Special Issue Article: Advancing Environmental Conservation: Essays In Honor Of Navjot Sodhi
Global food security, biodiversity conservation and the future
of agricultural intensification
Teja Tscharntke a,⇑
, Yann Clough a
, Thomas C. Wanger b,c
, Louise Jackson d
, Iris Motzke a,c
, Ivette Perfecto e
,
John Vandermeer f
, Anthony Whitbread g
a
Agroecology, Department of Crop Sciences, Georg-August University, Grisebachstrasse 6, 37077 Göttingen, Germany
b
Centre for Conservation Biology, Department of Biology, Stanford University, 371 Serra Mall, CA 94305-5020, USA
c
Ecosystem Functions, Institute of Ecology, Leuphana University, Scharnhorststrasse 1, 21335 Lüneburg, Germany
d
Department of Land, Air and Water Resources, University of California, Davis, CA 95616, USA
e
School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI 48109, USA
f
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
g
Crop Production Systems in the Tropics, Georg-August University, Grisebachstrasse 6, 37077 Göttingen, Germany
a r t i c l e i n f o
Article history:
Received 30 August 2011
Received in revised form 29 January 2012
Accepted 31 January 2012
Available online 13 March 2012
Keywords:
Land sparing vs sharing
Wildlife-friendly farming
Land grabbing
Biofuel directive
Food wastage
Yield-biodiversity trade offs
a b s t r a c t
Under the current scenario of rapid human population increase, achieving efficient and productive agricultural
land use while conserving biodiversity is a global challenge. There is an ongoing debate whether
land for nature and for production should be segregated (land sparing) or integrated on the same land
(land sharing, wildlife-friendly farming). While recent studies argue for agricultural intensification in a
land sparing approach, we suggest here that it fails to account for real-world complexity. We argue that
agriculture practiced under smallholder farmer-dominated landscapes and not large-scale farming, is
currently the backbone of global food security in the developing world. Furthermore, contemporary food
usage is inefficient with one third wasted and a further third used inefficiently to feed livestock and that
conventional intensification causes often overlooked environmental costs. A major argument for wildlife
friendly farming and agroecological intensification is that crucial ecosystem services are provided by
‘‘planned’’ and ‘‘associated’’ biodiversity, whereas the land sparing concept implies that biodiversity in
agroecosystems is functionally negligible. However, loss of biological control can result in dramatic
increases of pest densities, pollinator services affect a third of global human food supply, and inappropriate
agricultural management can lead to environmental degradation. Hence, the true value of functional
biodiversity on the farm is often inadequately acknowledged or understood, while conventional intensification
tends to disrupt beneficial functions of biodiversity. In conclusion, linking agricultural intensification
with biodiversity conservation and hunger reduction requires well-informed regional and targeted
solutions, something which the land sparing vs sharing debate has failed to achieve so far.
Ó 2012 Elsevier Ltd. All rights reserved.
Contents
1. Introduction: setting the scene – land sparing vs wildlife friendly farming? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
2. Global food security is not directly linked to global food production but rather is determined by many important drivers. . . . . . . . . . . . . . . . . 54
2.1. Food production from smallholder farms, not large-scale commercial farms, is the backbone of global food security . . . . . . . . . . . . . . . . 54
2.2. Global food production is sufficient, but not available to the hungry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
2.3. Food usage is inefficient – one third is wasted and one third fed to livestock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
2.4. The EU ‘10% biofuel directive’ causes increased food prices and contributes to rainforest destruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
2.5. Land grabbing and speculation on food commodities jeopardizes food security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3. Increasing yields need not translate into biodiversity loss or more land spared for nature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4. Agroecological intensification sustains ecosystem services, while minimizing environmental costs and maintaining functional biodiversity . . 56
4.1. Wildlife-friendly farming sustains cultural ecosystem services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.2. Conventional intensification causes often overlooked environmental costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.3. The role of agrobiodiversity and associated ecosystem services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
0006-3207/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.biocon.2012.01.068
⇑ Corresponding author.
E-mail address: ttschar@gwdg.de (T. Tscharntke).
Biological Conservation 151 (2012) 53–59
Contents lists available at SciVerse ScienceDirect
Biological Conservation
journal homepage: www.elsevier.com/locate/biocon
5. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
1. Introduction: setting the scene – land sparing vs wildlife
friendly farming?
Combining efficient agricultural land use with biodiversity conservation
is a challenge. With the global population approaching
9 billion people in the next few decades, it is often asserted (e.g.,
from United Nations (UNs) and Food and Agricultural Organization
(FAO)), that there is a need for 70–100% more food (Godfray et al.,
2010). At the same time, the UN declared the current decade
(2011–2020) the ‘Decade of Biodiversity’ with the EU (2011; the
EU Biodiversity Strategy to 2020) setting the targets of halting
the loss of biodiversity and degradation of ecosystem services as
major goals and setting 2020 as the target for restoring at least
15% of degraded ecosystems.
In some recent analyses (e.g., Phalan et al., 2011a,b; Green et al.,
2005) the question is posed whether (or alternatively, at what
scale) farming and conservation land management should be separated;
segregating land for nature from land for production (land
sparing), or integrated with production and conservation on the
same land (land sharing or wildlife-friendly farming). As many
wild species cannot survive in even the most wildlife-friendly
farming systems, protection of wild land is essential (Barlow
et al., 2007; Schulze et al., 2004; Maas et al., 2009; Phalan et al.,
2011a,b; Kleijn et al., 2011). This fact led Phalan et al. (2011a) to
the conclusion that yield increase from agricultural intensification
could be used as a strategy to restrict human requirements for
land. The general argument for land sparing is that increased food
production per area farmland can help to reduce encroaching on
natural habitats (see also Fischer et al., 2008, 2011; Green et al.,
2005; Vandermeer and Perfecto, 2005; Gabriel et al., 2010;
Hodgson et al., 2010; Phalan et al., 2011b).
In this essay we aim to highlight the shortcomings of a dichotomic
view between land sharing and land sparing for real world
application. The strategy put forward by Phalan et al. (2011a)
may appear to maximize both biodiversity conservation and yield
via efficient ecological-economic trade-offs at first glance. But
upon closer examination, it fails to take into account the complexity
of the real world and the opportunities for agricultural landscapes
to provide multiple ecosystem services beyond food
production and wild land biodiversity.
In the following, we outline major caveats inherent to the land
sparing vs sharing debate. We discuss important drivers of global
food security to indirectly address whether sparing land for nature
needs higher intensity of farming to produce adequate food. In the
third and fourth section, we directly question the land sparing vs
sharing dichotomy and present evidence that agroecological approaches
can support high yields. We also provide facts to challenge
the strategy of Phalan et al. (2011a) to increase yields
without explicitly considering the actual and potential cost of biodiversity
losses, which can compromise ecosystem functionality
and resilience in agriculture.
2. Global food security is not directly linked to global food
production but rather is determined by many important drivers
2.1. Food production from smallholder farms, not large-scale
commercial farms, is the backbone of global food security
Food security and food sovereignty are needed where the hungry
live, which is often within a landscape matrix of ecosystems
that are rich in biodiversity (Perfecto and Vandermeer, 2010). Hunger
– somewhat counter intuitively – is not so much linked to the
quantity of food that is globally produced but to poverty (Adams
et al., 2004; Sachs et al., 2009). The majority of poor people live
in rural areas with little or no access to productive agricultural
lands. Hence, hunger is linked to farm size: 90% of farmers worldwide
farm on <2 ha, producing food where it is needed – in much
of the developing world. Eighty percentage of the hungry live in
developing countries with 50% being smallholders (World Bank,
2007). Therefore, smallholders rather than large-scale commercial
farmers are the backbone of global food security (Horlings and
Marsden, 2011; Chappell and LaValle, 2011).
The ‘‘conventional’’ vs ‘‘agroecological’’ dichotomy is a simplified
and heuristic device, as much of the world’s agriculture lies
somewhere between these categories (e.g. traditional smallholders
with heavy pesticide use, e.g. Wanger et al., 2010, or large-scale organic
farms). However, in general the potential for increasing food
production with conventional intensification of agriculture is
geared towards high-input agriculture, whereas the low-input
agriculture of the poor relies more strongly on biodiversity and
associated ecological processes (beneficial trophic interactions, soil
food webs, stress-adapted crop genotypes; Lewis et al., 1997;
Jackson et al., 2007). Moreover, it is well established that small
and diversified farms rather than large monocultures show greater
productivity per area; a phenomenon referred to as the ’paradox of
the scale’ or the ‘inverse farm size-productivity relationship’
(Cornia, 1985; Halweil, 2006; Barrett et al., 2009; de Schutter,
2011; Horlings and Marsden, 2011). For resilient and productive
smallholder systems, food security policies must emphasize an
increase in agroecological capacity. This includes eco-efficient
(Keating et al., 2010), environmentally friendly and sustainable
techniques to typically manage highly diversified cropland
(Ratnadass et al., in press), avoiding pesticide use as much as
possible, integrating soil fertility strategies (combining organic
and inorganic fertilisers) and intensifying production in combination
with preservation of functional biodiversity, thereby avoiding
environmental risks smallholders face (see Fig. 1). The latter is often
differently perceived by risk-averse farmers relying on longFig.
1. The relationship between intensified agriculture (increasing yield) and
biodiversity (including associated ecosystem services). In European agriculture, a
slight increase in (high-input) intensification can cause a steep drop in biodiversity
(Kleijn et al., 2009) or, alternatively, only a linear relationship (Geiger et al., 2010).
In tropical agroforestry, biodiversity is often not related to yield, at least up to a
certain level of intensification (Steffan-Dewenter et al., 2007; Clough et al., 2011). In
all cases, the variability in the yield-biodiversity relationship is high suggesting
potential for the identification of agroecological practices in favor of biodiversityconservation
trade-offs or even synergies, while similar biodiversity does not mean
similar community composition or functionality per se.
54 T. Tscharntke et al. / Biological Conservation 151 (2012) 53–59
term resilience of their farms, in contrast to short-term yield-maximizing
farmers (Baumgärtner and Quaas, 2010; Tscharntke et al.,
2011).
Environmentally friendly land use contributes to biodiversity
conservation, but poor rural based population tends to encroach
forests to extract forest products, thereby endangering the sensitive
forest fauna and flora (Schwarze et al., 2007; Michalski et al.,
2010). On the other hand, participation of rural communities can
be important: community-managed forests suffer from lower
deforestation rates than protected forests, shown by a recent review
across the tropics (Porter-Bolland et al., 2012).
2.2. Global food production is sufficient, but not available to the
hungry
Current global food production is sufficient to feed the world,
but the hungry cannot afford the food (>1 billion of people are hungry
and >2 billion malnourished today; Chappell and LaValle, 2011;
FAO, 2011). The Millennium Development Goals (UN Millennium
Project, 2005) target of halving the number of hungry before
2015 is more related to food distribution than to agricultural intensification.
Hence, food security is largely independent of the land
sharing vs sparing debate. The UN Special Rapporteur on the Right
to Food, Olivier De Schutter (2011), highlights in his recent report
that small-scale ecological farming is already very productive and
can do even better (see also IAASTD, 2009). He calls for increases of
food production where the hungry live and the use of agroecological
methods. These methods of improving yields are more
accessible and viable for poor smallholder livelihoods than high
agrochemical inputs. The notion of eco-farming for food security
can be expanded to include the matrix of adjacent wild land, given
the importance of landscape complexity for agroecological functions
such as pest management, pollination, soil and water quality
(Tscharntke et al., 2005, 2007a; Bianchi et al., 2006; Perfecto et al.,
2009; Ricketts et al., 2008; Jackson et al., 2009; Blitzer et al., 2012).
The huge surplus production of large commercial farms generally
contrasts with the low surplus of smallholder enterprises.
While increasing urbanization in the tropics necessitates high food
production for regional and global markets, it often leads to cheap
retail prices. However, this does not indicate eventual inefficiency
of smallholdings (Barrett et al., 2009; see Badgley et al., 2007), but
simply their limited importance for large-scale markets. Increasing
migration from the tropical countryside into big cities is driven by
poverty, hunger and income opportunities offered by industrialization
of urban centres. Hence, support for more efficient, profitable
and sustainable production of smallholder farming enterprises and
more independence (sovereignty) from large commercial operations
(at national and international levels) may help to better secure
access to food of the rural poor.
2.3. Food usage is inefficient – one third is wasted and one third fed to
livestock
Why focus on increasing food production when the efficiency of
food usage is low? A recent report commissioned by the FAO estimates
that globally a third of harvested food is thrown away
(Gustavsson et al., 2011; or even half of all food is lost, Foley
et al., 2011). These food losses occur in industrialized countries
as well as in developing countries, but in the latter 40% losses occur
at post-harvest and processing levels, whereas in the industrialized
countries, 40% occur at retail and consumer levels (Gustavsson
et al., 2011). Improving post-harvest technologies (in particular
for smallholders) and reducing food waste is a major challenge
for our future.
Inefficient use of food stocks also occurs by feeding cereal and
fodder starch to animals, which are poor converters of energy into
meat. Livestock requires on average 7 kcal input (cereal grain feed)
for every kcal generated (range: 16 kcal for beef to 3 kcal for broiler
chickens). Currently, cereals fed to livestock make up 30–50% of
global cereal production (FAO, 2006; de Schutter, 2011). With meat
consumption predicted to rise from 37 to 52 kg/person/year
(2000–2050; FAO, 2006) cereals are increasingly diverted to animal
feed streams, a trend that should be reversed. Cereals and grain legumes
convert energy into protein much more efficiently than animals
do. Shifting diets from beef to poultry or from grain-fed to
pasture-fed beef would already meaningfully increase food supplies
by closing a ‘diet gap’ (Foley et al., 2011). Efforts to promote
more efficient food systems (Ericksen, 2008) must be seriously
considered before championing the widespread adoption of
increasing food production with high-input agricultural intensification
(independent of the land sharing vs sparing debate).
2.4. The EU ‘10% biofuel directive’ causes increased food prices and
contributes to rainforest destruction
The EU biofuel directive (2008) requires that 10% of all transport
fuel should come from biofuel by 2050 (Vidal, 2010). In general,
bioenergy production tripled in the last decade and until 2020,
15% of global cereal and plant oil production as well as 30% of sugarcane
production is expected to go into biofuel (OECD-FAO, 2011).
This is a policy with unintended consequences and does not help
mitigate hunger. On the contrary, this directive increases the rate
of land grabs (see the next section below) and increases food
prices. According to a World Bank Report (2008) and many other
expert opinions, biofuels were responsible for a meaningful part
of the global food price spike in 2008. Further, large-scale destruction
of rainforests for oil palm plantations (mainly in Indonesia and
Malaysia) results in the destruction of major global carbon and biodiversity
reservoirs. While the elimination of oilpalm-based biofuel
production is unlikely, designing landscapes that integrate smallholder
agroforestry systems between plantations and conservation
areas may provide a more sustainable solution, especially if climate
policies allow REDD credits to be traded (Koh et al., 2009;
Koh, 2011).
2.5. Land grabbing and speculation on food commodities jeopardizes
food security
Food security and food sovereignty is further hindered by direct
and indirect ‘‘land grabbing‘‘, because local food security, especially
in developing countries, can be undermined by the export
of agricultural products. According to von Witzke and Noleppa
(2011), indirect land grabbing applies, for example, to the European
Union (EU), the world‘s largest net importer of agricultural
products, which are grown on an agricultural area larger than the
territory of Germany. More than half of these imported products
are soybeans, mainly from South America (most of the soy is genetically
modified and 50% of it is used for animal feed). Direct land
grabbing refers to the fact that international investors are increasingly
leasing or buying farmland in Africa, Asia, and Latin America
for food and fuel production. This is a serious threat to food selfsufficiency
and food sovereignty in most cases (La Via Campesina,
2010). Policy instruments that incorporate the views and land
rights of communities of local smallholders have been difficult to
design and implement (Horlings and Marsden, 2011).
Economic markets for primary food commodities are increasingly
taking on the role of a new kind of investment product (incorporated
into new derivative investment instruments) enhancing
speculation and contributing to rising food prices and insecurity
of supply. The 2008 price spike of food (cereals) was at least partially
due to a speculative food bubble (Kaufmann, 2011). Recently,
speculation pushed cocoa to a 33 year high (Allen, 2010). SpeculaT.
Tscharntke et al. / Biological Conservation 151 (2012) 53–59 55
tion on food commodities therefore suggests negative effects on
rural dwellers in the developing world. It brings uncertainty, loss
of global food security, less rural self-reliance and weakened local
markets.
3. Increasing yields need not translate into biodiversity loss or
more land spared for nature
The land sparing vs sharing dichotomy is based on the argument,
demonstrated mostly for temperate regions, that yields are
negatively correlated to wildland biodiversity (Kleijn et al., 2009;
Geiger et al., 2010). High yields and high biodiversity, however,
can co-exist in tropical smallholder agricultural systems (Perfecto
et al., 2007; Perfecto and Vandermeer, 2010; Clough et al., 2011).
In cacao agroforestry, for example, management could be further
optimized for more diversity in the different strata (litter, herbs,
cacao itself and the shade trees), and conserving surrounding forests,
without compromising food production (Clough et al.,
2011). In addition, it is well-known that traditional coffee production
systems are biodiversity friendly both in their biodiversity
content and in the quality of the matrix they create, as well as producing
reliable yields (Perfecto et al., 2005; Perfecto et al., 2009).
There may not be the need to consider trade-offs (see Fig. 1, de
Fries et al., 2004), although similar biodiversity does not mean similar
community composition or functionality per se.
There is little evidence for a substantial decrease in cropland as
yield in tropical crops increases (Ewers et al., 2009). Higher yield
and profitability tend to attract migrants and hence, to frequently
increase deforestation rates (Angelsen and Kaimowitz, 1999;
Angelsen, 2010). This is contrary to the widespread assumption
(also called the Borlaug hypothesis) that yield increases take pressure
off forests. As such, allowing intensification does not necessarily
increase the amount of land that will be spared for nature
(Perfecto and Vandermeer, 2010). Given that there is no link between
yield increases and forest conservation, it is really not the
question here whether yield is based on agroecological or conventional
intensification, but agroecological intensification is likely to
enhance other ecosystem services, as will be discussed below.
4. Agroecological intensification sustains ecosystem services,
while minimizing environmental costs and maintaining
functional biodiversity
4.1. Wildlife-friendly farming sustains cultural ecosystem services
Last but not least, cultural ecosystem services need to be taken
into account. Often, religious and ethical attitudes are important
drivers of choosing agricultural practices (Sodhi and Ehrlich,
2010). In developed countries for example, people value traditional
heterogeneity and complexity of their surroundings such as hedges,
flowering field margins, fallows, and forest margins – all of which
benefit biodiversity (Brodt et al., 2009; Soliva et al., 2010). In addition,
people appreciate the biodiversity in agricultural landscapes
allowing, for example, bird watching. This interest is also reflected
in large numbers of publications dealing with the current decline
of common farmland birds that is perceived as a severe problem
in Europe (Whittingham, 2011). The public has to a large extent
identified habitat destruction, increased use of agrochemicals, and
landscape-wide structural simplification as unwanted. This desire
for heterogeneous human-dominated landscapes needs to be an
important part of concepts aiming to sustain multifunctionality of
landscapes, integrating food production and conservation of both
openland and forest species. The fact that 40% of terrestrial area is
under agricultural management and just 12% is protected (Perfecto
and Vandermeer, 2010) also means that, for example, endangered
large carnivores (lynx, wolf, bear, etc.) cannot be conserved by a system
of reserves, but need a highly connected matrix made up of
semi-natural habitats, managed habitat and reserves (Linnell
et al., 2005).
4.2. Conventional intensification causes often overlooked
environmental costs
Environmental quality in agricultural landscapes dominated by
smallholders is often overlooked in the land sparing vs sharing debate
(Perrings et al., 2006). Conventional agricultural intensification
often results in contamination by pesticides and fertilizers,
which can affect human health and create non-target effects on
wildlife and functional agrobiodiversity (Dutcher, 2007; Gibbs
et al., 2009; Geiger et al., 2010; Meehan et al., 2011). Eco-efficient
fertilization of poor soils is essential for sustainable agriculture
(Tilman et al., 2001; Keating et al., 2010). Environmental costs of
all N losses in Europe have recently been estimated at €70–
€320 billion per year, which outweighs the direct economic benefits
of N in agriculture (Sutton and van Grinsven, 2011). These high
societal costs are due to losses in air quality, water quality and
especially human health (Sutton and van Grinsven, 2011). At a global
scale, sevenfold increase in N-fertilizer application in 1960–
1995 resulted in doubling of cereal yields, but efficiency declined
from 70 to 25 kg grain per kg N (Keating et al., 2010). Agriculture
causes 30–35% of global greenhouse gas emissions, mainly due to
tropical deforestation, methane emissions from livestock and rice
fields, and nitrous oxide emissions from fertilized soils (Foley
et al., 2011). Soil degradation has been estimated to affect 16–
40% of terrestrial area (Chappell and LaValle, 2011) and even for
Europe, meaningful soil losses causing reduced yields are predicted
for the coming century (Banwart, 2011). However, little quantitative
detail of costs and benefits of technical improvements is
known, i.e. which changes in agroecological or conventional management
regime (from crop rotation to agrochemical use) should
be implemented to maximize productivity and to minimize negative
externalities at the same time (see Fig. 1). Implementing agroecological
principles in agriculture, i.e. adopting eco-efficient and
environmentally friendly management with a focus on more diversified
cropping systems (Letourneau et al., 2011; Ratnadass et al.,
in press), can greatly improve productivity and contribute to closing
yield gaps (Foley et al., 2011) and to promoting agroecosystem
resilience, i.e. the capacity to reorganize food production after disturbances
or disasters (Tscharntke et al., 2011). Enhancing sustainable
productivity of farmland needs a holistic, integrated strategy
considering all resources (from e.g. labor, capital, energy, soil and
water to biodiversity and climate) as well as external effects (environmental
costs). Adoption of the most efficient techniques from
the toolbox of sustainable land-use practices means, for example,
enhanced fertilization and use of resource-efficient crop varieties
in southern Africa, whereas current surplus fertilization in Europe
needs to be sanctified.
4.3. The role of agrobiodiversity and associated ecosystem services
Agricultural production is highly dependent on ecosystem services
such as pest control, pollination and soil fertility amongst
others (Power, 2010). Both ‘‘planned’’ and ‘‘associated’’ biodiversity
in farming systems and agricultural landscapes provide important
ecosystem services. The concept of land-sparing, however, implicitly
neglects the fact that biodiversity in agroecosystems can be of
high short-term and long-term functional importance (Tscharntke
et al., 2005; Jackson et al., 2009). So then, what are the benefits of
30% higher species richness and 50% higher density in organic
farms (Bengtsson et al., 2005)? Consider, for example, the role of
predators and pollinators in agroecosystems. A 1-hectare cereal
56 T. Tscharntke et al. / Biological Conservation 151 (2012) 53–59
field (in Central Europe) hosts several 100,000 individuals and several
100’s of species of predators (beetles, spiders, flies; Tischler,
1980). The experimental exclusion of predators results in dramatic
increases in pest aphid density (Schmidt et al., 2003; Costamagna
and Landis, 2006) across European countries (Thies et al., 2011),
with relative importance of predators changing with region indicating
an insurance value of functional redundancy (Thies et al.,
2011). In coffee production, the complex interactions of multiple
ecosystem players combine to effectively create an autonomous
control of pests (Vandermeer et al., 2010) and in maize as well as
in other crops, push–pull strategies for natural pest control are successful
(Cook et al., 2007). A textbook example is the biological
control of Indonesian rice pests by avoiding pesticide use and
increasing habitat heterogeneity (Settle et al., 1996). In a recent
meta-analysis, Letourneau et al. (2011) demonstrated that diverse
agroecosystems have less pest damage, fewer herbivores and more
natural enemies than less diverse cropping systems. Globally,
30–40% of potential crop yield is destroyed by pathogens and pests
(Oerke, 2006).
Pollinators are required for reproduction of almost 90% of
angiosperms and consequently are a limiting factor of most plant
communities and vegetation types. Further, pollinators improve
production of 70% of the globally most important crop species
(124 crop species, based on data from 200 countries) and influence
35% of global human food supply (although staple crops such as
cereals, corn and rice are predominantly self-pollinating) (Klein
et al., 2007; see also Gallai et al., 2009; Garibaldi et al., 2011). A little
known and underappreciated fact is that important commodities
such as cocoa completely depend on insect-mediated
pollination (e.g. Groeneveld et al., 2010). Pollinator-dependent
crops include particularly vitamin-rich foods (Eilers et al., 2011).
There is increasing evidence that a diverse assemblage of pollinators
can maximize crop yields, compared to the abundance of just
one pollinator species (usually the honeybee) (Klein et al., 2003;
Hoehn et al., 2008; Winfree and Kremen, 2009).
Despite the need to protect functional biodiversity and its services,
conventional agricultural practices increasingly rely on frequent
pesticide application, resulting in negative effects on
functional biodiversity, for example on bees (Brittain and Potts,
2011) or soil biota (Culman et al., 2010). Hence, the true value of
functional biodiversity on the farm in mitigating potential pesticide
impacts is often not adequately acknowledged and understood
– even in major commodities such as coffee and cocoa.
In agricultural landscapes, natural habitat and habitat heterogeneity
is known to enhance sufficient natural enemy density and
diversity to reduce crop pest pressure (Thies and Tscharntke,
1999; Bianchi et al., 2006; Letourneau et al., 2011; Tscharntke
et al., 2011). If human-dominated landscapes comprise a mix of
land-use systems and forest remnants, re-colonization processes
reduce extinction and allow for a combination of high functional
biodiversity and efficient as well as sustainable food production
(Tscharntke and Brandl, 2004; Steffan-Dewenter et al., 2007;
Chazdon et al., 2009; Perfecto and Vandermeer, 2010; Clough
et al., 2009, 2011; Tscharntke et al., 2011).
5. Conclusions
In conclusion, conventional (‘‘industrial’’; de Schutter, 2011)
intensification of agriculture increasing yields in the developed
world does not necessarily contribute to global hunger reduction.
Food security and food sovereignty need to increase in areas where
the hungry live, based on robust, eco-efficient approaches (Keating
et al., 2010) and ‘‘agroecological intensification’’ (or ‘‘ecological
engineering’’ increasing sustainable productivity), which incorporates
natural biodiversity patterns and processes. We see three
main problems with the land sharing vs sparing debate. First, yield
and biodiversity are not necessarily negatively correlated where
farms are efficiently managed. Second, increased yield does not
necessarily spare land for nature; and third, conventional intensification
tends to disrupt beneficial functions of biodiversity (e.g.,
natural pest control and pollination) and degrades environmental
quality, threatening sustainability of food production. The high
variability in yield-biodiversity relationships due to high variability
of economically viable agricultural practices in both temperate
and tropical regions illustrate that there are promising management
options balancing human and ecological needs (Figs. 1 and
2). In any case, sensitive wildland ecosystems cannot be converted
into agriculture and remaining natural habitat needs to be protected
due to the high sensitivity of many species to anthropogenic
disturbance (Kleijn et al., 2011). Linking agricultural intensification
with biodiversity conservation and hunger reduction is a great
challenge for the future. We do agree with Phalan et al. (2011a)
Fig. 2. Cartoon illustrating the possible combination of global food security with biodiversity conservation. The land sparing vs wildlife-friendly farming strategy (Phalan
et al., 2011a,b) (A), which we here call ‘‘conventional intensification strategy’’, is contrasted with an agroecological intensification strategy based on the arguments presented
in this paper (B). (A) Phalan et al. (2011a,b) introduce a region with equal areas of natural habitats, low-yield farmland and high-yield farmland (top). Land sparing (centre)
involves increasing yields in the production landscape while protecting or restoring natural habitats. Wildlife-friendly farming (bottom) involves expanding the area of lowyield
farmland at the expense of natural habitats. (B) In the same style of (A), three equal areas and natural habitats are shown, but conventional intensification (not wildlife
friendly farming) is considered to be associated with low-yield farmland, while agroecological intensification (wildlife-friendly farming) is associated with high-yield
farmland providing a multifunctional set of ecosystem services. The well-known inverse relationship between farm size and food productivity per unit of land (see text)
means that increasing small-scale agroecological intensification (where the poor and hungry live) could combine wildlife-friendly farming with land sparing. More scientific
effort needs to be invested to demonstrate and improve such agroecological strategies, combining high-quality matrix for wildlife and environmental quality with increased
yields and land spared for undisturbed nature.
T. Tscharntke et al. / Biological Conservation 151 (2012) 53–59 57
that this requires well-informed regional and targeted solutions but
these are more complex than currently discussed in the
‘‘black-and-white’’ land sparing vs sharing debate.
Acknowledgments
We note with sadness the passing of our friend, colleague, and
mentor Navjot Sodhi; working with him was wonderful and we
strongly believe that he would have loved to coauthor this opinion
paper – we miss him. Ben Phalan and an anonymous reviewer
provided very helpful comments. Author sequence follows
the ‘‘sequence-determines-credit’’ (from T.T. to T.C.W.) and the
‘‘equal-contribution’’ norm (from L.J. to A.W.) (see Tscharntke
et al., 2007b). Financial support for T.T. came from the German
Ministry of Research and Education (BMBF) and the German
Research Foundation (DFG) and for J.V. and I.P. from the University
of Michigan.
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