ArticlePDF Available

Resilience in Agriculture through Crop Diversification: Adaptive Management for Environmental Change


Abstract and Figures

Recognition that climate change could have negative consequences for agricultural production has generated a desire to build resilience into agricultural systems. One rational and cost-effective method may be the implementation of increased agricultural crop diversification. Crop diversification can improve resilience in a variety of ways: by engendering a greater ability to suppress pest outbreaks and dampen pathogen transmission, which may worsen under future climate scenarios, as well as by buffering crop production from the effects of greater climate variability and extreme events. Such benefits point toward the obvious value of adopting crop diversification to improve resilience, yet adoption has been slow. Economic incentives encouraging production of a select few crops, the push for biotechnology strategies, and the belief that monocultures are more productive than diversified systems have been hindrances in promoting this strategy. However, crop diversification can be implemented in a variety of forms and at a variety of scales, allowing farmers to choose a strategy that both increases resilience and provides economic benefits.
Content may be subject to copyright.
Articles March 2011 / Vol. 61 No. 3 • BioScience 183
Resilience in Agriculture through
Crop Diversification: Adaptive
Management for Environmental
Brenda B. Lin
Recognition that climate change could have negative consequences for agricultural production has generated a desire to build resilience into
agricultural systems. One rational and cost-effective method may be the implementation of increased agricultural crop diversification. Crop
diversification can improve resilience in a variety of ways: by engendering a greater ability to suppress pest outbreaks and dampen pathogen trans-
mission, which may worsen under future climate scenarios, as well as by buffering crop production from the effects of greater climate variability
and extreme events. Such benefits point toward the obvious value of adopting crop diversification to improve resilience, yet adoption has been
slow. Economic incentives encouraging production of a select few crops, the push for biotechnology strategies, and the belief that monocultures are
more productive than diversified systems have been hindrances in promoting this strategy. However, crop diversification can be implemented in a
variety of forms and at a variety of scales, allowing farmers to choose a strategy that both increases resilience and provides economic benefits.
Keywords: resilience, climate change, diversified agroecosystems, adaptation, trade-offs
and soil moisture, as well as shifts in pest occurrences and
plant diseases, all of which will greatly influence food pro-
duction and food security (Fuhrer 2003, Jones and Thorn-
ton 2003). These changes are expected to increase abiotic
and biotic stress, forcing agricultural systems to function
under greater levels of perturbation in the future.
Resilience is defined as the propensity of a system to retain
its organizational structure and productivity following a
perturbation (Holling 1973). Thus, a resilient agroecosystem
will continue to provide a vital service such as food produc-
tion if challenged by severe drought or by a large reduction
in rainfall. In agricultural systems, crop biodiversity may
provide the link between stress and resilience because a
diversity of organisms is required for ecosystems to function
and provide services (Heal 2000). Removing whole func-
tional groups of species or removing entire trophic levels
can cause ecosystems to shift from a desired to less-desired
state, affecting their capacity to generate ecosystem services
(Folke et al. 2004). This effect highlights the possibility that
agricultural systems already may be in a less-desired state
for the continued delivery of ecosystem services.
Vandermeer and colleagues (1998) elucidated the main
issues linking the role of diversity in agroecosystems to func-
tional capacity and resilience. First, biodiversity enhances
ecosystem function because different species or geno-
types perform slightly different roles and therefore occupy
The observation that managed ecosystems often fail to
respond smoothly to external changes and pressures has
led to greater research on ecological regime shifts, thresholds,
and resilience (Folke et al. 2004). Although the idea of build-
ing resilience has been studied in a broad range of ecosystems,
from coral reefs to forests (Nyström et al. 2000, Chapin 2004),
this idea has not been well studied in an especially important
system to human society: the agroecosystem. The develop-
ment of resilient agricultural systems is an essential topic
of study because many communities greatly depend on the
provisioning ecosystem services of such systems (food, fodder,
fuel) for their livelihoods (Altieri 1999). Many agriculturel-
based economies have few other livelihood strategies (Tilman
et al. 2002), and small family farms have little capital to invest
in expensive adaptation strategies, which increases the vul-
nerability of rural, agricultural communities to a changing
environment. The challenge for the research community is to
develop resilient agricultural systems using rational, afford-
able strategies such that ecosystem functions and services can
be maintained and livelihoods can be protected.
Environmental changes may affect many different aspects
of agricultural production. With greater climate variability,
shifting temperature and precipitation patterns, and other
global change components, we expect to see a range of crop
and ecosystem responses that will affect integral agricultural
processes. Such effects include changes in nutrient cycling
BioScience 61: 183–193. ISSN 0006-3568, electronic ISSN 1525-3244. © 2011 by American Institute of Biological Sciences. All rights reserved. Request
permission to photocopy or reproduce article content at the University of California Press’s Rights and Permissions Web site at
reprintinfo.asp. doi:10.1525/bio.2011.61.3.4
184 BioScience • March 2011 / Vol. 61 No. 3
different niches. Second, biodiversity is neutral or negative
in that there are many more species than there are func-
tions; thus, redundancy is built into the system. Third,
biodiversity enhances ecosystem function because those
components that appear redundant at one point in time
may become important when some environmental change
occurs. The key here is that when environmental change
occurs, the redundancies of the system allow for continued
ecosystem functioning and provisioning of services. These
three hypotheses are not mutually exclusive and change over
time and space; therefore, all linkages between diversity and
function may be useful for the long-term maintenance of
sustainable agricultural systems.
Biodiversity—which allows for the coexistence of mul-
tiple species, fulfilling similar functions, but with different
responses to human landscape modification—enhances
the resilience of ecosystems (Walker 1995). This concept is
linked to the insurance hypothesis (Yachi and Loreau 1999),
which proposes that biodiversity provides an insurance, or a
buffer, against environmental fluctuations because different
species respond differently to change, leading to more pre-
dictable aggregate community or ecosystem properties. Such
diversity insures the maintenance of a system’s functional
capacity against potential human management failure that
may result from an incomplete understanding of the effects
of environmental change (Elmqvist et al. 2003).
The recognition that biodiversity is integral to the mainte-
nance of ecosystem functioning points to the utility of crop
diversification as an important resilience strategy for agro-
ecosystems. There can be enormous diversity within agricul-
tural systems, and diversification can occur in many forms
(genetic variety, species, structural) and over different scales
(within crop, within field, landscape level), giving farmers
a wide variety of options and combinations for the imple-
mentation of this strategy. Diversification at the within-crop
scale may refer to changes in crop structural diversity; for
example, using a mixture of crop varieties that have different
plant heights. Diversification at the within-field scale may be
represented by areas between and around fields where trap
crops or natural enemy habitat can be planted. At the land-
scape scale, diversification may be achieved by integrating
multiple production systems, such as mixing agroforestry
management with cropping, livestock, and fallow to create a
highly diverse piece of agricultural land (table 1; Altieri 1999,
Gurr et al. 2003). It is important to recognize that diversity
can be created temporally as well as spatially, adding even
greater functional diversity and resilience to systems with
sensitivity to temporal fluctuations in climate.
Because of the impacts that climate change may have on
agricultural production, the need to consider diversified agri-
cultural systems is ever more pressing. The following sections
review the current knowledge about agricultural diversity
and its ability to protect agriculture from the consequences
of climate change, as well as the barriers that remain for its
adoption as a climate change adaptation strategy. In the first
section, I discuss the advantages of diversified agroecosystems
under a future climate by looking at pest, disease, and plant
physiological effects. The second section discusses the barri-
ers to the adoption of diversified agriculture as an adaptation
strategy, and the third section examines methods to help
farmers optimize diversification strategies to improve resil-
ience and protect agricultural production.
Advantages of diversified agroecosystems
Current knowledge suggests that climate change will affect
both biotic (pest, pathogens) and abiotic (solar radiation,
water, temperature) factors in crop systems, threatening crop
sustainability and production. More diverse agroecosystems
with a broader range of traits and functions will be better
able to perform under changing environmental conditions
(Matson et al. 1997, Altieri 1999), which is important given
the expected changes to biotic and abiotic conditions. The
following are a few of the major ways that the greater func-
tional capacity of diverse agroecosystems has been found to
protect crop productivity against environmental change.
Pest suppression. Pest suppression is a perennial challenge
to farmers, and it is a very important ecosystem service. In
agricultural systems, as in natural ecosystems, herbivorous
insects can have significant impacts on plant productivity.
The challenges of pest suppression may intensify in the
future as changes in climate affect pest ranges and poten-
tially bring new pests into agricultural systems. It is expected
that insect pests will generally become more abundant as
temperatures rise as a result of range extensions and phe-
nological changes. This abundance will be accompanied by
higher rates of population development, growth, migration,
and overwintering (Cannon 1998, Bale et al. 2002). Changes
in the distribution and abundance of species and communi-
ties are unlikely to occur at the same rates. Migrant pests are
expected to respond more quickly to climate change than
plants, and they may be able to colonize newly available
crops and habitats (Cannon 1998, Bale et al. 2002). However,
there are a variety of barriers to range expansions, including
such biotic factors as competition, predation, and parasitism
from other species (Patterson et al. 1999). Promoting such
barriers to range expansion and pest viability will have an
immediate negative impact on pest outbreaks and will help
protect agricultural production.
Farmers may be able to assist in creating biotic barriers
against new pests by increasing the plant diversity of their
farms in ways that promote natural enemy abundance. The
composition of the plant community, as determined by a
farmer, may be described as the planned diversity of the
system. Crop diversity is critical not only in terms of produc-
tion but also because it is an important determinant of the
total biodiversity in the system (Matson et al. 1997). With
greater plant species richness and diversity in spatial and
temporal distribution of crops, diversified agroecosystems
mimic more natural systems and are therefore able to main-
tain a greater diversity of animal species, many of which are
natural enemies of crop pests (Altieri 1999). Many examples
Articles March 2011 / Vol. 61 No. 3 • BioScience 185
of pest suppression have been shown within agricultural
systems possessing diversity and complexity, especially in
comparison with less-complex systems (Cannon 1998). For
example, in willow systems, insect pest outbreaks of the leaf
beetle Phratora vulgatissima have been shown to be greater
in willow monocultures than in natural willow habitats
(Dalin et al. 2009). However, in a review of specialist and
generalist natural enemy responses to agricultural diversifi-
cation, it was found that diversification may reduce natural
enemy searching efficiency. Moreover, pest control by spe-
cialist enemies may be less effective in a more diverse agro-
ecosystem because a lower concentration of host plants may
reduce attraction or retention of these specialist enemies
(Sheehan 1986).
Table 1. Examples of diversification in agricultural systems and the potential benefits for farmers under climate change.
Type of diversification Nature of diversification Benefit Examples
Increased structural
Makes crops within the field more
structurally diverse
Pest suppression Strip-cutting alfalfa during har vest allows natural enemies
to emigrate from har vested strips to adjacent nonharvest-
ed ones (Hossain et al. 2001)
Genetic diversity in
Growing mixed varieties of a
species in a monoculture
Disease suppression Genetic diversity of rice varieties reduces fungal blast
occurrence (Zhu et al. 2000)
Increased production
Increased genetic diversity was positively related to mean
income and stability of income (Di Falco and Perrings 2003)
Diversify field with
Growing weed strips or vegetation
banks in and alongside crops
Pest suppression Grassland or refugia planted at field margins (beetle
banks) were used as overwintering habitat for natural
enemies (Thomas et al. 1991)
Pest suppression Using white and black mustard on the field margins of
sweet corn crops trapped pests and prevented them from
entering the cornfield (Rea et al. 2002)
Crop rotations Temporal diversity through crop
Disease suppression Alternating cereal crops with broadleaf crops and changing
stand densities disrupts the disease cycles (Kr upinsky et
al. 2002)
Increased production Manipulating diversity through crop rotations of greater
cover crop and nitrogen-fixing crops increased the yield of
the primary crop (Smith et al. 2008)
Polycultures Growing two or more crop species
and wild varieties within the field;
spatial and temporal diversity of
Disease suppression Grassland fields planted with multiple species to decrease
disease transmission (Mitchell et al. 2002)
Climate change
More ecologically complex systems with wild varieties and
temporal and spatial diversity of crops were able to grow
under climate stress (Tengö and Belfrage 2004)
Increased production Grassland plots with greater in-field species diversity led
to more stable feed and fodder production (Tilman et al.
Increased production Grassland plots with greater in-field species diversity led
to increased production (Picasso et al. 2008)
Agroforestry Growing crops and trees together ;
spatial and temporal diversity
Pest suppression Willow trees grown in natural willow habitats experience
lower rates of pest outbreak of the leaf beetle (Dalin et
al. 2009)
Pest suppression Greater shade diversity increased bird natural enemy abun-
dance for larval control on crop plant (Perfecto et al. 2004)
Pest suppression Coffee berry borer control increased with greater ant
diversity and abundance in shade systems (Armbrecht and
Gallego 2007)
Climate change
Greater shade cover led to increased buffering of crop to
temperature and precipitation variation (Lin 2007)
Climate change
Greater shade tree cover led to increased buffering from
storm events and decreased storm damage (Philpott
et al. 2008)
Mixed landscapes Development of larger-scale
diversified landscapes with
multiple ecosystems
Pest suppression Complex landscapes that have areas of woodland and
hedgerows interspersed within fields had higher rates of
larval parasitism (Marino and Landis 1996)
Pest suppression Oilseed rape crops adjacent to complex, structurally rich,
and large old fallows had higher rates of parasitism by the
rape pollen beetle (Thies and Tscharntke 1999)
Increased production Mixed land use of organic cropland, crop rotations, and
intensive managed grazing led to optimal diversity and
profitability strategies (Boody et al. 2009)
186 BioScience • March 2011 / Vol. 61 No. 3
Habitat management is one method used within agricul-
tural systems to alter habitats to improve the availability of
the resources natural enemies require for optimal perfor-
mance (Landis et al. 2000). Such management techniques
have been developed for use at within-crop, within-farm,
or landscape scales, and some have been proven to be very
economical for farmers. In one review examining pest man-
agement in agriculture (Gurr et al. 2003), the authors found
that many degrees of complexity exist in increasing biodi-
versity for pest management. Simply diversifying the plant
age structure of a monoculture or strip-cutting fields such
that natural enemies have a temporal refuge can improve
in-field habitats for natural enemies. Larger-scale changes,
such as integrating annual and perennial noncrop vegeta-
tion; increasing crop diversity within the field; or increasing
farmwide diversification with silvoculture, agroforestry, and
livestock may also provide a variety of other functions to the
system (table 1; Gurr et al. 2003).
In an example from a meta-analysis of the density
response of natural enemies (invertebrate predators and
parasitoids) to experimental changes in structural complex-
ity, Langellotto and Denno (2004) found that increasing
structural complexity led to a significant rise in natural
enemy abundance at habitat and within-plant scales. Hunt-
ing and web-building spiders showed the strongest response
to structural complexity, followed by hemipterans, mites,
and parasitoids. Evidence of greater spider abundance in
response to diversification has also been shown by Sunder-
land and Samu (2002), who found that abundance increased
with structural complexity in 63% of the studies they exam-
ined. The central conclusion of this review was that spiders
tend to concentrate in diversified patches, and greater diver-
sification throughout the whole crop would offer the best
prospect of improving pest control (Sunderland and Samu
One example of a perennial system that exhibits a rich
range of natural enemy pest control is the coffee agroforestry
system, where there is a wide variety of spatial and tempo-
ral diversity determined by the shade trees planted within
the cropping system. Greater natural enemy presence has
been observed in the more diverse and shaded agroforestry
systems, and increased bird diversity and density have been
shown to reduce herbivore plant damage through greater
insectivorous bird predation (Perfecto et al. 2004). It has
also been observed that predatory ground-dwelling ants are
attracted to and prey upon the coffee berry borer, a major
pest of coffee production, with greater efficiency in diversi-
fied coffee systems when compared with unshaded mon-
ocultures (Armbrecht and Gallego 2007).
The integration of diversified systems into agriculture can
have financial benefits for the farmer, as well. One financially
beneficial type of habitat management that has been widely
adopted at the within-field scale is the beetle bank, where
native grasslands and refugia are maintained at the field mar-
gins to protect carabid beetle populations. In one analysis of
the costs and benefits associated with pest suppression, the
cost of establishing a beetle bank in a 20-hectare (ha) wheat
field, combined with yield loss resulting from land removed
from production, was calculated at $130 for the first year with
subsequent costs and yield losses of $45 per year. However,
the ability to keep aphid populations below a spray threshold
through natural enemy suppression saved about $450 per
year in labor and pesticide costs, and the prevention of aphid-
induced yield loss saved about $1000 per year for the 20-ha
field. These figures show that the loss in productive land for
the establishment of the beetle banks was more than offset
by the money saved from reduced pesticide use and aphid-
induced yield loss (Thomas et al. 1991).
Although climate change may produce a shift in pest and
natural enemy ranges, an agricultural system with greater
plant biodiversity improves the system’s resilience by har-
boring greater natural enemy biodiversity, thereby protect-
ing crops from a large variety of potential future pests.
Although natural enemies in a diverse system may be func-
tionally redundant at the present, they may no longer prove
redundant as future changes occur. The diversity of plant
species within the agroecosystem therefore provides long-
term pest suppression for agricultural systems by building
up a bank of potential natural enemies for any future pest
outbreaks in the system.
Disease suppression. Losses caused by pathogens can contrib-
ute significantly to declines in crop production, and changes
in climate potentially could affect plant disease distribution
and viability in new agricultural regions. From 2001 to 2003,
10% of the global crop losses in wheat, rice, and maize were
shown to be a result of pathogens (Oerke 2006).
The diversity of crop species in an agroecosystem has a
much less predictable effect on microbial pathogens com-
pared with crop pests, as microclimatic conditions play an
important role in the development and severity of a disease
(Matson et al. 1997, Fuhrer 2003). The effect of climate
change on disease prevalence is therefore much less certain.
Climate change could have positive, negative, or no impact
on individual plant diseases (Chakraborty et al. 2000), but
it is suspected that milder winters may favor many crop
diseases, such as powdery mildew, brown leaf rust, and strip
rust, whereas warmer summers may provide optimal condi-
tions for other diseases, such as cercosporea lead spot disease
(Patterson et al. 1999). Global change is also predicted to
alter the distribution and abundance of arthropod vectors
that distribute viruses, thereby affecting the rates of and
chances for crop transmission (Anderson et al. 2004).
A central tenet of epidemiology is that both the number
of diseases and the incidence of disease should increase pro-
portionally to host abundance (Tilman et al. 2002). In one
grassland study, in which grassland plant species richness
and composition were manipulated, the pathogen load was
almost three times greater in the monoculture plots, where
host abundance was at a maximum, than in the polyculture
plots planted with 24 grassland species (an approximation
of natural diversity; Mitchell et al. 2002). Eleven diseases
Articles March 2011 / Vol. 61 No. 3 • BioScience 187
were more severe at lower plant species richness, with
most of the diseases correlating with host abundance,
showing that the greater abundance of host species within
lower-species-diversity plots increased disease transmission.
The loss of genetic diversity in crop production has led
to a hypothesized increase in crop disease susceptibility as a
result of higher rates of disease transmission. Many mecha-
nisms reduce the spread of disease in agricultural systems
with greater varietal and species richness. Barrier and fre-
quency effects occur when other disease-resistant varieties
or species block the ability of a disease or virus to transmit
and infect a susceptible host (Finckh et al. 2000). These
effects increase with greater spatial and temporal diversity in
the agricultural system, and intentional crop system diversity
with greater barrier effects can significantly reduce pathogen
impacts on crop production. Multiline cultivars and varietal
mixtures have been used to effectively retard the spread and
evolution of fungal pathogens in small grains and to control
some plant viruses (Matson et al. 1997).
One well-known example of barrier effects in rice pro-
duction showed that genetic variation within species and
within populations can increase the ability of an agricultural
system to respond to pathogen diseases. Zhu and colleagues
(2000) demonstrated that in-field genetic crop heterogene-
ity suppresses disease in rice crops suffering from rice blast.
Disease-susceptible rice varieties, when planted in mixtures
with resistant varieties over large tracts of land, had 89%
greater yield and 94% reduced fungal blast occurrence than
when planted in monoculture. Because of this experiment’s
success, fungicidal sprays were no longer applied to these
fields after the trial. Rather, farmers grew rice in mixtures in
order to improve the resilience of the systems while reduc-
ing economic costs. There have been few such large-scale
experiments to study the efficacy of genetic heterogeneity
to increase production, reduce chemical use, and potentially
stabilize or even reduce food prices for a region, but these
results do provide evidence that intraspecific crop diversifi-
cation has the potential to effectively control fungal disease
spread and protect against crop loss.
Increasing diversification of cereal cropping systems by
alternating crops, such as oilseed, pulse, and forage crops, is
another option for managing plant disease risk (Krupinsky
et al. 2002). Disease cycles could be interrupted through crop
rotation by interchanging cereal crops with broadleaf crops
that are not susceptible to the same diseases. Reduced tillage
could enhance soil biodiversity, leading to greater disease
suppression, and stand densities could be adjusted to allow
for better microclimatic adjustments to disease growth.
These examples show that farmers can take advantage of
greater crop diversification to reduce disease susceptibility
in agricultural systems, thereby limiting the amount of pro-
duction loss as a result of crop diseases. Although changes
in disease spread and severity are uncertain under climate
change, greater genetic variation across space and time could
potentially reduce adverse disease transmission impacts that
may accompany climate change.
Climate variability buffering and mitigation. Diversified agro-
ecosystems have become more important for agriculture as
climate fluctuations have increased. Research has shown that
crop yields are quite sensitive to changes in temperature and
precipitation, especially during flower and fruit develop-
ment stages. Temperature maximums and minimums, as
well as seasonal shifts, can have large effects on crop growth
and production. Greater variability of precipitation, includ-
ing flooding, drought, and more extreme rainfall events,
has affected food security in many parts of the world (Parry
et al. 2005).
Agricultural vulnerabilities have been found in a number
of important crop species. Observations of rice production
in the Philippines during an El Niño drought season showed
reductions in seed weight and overall production (Lansigan
et al. 2000). Studies of wheat have demonstrated that heat
pulses applied to wheat during anthesis reduced both grain
number and weight, highlighting the effect of temperature
spikes on grain fill (Wollenweber et al. 2003). In maize,
researchers observed reduced pollen viability at tempera-
tures above 36 degrees Celsius, a threshold similar to those in
a number of other crops (Porter and Semenov 2005).
Such observed agricultural vulnerabilities to changes in
temperature and precipitation point to the need to develop
resilient systems that can buffer crops against climate vari-
ability and extreme climate events, especially during highly
important development periods such as anthesis. There
are a variety of ways that diversified agricultural systems
exemplify that more structurally complex systems are able to
mitigate the effects of climate change on crop production.
Agroforestry systems are examples of agricultural systems
with high structural complexity. Although the primary crop
of interest (e.g., coffee, cacao) is sometimes grown in more
intensively managed systems with little shade cover, the
more structurally complex systems have been shown to buf-
fer crops from large fluctuations in temperature (Lin 2007),
thereby keeping crops in closer-to-optimal conditions. The
more shaded systems have also been shown to protect crops
from lower precipitation and reduced soil water availability
(Lin et al. 2008) because the overstory tree cover reduces soil
evaporation and improves soil water infiltration.
Agroforestry systems also protect crops from extreme
storm events (e.g., hurricanes, tropical storms) in which
high rainfall intensity and hurricane winds can cause land-
slides, flooding, and premature fruit drop from crop plants.
In one example from Mexico, greater farming intensity of
coffee agroforestry systems was correlated with the percent-
age of farm area lost to landslides and the amount of cof-
fee production lost to premature fruit drop (Philpott et al.
2008). In another example of diverse agriculture systems
and hurricanes, a study of Nicaraguan farms following
Hurricane Mitch in 1998 showed that less intensively man-
aged land, which exhibited greater diversity and structural
complexity, suffered less erosion, had more vegetation, and
experienced lower economic losses from hurricane damage
(Holt-Giménez 2002). Resistance patterns became more
188 BioScience • March 2011 / Vol. 61 No. 3
apparent in areas with high storm intensity, and complex
interactions and thresholds exist, but are difficult to detect.
In a comparative study of farming systems in Sweden
and Tanzania, two locations where agriculture has suffered
from climate variation and extreme events, it was found that
agricultural diversity increased the resilience of the produc-
tion systems. Sweden suffered from cold-tolerance issues,
whereas Tanzania suffered from problems of heat tolerance
and irregular El Niño cycles. Both locations experienced
greater seasonal drought. In these cases, research showed
that successful management practices able to buffer systems
from climate variation and protect production were those
that were generally more ecologically complex, incorporat-
ing wild varieties into the agricultural system and increas-
ing the temporal and spatial diversity of crops (Tengö and
Belfrage 2004).
These examples present a potential long-term strategy
for farmers experiencing patterns of reduced rainfall and
growing temperature variability. Diversification of agri-
cultural systems can significantly reduce the vulnerability
of production systems to greater climate variability and
extreme events, thus protecting rural farmers and agricul-
tural production.
Barriers and challenges to the increased adoption of
diversified agriculture
Although many recognize that diversity can improve the
resilience of agricultural systems to environmental change,
the adoption of increased diversification has been slow for a
number of reasons. First, economic policy incentives for the
production of monoculture row crops under intensive man-
agement have outweighed the perceived incentives to imple-
ment diversified farming systems, although this may change
as climatic variations increase. Second, many of the efforts
to adapt agriculture to climate change have focused on
the development of biotech solutions to produce drought-
resistant crops, pushing agriculture toward more expensive
and intensive forms of management. Lastly, the mistaken
belief that biomass production is substantially greater in
monocropped systems than in multispecies systems has dis-
couraged the move toward more diversified systems. Such
barriers slow the rate of adoption of diversified agricultural
systems as adaptation options and must be addressed in or-
der to hasten the implementation of this strategy.
Farm price and income supports: A US example. In the United
States, the economic incentives to intensify production in
monoculture systems outweigh the incentives to diversify
agriculture systems. Agricultural subsidies select mainly
for five crops—corn, wheat, soybean, cotton, and rice—
thereby incentivizing greater production of these few crops.
Between 1995 and 2002, 89% of the $91.2 billion disbursed
in commodity payments went to these crops in order to
boost the income of crop and livestock farmers. Soybean
and corn farmers alone received 56% of that money (Boody
et al. 2009). The commodity payment system encourages
monocropping of select crops because payments are deter-
mined by acreage of crop produced, thereby incentivizing
the maximum production of one or a few crops over large
tracts of landscape. Such incentives favor greater production
of fewer species planted in space and time, at the expense
of ecosystem services and ecosystem function (Altieri 1999,
Tilman et al. 2002).
Incentives for the greater production of fewer crops have
also been supported by the mechanization of many agri-
cultural production practices (e.g., planting, harvesting).
Mechanization is now the status quo in the United States
and is necessary for this type of production system. The
mechanization of crop species for maximum production,
in general, is most efficient when only one crop is planted
because management systems (e.g., planters, harvesters,
chemical inputs, irrigation systems) can be designed for one
crop type and one crop structure, thereby decreasing labor
time and costs (Pimentel et al. 2008). In this sense, an agri-
cultural system that selects mainly for one or two main crops
and is highly mechanized can be very efficient and produc-
tive, and certainly this ability to scale up production and
increase yield has had many advantages for food production
and the maintenance of stable food prices in the past.
However, farm price and income supports were origi-
nally developed because farm households were financially
disadvantaged compared with other US households, not
to increase the production of specific crops. Current data
show that farm household incomes have risen above those
of the average nonfarm household (Mishra and Sandretto
2002), and that much of the subsidy program does not
support small farmers; rather, the majority of the money
goes to large farms that own wide swaths of land (Riedl
2007), thereby negating the original intent of the price- and
income-support mechanisms. This brings into question the
true economic benefit of subsidies for many small farmers,
who will be most vulnerable to climate change–induced
production losses in the future. Incentives that can increase
economic productivity of farms by permitting the selling
of ecosystem services, such as carbon sequestration, have
the potential to increase the adoption of diversified farm
systems such as terraces and agroforestry (Antle et al. 2007).
Developing policy that incentivizes the diversification of
agricultural crops and landscapes may be a more rational
strategy for developing resilient agricultural systems and
protecting food production in the future under climate
change (Boody et al. 2009).
Biotech solutions. The recognition that agriculture will face
challenges under climate change has brought about a major
effort to adapt agriculture through technical means, primar-
ily the research and development of drought-resistant bio-
tech crops. The push for greater use of biotechnology that
focuses on sole-crop agriculture has made some headway
in protecting production yields for some farmers, but it has
not succeeded in many situations, especially in developing
nations (Herdt 2006). Yet biotech continues to be a major
Articles March 2011 / Vol. 61 No. 3 • BioScience 189
focus in agricultural adaptation solutions to climate change.
According to assessments by the Australian government,
crops genetically engineered for drought tolerance have not
been found to outperform traditional varieties (Braidotti
2008), and in fact, many traits are most easily bred into crop
systems using conventional breeding through crop genetic
diversity (USDA 2008). The authors of an International
Water Management Institute report (IWMI 2007) concluded
that improvements in biotech products would have only
a moderate impact over the next 15 to 20 years in making
crops more efficient in using water. They also concluded that
“greater, easier, and less contentious gains” could come from
managing water supplies better, rather than trying to develop
crops that can flourish with less water (IWMI 2007).
Additionally, the speed of research and development of
new biotech crops must be assessed in comparison with
the speed of climate change effects on agriculture. A recent
New York Times article (Pollack 2008) that interviewed a
researcher on Monsanto drought-tolerant corn stated that
drought-tolerant varieties could reach American farmers
in four years, with a 10% increase in yield. Other varieties
could reach Africa by 2017 (Pollack 2008). The difficulty
with assessing such scenarios is the uncertainty in the rate
of change that farmers will have to contend with in the
next 5 to 10 years. Will the technology developed today be
sufficient to protect farmers under the climate conditions
of the future when it is launched in 5 to 10 years? For how
long will the technology be useful? Such products may also
be prohibitively expensive, which will pose a challenge for
smallholder rural farmers who may want to pursue this
adaptation option under climate change.
If there is indeed a temporal scale mismatch in the rate of
development of adequate biotech lines and the rate and extent
of climate change effects on agriculture, farmers will have to
turn to other adaptation options to improve the resilience of
their systems to climate change. The need to develop options
for present and expected climate change and for those who
will have no access to such technology remains a great prob-
lem for agricultural development and food security fields.
Diversified agriculture in such cases remains a highly acces-
sible adaptation option for many farmers.
Biomass production. The belief that monocultures and inten-
sively managed systems are more productive than diversified
agricultural systems is another challenge to moving agricul-
tural systems toward more diversity. Maximizing biomass
production of one or two specific crops is essentially the
goal of the current modern agricultural paradigm. Although
ecosystem functioning of such systems persists at much
reduced capacity, outside infrastructure such as mechani-
zation, chemical inputs, and irrigation systems can help
replace the lost functionality (Altieri 1999) to enable high
production. However, the potential effects of climate change
on agriculture stability will further complicate our predic-
tions of production and pricing of goods from large-scale,
monocropped systems.
In many regions of the world, the ability to use intensified
production practices and products is limited by cost and
transportation. Petroleum for mechanization techniques
and chemical inputs can be prohibitively expensive. Even in
regions with access to mechanization and chemical inputs,
a lack of water resources can severely reduce production
capacity. In such cases, diversified agricultural systems that
are able to produce under extreme climate scenarios are
preferable because many of the ecosystem functions that
cannot be brought into the system through inputs and
mechanizations can be provided through natural means.
Such solutions support both biodiversity and community
resilience to climate change by taking advantage of ecosys-
tem functions and services, supporting high production
yields in potentially adverse environmental conditions.
A variety of research has shown that high plant diversity
within agricultural plots can yield higher production levels
than systems with low plant diversity. Grassland experiments
have shown that greater plant species diversity is correlated
with greater temporal stability in annual aboveground
plant production, demonstrating that a more efficient and
sustainable supply of food, such as fodder, can be enhanced
by increasing biodiversity (Tilman et al. 2006). In a study
examining the effect of species diversity on crop and weed
biomass in perennial herbaceous polycultures, biomass
increased log linearly with species richness and polycultures
outyielded monocultures by an average of 73% (Picasso
et al. 2008). A growth in production has also been seen in
field experiments manipulating diversity in crop rotations
(crops, cover crops, and chemical inputs), showing signifi-
cantly greater corn grain yields with increased diversification
over time (Smith et al. 2008). Such results demonstrate that
diverse polycultures can have higher and more stable yields
that lead to increased economic benefits for farmers as well.
However, not all studies have shown that greater diversity
leads to increased production yield. In one study, biodiverse
rotational systems of three to six species produced 25%
lower yield versus integrated monocropped grain systems,
but the grain was of higher quality. The high-quality grain
from the more biodiverse system must be of greater value to
overcome the economic benefit of higher production in the
lower-quality monoculture (Snapp et al. 2010).
Developing optimization strategies and win-win
solutions for diversification
A major challenge for the implementation of diversified
agricultural systems for farmers is finding the appropriate
balance of diversification within the farm system to satisfy
both production and protection values. Farmers and agri-
cultural managers must consider the variety of ways that
diversification can occur within the system and develop
methods that best meet their specific needs of crop produc-
tion and resilience. Of course, as climate change variability
increases, the value of resilience will also increase, espe-
cially in production systems sensitive to climate variation.
However, a farmer’s decision to move toward diversified
190 BioScience • March 2011 / Vol. 61 No. 3
adoption of diversified agricultural systems. In one model of
the potential of farmers to participate in carbon sequestra-
tion contracts and increase sequestration potential through
agroforestry and terracing of fields, analysis showed that at
prices higher than $50 per metric ton of carbon, adoption
would increase substantially, and at prices of $100 per metric
ton of carbon, terrace and agroforestry adoption for carbon
sequestration would have the potential to raise per capita
incomes by up to 15% (Antle et al. 2007). Such economic
models are also helpful for understanding whether price
incentives are effective for a particular goal. In a study by Wu
and colleagues (2004) of price incentives for agriculture con-
servation practices in order to reduce nutrient and soil pol-
lution of the Mississippi River, an economic model showed
that payments of $50 per acre for conservation tillage and
crop rotation increased the adoption of these conserva-
tion practices but were limited in their potential to reduce
hypoxia, the ultimate goal. Such results allowed policymak-
ers to concentrate on alternate conservation options and
incentives that would have a larger impact on the ultimate
goal of reducing hypoxia (Wu et al. 2004).
Development of larger-scale diversified landscapes that
support and improve ecological resilience in agricultural
systems requires a more in-depth analysis of the farm
business and landscape-level scenario modeling for on-farm
diversity possibilities. For example, Boody and colleagues
(2009) examined how two watersheds in Minnesota would
fare under a variety of future land-use scenarios including
(a) a continuation of current trends, (b) the application
of best management practices (BMPs) over the landscape,
(c) a mixture of agricultural uses that maximize diversity
and profitability, and (d) a scenario increasing vegetative
cover over the landscape (Boody et al. 2009). The scenario
that maximized on-farm diversity and profitability moved
beyond BMPs alone and included organic cropland, five-year
crop rotations, and intensive managed grazing. This diverse
system increased profits and biodiversity while reducing
environmental externalities (e.g., water quality, greenhouse
gases, sedimentation, and flooding), thereby creating a
win-win-win solution. Such scenario modeling of land-
scapes could be very useful for farmers making decisions
about large tracts of land or in systems where there is a
cooperative structure in land management. These types of
modeling scenarios may also assist decisionmakers in long-
term planning of landscapes.
Stakeholder involvement and participatory research. The adop-
tion of sustainable agricultural options under climate change
has been a challenge for many communities, as the idea of
climate change adaptation can seem overwhelming. The
ability and space to communicate adaptation options is very
important to implementation success; discussing the risk
and uncertainty of climate change is especially critical, as
sound climate science is required to implement rational and
useful strategies. Additionally, stakeholders must understand
that adaptation options become fewer as climate variability
agricultural systems will be highly influenced by the abil-
ity of the diversification strategy to support the economic
resilience of farms. Cost-cutting examples, such as the use
of beetle banks to reduce pesticide costs (Thomas et al.
1991) or the reduction of fungicide use in integrated rice
systems (Zhu et al. 2000), illustrate the significant possible
economic benefits of greater biodiversity. Policy incentives
that strongly promote adaptation are also necessary for
transitioning agriculture to a long-term sustainable state.
Finding win-win solutions that account for farmers’ vari-
ous production and protection goals is necessary to develop
long-term, viable strategies.
Optimizing diversification strategies at various scales. Develop-
ing tools that can help managers understand best practices
on a farm field or landscape scale can significantly enhance
diversity in agricultural systems while increasing the resil-
ience of systems to climate change and maintaining high
At the farm field level, techniques such as crop modeling
(e.g., Decision Support System for Agrotechnology Transfer
[Jones et al. 2003], Agricultural Production Systems Simu-
lator [Keating et al. 2003]) allow researchers to simulate
crop mixtures within a specific regional setting in order
to model crop thresholds and production levels to climate
and management variables. Such systems can be very pow-
erful for modeling crop outcomes under climate change
scenarios, as climate data can be adjusted to mimic greater
climate variation as well as any accompanied changes in
agricultural farm management (e.g., crop mixtures and
rotations; Weiss et al. 2003). However, accurate modeling
of agricultural systems requires extensive knowledge of on-
the-ground parameters, such as soil profiles for water and
nutrient distribution, as well as a variety of crop-specific
physiological development data usually gained through
field trials. This information can be difficult to obtain, as
it requires labor and technical understanding to collect the
appropriate data.
However, it will greatly benefit future planning if there
is greater development of extension and on-the-ground
research staff who are able to assist in collecting relevant
soil and plant development data and in modeling cropping
strategies to specific location variables. Simulation analyses
conducted on specific production scenarios are especially
useful in improving decisionmaking (e.g., what crops should
be planted, and when), particularly when performed in con-
junction with local knowledge of potential environmental
and socioeconomic challenges. The use of interdisciplinary
research to consider the overall crop management system
will allow for better adaptation method development and
implementation (Stone and Meinke 2005).
Because farmers require economic incentives to be willing
and able to adopt new practices, economic models that can
predict threshold prices at which farmers begin to adopt
environmental land-use practices or payments for ecosys-
tem services can be highly effective in encouraging farmer
Articles March 2011 / Vol. 61 No. 3 • BioScience 191
more complex systems could be used to protect farmers
from climatic change and improve food security.
Understanding the potential of increasing diversity within
farm systems is essential to helping farmers adapt to greater
climate variability of the future. By adopting farm systems
that promote ecosystem services for pest and disease control
and resilience to climate change variability, farmers are less
at risk to production loss and are more generally resilient to
environmental change.
I thank the Berkeley Environmental Institute, Claire Kre-
men, and Miguel Altieri for spurring me to develop this
topic. I also thank Ivette Perfecto, John Vandermeer, Miguel
Altieri, and three anonymous reviewers for their comments
in improving this manuscript.
This publication was developed under Cooperative Agree-
ment no. X3 83232801 awarded by the US Environmental
Protection Agency (EPA) to the American Association for
the Advancement of Science. It has not been formally
reviewed by the EPA. The views expressed in this document
are solely my own and do not necessarily reflect those of the
agency. The EPA does not endorse any products or commer-
cial services mentioned in this publication.
References cited
Altieri MA. 1999. The ecological role of biodiversity in agroecosystems.
Agriculture, Ecosystems and Environment 74: 19–31.
Anderson PK, Cunningham AA, Patel NG, Morales FJ, Epstein PR, Daszak
P. 2004. Emerging infectious diseases of plants: Pathogen pollution,
climate change and agrotechnology drivers. Trends in Ecology and
Evolution 19: 535–544.
Antle JM, Stoorvogel JJ, Valdivia RO. 2007. Assessing the economic impacts of
agricultural carbon sequestration: Terraces and agroforestry in the Peru-
vian Andes. Agriculture, Ecosystems and Environment 122: 435–445.
Armbrecht I, Gallego MC. 2007. Testing ant predation on the coffee berry
borer in shaded and sun coffee plantations in Colombia. Entomologia
Experimentalis et Applicata 124: 261–267.
Bale JS, et al. 2002. Herbivory in global climate change research: Direct effects
of rising temperature on insect herbivores. Global Change Biology 8: 1–16.
Boody G, Vondracek B, Andow DA, Krinke M, Westra J, Zimmerman J,
Welle P. 2009. Multifunctional agriculture in the United States. BioSci-
ence 55: 27–38.
Braidotti G. 2008. Scientists Share Keys to Drought Tolerance. Austra-
lian Government Grains Research and Development Corporation,
Ground Cover 72. (8 December 2010;
Cannon RJC. 1998. The implications of predicted climate change for insect
pests in the UK, with emphasis on non-indigenous species. Global
Change Biology 4: 785–796.
Chakraborty S, Tiedemann AV, Teng PS. 2000. Climate change: Potential
impact on plant diseases. Environmental Pollution 108: 317–326.
Chapin FS III, Bergeron Y, Fukuda M, Johnstone JF, Juday G, Zimov SA.
2004. Global change and the boreal forest: Thresholds, shifting states or
gradual change? Ambio 33: 361–365.
Dalin P, Kindvall O, Björkman C. 2009. Reduced population control of an
insect pest in managed willow monocultures. PLoS ONE 4: e5487.
Di Falco S, Perrings C. 2003. Crop genetic diversity, productivity and stabil-
ity of agroecosystems. A theoretical and empirical investigation. Scottish
Journal of Political Economy 50: 207–216.
increases; the cost and complexity of adaptation will in-
crease, yet the benefits of adaptation will increase as well
(Howden et al. 2010).
Stakeholder involvement and participatory research are
often very useful tools in developing adaptation options
that will be adopted by a local community because these
methods recognize that knowledge often lies with the farm-
ers in the field, and that local considerations should be
integrated into long-term planning (Rivington et al. 2007).
In Australia, the Commonwealth Scientific and Indus-
trial Research Organisation engages with rural agricultural
communities through agricultural stakeholder meetings to
discuss the effect of climate variability on challenges and
priorities for local farmers. Farmers are active participants
in developing adaptation solutions, such as the modeling
scenarios of on-farm crop mixtures and rotations. Because
of stakeholder engagement, farmers develop ownership
of solutions and therefore more readily adopt adaptation
strategies onto their farms (Gardner et al. 2009). Thus,
partnerships among stakeholders (farmers and scientists)
are necessary for the successful development and adoption
of sustainable management, such as the use of simulation
approaches to help farmers find optimal strategies.
It is abundantly clear that farmers are facing growing stress
from climate change, and that the greater implementation of
diversified agricultural systems may be a productive way to
build resilience into agricultural systems. The challenges to
increasing adoption of diversified agricultural management
strategies are both scientific and policy based. In the scientific
realm, the adoption of diversified agricultural systems could
be bolstered if farmers had a better idea of how to optimize a
diversified structure to maximize production and profits. Crop
and landscape simulation models that can model a range of
climate scenarios and landscape modeling with farm profit-
ability scenarios would help farmers find optimal strategies for
maintaining production and profit. Stakeholder-based partici-
patory research would also be highly beneficial, as researchers
could model strategies that seem plausible to farmers.
In the policy realm, diversification within agricultural
systems could potentially increase in the United States
through the adjustment of the farm income support systems
to incentivize more diverse cropping systems that support
small farmers. Internationally, diversified agriculture can
have a large role in protecting food security and produc-
tion in regions where farmers have little access to chemical,
structural, or technological resources. Diversified farming
strategies are supported by international research efforts,
including the International Assessment on Agricultural
Knowledge, Science and Technology for Development, a
global report of more than 400 scientists that concluded that
locally adapted seed and ecological farming better addressed
the complexities of climate change, hunger, poverty and
productive demands on agriculture in the developing world.
The report also showed that the ecological processes of these
192 BioScience • March 2011 / Vol. 61 No. 3
Matson PA, Parton WJ, Power AG, Swift MJ. 1997. Agricultural intensifica-
tion and ecosystem properties. Science 277: 504–509.
Mishra AK, Sandretto CL. 2002. Stability of farm income and the role of
nonfarm income in U.S. agriculture. Review of Agricultural Economics
24: 208–221.
Mitchell CE, Tilman D, Groth JV. 2002. Effects of grassland plant species
diversity, abundance, and composition on foliar fungal disease. Ecology
83: 1713–1726.
Nyström M, Folke C, Moberg F. 2000. Coral reef disturbance and resilience
in a human-dominated environment. Trends in Ecology and Evolution
15: 413–417.
Oerke E-C. 2006. Crop losses to pests. Journal of Agricultural Science 144:
Parry M, Rosenzweig C, Livermore M. 2005. Climate change, global food
supply and risk of hunger. Philosophical Transactions of the Royal
Society B 360: 2125–2138.
Patterson DT, Westbrook JK, Joyce RJV, Lingren PD, Rogasik J. 1999. Weeds,
insects, and diseases. Climatic Change 43: 711–727.
Perfecto I, Vandermeer JH, Bautista GL, Nuñez GI, Greenberg R, Bichier P,
Langridge S. 2004. Greater predation in shaded coffee farms: The role of
resident Neotropical birds. Ecology 85: 2677–2681.
Philpott SM, Lin BB, Jha S, Brines SJ. 2008. A multi-scale assessment of
hurricane impacts on agricultural landscapes based on land use and
topographic features. Agriculture, Ecosystems and Environment 128:
Picasso VD, Brummer EC, Liebman M, Dixon PM, Wilsey BJ. 2008. Crop
species diversity affects productivity and weed suppression in peren-
nial polycultures under two management strategies. Crop Science 48:
Pimentel D, Williamson S, Alexander C, Gonzalez-Pagan O, Kontak C,
Mulkey S. 2008. Reducing energy inputs in the US food system. Human
Ecology 36: 459–471.
Pollack A. 2008. Drought resistance is the goal, but methods differ. New
York Times. 22 October, p. B1.
Porter JR, Semenov MA. 2005. Crop responses to climatic variation. Philo-
sophical Transactions of the Royal Society B 360: 2021–2035.
Rea JH, Wratten SD, Sedcole R, Cameron PJ, Davis SI, Chapman RB. 2002.
Trap cropping to manage green vegetable bug Nezara viridula (L.) (Het-
eroptera: Pentatomidae) in sweet corn in New Zealand. Agricultural and
Forest Entomology 4: 101–107.
Riedl BM. 2007. How Farm Subsidies Harm Taxpayers, Consumers,
and Farmers, Too. The Heritage Foundation, Backgrounder 2043. (8
December 2010;
Rivington M, Matthews KB, Bellocchi G, Buchan K, Stöckle CO, Donatelli
M. 2007. An integrated assessment approach to conduct analyses of cli-
mate change impacts on whole-farm systems. Environmental Modelling
and Software 22: 202–210.
Sheehan W. 1986. Response by specialist and generalist natural enemies to
agroecosystem diversification: A selective review. Environmental Ento-
mology 15: 456–461.
Smith R, Gross K, Robertson G. 2008. Effects of crop diversity on agroeco-
system function: Crop yield response. Ecosystems 11: 355–366.
Snapp SS, Gentry LE, Harwood R. 2010. Management intensity—not
biodiversity—the driver of ecosystem services in a long-term row crop
experiment. Agriculture, Ecosystems and Environment 138: 242–248.
Stone RC, Meinke H. 2005. Operational seasonal forecasting of crop
performance. Philosophical Transactions of the Royal Society B 360:
Sunderland K, Samu F. 2000. Effects of agricultural diversification on the
abundance, distribution, and pest control potential of spiders: A review.
Entomologia Experimentalis et Applicata 95: 1–13.
Tengö M, Belfrage K. 2004. Local management practices for dealing with
change and uncertainty: A cross-scale comparison of cases in Sweden
and Tanzania. Ecology and Society 9: 4.
Thies C, Tscharntke T. 1999. Landscape structure and biological control in
agroecosystems. Science 285: 893–895.
Elmqvist T, Folke C, Nyström M, Peterson G, Bengtsson J, Walker B,
Norberg J. 2003. Response diversity, ecosystem change, and resilience.
Frontiers in Ecology and the Environment 1: 488–494.
Finckh MR, et al. 2000. Cereal variety and species mixtures in practice, with
emphasis on disease resistance. Agronomie 20: 813–837.
Folke C, Carpenter S, Walker B, Scheffer M, Elmqvist T, Gunderson L, Hol-
ling CS. 2004. Regime shifts, resilience, and biodiversity in ecosystem
management. Annual Review of Ecology, Evolution, and Systematics
35: 557–581.
Fuhrer J. 2003. Agroecosystem responses to combinations of elevated CO2,
ozone, and global climate change. Agriculture, Ecosystems and Environ-
ment 97: 1–20.
Gardner J, Dowd A-M, Mason C, Ashworth P. 2009. A Framework for Stake-
holder Engagement on Climate Adaptation. Commonwealth Scien-
tific and Industrial Research Organisation Climate Adaptation Flagship
Working Paper no. 3. CSIRO.
Gurr GM, Wratten SD, Luna JM. 2003. Multi-function agricultural biodi-
versity: Pest management and other benefits. Basic and Applied Ecology
4: 107–116.
Heal G. 2000. Nature and the Marketplace: Capturing the Value of Ecosys-
tem Services. Island Press.
Herdt RW. 2006. Biotechnology in agriculture. Annual Review of Environ-
ment and Resources 31: 265–295.
Holling CS. 1973. Resilience and stability of ecological systems. Annual
Review of Ecology and Systematics 4: 1–23.
Holt-Giménez E. 2002. Measuring farmers’ agroecological resistance after
Hurricane Mitch in Nicaragua: A case study in participatory, sustain-
able land management impact monitoring. Agriculture, Ecosystems and
Environment 93: 87–105.
Hossain Z, Gurr GM, Wratten SD. 2001. Habitat manipulation in lucerne
(Medicago sativa L.): Strip harvesting to enhance biological control of
insect pests. International Journal of Pest Management 47: 81–88.
Howden S, Crimp S, Nelson R. 2010. Australian agriculture in a climate
of change. Pages 101–111 in Jubb I, Holper P, Cai W, eds. Managing
Climate Change. CSIRO.
[IWMI] International Water Management Institute. 2007. Water for Food,
Water for Life: A Comprehensive Assessment of Water Management in
Agriculture. IWMI.
Jones JW, Hoogenboom G, Porter CH, Boote KJ, Batchelor WD, Hunt LA,
Wilkens PW, Singh U, Gijsman AJ, Ritchie JT. 2003. The DSSAT crop-
ping system model. European Journal of Agronomy 18: 235–265.
Jones PG, Thornton PK. 2003. The potential impacts of climate change on
maize production in Africa and Latin America in 2055. Global Environ-
mental Change 13: 51–59.
Keating BA, et al. 2003. An overview of APSIM, a model designed for farm-
ing systems simulation. European Journal of Agronomy 18: 267–288.
Krupinsky JM, Bailey KL, McMullen MP, Gossen BD, Turkington TK. 2002.
Managing plant disease risk in diversified cropping systems. Agronomy
Journal 94: 198–209.
Landis DA, Wratten SD, Gurr GM. 2000. Habitat management to conserve
natural enemies of arthropod pests in agriculture. Annual Review of
Entomology 45: 175–201.
Langellotto G, Denno R. 2004. Responses of invertebrate natural enemies
to complex-structured habitats: A meta-analytical synthesis. Oecologia
139: 1–10.
Lansigan FP, de los Santos WL, Coladilla JO. 2000. Agronomic impacts of
climate variability on rice production in the Philippines. Agriculture,
Ecosystems and Environment 82: 129–137.
Lin BB. 2007. Agroforestry management as an adaptive strategy against
potential microclimate extremes in coffee agriculture. Agricultural and
Forest Meteorology 144: 85–94.
Lin BB, Perfecto I, Vandermeer J. 2008. Synergies between agricultural in-
tensification and climate change could create surprising vulnerabilities
for crops. BioScience 58: 847–854.
Marino PC, Landis DA, 1996. Effect of landscape structure on parasitoid
diversity and parasitism in agroecosystems. Ecological Applications 6:
Articles March 2011 / Vol. 61 No. 3 • BioScience 193
Thomas MB, Wratten SD, Sotherton NW. 1991. Creation of “island” habitats
in farmland to manipulate populations of beneficial arthropods: Preda-
tor densities and emigration. Journal of Applied Ecology 28: 906–917.
Tilman D, Cassman KG, Matson PA, Naylor R, Polasky S. 2002. Agricultural
sustainability and intensive production practices. Nature 418: 671–677.
Tilman D, Reich PB, Knops JMH. 2006. Biodiversity and ecosystem stability
in a decade-long grassland experiment. Nature 441: 629–632.
[USDA] US Department of Agriculture. 2008. Drought-hardy Soybean
Lines Show Their Stamina. USDA. (8 December 2010; www.ars.usda.
Vandermeer J, van Noordwijk M, Anderson J, Ong C, Perfecto I. 1998.
Global change and multi-species agroecosystems: Concepts and issues.
Agriculture, Ecosystems and Environment 67: 1–22.
Walker B. 1995. Conserving biological diversity through ecosystem resil-
ience. Conservation Biology 9: 747–752.
Weiss A, Hays CJ, Won J. 2003. Assessing winter wheat responses to climate
change scenarios: A simulation study in the U.S. Great Plains. Climatic
Change 58: 119–147.
Wollenweber B, Porter JR, Schellberg J. 2003. Lack of interaction between
extreme high-temperature events at vegetative and reproductive
growth stages in wheat. Journal of Agronomy and Crop Science 189:
Wu J, Adams RM, Kling CL, Tanaka K. 2004. From microlevel decisions to
landscape changes: An assessment of agricultural conservation policies.
American Journal of Agricultural Economics 86: 26–41.
Yachi S, Loreau M. 1999. Biodiversity and ecosystem productivity in a
fluctuating environment: The insurance hypothesis. Proceedings of the
National Academy of Sciences 96: 1463–1468.
Zhu Y, et al. 2000. Genetic diversity and disease control in rice. Nature 406:
Brenda B. Lin ( is a fellow of the American Association for
the Advancement of Science and when this article was written was with the
Environmental Protection Agency. She is now with the Australian Common-
wealth Scientific and Industrial Research Organisation.
MIT Press Journals
Werner Callebaut, Editor-in-Chief
Biological Theory
Biological eory is devoted to theoretical advances in the fields of evolution
and cognition with an emphasis on the conceptual integration afforded by
evolutionary and developmental approaches. e journal appeals to a wide
audience of scientists, social scientists, and scholars from the humanities,
particularly philosophers and historians of biology.
Published by the MIT Press and the Konrad Lorenz Institute for Evolution and Cognition Research.
and Cognition
BIOT-halfpage-sept-2010.indd 1 9/14/2010 10:40:36 AM
... La biodiversité est l'un des piliers des systèmes agricoles agroécologiques (Altieri, 1999;Tittonell et al., 2020). La diversité spatiale et temporelle des espèces cultivées, au niveau des parcelles, des exploitations agricoles et des territoires, constitue la composante la plus planifiable de cette biodiversité agricole (Beillouin et al., 2019;Duru et al., 2015;Lin, 2011). ...
... La diversité des cultures contribue, sous certaines conditions, à maintenir la production alimentaire en limitant le recours aux intrants externes à l'exploitation agricole ou au territoire : elle réduit ainsi les externalités négatives associées aux modes de production simplifiés et spécialisés (Davis et al., 2012;Isbell et al., 2017;Mediene et al., 2011;Rosset and Altieri, 1997), et améliore la résilience des systèmes agricoles face aux aléas (Liebman and Schulte, 2015;Lin, 2011;Peoples et al., 2019). Combinée à un ensemble cohérent de pratiques, la diversification des cultures permet en effet de mieux contrôler les populations d'adventices (Adeux et al., 2019;Weisberger et al., 2019;Yvoz et al., 2020) et de réduire la pression des maladies et des ravageurs (Ratnadass et al., 2011;Storkey et al., 2019) au champ. ...
... En termes de travail, les motivations des agriculteurs concernent le niveau de simplicité ou de complexité dans la gestion de leurs systèmes de culture, la distribution du travail au cours de l'année, la gestion des concurrences entre chantiers, la recherche d'un travail « intéressant », ou la curiosité autour de nouvelles cultures. Des ressources pour accompagner les agriculteurs dans cette gestion de systèmes complexes pour qu'elle réponde à leurs objectifs en termes de travail sont nécessaires (Delecourt et al., 2019;Lin, 2011;Merot and Wery, 2017 La question des impacts de la production agricole sur l'environnement, centrale dans les articles académiques explicitant les enjeux de la diversification (Beillouin et al., 2021;Kremen and Miles, 2012), est peu explicitée comme telle par les agriculteurs. Ils évoquent cependant le rôle que jouent parfois, dans leur choix de diversifier, des préoccupations autour de la réduction d'intrants, de l'évolution des conditions climatiques et de la disponibilité en eau, ou des déséquilibres de biodiversité ayant une incidence sur les maladies, les ravageurs et les niveaux de régulation biologique. ...
La diversification des cultures est un enjeu majeur de l’agroécologie, mais se heurte à une situation de verrouillage autour de quelques espèces cultivées dominantes. L’objectif de la thèse est d’identifier des moyens de sortir de ces situations de verrouillage, en s’appuyant sur des expériences existantes de diversification des cultures dans trois territoires en France, en Italie et en Suède. En identifiant des mécanismes de diversification transversaux à ces trois territoires, ce travail donne à voir la diversité des manières de diversifier et des processus qui y sont associés.L’analyse des trajectoires d’exploitations agricoles ayant diversifié leurs cultures nous permet de mettre en évidence les motivations à diversifier des agriculteurs et leurs combinaisons. La diversité de ces motivations et des ressources mobilisées par les agriculteurs au cours de leur trajectoire conduisent à des processus de diversification de nature et d’intensité variées.Au niveau des territoires, nous caractérisons différents types de systèmes d’approvisionnement à travers lesquels sont commercialisées les cultures de diversification. La caractérisation de ces systèmes nous permet de comprendre la relation entre les stratégies des entreprises d’aval et les dynamiques de diversification, et de montrer l’importance de la complémentarité des systèmes d’approvisionnement pour la diversification des territoires.Enfin, nous éclairons les modalités d’apprentissage des agriculteurs qui diversifient. Celles-ci évoluent au cours des trajectoires, selon l’objet sur lequel portent les apprentissages, mais aussi en fonction des attentes des agriculteurs vis-à-vis de la diversification, et des systèmes d’approvisionnement dans lesquels ils s’engagent.Nous concluons en proposant aux acteurs des filières et des territoires, ainsi qu’aux pouvoirs publics, quelques leviers d’action favorables à la restauration d’une dynamique de diversification.
... In principle, crop diversification is considered as a sustainable agricultural strategy because of its potential ecological benefits (Lin, 2011) that translate into cost savings (Rahman, 2009;Arslan et al., 2018) and increased incomes (Guvele, 2001;Makate et al., 2016). Given its potential implications on farmer welfare, several governments and international development agencies/organizations [e.g., US Agency for International Development, the Food and Agricultural Organization (FAO), World Bank (WB), and the Intergovernmental Panel on Climate Change (IPCC)] have continuously increased their support for crop diversification (Mzyece, 2020). ...
... On the other hand, results from the EP model suggest that the Mz/Gn/Ct, Mz/Ct, Mz/Gn/Sb, Mz/Ct/Sf as well as Mz/Gn statistically increase gross margin per hectare relative to the Mz EP. This could be due to the increased ecological benefits from leguminous crops such as groundnuts or higher prices associated with cotton, or soybeans which have the potential to alleviate farmers' exposure to price fluctuations effecting a single commodity (Hahn et al., 2009;Lin, 2011;Mulwa et al., 2017;Maggio and Sitko, 2021). Additionally, the Mz/Sp, Mz/Sf, Mz/Sb, Mz/Gn/Sf, Mz/Gn/Sp, Mz/Gn/Mb, and the Mz/Gn/Sb/Sf EPs do not statistically offer higher profitability than specializing in Mz which could be due to biological and economic attributes of the crops and their combinations (Tilman et al., 2005). ...
Full-text available
Introduction: While crop diversification indices are relatively simple and useful for quantifying the extent of crop diversification, they may not account for the potential differences in the types of crops grown. This study shows the need to complement crop diversification indices with an enterprise structure approach to improve index- based crop portfolio decision making. Methods: The study uses linear regression models and nationally representative farm survey data from 7,934 farmers in Zambia. The study compares the enterprise approach and the Simpson index of diversification which is commonly used in crop diversification studies. Results and discussion: We find that complementing the enterprise structure approach with the Simpson index of diversification can increase profitability by as high as 77.89% for farmers. The cassava enterprise structure had the most returns for farmers. It had a gross margin of ZMW 3,887 per hectare and was trailed by the maize/groundnuts/cotton/rice enterprise structure with a gross margin of ZMW3,681 per hectare. These results suggest that the use of aggregation crop diversification indices, without an additional enterprise structure analysis, may obscure the necessary insights needed to practically help farmers.
... The economic diversity indicator measures the diversity of activities at the farm level, assuming that the greater the number of activities, the higher the economic risk. Agricultural biodiversity is an important lever to improve resilience and climate change adaptation in addition to food security [52,53]. The indicator proposed here is adapted from the "Shannon diversity index" and provides a measure of crop diversity in relation to economic value, i.e., gross margins. ...
Full-text available
Conceptualized by the Food and Agriculture Organization in 2010, climate-smart agriculture aims to simultaneously tackle three main objectives. These are increasing food security, building the resilience of agricultural systems for adaptation to climate change and mitigation of GHG. As much research focuses on one of these three objectives, our understanding of how agricultural systems address these three challenges simultaneously is limited by the lack of a comprehensive evaluation tool. In order to fill this gap, we have developed a generic evaluation framework that comprises 19 indicators that we measured in a sample of 12 representative farms of the North Basse-Terre region in Guadeloupe. The evaluation revealed clear differences in the performance of these farming systems. For example, nutritional performance varied from 0 to 13 people fed per hectare, the average potential impact of climatic conditions varied from 27% to 33% and the GHG emissions balance varied from +0.8 tCO2eq·ha−1 to +3.6 tCO2eq·ha−1. The results obtained can guide the design of innovative production systems that better meet the objectives of climate-smart agriculture for the study region. The evaluation framework is intended as a generic tool for a common evaluation basis across regions at a larger scale. Future prospects are its application and validation in different contexts.
... Agroforestry trees contribute to soil protection, water regulation, enhancement of microclimatic conditions, reduces impacts on natural forests and other environmental benefits in addition to its major climate regulation function (carbon sequestration) (Mbow et al., 2014b). When trees are integrated on farms, improvements in land productivity and resilience of households has been shown through products diversification for human sustainability (Lin, 2011;Agevi et al., 2017;Mbow et al., 2014a). ...
Full-text available
Agroforestry (AF) is being practiced traditionally as a sustainable land- use option, in many agro-ecological zones of Sub-Saharan Africa. Agroforestry is important as incorporating trees and shrubs in food crop systems can help address food insecurity issues and reduce vulnerability of agricultural systems to climate change. The purpose of this study was to investigate the current agroforestry practices and their relevance to enhancing food security and climate change resilience among rural communities in Rajaf County. Household surveys using structured and semi-structured questionnaires, Key informants interviews (KIIs) and Focused Group Discussions (FGDs) were used as tools to collect survey data in which 332 household respondents were sampled and interviewed. Results indicated that most people practiced agrisilvicultural and agrisilvopastoral AF systems with scattered trees on farms, boundary plantings, homegardens, and woodlots as their on-farm arrangements. While goats and chicken were most reported domestic animals; sorghum, beans, groundnuts, cassava, maize, and simsim were the most reported food crops. The most preferred tree species were Mangifera indica, Azadiractha indica, Balanites aegyptiaca, Mahogany spp, Acacia spp, etc for distinguished uses. Over 350 trees were inventoried by non-destructive methods through systematically established line transects and circular sample plots. The tree species parameters (DBH, H & CR) were measured and used to determine their diversity, abundance and carbon sequestration potentials. It was found that average DBH of trees in AF farms was 12.68cm with a minimum and maximum DBH of 5.0 cm and 62.9 cm respectively. Densities for respective species were calculated and above-ground biomass (AGB) equations or models were then used to generate results to estimate carbon sequestration potential of AGB. Chave 2014 was taken as the baseline model to compare among the other models used and select the best fitting model for computation of aboveground carbon (AGC). From the calculated AGB, it is revealed that most carbon sequestration stock accrued from boundary planting (183.1 tons/ha), homegardens spp (142.5 tons/ha), scattered trees in farms (132.2 tons/ha). Tree diversity was not uniform as few species are found in other AF sites although there was abundance of some species such as citrus spp, Mangifera indica, Psidium guajava, Acacia spp and Tectona grandis. The values of Shannon diversity indices varied among the sites: Kolye west (2.211), Gumbo (1.726), Kolye East (2.268) and Tokiman Island (1.699). Agroforestry practices have the potential to food security and climate change because it holds more components as compared to conventional Agriculture and Forestry, resulting into diversified alternative sources despite its intensive labour requirements i.e there is always a secured next component in case of failure of one component. Therefore, farmers should be encouraged to practice AF that results to food availability and accessibility. Keywords: Traditional agroforestry, on-farms trees, aboveground biomass, carbon sequestration, homegardens, diversity, climate change resilience, farmer’s perceptions, South Sudan
... Therefore, more diversified cropping systems are needed to enhance the agroecological transition towards more sustainable agriculture (Lechenet et al. 2014;Duru et al. 2015;Liebman and Schulte 2015;Liu et al. 2019;Beillouin et al. 2020). For instance, lengthening crop rotations through the introduction of diversifying crops has been shown to be relevant to, among others, reducing pesticide use, as a result of a better biological control of weeds, diseases, and pests (Colbach et al. 2010;Lin 2011;Wezel et al. 2014). Building on the acknowledged benefits of crop diversification, the transition process towards more diversified cropping systems has already begun in various regions of the world but remains slow due to many obstacles (Roesch-McNally et al. 2018;Burchfield and Poterie 2018;Audouin et al. 2018;Weituschat et al. 2022), including socio-technical lock-ins favoring major dominant crop species. ...
Full-text available
Despite the acknowledged benefits of crop diversification, the transition towards more diversified cropping systems needs to be supported, mainly due to socio-technical lock-ins favoring major dominant crop species. This calls for the development of new approaches to support the design of locally tailored diversified cropping systems. This paper aims to present an original participatory and multi-actor design approach, developed to support the introduction of camelina ( Camelina sativa ) into the cropping systems of northern France and to provide some insights about the characteristics, the specificities, and the limits of this approach to support its use and adaptation to other contexts. For 3 years, and in connection with the development of an oilseed biorefinery, we gathered a variety of actors (farmers, advisors, engineers in agronomy, researchers, and industrialists) to locally support the introduction of camelina in the cropping systems. First, we illustrate the diversity of the modalities that have been collectively imagined to introduce and manage camelina in the local cropping systems. Then, we describe the originality and the diversity of the knowledge produced on camelina, especially during the assessment of some of these modalities within on-farm experiments. Finally, drawing on concepts and theories from design sciences, we show that (i) the pre-existence of networks of actors, (ii) the rationale involvement of the actors, (iii) the implementation of a situated design process fueled by action and distributed among actors, (iv) the sharing and the circulation of knowledge among a diversity of actors involved in the production and use of the new crop, and (v) the implementation of an effective network management contributed to foster the three key elements that we identified as crucial to support crop diversification, namely, the production of actionable knowledge, the exploration of new ideas/concepts, and the active participation of a diversity of actors of the agri-food system.
... The continuous improvement of crop adaptation to the environment is essential for maintaining crop productivity in the context of increasing food demand [1]. Furthermore, crop diversification is essential to more sustainable agriculture [2]. This diversification could be implemented either by the adaptation of species that are not cultivated yet, requiring considerable breeding efforts, or by the deployment of crops that are at the limit of their distribution area [3,4]. ...
Full-text available
Deploying crops in regions bordering their initial distribution area requires adapting existing cultivars to particular environmental constraints. In this study, we revealed the main Eco-climatic Factors (EFs)—climatic factors recorded over specific phenological periods—impacting both yields and Genotype by Environment Interactions (GEI) for yield in early maturity soybeans (Glycine max (L.) Merrill) under high latitudes. A multi-year (2017–2021) and multi-environment (n = 112) database was built based on the official post-inscription French soybean trial network “SOJA Terres Inovia-GEVES-Partenaires”. Yields of 57 cultivars covering MG00 and MG000 maturity groups were considered. For each environment, 126 EFs were calculated using a Crop Growth Model (CGM) based on observed weather data and simulated developmental stages. Partial Least Square (PLS) regression analyses using the Variable Importance in Projection (VIP) score were used to sort out the most relevant EFs for their impact on yield levels on the one side and on GEI for yield on the other side. Our results confirmed that yield levels for both maturity groups were greatly influenced by climatic factors from the seed filling phenophases, mainly End of Pod to Physiological Maturity. The cumulative potential evapotranspiration during the End of Pod to Physiological Maturity period was the main EF affecting yield levels positively for both maturity groups (VIP = 2.86; R² = 0.64). Interestingly, EFs explaining yield levels strongly differed from those explaining GEI, in terms of both climatic factors and phenophases. GEI were mostly influenced by climatic factors from First Flower to End of Pod; these factors were maximum temperatures and solar radiation intensity. Cold stress from Sowing to First Seed also appeared to be a critical driver for GEI in MG00 soybeans. The contrasted responses of several cultivars to the main GEI-drivers highlighted a potential genetic variability that could be exploited in early maturity soybean breeding. This study revealed the complexity of GEI ecophysiology, and our results should help breeding strategies to deliver germplasm that outperforms the existing genetic material for expanding the crop to northern European regions.
... Many pathways have been put forth to enable this transformation, including changes that increase the efficiency of production, use less land under cropping systems, reduce food waste and allow for more plant-based diets (Foley et al. 2011;Lin 2011;Springmann et al. 2018;Stehfest et al. 2009;Thompson 2015). Researchers agree that more than one strategy is needed to meet the 2 • target of the Paris Agreement (Foley et al. 2011;Springmann et al. 2018), and thus that we need to take into account trade-offs and synergies in the adoption of different strategies and seek synergies that will maximize outcomes with multiple benefits among food security, adaptation and mitigation (Saj et al. 2017;Springmann et al. 2018). ...
Full-text available
Food systems are responsible for pushing human resource use past three thresholds of safe planetary operating space, yet the potential of agroecosystems to contribute to sustainability of food systems when managed for multiple benefits is underexplored. This gap has led to a call for food systems transformation. Previous reviews have acknowledged that governance of food systems transformations is not well understood. The aim of this review is to examine the challenges to transformative governance of agroecosystems, and the potential to apply existing paradigms of adaptiveness in agroecosystems for this transformation. Agricultural production landscapes have been found to be a key level of governance for realizing sustainability transformations of food systems and the landscape concept has been a key paradigm for managing multiple social and ecological objectives at a landscape scale. An examination of the landscape concept using five transformative governance characteristics and applying the earth system governance research lenses illustrated two key areas for further investigation and action for transformative governance. The first is landscape design for continuous social and ecological changes and evolving understandings of sustainability, and the second is the allocation of landscape costs, rights and benefits in present and future decision-making and among human and non-human entities. Managing the pluralistic diversities inherent to agroecosystems will be a key dynamic important to governance and policy for food systems transformations.
... and protecting crops from disease, insect and weed pests must be done concomitantly to improve crop yields [5]. Plant diversification in the form of greater vegetation complexity and/or diversity has been proposed as a natural and eco-friendly method to regulate agricultural pests and create resilient farming systems [6,7]. As such, a captious complaint of monoculture cropping systems is that reduced habitat complexity causes these systems to be more vulnerable to pest outbreaks [8]. ...
Full-text available
There is increased adoption of cover cropping and conservation tillage in the USA. Many farmers view these practices as methods for improving their soils. However, different cover cropping and tillage practices conducted post-harvest can have a disparate impact on arthropods within the subsequent cash crop. Field experiments were conducted during 2017 and 2018 at two experimental sites to examine the influences of different post-harvest practices following corn (Zea mays L.) harvest on pests and beneficials in subsequent soybean [Glycine max (L.) Merr.] plantings. Experimental treatments included: (1) tillage via chisel plow (CP), (2) no-tillage in which corn residue/stubble remained on the soil surface (CS), and (3) planting a cover crop into corn residue (CC) following corn harvest. Overall, insect herbivore abundance was greater in the CP treatment. Foliar predator numbers were similar among treatments or of greater abundance in CP. The activity density of epigeal insect predators varied according to site and feeding guild. However, spider activity density was greatest in CP. Stink bug egg mortality due to predation and parasitism varied among treatments. However, the percentage of stink bug eggs that hatched was greatest in the CC during both years. Findings suggest that post-harvest practices investigated during this study will have a similar influence on most epigeal and foliar arthropods in soybean.
... Although the potential contribution of agroforestry systems to the maintenance of the ecosystem is still in argument and it remains largely unexplored (Harvey and Villalobos, 2007). Furthermore, there is a lack of empirical data on the relationships between agroforestry and household livelihood resilience, particularly concerning mitigating climate change (Lin, 2011;Nair and Garrity, 2012). These are all brought on by a lack of comprehensive empirical data. ...
Full-text available
Agro forestry systems are believed to provide several ecosystem services; however, until recently evidence in the agro forestry literature supporting these perceived benefits has been lacking. This paper aimed to provide empirical information on the role of agro forestry in ecosystem maintenance and climate change adaptation and mitigation provided by agro forestry. Agro forestry has played a greater role in the maintenance of the ecosystem and mitigation of CO 2 than monocropping and open cereal-based agriculture but less than natural forest. Agro forestry is important for preserving biodiversity, CO 2 sequestration, and adapting to climate change. CO 2 sequestration through above and ground biomass, offsetting CO 2 emission from deforestation and microclimate modification are major climate change mitigation effects. Provision of numerous ecosystem services such as food, fodder, and fuel wood, income source, and enhancing soil productivity help the community to sustain changing climate effects. Hence, considerable attention needs to be given to agro forestry to contribute considerable benefit to the maintenance of the ecosystem, and climate change mitigation and adaptation next to a forest.
Full-text available
Crop diversification has shifted the cultivation of the low-value crops towards the high value crops. The crop diversification in the hilly regions has led to the increase in the income and improves standard of living of the farmers of these regions. Crop diversification in the hilly regions has boosted in the past few decades due to the congenial Agro climatic conditions and niche areas for the production of fruits and vegetables. The production of food crops in the North western and North eastern hilly areas shifted from cereals and pulses towards the high value crops like fruits and vegetable. The share of the cereals and pulses has declined in the value of output of agricultural commodities over the years however, the share of fruits and vegetables, condiments and spices, etc. was increased and the growth was observed in the condiments and spices. In certain regions the cultivation of the medicinal plants as well as condiments and spices has led to great achievement in respect of the diversification and there were certain potential unharvest which can harnessed by utilization of various technologies and further research
Full-text available
The armyworm (Pseudaletia unipuncta) was used as a model host insect to explore the influence of agricultural landscape structure at two spatial scales on larval parasitoid species richness and rates of larval parasitism in southern Michigan. First, within fields, we compared parasitoid communities in maize fields near, and distant from, a hedgerow edge. Second, we replicated these studies within a complex landscape (agricultural fields of small size embedded in a landscape with abundant hedgerows and woodlots) vs. a simple landscape (agricultural fields of large size embedded in a landscape with few hedgerows and woodlots). The structural differences between the simple and complex agricultural landscapes were characterized by analysis of aerial photographs and digital land-use data. After landscape analysis, three maize fields from each area were selected for the experimental studies. The complex landscape contained fields that were 75% smaller, had 63% more perimeter of wooded field edge per hectare of field area, and had 81% more field edge in wide hedgerow than fields in the simple landscape. Fields in the simple landscape had 74% and 53% more field edge in herbaceous roadside and crop-to-crop interfaces, respectively, than did fields in the complex landscape. In the six selected maize fields, third and fifth instar P. unipuncta were released individually onto maize plants 5 m and 90 m from a hedgerow edge. Larvae were recovered after 4-5 d and reared in the laboratory to record parasitoid emergence. Parasitoid species diversity was similar in both landscape types (simple landscape: four species; complex landscape: five species). Mean percentage parasitism was significantly higher in the complex landscape than in the simple landscape (13.1% vs. 2.4%) but was not affected by the location within fields (near hedgerows vs. distant from hedgerows) in either landscape type.
Conference Paper
Diversification of cereal cropping systems with alternative crops, such as oilseed, pulse, and forage crops, furnishes producers with a range of agronomic and economic options. Crop diversification also improves management of plant diseases through manipulation of host factors such as crop and cultivar selection; interruption of disease cycles through crop rotation, fungicide application. and removal of weeds and volunteer crop plants; and modification of the microenvironment within the crop canopy using tillage practices and stand density. Management practices, such as seed treatment, date and rate of seeding. balanced fertility, control of weeds, field scouting, harvest management, and record keeping, can also be utilized to manage plant diseases. This review evaluates the risks to diversified crop production systems associated with the major plant diseases in the northern Great Plains and the influence of host, pathogen, and environmental factors on disease control. Principles to help producers reduce and manage the risk from plant diseases are presented, and discussion includes strategies for countering fusarium head blight (Fusarium spp.). commonly called scab; and leaf spot diseases in cereals; sclerotinia stem rot [Sclerotinia sclerotiorum (Lib.) De Bary] in oilseed and pulse crops; and ascochyta blight (Ascochyta lentis Vassil.; teleomorph: Didymella lentis Kaiser, Wang & Rogers) and anthracnose blight [Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore] in pulse crops. Producers should not rely exclusively on a single management practice but rather integrate a combination of practices to develop a consistent long-term strategy for disease management that is suited to their production system and location.
Human-driven ecosystem simplification has highlighted questions about how the number of species in an ecosystem influences its functioning. Although biodiversity is now known to affect ecosystem productivity, its effects on stability are debated. Here we present a long-term experimental field test of the diversity–stability hypothesis. During a decade of data collection in an experiment that directly controlled the number of perennial prairie species, growing-season climate varied considerably, causing year-to-year variation in abundances of plant species and in ecosystem productivity. We found that greater numbers of plant species led to greater temporal stability of ecosystem annual aboveground plant production. In particular, the decadal temporal stability of the ecosystem, whether measured with intervals of two, five or ten years, was significantly greater at higher plant diversity and tended to increase as plots matured. Ecosystem stability was also positively dependent on root mass, which is a measure of perenniating biomass. Temporal stability of the ecosystem increased with diversity, despite a lower temporal stability of individual species, because of both portfolio (statistical averaging) and overyielding effects. However, we found no evidence of a covariance effect. Our results indicate that the reliable, efficient and sustainable supply of some foods (for example, livestock fodder), biofuels and ecosystem services can be enhanced by the use of biodiversity.
Diversification of cereal cropping systems with alternative crops, such as oilseed, pulse, and forage crops, furnishes producers with a range of agronomic and economic options. Crop diversification also improves management of plant diseases through manipulation of host factors such as crop and cultivar selection; interruption of disease cycles through crop rotation, fungicide application, and removal of weeds and volunteer crop plants; and modification of the microenvironment within the crop canopy using tillage practices and stand density. Management practices, such as seed treatment, date and rate of seeding, balanced fertility, control of weeds, field scouting, harvest management, and record keeping, can also be utilized to manage plant diseases. This review evaluates the risks to diversified crop production systems associated with the major plant diseases in the northern Great Plains and the influence of host, pathogen, and environmental factors on disease control. Principles to help producers reduce and manage the risk from plant diseases are presented, and discussion includes strategies for countering fusarium head blight (Fusarium spp.), commonly called scab; and leaf spot diseases in cereals; sclerotinia stem rot [Sclerotinia sclerotiorum (Lib.) De Bary] in oilseed and pulse crops; and ascochyta blight (Ascochyta lentis Vassil.; teleomorph: Didymella lentis Kaiser, Wang & Rogers) and anthracnose blight [Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore] in pulse crops. Producers should not rely exclusively on a single management practice but rather integrate a combination of practices to develop a consistent long-term strategy for disease management that is suited to their production system and location.
(1) Grass-sown raised earth banks were created as `islands' in the centres of two cereal fields to provide improved overwintering conditions for invertebrate predators. They recreated those aspects of existing field boundaries which had previously been shown to favour predator overwintering. (2) During the first year of establishment, the new habitats provided overwintering refuge sites for many species of Araneae, Carabidae and Staphylinidae. Ground-zone searches produced total polyphagous predator densities of up to 150 m-2. (3) During the second year, grass establishment increased still further and destructive sampling revealed predator numbers exceeding 1500 m-2 in some grass treatments. (4) Vacuum-net samples taken during the second spring after establishment, showed that the overwintering populations of two predator species in the new habitats influenced dispersal patterns into the crop. (5) Prospects for the long-term enhancement of predator populations via field scale manipulations of farmland habitats are discussed.