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FORUM
What is Novel About Novel Ecosystems: Managing Change
in an Ever-Changing World
Amy M. Truitt
1
•Elise F. Granek
1
•Matthew J. Duveneck
2
•Kaitlin A. Goldsmith
1
•
Meredith P. Jordan
1
•Kimberly C. Yazzie
1
Received: 22 September 2014 / Accepted: 21 March 2015 / Published online: 31 March 2015
Springer Science+Business Media New York 2015
Abstract Influenced by natural climatic, geological, and
evolutionary changes, landscapes and the ecosystems
within are continuously changing. In addition to these
natural pressures, anthropogenic drivers have increasingly
influenced ecosystems. Whether affected by natural or
anthropogenic processes, ecosystems, ecological commu-
nities, and ecosystem functioning are dynamic and can lead
to ‘‘novel’’ or ‘‘emerging’’ ecosystems. Current literature
identifies several definitions of these ecosystems but lacks
an unambiguous definition and framework for categorizing
what constitutes a novel ecosystem and for informing de-
cisions around best management practices. Here we ex-
plore the various definitions used for novel ecosystems,
present an unambiguous definition, and propose a frame-
work for identifying the most appropriate management
option. We identify and discuss three approaches for
managing novel ecosystems: managing against, tolerating,
and managing for these systems, and we provide real-world
examples of each approach. We suggest that this frame-
work will allow managers to make thoughtful decisions
about which strategy is most appropriate for each unique
situation, to determine whether the strategy is working, and
to facilitate decision-making when it is time to modify the
management approach.
Keywords Anthropogenic Ecosystem services
Eradication Management No-analog Tolerate
Introduction
Ecosystems, their species assemblages and their function-
ing are dynamic (Pickett et al. 1994). Natural climatic
variability causes species range shifts and the rise of new
species assemblages (e.g., Davis and Shaw 2001). Shifting
tectonic plates have both separated landscapes and seas-
capes once connected, and connected landscapes which
were previously separated. Humans have also changed the
earth’s land- and seascapes for thousands of years through
management, manipulation, extraction, and exploitation,
which have caused extinctions, habitat changes, and the
rise of new ecosystems and species combinations (e.g.,
Vitousek et al. 1997). Technological and industrial ad-
vances have led to the dispersal and introduction of species
into foreign habitats, where, in many cases, they are able to
thrive without their natural predators or competitors (e.g.,
Jenkins 1996; Ruiz et al. 1997). These introductions affect
local native species assemblages, resulting in fundamen-
tally new communities and ecosystem elements. These
profound anthropogenic changes to ecosystems have re-
sulted in ‘‘novel’’ or ‘‘emerging’’ ecosystems (Milton 2003;
A. M. Truitt and E. F. Granek have contributed equally.
&Elise F. Granek
graneke@pdx.edu
Amy M. Truitt
amtruitt@pdx.edu
Matthew J. Duveneck
mduveneck@fas.harvard.edu
Kaitlin A. Goldsmith
kaitygoldsmith@yahoo.com
Meredith P. Jordan
meredith.jordan@pdx.edu
Kimberly C. Yazzie
kiyazzie@pdx.edu
1
Environmental Science and Management, Portland State
University, 1719 SW 10th Ave, Portland, OR 97201, USA
2
Harvard Forest, Harvard University, Cambridge, MA, USA
123
Environmental Management (2015) 55:1217–1226
DOI 10.1007/s00267-015-0465-5
Hobbs et al. 2006) where selection of appropriate strategies
for managing these changing ecosystems is challenging
(Seastedt et al. 2008).
While over the past several hundred years most land-
scapes have been altered by anthropogenic activities, and in
many cases outright habitat destruction, the terminology
describing the resulting ecosystems is inconsistent and
inadequate for effective cross-sectoral management. Due to
the dynamic nature of ecosystems and the varied disciplines
that have evolved in the Anthropocene to study them, it has
proven challenging to find a universal language that defines
‘‘novel’’ ecosystems (e.g., Milton 2003; Hobbs et al. 2013;
Morse et al. 2014; see Table 1). Equally challenging is the
development of a common set of metrics to quantify
ecosystem changes and the functional impacts resulting
from those changes (Murcia et al. 2014). Neutral, unam-
biguous, and consistent terminology with a framework for
categorizing novel ecosystems is needed to classify, de-
scribe, and manage these systems. Such classification can
facilitate decision-making in a landscape of diverse man-
agement objectives and variable social perceptions around
novel systems (but see Murcia et al. 2014).
New species combinations, which, in some cases drive
the development of novel ecosystems (e.g., Milton 2003;
Hobbs et al. 2006,2009), have been differentiated into
three phases (1) introduction, as the arrival to a new site
beyond a species’ geographic range; (2) colonization,
where individuals reproduce and increase in number; (3)
naturalization, where species are established as a part of the
new ecosystem (Richardson et al. 2000). Since no similar
differentiation exists for novel ecosystems, their catego-
rization is inconsistent and poorly characterized. For ex-
ample, in North America, terrestrial ecosystems with
European earthworms may be considered novel because
‘‘introduced’’ earthworms have modified the hydrological
flow and plant diversity of those systems (Hendrix et al.
2008). However, under the categorization used by Black-
burn and Richardson (2011), earthworms ‘‘colonized’’
North America with European settlement of the continent
(Hale et al. 2005) and have since become ‘‘naturalized’’ as
part of existing ecosystems.
A number of researchers have defined and developed
frameworks for understanding and categorizing novel
ecosystems (e.g., Richardson et al. 2000; Hobbs et al. 2009,
2013; Morse et al. 2014; Table 1), and some have proposed
possible management alternatives (Hobbs et al. 2009;
Murcia et al. 2014; Hobbs et al. 2014). However, there is
no consensus on the role of historical versus current data in
identifying novel ecosystems (Williams et al. 2007; Keane
et al. 2009; Magurran et al. 2010; Safford et al. 2012;
Wiens et al. 2012), the most appropriate definition, or what
criteria to use to categorize or manage these ecosystems.
These discrepancies in terminology and differences in
perspectives complicate management of systems referred
to as novel: what some consider ‘‘novel’’ may not qualify
as novel under other definitions or criteria. Priorities for
and approaches to managing novel ecosystems vary based
on perspective of the scientists, managers, and policy-
makers along the anthropocentric–biocentric continuum.
Practitioners with a biocentric perspective are more con-
cerned with impacts that novel ecosystems have on biodi-
versity, community composition, and ecosystem function,
while those with an anthropocentric perspective may be
more interested in how novel ecosystems will affect
ecosystem services on which humans depend. Management
approaches to novel ecosystems range from strategies that
actively promote the ability of novel ecosystems to achieve
conservation goals (Zedler et al. 2012), to active prevention
of novel ecosystems (Stromberg et al. 2009). These ap-
proaches range from accepting irreversible landscape al-
terations and promoting and accounting for ecosystem
services provided by novel assemblages (Melo et al. 2013)
to active prevention of native species and ecosystem loss
(Willis et al. 2010; Lindenmayer et al. 2008) or land
restoration to prioritize ecosystem functions and processes
in certain novel ecosystem scenarios (Hobbs et al. 2009).
On some sites, assisted migration, such as purposefully
moving species to more climate suitable habitat (Richard-
son et al. 2009) has been recommended. Some practitioners
suggest that novel ecosystems should be recognized as
achieving conservation goals and remain where they arise,
rather than be managed (Hobbs et al. 2006;2011; Martin
et al. 2012). Others suggest eliminating the term ‘‘novel
ecosystems’’ as it could be a hindrance to ecologically
sound restoration efforts (see Murcia et al. 2014). Ac-
knowledging the diverse perspectives may facilitate com-
promise and development of mutually acceptable
management approaches. The term itself may be useful in
delineating to the public and policy-makers the far-reach-
ing effects of anthropogenic activities on proximal and
remote ecosystems (e.g., Blight and Ainley 2008; Holt-
grieve et al. 2011), which may facilitate greater consensus
on appropriate management strategies.
Here we ask whether novel ecosystems are, in fact
novel, or whether these systems are a manifestation of
ongoing evolutionary change in ecosystem and species
assemblages. Given the many definitions of novel ecosys-
tems, we present previous and current definitions, offer a
working definition for use in management decision-mak-
ing, and differentiate the frameworks surrounding each to
organize possible management approaches to novel
ecosystems. Finally, we propose a categorization scheme
and framework (Figs. 1,2) for managing novel ecosystems
now and in the future.
1218 Environmental Management (2015) 55:1217–1226
123
Table 1 Novel, emerging, or no-analog ecosystems and the primary cause(s) of change, timescales over which change occurs, literature source,
and definitions. Organized by term used, then time since publication
Term Cause Timescale Source Definition
Novel
ecosystem
Anthropogenic 10–100 years Morse et al.
(2014)
‘‘A novel ecosystem is a unique assemblage of biota and
environmental conditions that is the direct result of intentional
or unintentional alteration by humans, i.e., human agency,
sufficient to cross an ecological threshold that facilitates a new
ecosystem trajectory and inhibits its return to a previous
trajectory regardless of additional human intervention. The
resulting ecosystem must also be self-sustaining in terms of
species composition structure, biogeochemistry, and
ecosystem services. A defining characteristic of a novel
ecosystem is a change in species composition relative to
ecosystems present in the same biome prior to crossing a
threshold’’
Novel
ecosystem
Anthropogenic Recent Hobbs et al.
(2013)
‘‘…a system of abiotic, biotic and social components (and their
interactions) that, by virtue of human influence, differ from
those that prevailed historically, having a tendency to self-
organize and manifest novel qualities without intensive human
management. Novel ecosystems are distinguished from hybrid
ecosystems by practical limitation (a combination of
ecological, environmental and social thresholds) on the
recovery of historical qualities’’
Novel
ecosystem
Anthropogenic Recent, future Doney et al.
(2012)
‘‘Community-level impacts of climate change stem from altered
physiology that translates to changing interactions among
species such as competition, grazing, predation, and disease
dynamics. Together with local climate-driven invasion and
extinction, these processes result in altered community
structure and diversity, including emergence of novel
ecosystems’’
Novel
ecosystem
Naturally occurring,
Anthropogenic
Geologic,
recent,
future
Hobbs et al.
(2009)
‘‘Change is a normal characteristic of ecosystems…However,
the rapid pace of current change…sets the current era apart
from previous times in terms of the increasing rate of
appearance of novel environments, species combinations and
altered ecosystem function’’
Novel
ecosystem
Naturally occurring,
Anthropogenic (solely
climate change)
Geologic,
future
Willis et al.
(2010)
‘‘Ecological thresholds, where a community or ecosystem
switches from one stable state to another, usually with a
relatively short time-interval…. have long been recognised in
sedimentary records. Past and present human impact is well
known to be the driver of such switches with evidence to
suggest that the likelihood of ecological thresholds may
increase when humans reduce resilience’’. ...‘‘assembly and
disassembly of ecological communities are common leading
to ecosystems with a variety of structure and function’’
Novel
ecosystem
Anthropogenic Geologic,
recent,
future
Lindenmayer
et al. (2008)
‘‘Novel ecosystems that do not fall along the traditional gradient
of pristine to degraded landscapes contain ‘‘new combinations
of species that arise through human action, environmental
change, and the impacts of the deliberate and inadvertent
introduction of species’’ In novel ecosystems, species ‘‘occur
in combinations and relative abundances that have not
occurred previously in a given biome’’ (Hobbs et al. 2006)
Novel
ecosystem
Anthropogenic Recent, future Hobbs et al.
(2006)
‘‘(1) novelty: new species combinations, with the potential for
changes in ecosystem functioning; and (2) human agency:
ecosystems that are the result of deliberate or inadvertent
human action, but do not depend on continued human
intervention for their maintenance’’
Emerging
ecosystem
Anthropogenic Recent, future Milton (2003) ‘‘An ecosystem whose species composition and relative
abundance have not previously occurred within a given
biome.’’ ‘‘[…] an initial, often short-lived, anthropogenic
driver of persistent biological and physical change and
emergence of novel combinations of species’’
Environmental Management (2015) 55:1217–1226 1219
123
Defining ‘‘Novel’’ Ecosystems
The scientific literature lacks a clear and commonly ac-
cepted definition and categorization of novel ecosystems
(Blackburn et al. 2011), particularly with respect to tem-
poral and/or spatial differentiation (Table 1). ‘‘Novel,’’
‘‘emerging,’’ or ‘‘no-analog’’ are adjectives used to define
ecosystems with ecological function or species assem-
blages that, according to available historical evidence, have
not existed previously (Milton 2003; Hobbs et al. 2006;
Williams and Jackson 2007). Hobbs et al. (2006) first used
the term ‘‘novel ecosystem’’ to describe (1) recent or future
anthropogenic changes characterized by new species
combinations that have the potential to change ecosystem
function and (2) ecosystems resulting from either deliber-
ate or inadvertent human actions that do not require
maintenance to persist.
Not all definitions consider human intervention as an
indicator for an ecosystem to be labeled ‘‘novel’’. In some
instances, the term refers to ecosystems characterized by new
compositions of species and/or relative abundances that
differ from historic or geologic systems, without the inter-
vention of humans; examples include novel or ‘‘no analog’’
ecosystems that occurred in the past as represented by
sediment and fossil records (Williams and Jackson 2007;
Hobbs et al. 2009; Willis et al. 2010) (Table 1). Yet, the
majority of scholars attribute novel ecosystems to anthro-
pogenic stressors that persistently change biotic and abiotic
elements of ecosystems (Milton 2003; Hobbs et al. 2006;
Williams and Jackson 2007; Lindenmayer et al. 2008; Hobbs
et al. 2009; Morse et al. 2014).
Anthropogenic drivers can be advertent or inadvertent
and include the introduction of exotic species (Milton
2003; Hobbs et al. 2006,2009; Lindenmayer et al. 2008;
Fig. 1 Conceptual model for identifying the most appropriate management option: managing against, tolerating, or managing for novel
ecosystems
Table 1 continued
Term Cause Timescale Source Definition
No-analog
communities
Naturally occurring;
Anthropogenic
Geologic,
historic,
recent,
future
Williams and
Jackson
(2007)
‘‘[…] communities that are compositionally unlike any found
today…occurred frequently in the past and will develop in the
greenhouse world of the future…closely linked to ‘‘novel’’
climates’’
1220 Environmental Management (2015) 55:1217–1226
123
Doney et al. 2012) and human-induced climate change that
alters species distribution and occurrence (Lindenmayer
et al. 2008; Hobbs et al. 2009; Willis et al. 2009; Doney
et al. 2012). Willis et al. (2010) discuss that ecological
thresholds can be exceeded in the absence of human in-
terference and understanding the combination of variables
affected by a shift is important for managing biodiversity.
Quantitative criteria that identify this threshold have been
exceeded will be essential to developing applicable tools
for restoring, tolerating, or managing novel ecosystems.
Management and conservation of novel ecosystems will
require more clarity on the timeframe qualifying a system
as novel. A novel ecosystem on one timescale may not be
considered novel on another timescale or across different
research disciplines (Table 1). ‘‘Geologic’’ time is defined
by major eras and periods in earth’s history, and focuses on
fossil and sedimentary records (e.g., Palmer 1983; Wil-
liams and Jackson 2007), whereas ‘‘historic’’ refers to an
era before major human settlement (e.g., Crumley 1987).
‘‘Present’’ represents events that are perceived directly,
rather than a recollection or a speculation, while ‘‘future’’
is an indefinite time period after the present.
Novel ecosystems include a range of abiotic and biotic
alterations, from changes in ecological community com-
position with some maintenance of structure and/or func-
tion, such as a shrub-invaded savanna, to highly degraded
mine tailing sites. The range of definitions (Table 1) fails
to provide sufficient parameters to determine how to
manage ecosystems with altered functions and species
compositions. We propose the following working defini-
tion of novel ecosystems: an ecosystem modified by an-
thropogenic drivers (changes in hydrologic, nutrient,
physical, or biotic conditions)during historic or present
time that substantially changes ecosystem functioning.
Developing a standardized metric, to provide reference
points against which change can be measured, will be
necessary to prevent the shifting baselines syndrome (Pauly
1995) in management of novel ecosystems. Criteria in-
cluding reference points, baselines, and bio- and environ-
mental indicators as metrics of change are needed to
standardize the use of the novel ecosystems concept for
management and policy decision-making.
Management Options: Managing against,
Tolerating, and Managing for Novel Ecosystems
We introduce a framework for identifying how to manage
novel ecosystems with three alternative directives to ad-
dress the spectrum of challenges posed by these ecosys-
tems. The directives include managing against,
tolerating, and managing for novel ecosystems and can
be directly tied to management objectives (Fig. 2). We
provide examples and discuss the social, economic, and
ecological advantages and disadvantages of each. No sin-
gle framework serves as an umbrella for all management
scenarios. Rather, decision makers must determine the
ecological conditions, ecosystem services, management
resources, and stakeholder interests and priorities in each
case to identify the most appropriate approach (Table 2;
Fig. 1).
Managing Against Novel Ecosystems
The concept of managing against novel ecosystems is
represented by restoration ecology approaches. This
Fig. 2 Framework for selecting
and optimizing management
approach
Environmental Management (2015) 55:1217–1226 1221
123
approach attempts to restore a system to something ap-
proximating its ‘‘historical’’ or ‘‘native’’ state with the
objective of removal and eradication of non-native species
and restoration of historical ecosystem function and/or
species assemblage (e.g., White and Walker 1997). For
example, highly invasive quagga (Dreissena rostriformis
Bugensis) and zebra (Dreissena polymorpha) mussels are
invading many lakes in the United States. Both of these
mussel populations expand rapidly causing serious eco-
nomic and ecological effects. Facilities that rely on water
intake, such as dams, become clogged with these invasive
mussel species, which leads to the need for removal
strategies, with large economic cost (Connelly et al. 2007).
In addition to the monetary cost, they also cause major
ecological effects by significantly reducing the biomass
and production of edible primary producers. Biomass re-
duction can result in a cascading effect on the composition
and abundance of all biota (Strayer 2010). Therefore, at
sites where quagga mussels have invaded, stakeholders
advocate for intensive management (or eradication) of
invasive mussels. A number of current eradication efforts
have reported early signs of success to manage against the
novel ecosystem created by quagga mussels (Wimbush
et al. 2009).
Tolerating Novel Ecosystems
We refer to the management approach of purposefully
taking no action as tolerating a novel ecosystem. Due to
inadequate funding, resources, or information, this ap-
proach frequently becomes the default. In some cases,
taking no action may be the best alternative. We present
three examples that may warrant tolerating a novel
ecosystem (1) a non-native species invasion is expected to
result in an insignificant change to ecosystem function due
to its similar functional characteristics to a native species.
(2) A non-native species within an ecosystem is expected
to be of insignificant abundance and/or of negligible im-
pact. (3) A non-native species has a large negative impact,
however, resources, information, or technology are not
available to manage against the effects or eradicate the
species. In all three cases, efforts to manage against the
novel ecosystem would be fiscally irresponsible, as limited
resources would be wasted on a strategy that has extremely
low probability of success or in a case where the impact of
the non-native species is negligible. In these cases, limited
resources could be used more effectively elsewhere, and/or
the expected net effect of the species is null. For example,
nightcrawler earthworms (Lumbricus terrestris) are found
Table 2 Management alternatives for novel ecosystems and examples
Novel ecosystem/vector of
change
Manage against Tolerate Manage for
Increased flooding, changing
water table and substrate
habitat (Kimmelman 2013)
Build retention walls and dams
(e.g., New Orleans, LA)
No action. Expect that flooding will
be infrequent. (e.g., Portland, OR)
Allow flooding and create
new industry from altered
water table and ecosystem
services (e.g., Holland)
Invasive grasses in endangered
butterfly habitat (e.g., Severns
and Warren 2008)
Eradicate invasive and restore native
grasses and habitat for endangered
butterfly. Captive rearing and
release program for butterfly
No action. Accept altered
ecosystem services provided by
invaded sites. Stop funding
reintroduction of endangered
butterfly
Manage new habitat and
discover new ecosystem
services provided by
invasive grasses
Introduction of non-native bees
(e.g., Goulson 2003)
Eradicate non-native bees. Invest in
restoring native pollinators and their
habitat
No action. Accept some ecosystem
services shifts
Develop market for non-
native bees and the products
they pollinate
Invasive barred owl hybridizing
with spotted owl (Buchanan
et al. 2007)
Eradicate barred owl. Protect spotted
owl habitat
No action. Expect some species
hybridization. Stop preserving
Northwest old growth habitat
Preserve habitat for barred
owl
Green crab invasion (Laffertty
and Kuris 1996)
Eradicate green crabs No action. Accept ecosystem
services change in some sites
Develop market for green
crab shellfish. Introduce
hatchery
Climate change causing suitable
habitat to shift north in boreal
temperate transition zone
(Ravenscroft et al. 2010)
Create refugia in cooler climate
refugia for spruce and fir boreal
species (e.g., north slopes)
No action. Accept some ecosystem
services change in some sites
Accept loss of boreal species.
Plant oaks and maples
expected to do well in
warmer climate
Invasive juniper in Eastern
Oregon (Kuhn et al. 2007,
Bendevis et al. 2010)
Restore native sagebrush habitat with
increased fire or harvesting of
juniper to increase water yield.
(Owens 2008)
No action. Accept some ecosystem
services change in some sites
Manage juniper for increased
carbon sequestration
ecosystem service
1222 Environmental Management (2015) 55:1217–1226
123
ubiquitously across North America, making eradication
infeasible. Similarly, exotic fungal diseases such as Chi-
nese chestnut blight (Cryphonectria parasitica) that attacks
American chestnut trees (Castanea dentata) have made the
restoration of eastern forests challenging (Schlarbaum et al.
1997). For example, in 1967, the US Forest Service gave
up on a long, expensive, and largely unsuccessful effort to
eradicate the alternate host for white pine blister rust
(Cronartium ribicola) by removing the co-host Ribes spe-
cies (Maloy 1997). The change in policy represented an
acceptance, among some practitioners, to tolerate the dis-
ease (though efforts to restore Whitebark pine communities
continue; Tomback et al. 2001). Blister rust caused a
[90 % reduction of western white pine (Pinus monticola)
stocks in western North America (Kinloch 2003), and
novel assemblages replaced the historical communities
(Ellison et al. 2005).
Managing for Novel Ecosystems
There is a threshold in some affected ecosystems at which
point either managing against or tolerating is no longer a
option (Fig. 1). Although this alternative is less common
and may be more controversial, we expect the need to
manage for novel ecosystems and the services they have
evolved to provide will become more prevalent in the fu-
ture under changing climatic conditions and increased
globalization. Where species have been lost or have
severely declined and restoration has been unsuccessful, or
where land use change has been intensive, managers may
find that managing for novel ecosystems provides the only
or best alternative. For example, in the Chesapeake Bay,
there is an interest in, though also controversy around, the
proposed introduction of a non-native oyster, Crassostrea
ariakensis, from Asia to substitute for the declining native
oyster, Crassostrea virginica (Rotschild et al. 1994;
Richkus 2013). Supporters of the introduction suggest that
in addition to bringing financial support to the oyster-har-
vesting industry, the non-native oysters will restore the
ecological function that the native oyster once provided to
the bay (Harwell et al. 2010). However, such an intro-
duction poses risks such as the potential introduction of
pathogens that can affect both the introduced and native
oysters (see Moss et al. 2007). For example, previous at-
tempts to introduce non-native oysters have led to the in-
troduction of exotic diseases into the native population,
further worsening the state of the native species (Ruesink
et al. 2006). As one might expect, Harwell et al. (2010)
indicate a non-perfect match regarding the functionality
between native and non-native oysters. Other examples of
managing for novel ecosystems include the plethora of
introduced plant species that have become important in the
agricultural sector; assisted migration of more climate
suitable tree species to managed forests (Gray et al. 2010;
Duveneck and Scheller 2014); managing non-native spe-
cies assemblages in parks (e.g., Underwood et al. 2004);
non-native species used for recreational purposes (e.g.,
Crawford and Muir 2008; Britton et al. 2011) and non-
native species for conservation (Schlaepfer et al. 2010; but
see Vitule et al. 2012 for rebuttal).
Determining Best Management Practices
To choose a management approach, we propose a frame-
work to assess the scenario and optimize effective out-
comes (Fig. 2). Preferred management approaches for a
novel ecosystem will differ depending on objectives and
regional variation, decision maker pressures and priorities,
resources and information, and local stakeholder prefer-
ences for maintaining certain ecosystem services or at-
tachment to historical conditions. Consideration of the
tradeoffs among services and the effects on ecological
functions will be an indispensable part of the decision-
making process. For example, the expansion of western
juniper (Juniperus occidentalis) in Eastern Oregon has left
managers with seemingly conflicting choices. Managers
are concerned that juniper is outcompeting native sage-
brush, changing the wildlife habitat, and decreasing the
water yield through increased evapotranspiration (Owens
2008). Managing against this novel ecosystem may include
removing juniper with increased prescribed burns, natural
fire, or by mechanical treatment. Tolerance of juniper ex-
pansion is a commonly employed management strategy as
it requires an inexpensive (in the short term), no-action
approach. Though juniper expansion represents a change in
both ecological function and ecosystem services provided,
the high cost and uncertain outcome of managing against
juniper may not warrant the investment in restoration
(Goldstein et al. 2008). Finally, there is some interest in
managing for juniper expansion because the ‘novel’ ju-
niper-dominated ecosystem has high potential for increased
carbon sequestration. For some, the increased carbon se-
questration benefit outweighs the cost of decreased
evapotranspiration (Kuhn et al. 2007; Bendevis et al.
2010).
Choosing the optimal approach will require consid-
eration of the social, ecological, and economic conditions
and resources, as well as the temporal and spatial scales of
novel ecosystems. The conservation and restoration science
communities support efforts to manage against novel
ecosystems where possible and feasible. Tolerating novel
ecosystems is increasingly the ‘‘default’’ where insufficient
data and financial resources limit the ability to manage
against novel ecosystems. There is an increasing tolerance
for certain invasive species that restore ecological function
where critical species have been extirpated [e.g., filter
Environmental Management (2015) 55:1217–1226 1223
123
feeders in estuaries (Pejchar and Mooney 2009); pollinators
in tropical forests (Cox 1983); and host plants for migra-
tory species (Lane 1993)]. We expect that with increasing
anthropogenic changes to land cover, hydrologic, and nu-
trient and climate cycles, there will be an inflation in the
number of cases in which managing for novel ecosystems
may be the best approach for maintaining ecological
functioning. These cases must be identified and ultimately
managed with caution, and should be guided by the pre-
cautionary principle.
Conclusion
In the Anthropocene, effects of humans on changing
ecosystems are ever-present, requiring iterative and adap-
tive approaches to management. A common understanding
of concepts and management approaches is essential to
continued progress. We present a definition of novel
ecosystems intended to facilitate management of ecosys-
tems undergoing substantial changes to structure and
function, and propose a framework (Figs. 1,2) for identi-
fying the most appropriate management strategy. Ulti-
mately, addressing the questions highlighted in the
framework will require interdisciplinary research and
practice that includes cross-sectoral collaboration.
Landscapes and ecosystems are inherently complex and
made more so by human impacts and interactions. The
spatiotemporal variability of ecosystems and the changes
they undergo make accepting any singular approach toward
dynamic, novel ecosystems imprudent. Whether intention-
ally or unintentionally influenced by humans, regardless of
the species composition, irrespective of the extent of nov-
elty and thresholds exceeded, we are unable to predict the
long-term prognosis of these novel ecosystems. Managing
novel ecosystems will therefore require consideration of
multiple possible approaches (Fig. 1), the tradeoffs among
various approaches, and how the outcomes of each will vary
across ecological conditions, desired ecosystem services
provisioning, temporal and spatial scales, economic costs,
and cultural attachments (Fig. 2). These evaluations will
allow managers to make thoughtful decisions about which
strategy is most appropriate, whether the strategy is work-
ing, and when it is time to take a different approach.
Acknowledgments This paper developed out of class discussions
and research conducted during a graduate seminar on Novel
Ecosystems at Portland State University, Department of Environ-
mental Science and Management. We thank the following classmates
for insightful thoughts and conversations that contributed to the de-
velopment of this paper: Sara Copp, Tim Elder, Laura Hill, Felipe
Ferreira, and Brianna Tarnower. The paper has been much improved
based on comments by three anonymous reviewers.
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