The Overstory: Biodiversity: ten strategies for commodity production landscapes

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The Overstory #231:
Biodiversity: ten strategies for commodity production landscapes
By Joern Fischer, David B Lindenmayer, and Adrian D Manning
November 15, 2010


Biodiversity conservation in forestry and agricultural landscapes is important
because (1) reserves alone will not protect biodiversity; (2) commodity
production relies on vital services provided by biodiversity; and (3)
biodiversity enhances resilience, or a systems capacity to recover from
external pressures such as droughts or management mistakes. We suggest ten
guiding principles to help maintain biodiversity, ecosystem function, and
resilience in production landscapes. Landscapes should include structurally
characteristic patches of native vegetation, corridors and stepping stones
between them, a structurally complex matrix, and buffers around sensitive
areas. Management should maintain a diversity of species within and across
functional groups. Highly focused management actions may be required to
maintain keystone species and threatened species, and to control invasive
species. These guiding principles provide a scientifically defensible starting
point for the integration of conservation and production, which is urgently
required from both an ecological and a long-term economic perspective. Only
about 12% of Earths land is located in protected areas, and less than half of
this is managed primarily for biodiversity conservation (Hoekstra et al.
2005). Although protected areas are an essential part of any credible
conservation strategy (Margules and Pressey 2000), it is becoming increasingly
clear that reserves alone will not protect biodiversity because they are too
few, too isolated, too static, and not always safe from over-exploitation (Liu
et al. 2001; Bengtsson et al. 2003; Rodrigues et al. 2004). For these reasons,
it is now widely recognized that conservation within protected areas needs to
be complemented by conservation outside protected areas (Daily 2001;
Lindenmayer and Franklin 2002).

Production industries like agriculture and forestry dominate human land use
(Morris 1995). These industries directly depend on a range of vital ecosystem
services, such as healthy soils, nutrient cycling, and waste decomposition
(Daily 1997). The diversity of genes, species, and ecological processes makes
a vital contribution to ecosystem services. For example, biodiversity provides
important pollinators, seed dispersers, and pest control agents on which
agriculture and forestry depend (Daily 1999). More generally, by providing
multiple species that fulfill similar functions but have different responses
to human landscape modification, biodiversity enhances the resilience of
ecosystems (Walker 1995). Such response diversity insures the system against
the failure of management actions and policies based on incomplete
understanding (Elmqvist et al. 2003). Maintaining biodiversity in production
landscapes therefore often constitutes an economically profitable synergy
between conservation and production (Daily 1997; Ricketts et al. 2004).
Pattern-oriented management strategies

Strategy 1: Maintain and create large, structurally complex patches of native

The species area curve is one of a few general principles in ecology
(McGuinness 1984). Other things being equal, larger patches tend to support
more species than smaller patches. In addition to its area, the structure of a
given patch of native vegetation is fundamentally important for biodiversity.
Again, other factors being equal, structurally characteristic and complex
vegetation tends to support higher biodiversity than structurally simple or
degraded vegetation (MacArthur and MacArthur 1961). Some structural elements
are particularly important because a large number of species and ecological
processes rely on them. What constitutes such keystone structures varies
between ecosystems, and can include a wide range of structural features,
ranging from ephemeral water bodies in recently plowed German agricultural
fields (Tews et al. 2004) to tree hollows in Australian woodlands and forests
(Gibbons and Lindenmayer 2002).

Strategy 2: Maintain structural complexity throughout the landscape

The area surrounding patches of native vegetation is often termed the matrix
(Forman 1995). The matrix is the dominant landscape element, and exerts an
important influence on ecosystem function. A matrix that has a similar
vegetation structure to patches of native vegetation (ie that has a low
contrast) will supply numerous benefits to ecosystem functioning. Three key
benefits of a structurally complex matrix are the provision of habitat for
some native species, enhanced landscape connectivity, and reduced edge

Strategy 3: Create buffers around sensitive areas

As outlined in Strategy 2, a structurally complex matrix can mitigate some of
the negative impacts of edge effects on biodiversity. An alternative, and not
mutually exclusive, strategy is to specifically create buffers around patches
of native vegetation. These can help to lessen negative edge effects, for
example by sealing off vegetation patches from strongly altered conditions in
the matrix (Noss and Harris 1986).

Strategy 4: Maintain or create corridors and stepping stones

A structurally complex matrix can contribute to the connectivity of habitat
patches for some species, and may enhance the connectivity of some ecological
processes (Strategy 2). A complementary strategy to enhance landscape
connectivity is to create or maintain corridors and stepping stones between
large patches of native vegetation. Corridors are elongated strips of
vegetation that link patches of native vegetation; stepping stones are small
patches of vegetation scattered throughout the landscape (Forman 1995).

Strategy 5: Maintain landscape heterogeneity and capture environmental gradients

>From the perspective of biodiversity conservation, vast areas of unmodified
land are likely to be optimal. Representative areas of wilderness are key to
biodiversity conservation and such areas should be protected in nature
reserves (Margules and Pressey 2000). However, where humans do use landscapes
for the production of agricultural or forestry commodities, there is
widespread evidence that heterogeneous landscapes, which resemble natural
patterns, provide greater biodi- versity benefits than intensively managed

Summary of pattern-oriented management strategies

Implementation of the five pattern-oriented strategies suggested above will
result in heterogeneous production landscapes, with large and structurally
complex patches of native vegetation scattered throughout. These patches will
be connected by corridors and stepping stones, and will be situated within a
matrix that attempts to retain structural characteristics similar to those of
native vegetation. The resulting production landscapes are likely to sustain
higher levels of biodiversity and will be more resilient to external shocks
(such as drought) than more simplified systems. Notably, determining the
appropriate mix of management strategies, and which ones are likely to be
particularly important, depends on the ecosystem in question, its species, and
current landscape patterns. Further safeguards for biodiversity, ecosystem
function, and resilience may be achieved by implementing the five additional,
processoriented management strategies set out below.

Process-oriented management strategies

Strategy 6: Maintain key species interactions and functional diversity

Human landscape modification for commodity production alters the composition
of ecological communities. This changes species interactions such as
competition, predation, and mutualist associations (Soul et al. 2005). Two
approaches focusing on species interactions may protect important ecosystem
functions. The first is conserving keystone species; the second is maintaining
species diversity within functional groups.

Strategy 7: Apply appropriate disturbance regimes

Landscape change often results in a change to historical disturbance regimes.
Such changes can substantially alter vegetation structure and species
composition (Hobbs and Huenneke 1992), and may trigger cascades that cause
fundamental and potentially irreversible changes to ecosystems (Hobbs 2001).
Pronounced ecological changes in production landscapes can result from changed
fire regimes (including intensity, frequency, and spatial extent), changed
grazing regimes, and logging (Hobbs 2001; Lindenmayer and Franklin 2002;
Bowman et al. 2004). Understanding the impacts that particular disturbance
regimes have on ecosystem functioning is therefore important for ecosystem
management. Broadly speaking, disturbance regimes that attempt to mirror
historical ones are probably a useful starting point for management
(Lindenmayer and Franklin 2002; Bowman et al. 2004).

Strategy 8: Control aggressive, over-abundant, and invasive species

Landscape change for commodity production tends to result in habitat loss for
many species. However, it also often strongly favors a small number of native
or introduced species. Some of the species which benefit from anthropogenic
landscape change can become overly abundant, and may negatively affect other
species through aggressive behavior, competition, or predation. For example,
in southeastern Australia, widespread land clearing for agriculture has led to
expanded populations of the noisy miner (Manorina melanocephala). The native
but highly aggressive honeyeater out-competes many other native birds. The
resulting decline in insectivorous birds has, in turn, been linked to insect
outbreaks and reduced tree health in many agricultural landscapes (eg Grey et
al. 1998).

Strategy 9: Minimize threatening ecosystem-specific processes

Although agriculture and forestry can threaten biodiversity, they are by no
means the only threats; a range of other processes can be equally or more
important in some landscapes. Examples include chemical pollution (Oaks et al.
2004) and hunting by humans (Reynolds 2003). Such ecosystemspecific threats
need to be considered in the management of biodiversity in production
landscapes, and situation-specific action taken to mitigate them.

Strategy 10: Maintain species of particular concern

The above guidelines have focused on maintaining biodiversity in general, and
functional groups in particular, with the aim of maintaining ecosystem
resilience. These approaches are likely to benefit a number of different
species. However, some species may still fall through the cracks (Hunter
2005). Unless they are keystone species, highly threatened species are often
very rare, and may contribute lit- tle to overall ecosystem function
(Sekercioglu et al. 2004). Nevertheless, maintaining such species should still
be an important priority because once extinct, their decline cannot be
reversed. The management of threatened species has a long history in
conservation biology, and highly focused case-specific recovery plans are
often needed to mitigate the decline of particular species (Caughley and Gunn
1996). Determining the potential presence of rare or threatened species is an
important first step in maintaining species of particular concern.

Summary of process-oriented management strategies

The process-oriented strategies listed here focus on the maintenance of
desirable species (keystone species, threatened species), and the control of
undesirable ones (invasive species). In addition, disturbance regimes are most
likely to maintain biodiversity if they mirror historical disturbance regimes.
Highly specific threats such as hunting or pollution need to be considered on
a case by case basis.

How do these strategies help in practice?

Management approaches that solve all ecological and economic problems at once
do not exist and the strategies suggested in this paper are therefore general.
Generality, by necessity, comes at a cost  the loss of precise details. This
means that the strategies outlined above do not amount to a prescriptive list
of management actions that will solve all conservation problems in all
production landscapes. Nevertheless, we believe that they provide a useful
conceptual basis for maintaining biodiversity, ecosystem function, and
ecosystem resilience in production landscapes. In fact, the first principles
for the design of nature reserves were also broad and non-quantitative. Yet,
in the 30 years since Diamond (1975) suggested these general principles,
sophisticated algorithms have been developed that take into consideration the
size, representativeness, and complementarity of nature reserves (Margules and
Pressey 2000). We argue that the successful integration of conservation and
production will be at least equally important to halting the current
biodiversity crisis as will widely agreed upon targets to protect some of
Earths land in formal nature reserves (Rodrigues et al. 2004). Moreover,
biodiversity in production landscapes is fundamental to ecosystem functioning,
which ultimately provides the basis not only for biodiversity conservation but
also for the continued production of marketable commodities (Daily 1997). The
ten guiding principles are put forward here as working hypotheses, to be
refined by the scientific community over time. A key challenge for future work
will be to further elucidate the trade-offs and potential inconsistencies
between different management strategies, both from an ecological and financial
perspective. Future work may be most effective if it is interdisciplinary and
considers both conservation and production objectives.

The strategies described above provide a basis for the integration of
conservation and production. The details of how large patches need to be, or
which introduced species should be controlled, need to be established on a
case by case basis.

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This article was excerpted with the kind permission of the authors and
publisher from:
Fischer, Joern, David B. Lindenmayer, and Adrian D. Manning. 2006.
Biodiversity, ecosystem function, and resilience: ten guiding principles for
commodity production landscapes. Frontiers in Ecology and the Environment 4:
8086.  The Ecological Society of America


Joern Fischer, David B Lindenmayer, and Adrian D Manning, Centre for Resource
and Environmental Studies, The Australian National University, Canberra, ACT
0200, Australia (Contact: joern at


Bioversity International: <> World
Resources Institute, Biodiversity and Protected Areas:
Biodiversity Support Programme: <>
UNDP Biodiversity
Agroforestry and the maintenance of
biodiversity:<> The
Nature Conservancy: <>


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