Ecological Engineering 20 (2003) 339–361

Concepts and methods of ecological engineering

Howard T. Odum a , B. Odum b,∗
a Environmental Engineering Sciences, P.O. Box 116450, University of Florida, Gainesville, FL 32611-6450, USA
b 2160 N.W. 9th Ave., Gainesville, FL 32603, USA

Received 14 June 2002; accepted 4 August 2003

Abstract

Ecological engineering was defined as the practice of joining the economy of society to the environment symbiotically by
fitting technological design with ecological self design. The boundary of ecological engineering systems includes the ecosystems
that self organize to fit with technology, whereas environmental engineering designs normally stop at the end of the pipe. For
example, the coastal marsh wildlife sanctuary at Port Aransas, Texas, developed when municipal wastewaters were released
on bare sands. The energy hierarchy concept provides principles for planning spatial and temporal organization that can be
sustained. Techniques of ecological engineering are given with examples that include maintaining biodiversity with multiple
seeding, experimental mesocosms, enclosed systems with people like Biosphere 2, wetland filtration of heavy metals, overgrowth
and climax ecosystems, longitudinal succession, exotics, domestication of ecosystems, closing material cycles, and controlling
water with vegetation reflectance.
© 2003 Elsevier B.V. All rights reserved.

Keywords: Ecological engineering; Waste recycle; Self organization; Energy hierarchy; Emergy; Transformity; Emdollars; Maximum power

1. Introduction 1.1. Definitions

The following commentary defines what ecological Engineering is sometimes described as the study
engineering is, explains some of its principles, and and practice of solving problems with technological
describes techniques of application with examples designs. The sketch in Fig. 1a shows the environment
from the author’s experience. Ecological engineering and the economy coupled symbiotically by exchange
started as people recognized cooperative environ- of materials and services. Environmental engineering
mental interfaces. In 1957, we applied the name develops the technology for connecting society to the
to the conscious use of ecosystem self design. By environment. But the technology is only half of the
the 1990s the concepts were used worldwide with interface with environment. The other half of the in-
formation of an International Society of Ecological terface is provided by the ecosystems as they self or-
Engineering. ganize to adapt to the special conditions. Ecological
engineering takes advantage of the ecosystems as they
combine natural resources and outputs from the econ-
∗ Corresponding author. omy to generate useful work.

0925-8574/$ – see front matter © 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.ecoleng.2003.08.008
340 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Fig. 1. Scale of ecological engineering, a larger realm than traditional environmental engineering. (a) Sketch of the unified system of
environment and technology sometimes used as a logo for ecological engineering; (b) traditional boundary of environmental engineering
designing; and (c) boundary of ecological engineering designing.

Ecological engineering is the study and practice of than typical environmental engineering. Fig. 1b shows
fitting environmental technology with ecosystems self environmental engineering at the edge of environmen-
design for maximum performance. tal technology, whereas Fig. 1c represents the larger
boundary of ecological engineering that includes the
1.2. Scale of ecological engineering free self adapting ecosystems.
Ecotechnology may not be a good synonym for
By considering the ecosystems that surround the ecological engineering because it seems to omit the
technology, ecological engineering uses a larger scale ecosystem part. It is the self regulating processes of
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 341

nature that make ecological self designs low energy, choices that fit the principles are sustained. In other
sustainable, inexpensive, and different. words, the realm of ecological engineering is based on
Odum (2001a) quotes Z. Naveh using the term scientific principle, not free for any human choice. The
techno-ecosystem to represent the combined systems reader is referred to publications elsewhere that jus-
of technology and ecology, which is the realm of tify these principles (Odum, 1971, 1975, 1983; Hall,
ecological engineering. 1995). The pertinent energy laws are reviewed briefly
People of many backgrounds seek methods of as follows:
managing environment for beneficial purposes. In
some groups and journals, managing ecosystems for 2.1. Maximum power, fourth energy law
productivity and harmony with the economy is called
restoration, which might imply going back to ecosys- Well stated by Lotka (1922a,b), system designs that
tems before conditions were changed by economic prevail are those that maximize power. For example,
development. For example, Middleton (1999) reviews the marshes at Port Aransas organized to utilized the
restoration and management of wetlands and their nutritive waters and sunlight to maximize photosyn-
adaptation to pulsing. Ecological engineering is a bet- thetic productivity. Energy corollaries 1–5 are conse-
ter word which welcomes the new ecosystems as well quences of this law.
as old systems when they are necessary for maximum
benefit. Corollary 1. Maximum power requires optimum
efficiency. For any energy transformation, there is an
1.3. An example, the Audubon sanctuary at Port optimum loading, and thus optimum efficiency that
Aransas, Texas produces maximum power (Odum and Pinkteron,
1955). Systems organized to be more efficient or
In 1954, the outer banks village of Port Aransas, to go more rapidly, generate less power output. For
Texas, had 500 residents increased by summer tourists. example, self organizing plants adjust their green
A sewage plant with primary and secondary treat- chlorophyll concentrations to maximize power.
ment released its nutritive waste waters on the flat
bare sands. Around the outfall, a pond and freshwater Corollary 2. Energy transformations that prevail
marsh developed and around that, salt adapted vegeta- store energy that can reinforce their inputs by ampli-
tion. By year 2000, the town had 5000 residents with fying feedbacks and recycle. The output of energy
many times that in summer. The outfall marshes had transformations that prevail store and feed back their
spread and attracted wildlife including alligators, tur- products to help maximize power. For example, algal
tles, and waterfowl (Fig. 2a). The area was adopted as populations reproduce and use the increased numbers
an Audubon Wildlife sanctuary with boardwalk and to process more energy.
tower added for observers (Fig. 2b). In this develop-
ment, ecological engineering meant letting nature self Corollary 3. Adapting to physiological stress reduces
organize a suitable tertiary treatment ecosystem and species diversity. Extremes and impacts that require
fitting human society to nature in a way that both pros- physiological adaptation take priority over supporting
pered. An emergy evaluation found large net benefit species diversity. For example, ecosystems adapting to
(Odum et al., 1987). extremes of temperature or salinity have lower species
variety. Networks may be simplified, causing energy
to concentrate in fewer pathways. For example, fish
2. Theoretical basis for ecological engineering production of a few species increased in hypersaline
bays of Texas.
Although the interface ecosystems that develop are
often unexpected surprises, the systems can be un- Corollary 4. Overgrowth prevails when resources are
derstood and sometimes predicted with the energy underutilized. The first priority for maximizing power
laws that control all systems. Whereas humans can is to transform energy into a form that can be stored
make free choices, these theories claim that only those and used to reinforce the capture of underutilized
342 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Fig. 2. The Audubon marshes at Port Aransas, Texas, an example of ecological engineering use of self organization. (a) Map view; and
(b) view from tower.
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 343

energy. In this situation power is maximized by letting that reinforce the source units upstream (Fig. 3a). For
free competition select species that overgrow others, example, in the waste marshes in Fig. 2, the alliga-
causing a low diversity, as suggested by Yount (1956). tors by their physical work maintain a central pool
For example, low diversity blooms prevail with excess of algal productivity. Also, nutrient materials from
resources in wastes released from the economy. the plants consumed by animals recycle to stimulate
plant growth again.
Corollary 5. Maximum efficiency develops diversity
and division of labor when resources are not in excess. Corollary 7. The scale of energy transformations
The second priority for maximizing power prevails increases downstream. Energy centers are larger and
when there are no more unutilized resources. Effi- have greater territory of support and influence with
ciency is increased by development of high diversity steps along the energy hierarchy (left to right in
and division of labor among species. For example, typ- Fig. 3b). Transformed outputs have less energy, but
ical plant succession develops high diversity in situa- by becoming concentrated can maximize their effect
tions where no new resources are being added. in feedback reinforcements. For example, the size and
share of area increases along a food chain from algae
The author recently published two models PIO- to alligator.
NINFO (Odum, 1999) and NUTRISPEC (Odum,
2000) that simulate the maximum power switch from
Corollary 8. The quantity of storage increases with
overgrowth to climax diversity or back, depending on
transformation steps, but the turnover time decreases.
input resources. People with background in popula-
Although there is less energy flow at each transfor-
tion ecology refer to growth and steady state using
mation step, the amount of energy stored increases
coefficients of growth models as R and K strategy,
(Fig. 3c). In ecosystems, biomass storage increases
but this language is less appropriate for the scale of
along the food chain, which facilitates the use of small
ecological engineering.
energies to have stronger feedback reinforcements.
For example, the alligator with less total energy flow
2.2. Energy hierarchy, a fifth energy law—a systems
is able to control the whole pond. With less energy
effect of the second law
flow but greater storage, the turnover time and percent
depreciation decreases.
A hierarchy is a design in which many units of one
kind are required to support a few of another. Accord-
ing to the second law, all energy transformation works Corollary 9. Pulses of accumulation and feedback in-
to convert many joules of available energy (exergy) of crease upscale. On all scales, power is maximized by
one kind to a few joules of another kind of energy. In accumulating output in storages, which are later con-
self organization, all energy transformations form hier- sumed in a pulse of feedback reinforcement. Although
archical chains, connecting each kind of energy to the energy flow is less along the networks (to the right in
next. For example, ecological systems form networks Fig. 3d), the accumulation times are longer, so that the
of energy transformation processes with their food pulses are shorter and stronger with greater impact.
chains. To illustrate energy transformation hierarchy, For example, there are many small actions but fewer
Fig. 3a simplifies the usual network by aggregating large impacts among storms, carnivores, and people.
units as a straight chain. From left to right energy flow By the store-pulse sequence all systems can reinforce
decreases, but the quality of transformed energy is of- better than by steady state. However, any scale of
ten said to increase. The following properties (Odum, pulsing can be averaged as if in steady state to sim-
1983) are revisited as consequences of the hierarchical plify calculations on larger scales of time and space.
self organization of energy (energy corollaries 6–12).
Corollary 10. Centers have high transformities and
Corollary 6. Units are controlled and reinforced from empower density. Energy transformations converge
downstream. Chains and networks that prevail feed flows to centers with decreasing energy flow, but with
back services and materials from downstream units an increase in spatial concentration of the emergy
344 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Fig. 3. Summary of the concept of energy hierarchy and the relationships with increasing scale. (a) Network aggregated as an energy
transformation chain; (b) size of centers and their territories; (c) quantity stored and turnover time; (d) period of pulses and time between
pulses; (e) rate of materials flow to centers; (f) pattern of money circulation; and (g) concentration of money circulation and prices.

(higher areal empower density). Concentrating emergy benefit or toxicity have high transformities (tobacco,
also increases transformities. cocaine).

Corollary 11. Items of higher transformity have Corollary 12. Material processing decreases with
greater unit effect. Self organization of networks available energy. On every scale materials are incor-
selects feedbacks with effects commensurate with porated and recycled, coupled to the transformations
their support. The more emergy an item receives the of available energy. Along the transformation chain
higher the transformity, and the more feedback effect (left to right in Fig. 3e) as energy flow decreases,
is selected. For example, drugs with high levels of the rate of material flow decreases, although the
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 345

storages become more concentrated in centers (Odum, The quotient of emergy flow divided by the energy
2001a,b). flow is defined as transformity, with the units emjoule
per joule. For example, solar transformity has the units
Corollary 13. Circulation of money is more con- solar emjoules per joule. The transformity increases
centrated in centers. Money circulates only among along energy transformation networks. Transformity
people and is not paid to environmental work pro- marks the position of something in the universal en-
cesses. Money is a counter current to the series of ergy hierarchy. An ecological engineering technique
energy transformations of the economy, becoming places processes and interfaces where transformities
more concentrated along with the energy in urban and are compatible.
financial centers (Fig. 3f, Odum, 2001a,b). No money
circulates in the realm of small scale processes. Prices 3.1. Mitigation with emdollars
rise along the chain (to the right in Fig. 3g).
In mitigation, developments are allowed in envi-
Following the energy laws, successful ecological ronmentally valuable areas if equivalent environmen-
engineering joins systems of nature, which are usually tal protection is added to comparable areas elsewhere.
the smaller scale networks on the left in Fig. 3, to Emergy–emdollar evaluation is the appropriate way to
the designs and uses of society, which are on a larger compare systems which need both environmental and
scale on the right. The energy hierarchy also provides economic inputs to be evaluated on a common basis.
quantitative measures to help people select alternatives In Florida, wetlands mitigation is still done without a
that contribute most. quantitative scientific basis, although emergy emdol-
lars have been much discussed.

3. Emergy, emdollars, and transformity 3.2. Economic matching which is sustainable

Attempts over 150 years to use available energy as 3.2.1. The investment ratio is the ratio of purchased
a general measure of work failed because energies of emergy to free environmental emergy
different kinds were regarded as equal. The energy To be sustainable, an ecological engineering inter-
hierarchy was not recognized. Now, energy of differ- face should have an investment ratio similar or less
ent kinds is put on a common basis by using emergy than other environmental uses in the region. Systems
(spelled with an “m”) as the available energy of one with higher ratios are too costly to compete.
kind used up directly and indirectly to generate a prod-
uct or service (Odum, 1988, 1996a,b)). It is a property
that recalls the energy flows in network back to the 4. Methods and examples of ecological engineering
left in Fig. 3. Units of emergy are emjoules, a numer-
ical memory of past energy transformation. Along the Next let us review some of the techniques of eco-
simplified energy transformation steps in Fig. 3a, the logical engineering that are now widely applied. Ex-
emergy flows in from the left and is constant. (Rate of amples are given from the author’s experience. An ex-
emergy flow is called empower.) tensive review of ecological microcosm research and
Emergy measures real wealth, which money buys. their potential for space was published in an earlier
Calculating the emergy/money ratio of an economy book (Beyers and Odum, 1993).
puts the buying power of money on an emergy ba-
sis. Vice versa, the ratio can be used to estimate the 4.1. Microcosms and multiple seeding
economic equivalent of emergy. Emdollars of some-
thing is the part of the gross economic product due to The self organizational principles and corollaries
its emergy. Emergy–emdollar evaluations have been of maximum power seemed to explain the self orga-
widely used in ecological engineering to appropriately nization observed in studies of energetics in Silver
compare the contributions of the environment to those Springs and other ecosystems. In order to apply the
proposed from the economy so as to maximize both. experimental method, efforts were made in 1954 to
346 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Fig. 4. Microcosms used for testing impacts on ecosystems. (a) Terrestrial microcosms started with rainforest soil, litter, and herbs and
metabolism measured from diurnal variation of carbon dioxide. (b) Microcosm simulating the circulating animal reef-plankton ecosystem
of South Texas, with metabolism indicated by diurnal variation in dissolved oxygen.

replicate ecosystems in miniature with experimental wild environments so that the self organization
microcosms. Interesting complex ecosystems formed could select optimum populations. Duplicate micro-
rapidly, rarely what was expected, depending on the cosms were usually different. If the duplicates were
species that had been introduced inadvertently or on regularly mixed, then they became similar. Thus,
purpose. With enclosed microcosms, it is easy to mea- the multiple seeding technique developed as a way
sure metabolism from observed changes of oxygen in to accelerate nature’s adaptation. Multiple seeding
the water or carbon dioxide in the atmosphere of ter- was applied on the larger scale of ecological engi-
restrial microcosms (Fig. 4a). neering as the first step in developing a new inter-
To generate duplicate microcosms and make face. The idea is to help nature find the competitive
happen-stance introductions less important, intense system, rather than trying to predict or chose in
seeding of species was brought from appropriate advance.
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 347

4.2. Microcosms for anticipating ecological in year 2001 no complex microcosm had yet been
engineering consequences tested in space.

The microcosms were also seen as a way to antici- 4.5. Mesocosm life support for people and
pate ecological engineering designs that might follow Biosphere 2
if implemented on a larger scale. For example, the oys-
ter reef mesocosms were able to duplicate the main The concept of a self organized mesocosm that
features of the estuarine ecosystem and its response to included people was offered in proposals to NASA
added nutrient water (Fig. 4b). At a smaller scale than for a ground test (Fig. 5a, Odum, 1971). Although
in nature, all the properties of size and time were to these were not funded, a billionaire, Edward P. Bass,
the left in Fig. 3. After extensive use of small micro- funded a highly original project led by John Allen,
cosms, they were criticized as not able to show what developing the 3-acre Biosphere 2 that used the mul-
was of importance on the large scale. The big animals tiple species complex ecosystem concept to support
and large scale pulses were absent. However, the re- eight people for 2 years (Figs. 5b, c and 6a). The
sults from microcosms can be multiplied by scale fac- scientific results were the subject of a special issue
tors (turnover time, territory, and transformity) to infer of Ecological Engineering journal (Marino et al.,
the equivalent at the larger scale. More efforts were 1999), documenting many insights about the earth
made to experiment with larger mesocosms, although (Biosphere 1) as well as showing what is required for
the costs were greater. The book of papers edited by space. Fig. 7b shows the near balance of production
Gardner et al. (2001) compares properties of ecosys- and consumption achieved by the self organization
tem with scale, including many new graphs that illus- inside after 2 years. Fig. 7c shows the species sur-
trate the energy hierarchy. vival in the self organization of the plants of the
rainforest zone. Without normal rainforest insects and
4.3. Achieving resilience with complexity birds, normal pollination was missing, and species
with strong asexual reproduction prevailed (Leigh,
It was soon obvious from microcosm studies by 1999).
many investigators that ecosystems developing after
multiple seeding were relatively resilient and immune 4.6. Search for adapted ecosystems, examples of
to disaster from changes in environmental condition wetland filtration
or further species introductions. The small ecosys-
tems were like the wild ones, using the diversity of Scanning environments in search of ecosystems that
their gene pool to stay adapted to various changes. have adapted to economic inflows and impacts is an
For example, the terrestrial microcosms simulating inexpensive way to find out what works. For example,
the rainforest floor (Fig. 4a) were very resistant when treated sewage waters discharged into marsh-bordered
exposed to gamma irradiation (Odum and Lugo, tidal channels in Morehead City, NC, were observed
1970). with lush growths and abundant wildlife in 1960s.
Measurements by Marshall (1970) confirmed the high
4.4. Microcosms and mesocosms for space productivity (Fig. 7). Similar discharges at Naples,
Florida, examined by Sell (1977), showed increased
The struggle within the National Aeronautics and productivity of mangroves.
Space Administration to find a more self supporting Examination of wetlands receiving lead and zinc
life support system for space that started in the 1950s from mining for 400 years in Poland by Wojcik and
seemed to be solved by the complex microecosystem Wojcik (2000) showed the long term ability of marshes
demonstrations. Even though complex ecosystem life for heavy metal removal (Fig. 8a). Lead from a battery
support was presented in NASA co-sponsored sympo- recovery operation in Jackson County, Florida, was
siums in 1962 (Taub, 1963a,b) and again in 1982, only largely sequestered in cypress swamps (Odum et al.,
pure cultures or limited species combinations were 2000a,b), which developed an interface ecosystem of
considered for space, and these were not stable. Even floating plants (Fig. 8b). Examples in Fig. 7 are im-
348 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Fig. 5. Concept of enclosed ecosystem with multiple species to support people adopted in Biosphere 2. (a) Concept published in 1971;
(b) view of Biosphere 2; and (c) floor plan of Biosphere 2.

portant in refuting those who claim wetland filtration in new situations with similar conditions elsewhere.
is not sustainable. In this way, ecosystems are domesticated. This is not
unlike the capture of the trickling filter and activated
4.7. Domestication of ecosystems sludge ecosystems in the 19th century. Those ecosys-
tems were enclosed in concrete boxes to become the
When a useful ecosystem interface is discovered, mainstays of environmental engineering ever since.
its conditions and species can be transplanted for use For the great variety of environmental conditions, a
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 349

Fig. 6. Biosphere 2 and its metabolism and diversity in Biosphere 2. (a) Cross section view; (b) nearly balanced production and consumption
after 2 years of self organization; and (c) diversity of plants after 7 years.

much larger repertoire of free ecosystems is available sewage wastewaters. In a project of the National
for ecological engineering use without the costs of Science Foundation and Sea Grant at the University
concrete enclosures. of North Carolina, one set of ponds received salt-
water and wastewater (Fig. 9), while the control set
4.8. Ecological engineering of an estuarine of ponds received saltwater and tap water. Whereas
wastewater ecosystem the control had plankton, invertebrate and fishes with
normal variety and seasonal cycle, the new ecosystem
In 1966–1970, a conscious test was made of the that adapted to the wastewaters had intense Monodus
ability of multiple-seeding self organization to de- bloom with ten times normal chlorophyll even in
velop an estuarine ecosystem adapted to treated winter, wide oxygen range, blue–green benthic algae,
350 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Fig. 7. Comparison of marsh productivity in marshes receiving municipal treated wastewaters at Morehead City, NC, compared with control
marshes (Marshall, 1970).

low diversity of zooplankton, but good population 4.9. Wetlands ecosystems for receiving
of blue-crabs, bait-suitable top minnows, mullet, and wastewaters
dense lateral masses of Spartina facilitated by mud
crabs. Fig. 10 shows the great differences in total In 1972, after a decade observing self-organizing
metabolism between waste ponds and controls. The wetlands doing filtration work, a national workshop
3-year experiment gave early insights on the microbial was held at Gainesville under Rockefeller Foundation
bloom ecosystems that have since become widespread support, after which large projects were funded at
in estuaries (Odum et al., 1982; Odum, 1983). the University of Florida, Michigan, and elsewhere.
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 351

Fig. 8. Sites where self-organized wetland ecosystems were able to sequester large quantities of lead and zinc. (a) Biala River marshes of
Poland; and (b) Sapp swamp in Florida.

The project at Gainesville established its Wetlands 4.10. Ecosystem interface with dispersed solid waste
Center and evaluated many wetlands using munici-
pal wastewaters, starting with cypress swamps. Re- A main branch of environmental engineering man-
sults were shared at a Rockefeller symposium at ages high concentrations of solid wastes, land fills, gas
Bellagio, Italy (Odum et al., 1977b). National Sci- production, groundwater toxicity, and other impacts. A
ence Foundation circulated a training film. After different interface using ecological engineering prin-
the studies in Florida and many other places, the ciples was tested by shredding and dispersing the solid
practice of arranging tertiary treatment with wet- wastes over landscape as litter joining the natural for-
lands spread all over Florida and the rest of the est litter. After covering bare land with 18 in. of shred-
world. Knowledge and ecological engineering guide- ded solid wastes, slash pine seedlings were planted by
lines on this was summarized by Kadlec and Knight Smith (Jokela and Smith, 1990). Very high rates of
(1996). forest growth resulted. After 20 years, the solid waste
352 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

The used car dump is mostly hidden by the wetland

trees. From what we know about wetlands absorbing
and holding heavy metals (Odum et al., 2000a,b), this
may not be a bad arrangement, a kind of ecological
engineering.

4.11. Utilizing succession

The maximum power principle and its corollaries

(above) explain the stages of ecological succession
to be expected in situations based on their resources
and seeding. Some kind of ecological succession was
observed in most new microcosms and new interfaces.
Succession from low to high diversity is typical of
succession that starts on bare lands because initially
there is unutilized energy (corollary 4).
Studies of regrowth after phosphate mining in
Florida suggested that using self organizing ecosys-
tems was the cheapest and fastest method of restora-
tion. Ecological engineering of the interface between
mining and the environment was accelerated by aid-
ing the self organization of succession. Effects of
landform, waters, nutrients, and seeding on min-
ing reclamation has had extensive testing in central
Florida (Brown and Tighe, 1991; Brown et al., 1992,
1997a,b, 2001; Erwin et al., 1997).

4.12. Arrested succession and thermal waters of

power plants

Power plants and many other kinds of industries

have irregular impacts on their environmental inter-
face that make the ecosystems develop short term
responses. Succession to larger components and di-
Fig. 9. Experimental and control ponds used to test self organi- versity is arrested in earlier stages. For example, the
zation of an estuarine interface ecosystem adapted to municipal
wastewaters. (a) Locations; (b) waste receiving ponds; and (c)
on and off release of hot waters from power plants at
control ponds. Crystal River, Florida, developed an interface ecosys-
tem displacing normal underwater grass flats with
forest looks like any other slash pine plantation in algae and other fast turnover producers and a lower
Florida, but one can find scattered bits of metal or rub- productivity. However, emergy evaluation showed
ber by digging in the soil profile. While on sabbatical more benefit with the interface ecosystem than with
at the LBJ school of Public Affairs in Texas, I raised the cooling towers and the impact of their manufac-
the idea of solving solid waste by dispersed littering ture (Kemp et al., 1977; Odum et al., 1977a).
with Lady Bird Johnson, who led national initiatives
against littering. It was not well received. 4.13. Longitudinal succession and the everglades
Along State Highway 100 between Palatka and
Bunnell, Florida, is a business in which old cars are Whereas succession is the sequence of stages of
dumped into wetlands, and parts removed for sale. an ecosystem over time in one place, longitudinal
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 353

Fig. 10. Annual record of metabolism of estuarine ponds determined from the diurnal variation of dissolved oxygen.

succession is the somewhat similar series of stages that For example, in year 2002, some proposals for
ecosystems develop in space in response to flowing re- partial restoration of the Everglades of south Florida
sources. To succeed, projects which interface flowing plan to retain the high nutrient muckland agriculture
waters with environment have to work with longitudi- while restoring the low nutrient Everglades without
nal succession, not try to omit or defeat its designs. the normal eutrophic stage in between to fix and de-
354 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Fig. 11. An improved plan for using self organization of longitudinal succession for restoration of Everglades. Annual contribution of each
area is given in emdollars.

posit nutrients as organic matter. Fig. 11 shows the to agriculture and urban development. At times, ex-
Everglades and its connecting inflows and outflows. cesses are wasted by pumping east and west into the
Water from the north in the Kissimmee River and sea. The restoration is intended to return more water
smaller streams enters the lake, which discharges to Everglades and Everglades National Park. Fig. 11
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 355

improves the present plan by restoring longitudinal 4.14. Water quantity management with wetland
succession with a eutrophic slough just south of Lake vegetation
Okeechobee. This is sustainable, reduces costs, can
accept nutrients from the surrounding agriculture, Studies in Florida found the vegetation of natural
and generates more emdollars for South Florida. watersheds improving regional productivity by con-
Each of the areas involved in the water flows was trolling evapotranspiration. Most of the headwaters of
evaluated with annual emergy production and use the small rivers of Florida originate in wetland plateaus
and expressed in Fig. 11 as economic-equivalent where pond cypress is dominant, mainly receiving
emdollars. rain water (for example, Okefenokee Swamp with the

Fig. 12. Spectra of solar energy reflectance of cypress species in Florida, mean graphs with 95% confidence interval. (a) Faster growing
bald cypress; and (b) water-saving pond cypress (McClanahan and Odum, 1991).
356 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Suwannee River and the Big Cypress area of South 4.15. Ecological engineering of alternatives for pulp
Florida in Fig. 11). Bald cypress is mainly found mill waters
in strands, stream margins and floodplains, where
flowing waters bring nutrients for growth. As illus- Pulp–paper mills use large quantities of water and
trated with Fig. 12, pond cypress reflects much of release wastewaters full of brown lignin, the peaty
the near infrared solar energy, thus reducing its tran- substance of tree trunks. Good ecological engineer-
spiration. With few nutrients and less transpiration, ing should conserve and reuse waters, process lignin
growth is slow but water is conserved as a headwater wastes for beneficial use, and protect open waters
source for small rivers. Emergy–emdollar evaluation from these high concentrations. For example, four al-
showed that retaining the peat base of the headwater ternatives are shown for the pulp mill wastewaters at
swamp of the Santa Fe river was much more valuable Perry, Florida, in Fig. 13. Wastes in 2002 pass down
than mining the peat as a fuel supplement (Odum, the small Fenholloway River that was declared an in-
1996a,b). dustrial river 50 years ago. Studies show that the tox-
By controlling the species of wetland vegetation, icity and shading of the outflow eliminates the fertile
waters may either be saved for regional productivity seagrasses and their fisheries in that zone. As envi-
downstream, or used to increase forest production up- ronmental agencies sought to eliminate wastes from
stream. The Australian exotic Melaleuca is adapted the stream, a plan was considered to pump the wastes
to maximize transpiration and dries out lands where to the mouth of the river by pipe, which would make
waters are intermittent. Ecological engineering of its the estuarine impact worse. The Center for Wetlands
areas needs a commercial use of Melaleuca, such as at Florida proposed two better alternatives (Odum and
paper manufacture. Brown, 1997): One was to send waters to the coast in

Fig. 13. Alternatives for pulp–paper mill interfaces with environment in the Fenholloway River watershed of Perry, Florida.
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 357

a strand (shallow slough full of wetland vegetation). 4.16. Use of exotics

The second was to pump the waters back into the small
wetlands among the pines from which the trees were Nature’s way of self organizing to new situations
harvested. In both of these alternatives, waters would is to allow adapted species that are part of its gene
be filtered by wetlands and recharge groundwaters for pool to replace dominants not adapted to new condi-
further use. Wastewater lignin would mix with normal tions. Sometimes the species that become dominant
peat. Emergy–emdollar evaluation showed great eco- are already present as minor constituents, and some-
nomic advantages of these alternatives to the public, times they come from other areas, in other words as
and in the long run to the industry. exotics.

Fig. 14. Example of ecological engineering with exotics, the self organization of Spartina anglica colonizing mud flats in New Zealand.
358 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

Using exotics is controversial. Many organismic- inant and useful in the cooperating ecosystems. How-
oriented scientists think of exotics as the cause of ever, ecological engineers should be legal, play safe,
ecosystem change, rather than as nature’s appropri- and avoid controversial publicity, by never importing
ate response to new conditions. In continental areas of exotics from another area.
the world with large gene pools and without changed
conditions, adding an exotic usually enriches its gene 4.17. Mud flat colonizing by exotic Spartina anglica
pool without much effect.
However, when the new situation has excess re- In temperate latitudes all over the world, the
sources, there is low diversity overgrowth by the salt–marsh grass Spartina anglica is colonizing the
exotic. The energy corollary 4 (above) explains why areas of bare mud-flats. Fig. 14 shows the spread
attempts to remove such exotics are futile as long as of the exotic grass at Havelock, New Zealand. Our
there are inputs of excess resources. With new exotic studies there showed much increased productivity,
plants, its normal animal and microbial associates increased nursery role for fishes and marsh birds, but
and control agents may be missing. Consequently, a loss of habitat for sandpipers and shore birds (Knox
the vegetation may be monolithic, and typical se- et al., 2002; Odum et al., 1983). It fits the principle
quences of succession absent. In time, the system of self organization for maximum productivity. But
improves when controlling organisms are introduced why did not the earth spread or evolve better adapted
or when complexity is developed with other self plants in millions of years of ecosystem evolution
organization. earlier? The much feared role of global transportation
However, on isolated islands like Hawaii, only a and trade spreading exotics may actually be one of
few species were introduced over thousands of years humanity’s beneficial contributions by increasing the
before the development of the global economy. Con- empower of the earth.
sequently, these few species evolved as generalists In western United States and New Zealand, the
able to occupy the many habitats, but not specialized Spartina anglica invasion is regarded as bad, and
for any one. Introducing more specialized main- efforts are made to kill the plants, but coloniza-
land species to these islands displaces the native tion is welcomed for its productivity and coastal
generalists, causing many extinctions. Costly efforts protection in China. It is used to pasture horses in
are required to preserve the original species in re- Wales.
serves in which exotics are removed as fast as they Spartina anglica and the east coast Spartina alterni-
come in. flora are both exotics on the west coast (California,
After multiple seeding of new situations, ecological Oregon, and Washington), the subject of the Washing-
engineering of interfaces will often find exotics dom- ton Sea Grant program (Aberle, 1990)

Fig. 15. Example of large scale ecological engineering, the coupling of the urban center of San Juan, Puerto Rico, with Luquillo Mountain
Rainforests, a geobiological center.
 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361 359

Fig. 16. Energy systems summary of ecological engineering interface of technology and ecosystems given at an ecological engineering
workshop at the National Academy of Science.

4.18. Ecological engineering of biodiversity tlements, and the laws protecting the rainforest. This
is large scale ecological engineering. Emergy evalua-
Interface ecosystems can be managed for maxi- tion can help select choices that maximize empower.
mum biodiversity by eliminating excess resources, For example, evaluation of six reforestation alterna-
multiple seeding, and managing succession, as ex-
plained in corollary 5 above. New systems sometimes
Table 1
favor endangered species. For example, the pattern of Ecological engineering techniques
golf courses and interfacing cypress swamps used as
Maximize diversity and complexity by multiple seeding.
roughs at Naples, Florida, were populated by fox squir-
To channel energy, reduce diversity by supplying excess raw
rels that were previously endangered in that region. materials or stress requiring physiological adaptation.
Include legal exotics in multiple seeding for self organization.
4.19. Interface of urban-environmental centers in Match environment and technology so that there are reinforcing
Puerto Rico loops.
Plan for longitudinal succession in flowing water environments.
Return used groundwaters through wetlands to the ground.
The energy theory of hierarchical centers given ear- Manage whole cycles of materials.
lier explains the self organization of human settle- Control chemical ratios of inputs to control species associations.
ments in cities and the self organization of geological Use mesocosms to anticipate large scale self organization.
processes in mountain centers. Ecological engineering Manage regional water with vegetation selected for reflectance.
Select alternatives with higher empower contributions.
theory predicts the symbiotic coupling of energy con-
Evaluate stored quantities with emergy and emdollars.
centrations of one scale with those of another. In east- Place units and functions in the spatial hierarchy according to
ern Puerto Rico, the intense concentration of empower the appropriate empower density or transformity.
and transformity in San Juan is only a few miles from Estimate impacts from transformity.
the concentration of empower and high transformity in Include purchased inputs according to the regional investment
ratio.
the Luquillo mountains (1333 m high) (Fig. 15). Many
Mitigate with emdollars.
connections are emerging between these two centers Use transformities to scale results in microcosms to the larger
including tourism, recreational living in second homes scale.
in the mountains, diversion of rainforest streams to Provide incentives for environmental management based on
the city, the spread of species adapting to human set- emdollar contributions.
360 H.T. Odum, B. Odum / Ecological Engineering 20 (2003) 339–361

tives showed the advantages of natural succession near in Florida: ecosystem and landscape organization. In: Erwin,
old forests and exotic reforestation elsewhere (Odum K.L., Doherty, S.J., Brown, M.T., Best, G.R. (Eds.), Evaluation
of Constructed Wetlands on Phosphate Mined Lands in Florida.
et al., 2000a,b). Publication No. 03-103-139, The Florida Institute of Phosphate
Research, Bartow, FL, pp. 8-1–8-82 (638 pp.).
Brown, M.T., Carstenn, S.M., Baker, J., Bukata, B.J., Gysan,
5. Summary T., Jackson, K., Reiss, K.C., Sloan, M., 2001. Successional
Development of Forested Wetlands on Reclaimed Phosphate
Mined Lands in Florida. Final Report to the Florida Institute
This introduction defined ecological engineering, of Phosphate Research. Center for Wetlands, University of
stated energy principles that guide the self-organizing Florida, Gainesville, 670 pp.
design of interface ecosystems, and suggests prac- Erwin, K.L., Doherty, S.J., Brown, M.T., Best, G.R. (Eds.), 1997.
tical techniques with examples. Fig. 16 summarizes Evaluation of Constructed Wetlands on Phosphate Mined Lands
the interface of technology and ecosystems and the in Florida. Publication No. 03-103-139, The Florida Institute
of Phosphate Research, Bartow, FL, 638 pp.
main pathways that interact to increase performance.
Gardner, R.H., W.M. Kemp, V.S. Kennedy, J.E. Petersen (Eds.),
Emergy, transformity, and emdollars are useful mea- 2001. Scaling Relations in Experimental Ecology. Columbia
sures for evaluating the best alternatives. Some ecolog- University Press, 373 pp.
ical engineering techniques are summarized in Table 1. Hall, C.A.S., 1995. Maximum Power (Festschrift of 1989 H.T.
Odum Celebration at the University of NC). University Press
of Colorado, Niwot, 393 pp.
Jokela, E., Smith, W.H., 1990. Growth in elemental composition
Acknowledgements of slash pine after sixteen years after treatment with garbage
composted with sewage sludge. J. Environ. Qual. 19, 146–150.
These comments introduced the first meeting of the Kadlec, R.H., Knight, R.L., 1996. Treatment Wetlands. Lewis
American Ecological Engineering Society in Athens, Publishers, Boca Raton, FL.
Georgia, in April, 2001. Illustrations are from a book Kemp, W.M., Smith, W.H.B., McKellar, H.M., Lehman, M.E.,
Homer, M., Young, D.L., Odum, H.T., 1977. Energy cost–
manuscript Environment Power and Society, second benefit analysis applied to power plants near Crystal River,
edition. Florida. In: Hall, C.A.S., Day, J. (Eds.), Ecosystem Modelling
in Theory and Practice. Wiley, New York, pp. 507–543.
Knox, G.A., Odum, H.T., Campbell, D.E., 2002. The ecology of
a salt marsh at Havelock, New Zealand, dominated by the
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