agricultural sys- tary. The insects provide a variety of outbreaks and to maintain biodiver- tem has provided, on average, 90% of functions, including that of enhancing sity. Lobsters and large parrotfish have the nutritional needs for the crew of food webs. Mapping and calculation been culled in the ocean when food eight, supplemented by food previ- of food chains and striving for redun- chain stress was evident. Without de- ously grown in Biosphere 2. The diet dancy through alternate pathways to liberate keystone predators (humans), is calorie-restricted (2000 calories/day offset species extinctions was impor- biological diversity would have been on average through the first ten tant preparatory research in the de- reduced during the initial operating months, gradually rising to the cur- sign of Biosphere 2. period of Biosphere 2. rent 2200 calories), thus facilitating Since closure, there has been a sharp The western wing of Biosphere 2 the first study of humans in a nutrient- reduction in the number of flying in- includes the two human-dominated dense, low-calorie regime, which has sects and loss of two bird species: the biomes. One is an agricultural area been extensively studied in laboratory emerald hummingbird (Amazilla (including rice paddies, which also animals (Weindruch and Walford amazilla) and the red-cheeked cordon rear fish; fodder plants; tropical or- 1988). Responses in the Biosphere 2 bleu finch (Uraeginthus bengalus). chard; chickens; goats; pigs; and veg- crew include weight loss, a sizable

232 BioScience Vol. 43 No. 4 decrease in blood cholesterol level 3500 (from an average of approximately December 1991 195 to approximately 125), reduction of blood pressure and white blood cell 3000 count, and other physiologic changes previously noted in laboratory experi- 2500 - ments with mice, which also showed a of and marked slowing aging processes Ei of et. 2000 - prolongation lifespan (Walford C1 al. 1992). A human habitat with living and // / 1500 - working areas for the crew adjoins the u - L I 1 IljI June 1992 agricultural area. Plant photosynthe- sis is powered by ambient sunlight, 1000 but technical systems, including those for thermal control, are required pow- a ered external natu- 500 __^ ___-r _-670 by co-generating - o ral gas electrical generators (Table 2). _-'-"--r.----- 40 7_/7 - or r7777_ , r7 r Heated, chilled, evaporatively / /,"' ( , / r ..7 w /, 4/ 7 - / 7; / / / x ?' ?8 ., x lo water o , cooled passes through Biosphere June c) 7 14 21 28 ' 2 isolated in closed-loop piping into air-handler units, where energy ex- change for thermal control takes place Time (day of the month) (Dempster 1988, 1989). Evaporative December water towers outside Biosphere 2 dis- sipate rejected heat. The air handlers Figure3. AtmosphericCO dynamicswithin Biosphere2 duringDecember 1991 and can circulate air up to 600 m3/sec June 1992. The overlappedbar values given for photosyntheticphoton flux (PPF)are throughout Biosphere 2. Velocities for total daily incidentsunlight at the projectsite; internallight levels vary depending on location in the but 40-50% of ambient range from 5 m3/sec at a few localized facility average sunlight.The large diurnal ducts to and seasonal fluxes are the result of the smalleratmospheric and oceanic buffersand discharge nearly impercep- denser concentrationsof and soil tible in areas. plant biota than are found in Earth'satmosphere. many Temperature pa- have a on and normal variations rameters have been set in accordance Cloudy days large impact CO2 dynamics, day/night are large, because photosynthesis dominates during hours, CO2 with normal tolerances of the daylight drawing biomes, levels sharply down, and soil and plant respirationat night lead to large rises. generally ranging from 15 to 35 ?C and kept at comfortable levels in the human habitat (Dempster 1989). Biosphere 2 has an approximate aged 2466 ppm of atmospheric CO2. 100:1 ratio of carbon in living bio- By contrast, during June 1992, Bio- Dynamics of carbon dioxide mass to atmospheric carbon, whereas sphere 2 recorded its lowest monthly and oxygen since closure the earth's ratio is 1:1. Organic car- average for CO2 of 1060 ppm at the bon in Biosphere 2 soils has a more highest daily PPF, 53.7 moles m-2. Rates of biogeochemical cycles are than 5000:1 ratio with atmospheric day'', since closure. greatly accelerated in small, closed carbon, compared to approximately Several options have been pursued ecological systems because there is an 2:1 in Earth's biosphere (Bolin and to manage CO2levels inside Biosphere absence of the large reservoir buffers Cook 1983). 2 within acceptable limits for ecosys- available in Earth's biosphere and Calculation and modeling of these tem and human health, including a because the ratios of living material to dynamics, plus experience with atmo- CO2precipitator and recycling chemi- inorganic substrate are much greater. spheric cycling in the Biosphere 2 test cal system, adjustments of ecosystem Even in a facility as large as Biosphere module, led project designers to an- growing periods, and buffering of 2, the mean residence time for atmo- ticipate the strong diurnal and sea- ocean waters. This challenge is antici- spheric CO2 is only 1-4 days, whereas sonal CO2 fluxes that have been seen pated to be greatest during the early in Earth's atmosphere it is approxi- in Biosphere 2 (Figure 3). Daily CO2 years of operation because living plant mately 3 years (Schlesinger 1991). can fluctuate as much as 700-800 biomass is projected to increase to as To comprehend these profound ppm, although the fluctuation is usu- much as five times the initial amount scale differences, it is useful to point ally 500-600 ppm and sometimes and because respiration of the new out that a 1500 ppm concentration of slightly lower, because the life system soils was probably greatest at the be- CO2 in the Biosphere 2 atmosphere is active photosynthetically during the ginning of the enclosed experiment. (approximately four times Earth's CO2 day and respiration is dominant dur- To help buffer the system during concentration) equals approximately ing the night. During December 1991, winter low-light months in its first 100 kg of carbon. This amount is when photosynthetic photon flux (PPF, years as biomass increases in Bio- dwarfed by the quantities of carbon in sunlight available for photosynthesis) sphere 2, a CO2recycling system was living biomass and organic carbon in reached its lowest annual value of 16.8 installed that first sequesters CO2into its soils. moles m-2 day 1, Biosphere 2 aver- calcium carbonate by the reactions:

April 1993 233 CO2 + 2NaOH -> Na2CO3+ H20 and soil moisture is an important re- Kristina Vogt, Daniel Vogt, and Tom search activity. But during this first Siccama of the Yale University School Na2CO3 + Ca(OH)2 -> CaCO3+ winter, rainfall was continued in the of Forestry and Environmental Stud- 2NaOH savannah to keep it actively growing, ies have begun collaborative work and the desert was brought out of aimed at tracking the carbon budget The second reaction returnsthe NaOH dormancy, by irrigating earlier, to of Biosphere 2-the distribution of for reuse in the first. Subsequent heat- assist in uptake of anticipated high carbon at initial closure throughout ing of the CaCO3 to 950 ?C in a CO2 levels. Nighttime temperatures the system and studying its dynamics furnace will dissociate were reduced to minimize soil and over time (Petersen et. al. 1992). plant respiration, savannah grasses, Biosphere 2 also provides an op- CaCO3 -> CaO + CO2 marsh cattails, and ginger-belt plants portunity to accurately measure the in the rainforest were pruned to stimu- metabolism of a complex ecosystem returning the CO2 to the atmosphere late rapid regrowth while the cut bio- for an extended period of time. Prior and regenerating CaO which, with mass was stored to slow its decompo- determinations of terrestrial ecosys- water, provides Ca(OH)2 to be reused sition. Compost-making was largely tem metabolism have usually involved in the second reaction. Failure of the suspended in the agriculturalarea from short-term measurements taken on furnace inside Biosphere 2 has thus far November to January to minimize its small components of ecosystems prevented the scheduled return of the release of CO2, and the crew made (Golley et. al. 1962, McKellar 1977, CO2into the atmosphere. During the additional plantings to promote under- Odum and Jordan 1970). Currently, first fall and winter, some 53,880 story development in the ecosystems carbon cycle modeling is under way moles (equivalent to 9450 ppm) of and use additional incident light. with a group that includes Daniel CO2 was deposited as CaCO3 through Another area of potential concern Botkin of the University of California, the periodic use of this physicochemi- because of the elevated CO2levels was Santa Barbara, and Robert Frye of the cal CO2system between October 1991 the ocean coral reef. Because atmo- University of Arizona. Nutrient cycles and January 1992. This deposition spheric CO2 comes to equilibrium with (e.g., nitrogen, phosphorus, and sul- also indirectly accounts for a nearly the dissolved CO2 in ocean water, it fur) are to be added as total systems 1% decrease in atmospheric oxygen was expected that rising CO would models of Biosphere 2 are developed. through oxidation of organic carbon tend to increase the acidity of marine and in cal- water. To buffer the influx subsequent sequestering expected Research opportunities cium carbonate. By contrast, the addi- of CO2 in the ocean, additions of tion of 10% ambient air in December sodium carbonate and bicarbonate Significant research opportunities are 1991 to compensate for leak rate tests have been made on several occasions offered by a facility like Biosphere 2, made a small impact-a momentary since closure with the goal of main- which has been designed for a lifetime reduction of CO2 levels by 200 ppm, taining pH above 7.7. of 100 years. Because the system is so approximately one-third of normal Oxygen dynamics have proved sur- tightly closed, it permits tracking of diurnal variations. prising. Since closure, oxygen has de- major nutrient cycles through ecosys- In addition, management of life clined from Earth's ambient level of tems, atmosphere, and water systems. systems was undertaken during the 20.94% to slightly lower than 14.5% No specific replicate for the entire critical low-light season. Biosphere 2 (middle of January 1993). On medical experiment could be made, given its had been originally designed with the recommendation, when this level was large size and cost, but comparative savannah active during spring and reached, pure oxygen was injected work can be done with similar ecosys- summer months and the desert active into Biosphere 2 over a period of tems outside Biosphere 2. during the winter. Reduced sunlight several weeks to increase its atmo- The greenhouses in BRDC have been would slow savannah grass growth spheric concentration to 19%. Much transformed into areas housing eco- during winter months, and some habi- of the decline occurred during the first systems paralleling those inside Bio- tats, for example thornscrub, should four months after closure. By the end sphere 2, with many of the same spe- be kept dry during late winter or of January 1992, it had reached 18 %. cies. In addition, comparative studies spring to simulate their typical mois- Since the end of April 1992, the de- can be conducted on a sequential basis ture regimes and to accommodate cline in oxygen has been fairly linear as daily, seasonal, and yearly cycles daylength responses of some species. at a rate of approximately 0.25% per recur in Biosphere 2. The small atmo- It was expected that during winter the month. Investigations of oxygen dy- spheric reservoir (compared to Earth's ratio of soil respiration to canopy namics are being carried out in a biosphere) greatly enhances its sensi- photosynthesis would increase in the collaborative study headed by Wil- tivity to biogeochemical processes. The savannah. The desert biome was de- liam Dempster and Wallace Broecker previously noted changes in oxygen signed to have its peak growth during of the Lamont-Doherty Laboratory, and CO2, as well as variations in bio- cooler months to help offset possible using several methods, including study- genic trace gases, are examples of CO2efflux from the savannah. ing the distribution of oxygen iso- opportunities for investigation. Understanding how vegetation re- topes in Biosphere 2. The Biosphere 2 test module can sponses could be tailored to atmo- Biosphere 2 offers an opportunity also provide subsystem analogues to spheric regulation has been a major to do sophisticated modeling of bio- Biosphere 2. In the test module ex- goal; observing how plant phenolo- geochemical cycles and to test them periments, there has been an exami- gies are correlatedwith temperature experimentally. SBV researchers and nation of the consequences of key

234 BioScience Vol. 43 No. 4 variables such as ratios of biogeo- opportunity to study changing species cant ways from the global system,the chemical reservoirs, effects of soil dis- demography and community domi- intensivestudy of theirnutrient cycles turbance, human and plant adapta- nance in response to environmental may shed great insight into the key tion to lower light/elevated CO2, and perturbations in both terrestrial and mechanisms of global ecology. In- dynamics of trace gases. aquatic ecosystems. deed, one problem in developing a The study of the component scienceof the biosphereis that Earth's microbiomes in Biosphere 2 should Summary: a new type of biosphere is unique. Because there advance of as knowledge ecosystem func- research facility are, yet, no other natural tion, restoration ecology strategies, known for comparison, synthetic bio- biological dynamics of atmospheric A new type of research tool has been spheres open prospects for compara- gases such as methane and CO2, bio- developed with the first microbio- tive biospherics. These studies should logical effects of the exclusion of UV sphere, Biosphere 2. It has operated deepen understanding of the nature of light, response of ecosystems to differ- successfully since its initial closure in the global biosphere just as compara- ent light regimes than those of their September 1991, maintaining the over- tive planetology has sharpened under- natural habitat, and viability of small all health of its diversity of internal standing of Earth as a planet. plant and animal populations. The ecosystems and a large proportion of Biosphere 2 agricultural system may its species. Biogeochemical cycles are References cited be of greatest applicability to tropical, operating, at least on the short term, W. and K. Loveland.1991. developing countries that at present with strong and seasonal fluxes Adey, H., Dynamic daily Aquaria:Building Living Ecosystems. Aca- are food impoverished, least able to of atmospheric CO2, although atmo- demic Press,New York. afford high-input agriculture, and spheric oxygen is showing a decline in Allen, J. 1991. Biosphere2: The Human Ex- which have great problems with waste concentration. Overall system bio- periment.Penguin Books, New York. recycling from human populations. mass continues to increase, with Alien, J., and M. Nelson. 1988. Space Bio- The detailed of these woodland spheres.Synergetic Press, Oracle, AZ. study integrated canopies rapidly develop- Ailing, A., L. Leigh, T. MacCallum, and N. cropping techniques, waste recycling ing in rainforest, savannah, and marsh. Alvarez-Romo.1990. Biosphere2 test mod- systems, air purification, and biologi- The Biosphere 2 desert biome has ule experimentationprogram. Pages 23-32 cal control of pests is especially timely shown a community dominance shift in M. Nelson and G. A. Soffen,eds. Biologi- in of the reexamination of alter- to subshrubs/annuals since closure. cal Life Support Technologies.Synergetic light AZ. native called for Such a human-made Press,Oracle, agriculture systems biosphere may Ailing, A., M. Nelson, L. Leigh, R. Frye, N. in the recent National Resource Coun- offer unique opportunities for advanc- Alvarez-Romo,T. MacCallum,andJ. Allen. cil report (NAS 1989). ing understanding of fundamental Inpress. Experiments on the closedecologi- Biomes (called in the Russian tradi- components and processes of Earth's cal system in the Biosphere2 test module. tion a role These include Appendixchapter in R. J. Beyersand H. T. bio[geo]coenoses) play key biosphere. opportunities Odum, eds. Ecological Microcosms. in the structural organization of the tracking in great detail the dynamics Springer-Verlag,New York. biosphere. The Russian biologist M. of land and water ecosystems and of Andre,M., F. Cotte,A. Gerbaud,D. Massimino, M. Kamshilov recognized their "abil- biotic interaction with the atmosphere, J. Massimino,and C. Richaud.1989. Effect to withstand various external human on of CO2and 02 on development and fructifi- ity evaluating impact complex cation of wheat in closed effects... to homeostasis or and technolo- systems. Pages [due their] , developing 17-28 in R. D. MacElroy,T. W. Tibbitts,B. buffering power. There seems to be a gies compatible with sustaining the G. Thompsonand T. Volk, eds. Naturaland direct relationship between the com- biosphere. Studying such a biospheric Artificial Ecosystems. Pergamon Press, plexity of [a] biocoenosis and its abil- system a Oxford,UK. may provide unique testing H. L. 1972. Soil of air ity to withstand diverse external for evaluation of its Bohn, adsorption pollut- ground self-regu- ants.J. Environ.Qual. 1: 372-377 effects...greater resistance not only to latory functions. This study is intended Bohn, H. L., and R. K. Bohn. 1986. Soil bed intrusion of individual species from to help evaluate the hypothesis that a scrubbingof fugitivegas releases.J.Environ. different ecosystems but also to abi- biosphere regulates its environment Sci. Health Part A Environ. Sci. Eng. 21: otic factors....The of the bio- means of an feedback 561-569. stability by ecological andR. B. as a and its to its Bolin,B., Cook, eds. 1983. TheMajor sphere whole, ability process involving microbial, plant, BiogeochemicalCycles and their Interac- evolve, depends, to a great extent, on fungal, and animal communities. SBV tions. John Wiley & Sons, New York. the fact that it is a system of relatively is exploring a number of collaborative Bubenheim,D. 1990. CELSSresearch and de- independent biogeocoenoses... [which] studies with researchers to further velopment program. Pages 53-59 in M. Nelson and G. A. eds. compete for habitat, substance and enrich the scientific information the Soffen, Biological Life Support Systems. Synergetic Press, energy provides optimal conditions facility can yield. The long-term de- Oracle,AZ. for the evolution of the biosphere as a sign of the project offers wide scope Bugbee,B., and 0. Monje. 1992. The limits of whole" (Kamshilov 1976). for potential investigations, including cropproductivity. BioScience 42: 494-502. In Biosphere 2, one can study the those that would commence after the Carlson,D. A., and C. P. Leiser.1966. Soilbeds for the control of sewage odors. J. Water interrelationship of biomic areas and first two-year closure.2 Pollut. ControlFed. 38: 829-840. how their interplay affects overall sys- Though human-made biospheres Cooke, G. D. 1971. Ecology of space travel. tem balances. The relation of diver- such as Biosphere 2 differ in signifi- Pages498-509 in E. P. Odum. Fundamen- sity to stability and resilience in eco- tals of Ecology. Saunders College Publ., systems is an issue that generates Philadelphia. 2SBV is receptive to research proposals for top- K. A., and R. M. Wheeler. 1992. Gas considerable controversy and theo- Corey, ics of mutual interest from private, university, exchange in NASA's biomass production retical interest. Biosphere 2 offers the or federal laboratories. chamber. BioScience 42: 503-509.

April 1993 235 Dempster, W. F. 1988. Biosphere II: design of a and gnotobiology. JPRS 54331, National sion Service, Washington, DC. closed manned terrestrial ecosystem. SAE Technical Information Service, Springfield, Paine, R. T. 1966. Food web diversity and Technical Paper Series #881096, 18th VA. species diversity. Am. Nat. 100: 65-75. Intersociety Conference on Environmental Leigh, L., K. Fitzsimmons, M. Norem, and D. Petersen, J., A. Haberstock, T. Siccama, K. Systems. SAE, Warrendale, PA. Stumpf. 1987. An introduction to the inten- Vogt, D. Vogt, and B. Tusting. 1992. The . 1989. Biosphere II: technical overview sive agriculture biome of Biosphere II. Pages making of Biosphere 2: frontiers in synthetic of a manned closed ecological system. SAE 76-81 in B. Faughnan and G. Maryniak, ecology. Restoration and Management Technical Paper Series #891599, 19th eds. Space Manufacturing 6: Nonterrestrial Notes 10: 158-168. Intersociety Conference on Environmental Resources. Biosciences and Space Engineer- Salisbury, F., B. Bugbee, and D. Bubenheim. Systems, SAE, Warrendale, PA. ing, AIAA, Washington, DC. 1987. Wheat production in controlled envi- Dustan, P. 1985. The bio-optics of coral reefs. MacElroy, R. D.,J. Tremor, D. T. Smernoff, W. ronments. Pages 123-132 in R. D. MacElroy Pages 189-198 in M. L. Reaka, ed. The Knott, and R. P. Prince. 1987. A review of and D. T. Smernoff, eds. COSPAR Ad- Ecology of Coral Reefs. NOAA Undersea recent activities in the NASA CELSS pro- vances in Space Research. vol. 7(4). Research Program, Rockville, MD. gram. Pages 53-58 in R. D. MacElroy and Pergamon Press, Oxford, UK. Dustan, P., and J. Halas. 1987. Changes in the D. T. Smernoff, eds. Controlled Ecological Schlesinger, W. H. 1991. Biogeochemistry: An reef-coral community of Carysfort reef, Key Life Support Systems. Pergamon Press, Analysis of Global Change. Academic Press, Largo, Florida, 1974 to 1982. Coral Reefs Oxford, UK. New York. 6: 91-106. McKellar, H. N. 1977. Metabolism and model Schwartzkopf, S. H. 1992. Design of a con- Ehleringer, J. 1978. Implications of quantum of an estuarine bay ecosystem affected by a trolled ecological life support system. Bio- yield differences on distribution of C3 and coastal power plant. Ecol. Modell. 3: Science 42: 526-535. C4 grasses. Oecologia (Berlin) 31:255-267. 85-118. Shepelev, Yevgeny Y. 1972. Biological life sup- Eley, J. H. Jr., and J. Myers. 1964. Study of a Myers, J. 1963. Space biology: ecological as- port systems. Pages 274-308 in M. Calvin photosynthetic gas exchanger: a quantita- pects; introductory remarks. Am. Biol. and 0. Gazenko, eds. Foundations of Space tive repetition of the Priestley experiment. Teach. 25:409-411. Biology and Medicine. vol. 3. Academy of Texas J. Sci. 16: 296-333. National Academy of Sciences (NAS). 1989. Sciences USSR, Moscow, , and NASA, Finn, M., and W. H. Adey. 1991. Mesocosms: Alternative Agriculture. Committee on the Washington, DC. encapsulated ecosystems on display. Sea Role of Alternative Farming Methods in Shmida, A. and T. L. Burgess. 1988. Plant Technol. 32: 85-88. Modern Production Agriculture, Board on growth form strategies and vegetative types Folsome, C. E., and J. A. Hanson. 1986. The Agriculture, National Research Council, in arid environments. Pages 211-241 in N. emergence of materially closed system ecol- National Academy Press, Washington, DC. J. A. Werger, P. J. M. van der Aart, H. J. ogy. Pages 269-288 in N. Polunin, ed. Eco- National Aeronautics and Space Administra- During, and J. A. Verhoeven, eds. Plant system Theory and Application. John Wiley tion (NASA). 1968. Bioregenerative Sys- Form and Vegetation Structure. S. P. Aca- and Sons, New York. tems. Proceedings of a conference in Wash- demic Publ., The Hague, Netherlands. Galston, A. W. 1992. Photosynthesis as a basis ington, DC, 15-16 November 1966. Skoog, A. I. 1987. Progress in European CELSS for life support on Earth and in space. NASA-SP-165, Science and Technical In- activities in controlled ecological life sup- BioScience 42: 490-493. formation Division, OTA, NASA, Wash- port systems. Pages 7-10 in R. D. MacElroy Glenn, E. P., and R. Frye. 1990. Soil bed reac- ington, DC. and D. T. Smernoff, eds. COSPAR Ad- tors as endogenous control systems of Nelson, M. 1989. The biotechnology of space vances in Space Research. vol. 7(4). CELSS. Pages 41-58 in Workshop on Arti- biospheres. Pages 185-200 in G. Malacinski, Pergamon Press, Oxford, UK ficial Ecological Systems. Proceedings of a ed. Fundamentals of Space Biology. Spoon, D., and A. Ailing. 1991. Preclosure meeting in Marseilles, France, October 1990, Springer-Verlag, New York. survey of aquatic microbiota of Biosphere sponsored by DARA and CNES. DARA, Nelson, M., L. Leigh, A. Ailing, T. MacCallum, 2. Paper presented at the Third East Coast Berlin. J. Allen, and N. Alvarez-Romo. 1991a. Bio- Conference on Protozoa, Mount Vernon Glenn, E., C. Clement, P. Brannon, and L. sphere 2 test module: a ground-based sun- College, VA, 21-22 May 1991. Leigh. 1990. Sustainable food production light-driven prototype of a closed ecological Terskov, I. A., et al. 1979. Closed System: Man- for a complete diet. HortScience 25: system. Pages 151-158 in R. D. MacElroy, Higher Plants (Four Month Experiment). 1507-1512. M. M. Averner, T. W. Tibbitts, B. B. Bugbee, Translation of Nauka Press, Siberian Golley, F. B., H. T. Odum, and R. F. Wilson. G. Horneck, and E. H. Dunlop, eds. Natural Branch, Novocibirsk, publication. NASA- 1962. The structure and metabolism of a and Artificial Ecosystems. Pergamon Press, TM-76452, Washington, DC. Puerto Rican red mangrove forest in May. Oxford, UK. Turner, R. M., and D. E. Brown. 1982. Sonoran Ecology 43: 9-19. Nelson, M., J. P. Allen and W. Dempster. desertscrub. Desert Plants 4: 181-221. Hammer, D., ed. 1989. Constructed Wetlands 1991b. Biosphere 2, prototype project for a Walford, R. L., S. B. Harris, and M. W. Gunion. for Wastewater Treatment: Municipal, In- permanent and evolving life system for a 1992. The calorically restricted low-fat nu- dustrial and Agricultural. Lewis Publ., Boca Mars base. Pages 211-218 in R. D. trient-dense diet in Biosphere 2 significantly Raton, FL. MacElroy, M. M. Averner, T. W. Tibbitts, lowers blood glucose, total leukocyte count, Hanson, J. 1982. Workshop on closed system B. B. Bugbee, G. Horneck, and E. H. Dunlop, cholesterol, and blood pressure in humans. ecology. Summary report. Jet Propulsion eds. Natural and Artificial Ecosystems. Proc. Natl. Acad. Sci. 89:11,533-11,537. Laboratory Publication 82-64, Pasadena, Pergamon Press, Oxford, UK. Weindruch, R., and R. L. Walford. 1988. The CA. Nitta, K. 1987. An overview of Japanese CELSS Retardation of Aging and Disease by Di- Hodges, C., and R. Frye. 1990. Soil bed reactor research activities in controlled ecological etary Restriction. Charles C. Thomas, New work of the Environmental Research Lab of life support systems. Pages 95-104 in R. D. York. the University of Arizona in support of the MacElroy and D. T. Smernoff, eds. COSPAR Westman, W. E. 1983. Xeric Mediterranean- Biosphere 2 project. Pages 33-40 in M. Advances in Space Research. vol. 7(4). type shrubland associations of Alta and Nelson and G. A. Soffen, eds. Biological Pergamon Press, Oxford, UK. Baja California and the community/con- Life Support Systems. Synergetic Press, Odum, H. T. 1963. Limits of remote ecosystems tinuum debate. Vegetation 32: 3-19. Oracle, AZ. containing man. Am. Biol. Teach. 25: Wolverton, B. C. 1987. Aquatic plants and Kamshilov, M. M. 1976. The Evolution of the 429-443. wastewater treatment (an overview). Pages Biosphere. Mir Publ., Moscow, Russia. 1983. Systems Ecology. Wiley- 3-15 in K. Reddy and W. H. Smith, eds. Knott, W. M. 1990. The CELSS Breadboard Interscience, New York. Aquatic Plants for Water Treatment and Project: plant production. Pages 47-52 in Odum, H. T., and C. F. Jordan. 1970. Metabo- Resource Recovery. Magnolia Publ., Or- M. Nelson and G. A. Soffen, eds. Biological lism and evapotranspiration of the lower lando, FL. Life Support Systems. Synergetic Press, forest in a giant plastic cylinder. In H. T. Vernadsky, V. I. 1986. The Biosphere. Oracle, AZ. Odum and R. F. Pigeon, eds. A Tropical Synergetic Press, Oracle, AZ. Lebedev, K. A., and R. V. Petrov. 1971. Immu- Rainforest. National Technical Informa- Zohary, J. 1962. Plant Life of Palestine. Ro- nological problems of closed environments tion Service, Technical Information Exten- nald Press, New York.

236 BioScience Vol. 43 No. 4