ecological engineering 35 (2009) 463–486
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/ecoleng
Maximizing empower on a human-dominated planet: The
role of exotic Spartina
Daniel E. Campbella, Hong-Fang Lub,∗, George A. Knoxc, Howard T. Odumd,1
aUSEPA, Office of Research and Development, National Health and Environmental Effects Research Laboratory,
Atlantic Ecology Division, Narragansett, RI, USA
bSouth China Botanical Garden, Chinese Academy of Sciences, Le Yiju, Guangzhou, Guangdong 510650, China
cCanterbury University, Christchurch, New Zealand
dUniversity of Florida, Gainesville, FL, USA
article info
Article history:
Received 1 May 2008
Received in revised form
15 July 2008
Accepted 24 July 2008
Keywords:
Exotic Spartina
Emergy analysis
Energy Systems Theory
Maximum empower
Human-dominated planet
Salt marshesabstract
The emergy signature of the earth has changed dramatically over the past 250 years as
a result of the development of technologies to use fossil fuels for human purposes. This
change has resulted in the self-organization of modern industrial societies and their con-
comitant processes now dominate the earth. One such process is the transport of species
from specific regions of the Earth, to which they were formerly confined, and their introduc-
tion to new territories. In this paper, we examine the role of exotic Spartina sp. in promoting
the self-organization of coastal ecosystems for maximum empower on three coasts, Marl-
borough Sounds, NZ, Willapa Bay, WA, USA and Jiangsu Province, PRC. We found evidence
to support the hypothesis that Spartina marsh maximizes empower through the building
of new land in coastal environments that are dominated by an excess of sediment. Where
excess sediments are present as a consequence of past geologic processes, and where a low
marsh plant was absent, Spartina has been seen as an interloper to be destroyed. There is
some evidence that given sufficient time, exotic Spartina marshes may increase productivity
and diversity in these coastal systems, as well as those that are actively prograding.
© 2008 Elsevier B.V. All rights reserved.
1. Introduction
The Earth has undergone a change of state over the past 250
years. This change has been characterized first by the devel-
opment of industrialized societies and then by the rise of the
information age with its concomitant use of complex tech-
nologies. As a result, in the present time lights seen from space
at night ( Plate 1 ) show that human beings occupy and to a
large extent control a large fraction of the surface of the earth,
as evidenced by the lighted areas which demarcate cities and
towns devoted, almost entirely, to human uses. Human con-
trol of the earth is manifested through the alteration of the
∗Corresponding author . Tel.: +86 20 37252585; fax: +86 20 37252585.
E-mail address: luhf@scbg.ac.cn (H.-F. Lu).
1Deceased.magnitude, speed and sometimes the nature of energy, mate-
rial and information fluxes of the biogeosphere ( Vitousek et
al., 1997 ). The new patterns of energy and material flux require
new structures to develop maximum empower ( Lotka, 1922a,b;
Odum, 1996; Campbell, 2001 ) through the altered ecological
networks. In this paper, we consider how the transfer and
development of biological information, in the form of exotic
Spartina species, provides new ecological structures that are
the basis for maximizing empower in systems where the flows
of sediment have been radically altered by human activities
and in other systems where a low salt marsh species with
Spartin a’s tolerance for inundation was formerly absent. The
0925-8574/$ – see front matter © 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.ecoleng.2008.07.022 464 ecological engineering 35 (2009) 463–486
Plate 1 – Earth at Night, 27 November 2000. Credit: C. Mayhew and R. Simmon (NASA/GSFC), NOAA/NGDC, DMSP Digital
Archive.
social and political reactions to the growth of exotic Spartina
were examined and the ecological and social outcomes that
have resulted from people’s actions to control or manage
exotic Spartina were compared to the ecological role of the
plant.
1.1. Origin and characteristics of industrial civilization
The rapid industrialization of the earth was made possible,
because human beings developed the technological expertise
to utilize the vast quantities of fossil energy stored within the
earth. Coal, oil, and petroleum natural gas had been accumu-
lating beneath the earth for many millions of years up to 1769
when James Watt patented his improvements to the New-
comen steam engine. Watt’s improved engine opened the way
to the wide spread use of coal to produce steam power that
ignited the industrial revolution in England and the world. By
1850 coal had become a discernable source of energy for the
U.S. ( EIA, 2008 ) and around 1885 it became the largest energy
source used by the United States. As a result of the rapid
increase in industrial development afforded by coal-power,
planetary material flows and processes began to change.
One of the chief characteristics of the aggregation of people
into societies is that the natural material cycles of the earth are
broken and rearranged into an alternate pattern ( Odum, 2000 ).
The extraction of fuels and minerals from their stable stored
states on or beneath the earth’s surface and the subsequent
transportation of these materials to sites where they are used
in some industrial process characterize this altered pattern.
The by-product of creating refined and synthetic materials
and the articles made from them is that some of the energy
and materials used in the process inevit ably become wastes.
Ecosystems have adapted over many millions of years of evo-
lution to minimize waste and to sequester harmful materials
in places where they become chemically or biologically bound,
and as a result, toxic materials are separated from most of
the living world ( Odum, 2000 ). For example, wetlands receive
natural concentrations of toxic metals that have been concen-
trated from the landscape by water flows. Chemical processes
in the wetland transform and sequester these materials incomplexes where they are bound with organic matter, e.g.,
peat, sediment organic matter, etc., ( Thurman, 1985 ) which
is eventually buried in the earth. Through this process natu-
rally occurring rare and toxic materials are removed from the
habitats of most living organisms ( Odum, 2000 ). The altered
pattern of material flow required to support civilization results
in highly concentrated waste materials being released in areas
where the existing ecosystems are not adapted to process
them effectively.
1.2. The altered sedimentary cycle and marsh growth
Whereas human alternation of the earth’s material cycles can
be easily demonstrated, if one considers the extraction, trans-
portation, and refining of petroleum and critical materials like
lead ( Odum et al., 2000 ), phosphorus, and iron, it is perhaps not
so evident with regard to the sedimentary cycle of the earth.
Yet the earth’s sedimentary cycle has been greatly altered by
human activities even prior to the industrial age. Before the
industrial age, human societies were based primarily on agri-
culture and the muscle power of animals and people. The
intense exploitation of regions for agricultural production was
and is a primary cause of human alteration of the sedimentary
cycle. Perhaps nowhere in the world is this more evident than
in the Yellow River Basin of China, where hundreds of years
of intensive agriculture resulted in enhancing the accumula-
tion of sediments in a vast delta at the mouth of the river that
has now become cut-off and submerged as a result of the river
changing course ( Zhang et al., 2002 ).
The balance of sediment supply from the land and sea with
the erosive forces of wind and water determines whether a
coast will prograde or retrograde. Wherever sediments accu-
mulate a substrate is available to support the growth of marsh
grass. Once marsh grasses colonize open mudflats the process
of building new land begins and it is accelerated by the feed-
back processes of marsh growth itself, by which the flow of
sediment bearing flood waters is slowed as they pass through
a dense sward of grass stems allowing particles to settle out
and further increase deposition ( Landin, 1991 ). The fact that it
is sediment supply and not marsh growth that is the primary ecological engineering 35 (2009) 463–486 465
factor in land building can be seen by examining a micro-
cosm of the process as it occurs along the coast of Maine in
the United States ( Kelley et al., 1988 ). Here steep coastal cliffs
or bluffs regularly slump into the sea below, forming hillocks
of sediment. This substrate is quickly colonized by Spartina
alterniflora Loisel that consolidates the loose sediment into a
small marsh. However, since slumping rarely occurs in the
same area with regularity, the newly formed marsh is soon
subjected to the erosive power of winter storms from the Gulf
of Maine. Without a continuous supply of sediment the new
marsh begins to erode and within a few years it is washed
away, only to reform when sediments slump off of the bluff
once again. This causal connection between sediment and salt
marsh ( Jacobsen et al., 1987; Kelley et al., 1988; Wood et al.,
1989 ) is a good example of an Energy Systems Theory hypoth-
esis that the signature of available energies and more exactly
the emergy signature supplied to a place uniquely determines
the ecological organization that develops there ( Odum et al.,
1977; T willy, 1995; Campbell, 2000b, 2005; Campbell et al., 2005 ).
1.3. Emergy and transformity
Before further considering the implications of this hypothe-
sis to our study, we briefly introduce two key ideas derived
from Energy Systems Theory ( Odum, 1994 ), emergy and trans-
formity, which are used in our analysis of exotic Spartina .
Emergy is all the available energy of one kind used up directly
or indirectly in creating a product or service in a natural or
human system ( Odum, 1996 ). If solar energy is used as the
base for determining the emergy contained in an item, the
unit of emergy is the solar emjoule (sej), which connotes the
past use of available solar energy required for the product’s
formation ( Scienceman, 1987 ). Solar transformity is the solar
emergy (sej) required to produce a unit of available energy
(J) in a product. Energy and emergy signatures can be pro-
duced for any location by first tabulating the available energies
for a defined set of spatial boundaries and then determining
the emergies that flow in over a defined time period. Next
both energy and emergy are plotted separately against a set
of categories arranged on the abscissa in order of increas-
ing transformity ( Odum, 1988 ). The plot of the magnitude of
the available energy inputs by category is called the energy
signature of the place and the plot of the magnitude of the
emergy inputs is called the emergy signature. A flow of emergy
(sej/unit time) is empower and the maximization of empower
through a system network is the criterion for success in evo-
lution proposed by the maximum empower principle ( Odum,
1996 ).
1.4. Exotic Spartina and the response of ecosystems to
change in their emergy signatures
Energy Systems Theory hypothesizes that the structure of an
ecosystem will alter to best use a new persistent suite of avail-
able energies, first by adaptation and then by evolutionary
change for signatures that are stable for longer times ( Fig. 1
and Campbell, 2000b ). In the short term, systems first resist
change and then respond dynamically to recover from pertur-
bations, a property described as resilience by Holling (1973) .
Under emergy signature changes of longer duration ecosys-
Fig. 1 – The major ecological processes acting over time in
response to changes or perturbations of the emergy
signature of a place. Resistance to change is seen in the
first three points after the signature changes. Resilience is
the process by which the system departs from and then
recovers its original state. In the long run evolution leads to
a new state with similar empower if the new signature
contains this potential.
tems may transition to a new stable state, which may differ
from the original state in structure and function. All these
responses are seen in the Earth’s ecosystems today ( Campbell,
2000b ), but here we are primarily concerned with the impetus
for state change that is manifest along the coasts of the world.
In this paper, we consider the ecological role played by
exotic Spartina in three coastal systems that originally lacked a
low marsh species with Spartina ’s tolerance for inundation; (1)
the coast of New Zealand (NZ), where Spartina ×townsendii H.
&J .G r o v e sa n d Spartina anglica C.E. Hubbard were introduced
to reclaim tidal lands for pasture, to protect shore lands, and
stop bank erosion ( Asher, 1991 ); (2) Willapa Bay, Washington,
on the northwestern coast of the United States where S. alterni-
flora was accidentally introduced from the east coast ( Boyle,
1991 ) with the oyster, Crassostrea virginica , which was brought
to the bay when the native Pacific oyster population collapsed
in the mid 1880s ( Sayce, 1977 ); and (3) the Yancheng Biosphere
Reserve on the coast of Jiangsu Province in China, where both
S. anglica and S. alterniflora have been introduced for shoreline
stabilization and land-building ( Chung, 1994 ).
2. Theoretical considerations
Often in the past, the evolutionary process is thought to
have played out in relatively isolated regions over long peri-
ods of time under relatively stable emergy signatures. This
isolation allowed flora, fauna and the ecosystems that they
compose to slowly diversify and become adapted to the pre-
vailing conditions as represented in the emergy signature of
the place. The maximum empower principle ( Lotka, 1922a,b;
Odum, 1996 ) hypothesizes that the process of evolution is
guided by a particular criterion, i.e., the emergy flow within
networks that prevail is maximized. Thus, the trajectory of
evolution is always toward developing greater empower for
a given set of emergy inputs and as a result the production
process for individual system components and processes pro-
ceeds towards the lowest possible set of transformities for
the system ( Odum, 1994; Campbell, 2000b ). Apparently, this
