2.2 Basic concepts of ecological engineering

Ecological principles are used widely in practical application of ecological engineering methods. There are some basic concepts that collectively distinguish ecological engineering from more conventional approaches to solving environmental problems with engineering approaches. These concepts are discussed in more details below. Much of this text is from Mitsch and Jørgensen.

2.2.1 Self-design

When change occurs in natural systems, species shift as they substitute for each other and as food chains reorganize. As individual species change, ultimately new systems emerge that are better suited to the environments that are superimposed on them. The natural systems then begin to manipulate the physical and chemical environment to make it a little more palatable. Humans participate by providing choice of initial species, matching species with the environment. Nature does the rest.

Odum referred to this capability of self-design as self-organization, which “designs a mix of man-made and ecological components” in a “pattern that maximizes performance, because it reinforces the strongest of alternative pathways that are provided by the variety of species and human initiatives.” Multiple seeding of species into ecological engineered systems is one way to speed the selection process in this self-organization or self-design.

Compared with imposed organization, such as is done in many conventional engineering approaches, self-organization develops flexible networks with a much higher potential for adaptation to new situations. It is this latter property that is desirable for solving many of our ecological problems. Here, when biological systems are involved, the ability for the ecosystems to change, adapt and grow according to forcing functions and internal feedbacks is most important.

A whole-system ecosystem experiment that was developed for almost a decade involved wetlands at the Olentangy River Wetland Research Park in Ohio, USA, where continual introduction of river water over a decade has accelerated the natural process of self-design. Mitsch et al. described how 2500 individuals of 12 plant species were introduced to one wetland basin while the other remained an unplanted control, essentially testing the self-design capabilities of nature with and without human help. Both basins (Fig.2.2.1) had identical inflows of river water and hydroperiods. After only 3 years, there was convergence of wetland function of the planted and unplanted basins with 71% of functional indicators essentially the same in the two basins. This convergence in year 3 followed the second year where only 12% of the indicators were similar. Most importantly, hundreds of taxa, both aquatic and terrestrial, were continually introduced to these wetland basins, primarily because the wetland basins were hydrologically open systems, and many taxa survived. In 3 years, over 50 species of macrophytes, 130 genera of algae, over 30 taxa of aquatic invertebrates, and dozens of bird species found their way naturally to the wetlands. After 6 years, there were over 100 species of macrophytes but a continued effect of the initial planting was still observed in ecosystem function. The continual introduction of species, whether introduced through flooding and other abiotic and biotic pathways, appeared to have a much more long-lasting effect on development of these ecosystems than did the introduction of a few species of plants. But both are important in self-design.

Fig. 2.2.1　Olentangy River Wetland Research Park

Note: Facility at Ohio State University, Columbus, OH, USA, shows two kidney-shaped experimental wetlands. Basin on right was planted with 12 species of wetland plants; basin on left was not planted. This photo was taken after six growing seasons in 1999. This represented a long-term experiment in self-design.

2.2.2 The acid test

Restoration ecologists have long suggested the tie between basic research and ecosystem restoration, stating that the best way to understand a system, whether a car, a watch, or an ecosystem, is to “attempt to reassemble it, to repair it, and to adjust it so that it works properly”. Ecological engineering will be the ultimate test of many of our ecological theories. Bradshaw has described the restoration of a disturbed ecosystem as the “acid test of our understanding of that system”. Cairns was more direct: “One of the most compelling reasons for the failure of theoretical ecologists to spend more time on restoration ecology is the exposure of serious weaknesses in many of the widely accepted theories and concepts of ecology.” Bradshaw calls ecosystem restoration, when done properly, “ecological engineering of the best kind”. Ecological theories that have been put forward in the scholarly publications over the past 100 years must serve as the basis of the language and the practice of ecological engineering. But just as there is the possibility of these theories providing the basis for engineering design of ecosystems, there is also a possibility of finding that some of these ecological theories are wrong. Thus ecological engineering is really a technique for doing fundamental ecological research and advancing the field of ecology.

2.2.3 A systems approach

Pahl-Wostl argues that just as self-organization is a property of a system as a whole, it is meaningless at the level of the parts. Ecological engineering requires a more holistic viewpoint than we are used to doing in many ecosystem management strategies. Ecological engineering emphasizes, as does ecological modeling for systems ecologists, the need to consider the entire ecosystem, not just species by species. Restoration ecology, a sub-field of ecological engineering, has been described as a field in which “the investigator is forced to study the entire system rather than components of the system in isolation from each other”. Conversely, the practice of ecological engineering cannot be supported completely by reductive, analytic experimental testing and relating. Approaches such as modeling and whole-ecosystem experimentation are more important, as ecosystem design and prognosis cannot be predicted by summing parts to make a whole. One must also be able to synthesize a great number of disciplines to understand and deal with the design of ecosystems. All applications of technologies, whether of biotechnology, chemical technology, or ecotechnology, require quantification. Because ecosystems are complex systems, the quantification of their reactions becomes complex. Systems tools, such as ecological modeling, represent well-developed approaches to survey ecosystems, their reactions, and the link age of their components. Ecological modeling is able to synthesize input from the pieces of ecological knowledge, which must be put together to solve a certain environmental problem. Ecological modeling takes a holistic view of environmental systems. Optimization of subsystems does not necessarily lead to an optimal solution of the entire system. There are many examples in environmental management where optimal management of one or two aspects of a resource separately does not optimize management of the resource as a whole. Ecological engineering projects, while they usually have one or more specific goals, will try to balance between the good of humans and the good of nature.

2.2.4 Non-renewable resource conservation

Because most ecosystems are primarily solar-based systems, they are self-sustaining. Once an ecosystem is constructed, it should be able to sustain itself indefinitely through self-design with only a modest amount of intervention. This means that the ecosystem, running on solar energy or the products of solar energy, should not need to depend on technological fossil energies as much as it would if a traditional technological solution to the same problem were implemented. The system’s failure to sustain itself does not mean that the ecosystem has failed us (its behavior is ultimately predictable). It means that the ecological engineering has not facilitated the proper interface between nature and the environment. Modern technology and environmental technology, for the most part, are based on an economy supported by non-renewable (fossil fuel) energy; ecotechnology is based on the use of some non-renewable energy expenditure at the start (the design and construction work by the ecological engineer) but subsequently depends on solar energy.

A corollary to the fact that ecological engineers’ systems use less non-renewable energy is that they generally cost less than conventional means of solving pollution and resource problems, particularly in systems maintenance and sustainability. Because of the reliance on solar-driven ecosystems, a larger amount of land or water is needed than would be for technological solutions. Therefore, if property purchase (which is, in a way, the purchase of solar energy) is involved in regions where land prices are high, then ecological engineering approaches may not be feasible. It is in the daily and annual operating expenses in which the work of nature provides subsidies and thus lower costs for ecological engineering alternatives.

2.2.5 Ecosystem conservation

We solve human problems and create ones for nature. That has been the history of mankind, at least in the western world. We need to adopt approaches to solving (at least) environmental problems not only to protect streams, river, lakes, wetlands, forests, and savannahs. We need to work symbiotically with nature where we use her public service functions but recognize the need to conserve nature as well. The idea of nature conservation is so important that it needs to become a goal of engineering, not just one of its possible outcomes. We must seek additional approaches to reduce the adverse effects of pollution, while at the same time preserving our natural ecosystems and conserving our non-renewable energy resources. Ecotechnology and ecological engineering offer such additional means for coping with some pollution problems, by recognizing the self-designing properties of natural ecosystems. The prototype machines for ecological engineers are the ecosystems of the world.

Ecological engineering involves identifying those biological systems that are most adaptable to human needs and those human needs that are most adaptable to existing ecosystems. Ecological engineers have in their toolboxes all of the ecosystems, communities, populations, and organisms that the world has to offer. Therefore, a direct consequence of ecological engineering is that it would be counter productive to eliminate or even disturb natural ecosystems unless absolutely necessary. This is analogous to the conservation ethic that is shared by many farmers even though they may till the landscape and suggests that ecological engineering will lead to a greater environmental conservation ethic than has been realized up to now. For example, when wetlands were recognized for their ecosystem values of flood control and water quality enhancement, wetland protection efforts gained a much wider degree of acceptance and even enthusiasm than what they had before, despite their long understood values as habitat for fish and wildlife. In short, recognition of ecosystem values provides greater justification for the conservation of ecosystems and their species. A corollary of this is the point made by Aldo Leopold that the tinker’s first rule is to not throw away any of the parts. The ecological engineer is nature’s tinker.