FIGURE 9.8 Diagram of a redox microcosm with artificial control from a simulation model.
(From Blersch, in preparation. With permission.)
FIGURE 9.8 Diagram of a redox microcosm with artificial control from a simulation model.
(From Blersch, in preparation. With permission.)
The main component elements of ecological engineering designs are species populations, and the designs themselves are ecosystems. If ecological engineering was similar to other fields such as chemical, electrical, or civil engineering, it would be possible to build up designs from component elements that are well known in terms such as capacity, conductance, and reliability. However, species populations are not so well known. A million species have been discovered in nature and even for the common, widely occurring species, knowledge isn't complete. Agricultural species are best known, and the discipline of agriculture involves design of production systems with these species. Ecological engineering seeks to use the much greater biodiversity of wild species for its designs. Attempts have been made to summarize information on wild species, but these efforts have always been incomplete. The closest examples to a handbook as exists in other engineering disciplines are those produced by the Committee on Biological Handbooks in the 1960s (see, for example, Altman and Dittmer, 1966), which are composed of hundreds of tables of data. While these are interesting compilations, the ecological engineer needs different information to design networks of species. Needed are lists of who eats what and whom, chemical compositions of excretion, behaviors, tolerances, performance ranges, adaptations to successional sequences, and much other information (i.e., the species
Mean Worldwide Usable civilized seeding products, waste / aesthetics
Mean Worldwide Usable civilized seeding products, waste / aesthetics
niche). The closest existing examples may be the work on national biotic inventories, such as exists for Costa Rica (Gamez et al., 1993; Janzen, 1983) or the records on species used for biological control of agricultural pests (Clausen, 1978). However, the conventional engineer would be disappointed even in these extensive sources.
In place of handbooks on component elements, the ecological engineer utilizes the self-organizing properties of nature. H. T. Odum envisioned an example of what might be a universal pollution treatment ecosystem based on this principle that has yet to be intentionally tried (Figure 9.9 and Figure 9.10). Basically, the design would mix a variety of pollutants together in a large circulating impoundment that would be seeded with as much aquatic biodiversity as possible. H. T. Odum projected that the result would be a treatment ecosystem that could absorb and cleanse any pollution source. The growth of treatment wetland technology as described in Chapter 2 demonstrates that such ecosystems are possible. Furthermore, species from around the world can self-organize into new networks, as discussed in Chapter 7. Thus, H. T. Odum's vision for a universal treatment ecosystem may be possible. The critical aspect seems to be size of the impoundment necessary for self-organization to transcend adaptation to any particular pollutant and result in more universal treatment capacity. Size relates to spatial heterogeneity, which improves ecosystem qualities such as diversity and stability. Interestingly, H. T. Odum expanded the size of his design from a maximum diameter of 1 mi (1.6 km) in 1967 (Figure 9.9) to 5 mi (8 km) in 1971 (Figure 9.10). Perhaps his experience at Morehead City, NC, with self-organization of marine ponds and domestic sewage in the late 1960s suggested to H. T. Odum that his conception needed enlargement.
H. T. Odum's design may be equivalent to a living machine consisting of a very large number of tanks connected in series (see Chapter 2). The hypothesis is that any pollution source can be treated, given a long enough set of tanks filled with
different biota. A quantitative expression for the treatment capacity of a living machine is given below:
T = total treatment capacity of the living machine P - C = physical-chemical treatment capacity of tank i Bi = biological treatment capacity of tank i n = number of tanks in the living machine
Treatment capacity is increased by increasing the number of tanks (n in the equation). In an analogous sense, the digestive system of a ruminant is an example of this principle. Three extra stomachs are found in ruminants which aid in digestion of plant material with low nutritive value (see Chapter 6). Each stomach has a different function in the digestion process, and recycle is even included in the regurgitation of cud.
While the experiments described above may be as much science fiction as terraforming, they also may be happening inadvertently in polluted bays and harbors around the world today. For example, see the discussion of San Francisco Bay in Chapter 7 for a possible candidate. Intentional ecological engineering of the design would increase progress, which may require "a national project of self-design" as proposed by H. T. Odum more than 30 years ago.
Strong ties already exist between architecture and ecological engineering. Architecture deals with design of human environments, and many architects have evolved approaches that are responsive to, or even inspired by, nature (Zeiher, 1996). Well-known examples are philosophies of organic or living architecture (Wright, 1958) and the idea of "design with nature" as a guide to landscape architecture (McHarg, 1969). McHarg's famous phrase actually may have been derived from Olgyay's (1963) treatise on bioclimatic architecture that was titled "Design with Climate."
The design process is somewhat different in architecture as compared with traditional engineering, and ecological engineers can learn much from the contrast. Often times, architects seem to open up new lines of thinking by creating bold designs that are unconstrained by practical limitations. Buckminister Fuller's "Dymaxion" house is an example of this creative approach to design from the 1920s. The Dymaxion house included many features that were completely unconventional but farsighted. For example, (1) it was made out of aluminum and could be mass-produced, and (2) it had a circular floor plan and was suspended on a central mast which made maximum use of space and facilitated climate control. Also, the amount of material used per unit floor space was minimized, which reflects Fuller's motto of "doing more with less." Although the Dymaxion house was never commercially produced, it generated new thinking that was influential (Baldwin, 1996). An example of an actual Dymaxion house is on exhibit at the Henry Ford Museum in Dearborn, MI (Figure 9.11). Paolo Soleri's "Arcosanti" is another example of an extremely visionary form of architecture. Soleri (1973) developed a unique philosophy of the future building environment and ecology of humans. His approach is to design and build huge skyscrapers of highly integrated living and working spaces, in this way concentrating the built environment onto a small footprint and leaving as much as possible of the surrounding open space for agriculture and nature preservation. An actual model of Soleri's Arcosanti exists and is growing as an experiment in the desert grassland north of Phoenix, AZ.
Of course, at another extreme architecture can be eminently practical, as demonstrated by Butler (1981) in his book on how to build an "ecological house" based on principles of energy efficiency. John and Nancy Todd's work on bioshelters is another expression of ecological architecture that also emphasizes food production and wastewater treatment designs (Todd and Todd, 1984). Reviews of these approaches to architecture are given by Steele (1997) and Stitt (1999).
Several initiatives of ecological architecture represent new directions for collaboration between architects and ecological engineers. Plant-based systems are being integrated with architecture in innovative ways, such as for air quality improvement in interior environments (see below) and roof gardens (Kohler and Schmidt, 1990) for stormwater management in external environments. Although these applications involved straightforward horticulture, ecological engineering may be important especially if treatment function is to be optimized. For example, Golueke and Oswald (1973) describe a plan for a home that uses an algal regenerative system for multiple functions. Another direction for collaboration may be in terms of the recycling of buildings and their materials (Brand, 1994). Here, ideas of industrial ecology such as life cycle analysis and network accounting of material flows may be appropriate. The term construction ecology recently has been used to describe some or all the applications listed above (Kibert et al., 2002).
The quality of the indoor environment is directly related to ecological architecture but at a smaller scale. Many aspects are involved (Godish, 2001), though air quality with respect to human occupation and activity has received the greatest attention (Meckler, 1991). Human health problems can arise inside buildings due to the accumulation of toxic chemicals or organisms. These accumulations are facilitated by the static atmosphere that occurs inside buildings, especially in those buildings that are tightly sealed for energy efficiency. Furthermore, because humans spend a high percentage of their time indoors, exposure levels can become critical. When the cause of the health problem is diagnosable, the condition is known as "building related illness." When the cause of the health problem cannot be diagnosed, the condition is known as "sick building syndrome." Together these kinds of problems are serious enough to require costly treatment or even the abandonment of whole buildings. Causes include such factors as volatile organic chemicals, dust fibers, asbestos, carbon monoxide, and molds.
Biofiltration is an ecological engineering approach that has been taken to solve these problems. The approach is to pass contaminated air through chambers containing media and organisms (i.e., biofilters) in order to remove the contaminants. Soil beds have a long history of use for this purpose, for example, in treating odors from sewage treatment plants (Bohn, 1972; Carlson and Leiser, 1966). However, recent trends are to explore more sophisticated designs (Darlington et al., 2000, 2001; Leson and Winer, 1991; Wood et al., 2002). Most biofilters rely on microbes for biological treatment processes such as oxidation of volatile organic chemicals. However, higher plants also are used. These applications can involve common houseplants that contribute to the air processing in buildings (Figure 9.12). B. C. Wolverton has been a leader in this approach, building on his early experience in treatment wetland design (see Chapter 2). Much of his extensive published research on use of houseplants in biofiltration is summarized in a text entitled How to Grow Fresh Air (Wolverton, 1996).
One direction for future design is to begin thinking of the indoor environment as an ecosystem. A significant amount of biodiversity can be found in houses, even though these species are largely considered pests. For example, Ordish (1981) lists more than 150 taxa as being found in a review of the history of a bicentennial house, and he even gives graphs of relative abundances and estimates of animal metabolism. These organisms are links in food webs and in biogeochemical cycles within the houses. Conscious design of house animal food chains might be able to control mold populations, when practically no other solutions are available. The ecosystem approach used by ecological engineers could aid in future solutions to indoor environmental quality problems.
Aquaculture is the controlled production of aquatic organisms for human use. This is an important field that has the potential to provide a significant source of food to the world's growing population (Bardach et al., 1972; Brown, 1980; Limburg, 1980; Naylor et al., 2001). Designs in aquaculture range from commercial scale, energy intensive, indoor tank systems to backyard-scale, low energy, outdoor pond systems. Engineering aspects of aquaculture, especially on a commercial scale, are well developed (Wheaton, 1977) and mostly concern problems such as temperature and oxygen controls, water filtration, and waste disposal. Thus, aquacultural engineering largely involves controlling and maximizing conditions for growth of particular species of fish and other organisms within constructed environments. The economic basis of commercial scale aquaculture is tenuous because both capital and operating costs are high and markets are often uncertain. Some systems such as catfish production in the southern U.S. are established and economically viable, while many others require stronger markets and/or further technological development.
Ecological engineering probably can make little contribution to commercial scale aquaculture where emphasis is on producing large amounts of food product from monocultures of single species. Work on intermediate scale or backyard-type aquaculture systems is more appropriate for ecological engineering. Systems that rely on a polyculture of multiple species and/or an integration of multiple uses of water may be able to be improved with ecological engineering knowledge. Much is already known about lower-energy aquaculture (Chakroff, 1976; Logsdon, 1978), but some new initiatives may be possible. Swingle's (1950; Swingle and Smith, 1941) old work on fishing ponds actually represents an early version of ecological engineering. He developed much design knowledge from experimentation with artificial impoundments at the Alabama Agricultural Experiment Station. For example, he found that the ratio of forage fish to game fish should be about 4 to 1 for optimal productivity of a fish community. One approach would be to try to incorporate aspects of Chinese fish culture, which focuses on a polyculture production system (Jingson and Honglu, 1989; Lin, 1982), into the Western world. The Chinese systems are remarkable for their diversity and they incorporate features based on ecological principles. Creative designs based on these models are possible and could be constructed widely in rural and suburban environments (Todd, 1998). Other models also are possible. For example, Pinchot (1966, 1974) designed an aquacultural system based on natural oceanic upwelling ecosystems. These ecosystems are usually found on the west coasts of continents where wind patterns cause a localized circulation that brings deep ocean water to the surface (i.e., upwelling). The water from the deep ocean is nutrient rich, because of the dominance of decomposition processes there. Thus, upwellings are naturally eutrophic sites with high production and short food chains due to the fertilization effect of nutrient rich water being brought to the surface where sunlight levels are highest (Boje and Tomczak, 1978; Cushing, 1971). Pinchot's design for an artificial upwelling involved pumping deep ocean water into a coral reef lagoon with power from windmills (Figure 9.13). Whales would then be raised in the lagoon where they could be easily harvested for food because of their confinement in the enclosure of surrounding reef. This is a rather imaginative design, which represents an ecological engineering approach, but it probably would not be feasible at present due to animal rights concerns about the welfare of whales. Other examples of integrated systems of aquaculture and sewage treatment are described in Chapter 2.
The last area in which ecological engineering may possibly contribute to aquaculture involves pest biodiversity. Outdoor aquacultural systems often attract natural predators that feed on the species being cultured. For example, fish-eating birds, such as pelicans and cormorants, are responsible annually through their feeding actions for millions of dollars of damage to outdoor aquaculture. An ecologically engineered design for reducing this energy flow in a humane fashion would be a significant achievement.
Biotechnology or genetic engineering, as it is sometimes referred to, involves the creation of organisms with new properties through various forms of genetic manipulation. The field has a long history of producing useful organisms that contribute to the well-being of humans, such as the centuries-old examples of microorganisms that function in the leavening of bread and the fermentation of grapes to make wine. Recombinant DNA technology, which developed in the mid-1970s, is only the most recent form of biotechnology. In all forms of biotechnology the genetic makeup of organisms is modified to produce an organism (or a product) that is different from the starting organism. However, significant differences exist between classical techniques such as controlled breeding and the new molecular techniques. The recombinant DNA technology is faster, can deal with many more kinds of genes, and is more precise than the classic methods. Because of these developments, a biotechnology revolution has been envisioned with great advances expected in medicine, agriculture, and other fields (see, for example, Koshland, 1989). Many kinds of improvements can be imagined and are being studied such as engineering crop species that use less water or that have enhanced resistance to disease, or microbes which metabolize hazardous wastes. The potential benefits of biotechnology seem endless, but there are risks associated with releasing genetically engineered organisms into the environment (Flanagan, 1986; Gillett, 1986; Pimentel et al., 1989; Tiedje et al., 1989). The risks are similar to those described in Chapter 7 for exotic species, but with a somewhat greater degree of uncertainty about impacts (Drake et al., 1988).
While there are fundamental differences between genetic and ecological engineering (Mitsch, 1991), the two fields might find areas of collaboration (Forcella, 1984). Ecological engineering could contribute the perspective of multispecies networks to genetic engineering which otherwise focuses on individual species. Perhaps biotechnology could involve pairs or sets of interacting species in a kind of coevo-lutionary genetic engineering. Thus, predator-prey pairs might be coengineered rather than just a single species. This might build more security into releases because a predator or parasite would be simultaneously designed for a specific purpose. In this way a predator would already be available to control the new engineered organism if its populations caused unintended impacts. Biotechnologists would need to collaborate with their ecological counterparts to ensure success of the pair of species. Other kinds of interspecific interactions could also be explored such as symbiotic systems for decomposition and nutrient cycling. Contributions from ecology in the relationship could be seen as amplifying biotechnology in the long run, though in the short run more genetic-ecological engineering design would be required than presently occurs. This would be the opposite of the typical negative role that ecology has had with biotechnology in terms of simply regulating releases of genetically engineered organisms.
Most designs discussed in this text have been the product of Western thinking. Possible examples from the Orient were mentioned in Chapter 3 but alternative designs might be employed by many different cultures. Perhaps biocultural surveys could be undertaken to search for these alternatives. An analogous approach exists for useful plants, called ethnobotany, in which anthropologists conduct studies of the ways different cultures utilize plants of economic importance. This is a well-known approach to learning about indigenous knowledge that can then be adapted to Western society. Interfacing with other cultures is a complicated enterprise that involves human rights issues (Rubin and Fish, 1994; Schmink et al., 1992), and biocultural surveys must be conducted with care and respect.
Alternate ways of thinking about ecological engineering can be expected to occur because different human societies are known to develop unique material cultures, such as house form (Rapoport, 1969) or agriculture (Gliessman, 1988). Todd (1996b) has warned against the disappearance of regional and local technologies and the spread of a "technological monoculture" found in Western society. Thus, there may be a need to search out and "salvage" cultural approaches to ecological engineering before they are lost (Cox, 2000). Balinese irrigation engineering may be one such example as shown in Lansing's studies (1987, 1991). In
Offerings to the Gods Nature gods (Earth Mother, Sea God, etc.)
Water Temple Congregation .
Gods of Gods of Other
Upstream Nearby Social Units
Water Temples (Village, Clans, etc.)
B. Sources of holy water
Upstream natural sources
Water Temple Congregation
Upstream Holy Water from
Water Temples Other Nearby Social Units
FIGURE 9.14 Two views of Balinese water temples in terms of (A) religion and (B) hydrology. (Adapted from Lansing, J. S. 1991. Priests and Programmers: Technologies of Power in the Engineered Landscape of Bali. Princeton University Press, Princeton, NJ.)
this case, social organizations and irrigation structures as well as management are highly integrated into a form of "ritual technology" (Figure 9.14). Kremer and Lansing (1995) constructed simulation models of this system of water management and used them as a way of facilitating communication between the indigenous culture and officials from the Westernized government of Bali. Further studies such as these are needed to know whether a kind of ethnoecological engineering would be an instructive activity. Perhaps similar philosophies to McHarg's "design with nature" or Buckminster Fuller's "do more with less" can be found embedded in some Amazon Indian cosmology (Reichel-Dolmatoff, 1976); or perhaps some new technology such as a novel living fence (Steavenson et al., 1943) tucked away in a Mayan field in the highlands of Guatemala can be discovered and incorporated into Western ecological engineering. Can the sacred groves of India (Gadgil and Vartak, 1976; Marglin and Mishra, 1993; Reddy, 1998) provide designs for socially integrated urban rain gardens and riparian buffers?
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