Ecological Engineering 20 (2003) 389–407 Distinguishing ecological engineering from environmental engineering T.F.H. Allen a,∗, M. Giampietro b, A.M. Little a a Department of Botany, University of Wisconsin Madison, Madison, WI 53706-1381, USA b INRAN-Unit of Technological Assessment, Rome, Italy Accepted 4 August 2003 Abstract This paper uses complex system thinking to identify key peculiarities of ecological engineering. In particular it focuses on the distinction between the purpose-driven design of structures in environmental engineering and the natural process of self-organization characteristic of life, which needs to be integrated into ecological engineering. Conventional engineering addresses the problem of fabrication of an organized structure, say a road, which reflects a goal at the outset, as well as considerations external to the road. At the outset there is an essence of which the organized structure is a realization. This realization belongs to a certain type (apartment building, suspension bridge). The type is in relation to: (a) the expected contexts (e.g. housing in Manhattan, a bridge in rural Africa) and (b) location-specific socio-economic constraints (low/high economic budget). Conventional engineering does not question the goals of the selected plan and can only object to the feasibility of a proposed typology in a given context. Engineers deal with the challenge of the realization of a plan at a given point in space and time. The central dogma of biology identifies organisms as informationally-closed and this makes possible their use as machines. Ecological systems, on the contrary, are informationally-open. They cannot be used as machines to create functional structures, because they are becoming in time. For engineered structures to work it is usually required that there is (1) stability of system components; (2) admissibility of a workable context; (3) validity of purpose and concept. Ecologically-engineered structures challenge these requirements because of specificity of required environments and lability of system parts over the time the engineered structure functions. Other engineering is better if it achieves flexibility, but ecological engineering must be so flexible as to take on a looping character that updates the system to meet changing requirements. Accordingly, the original goals cannot be taken for granted later in the process of ecological engineering. Ecological engineering has to be a flexible iterative process of design, in which the designer must continually update goals, essences, typologies and processes of realization. © 2003 Published by Elsevier B.V. Keywords: Ecological engineering; Complex systems thinking; Hierarchy theory; Rosen; Multiple scales; Beavers; Self-organization 1. Introduction Ecological engineering is one of several branches ∗ Corresponding author. of engineering that involves dealing with living ma- E-mail address: [email protected] (T.F.H. Allen). terial. Sometimes technological processes use living 0925-8574/$ – see front matter © 2003 Published by Elsevier B.V. doi:10.1016/j.ecoleng.2003.08.007 390 T.F.H. Allen et al. / Ecological Engineering 20 (2003) 389–407 organisms as machines, as in draft animals, fermen- are genuinely ecological. There are good reasons to tation agents or genetically-modified organisms. For cleave ecological engineering from civil and industrial the purposes of this paper, whether the horse power engineering, the orthodox categories of engineering to pulling a given load is generated by real horses or which environmental engineering naturally belongs. by a horse-equivalent generated by a steam engine is We believe that a solid body of knowledge already not the critical part of the story. The important point exists in the field of theoretical ecology, hierarchy the- for our narrative is that biological material introduced ory, and complex systems thinking that can clarify the into an engineering process or engineered structure situation. This clearer vision can generate in ecolog- requires a richer characterization of what should be ical engineering something of the sound predictions considered as a machine or an ecological system. This and proper precaution that are characteristic of engi- paper addresses that richer characterization, and what neering at large. However, this can only occur when it means for grouping types of engineering with their ecological engineers are conscious of the distinctive- respective distinct styles. ness of their practice relative to other types of en- Use of biological material has generated some con- gineering. The theory to which we refer introduces fusion as to the categorization of engineering in bio- a clear distinction between: (i) a process of design logical and ecological settings. Various adjectives and and fabrication of machines driven by human purpose, nouns have been freely combined in terms such as i.e. environmental engineering as described above and “ecological engineering”, “genetic engineering”, “bi- (ii) the processes of autopoiesis (self-definition) and ological monitoring” or “bio-chemical engineering”. self-organization (emergence or order) typical of life Sometimes entirely new terms have been coined, such and ecological systems (Maturana and Varela, 1980, as “bionics”. This new terminology, with its prefixes 1998) i.e. ecological engineering. of bio-, genetic-, or eco-, encourages a mistaken view This paper is divided in three sections. Section 1 that systems engineered to employ living things still deals with basic differences between conventional en- belong to the realm of ecology and ecological systems. gineering (which in our view still includes environ- Organisms employed as machines may not be as reli- mental engineering) and ecological engineering. This able as physical machine, but they can be constrained distinction is framed using concepts developed in the well enough so as to behave like ordinary machines. field of complex system thinking, especially in rela- In beer brewing or in cheese vats the context of the tion to theoretical ecology (i.e. the characterization organisms is tightly and skillfully constrained so that of “life-itself” as developed by Robert Rosen (1991, the cultures perform with reliability. The required con- 2000)). stancy of those created environments means we are Section 2 focuses on the peculiar challenges faced dealing there with engineering not ecology. Such sys- by ecological engineers. While organisms may be tems do not suffer from the constant change that is used as machines, we deny that ecological systems can ubiquitous in ecology at all levels. By contrast, what be used as machines to create ecologically-engineered the authors here call ecological engineering is still part functional structures. Unlike organisms, ecological of ecology and so must deal with the process of change systems are informationally-open, and cannot be used that can be expected at all levels. Environmental, not reliably in the medium term, let alone for extended ecological, engineering generally works only with the long-term periods. Rather than work as agents of structure. That is to say, environmental engineering creation, ecological processes act as constraints and lists its components and evaluates the effects of the perturbations on both the environment of the realiza- ecosystem on the components. Therefore environmen- tion process and the functional engineered structure. tal engineering remains part of engineering, although Koestler (1967) refers to the associative context as it has an awareness of ecology. Environmental engi- the context in which a process may occur or a struc- neering uses organisms as machine, but that does not ture may exist, part of which may be the context that make it ecological engineering. Confusing organismal makes the function of an engineered structure useful. machines with ecological situations is dangerous, be- Ecological engineering deals with structures whose cause it encourages over-confidence in the calculations realization process and structured functionality is dis- and predictions as to the engineering of situations that rupted by failure of the associative context such that T.F.H. Allen et al. / Ecological Engineering 20 (2003) 389–407 391 the original goals must be revisited. This is due to the give living material the constancy of behavior that systemic mismatch in time scale between: (a) the pace normally characterizes non-living materials. An ex- at which human decision making and engineering op- ample might be the engineered environment that keeps erates and (b) the pace at which ecological processes bacteria behaving in the desired manner of a sewage update their typologies and mechanisms of control. works. By contrast, the ecological engineer attempts Section 3 discusses the implications of a case study to live with the dynamical behavior of life and its con- provided by ecological engineering performed by stant change of purpose. There is a biological learning beavers: beavers show flexible/multiple scale strate- process here that is not often part of conventional gies. Beavers engineer at different levels of analysis engineering. In contrast to all other engineering, the simultaneously. This enables them to deal better with ecological engineer co-opts a creative process that is the complexity of ecological processes on different intrinsic to the emergent biological structure. Engi- scales. The cost to the beavers is that this forces them neers facing ecological dynamics would do well to to adapt their identity