Conservation biologists are devoting an increasing amount of energy to debating whether land sparing (high‐yielding agriculture on a small land footprint) or land sharing (low‐yielding, ...wildlife‐friendly agriculture on a larger land footprint) will promote better outcomes for local and global biodiversity. In turn, concerns are mounting about how to feed the world, given increasing demands for food. In this review, I evaluate the land‐sparing/land‐sharing framework—does the framework stimulate research and policy that can reconcile agricultural land use with biodiversity conservation, or is a revised framing needed? I review (1) the ecological evidence in favor of sparing versus sharing; (2) the evidence from land‐use change studies that assesses whether a relationship exists between agricultural intensification and land sparing; and (3) how that relationship may be affected by socioeconomic and political factors. To address the trade‐off between biodiversity conservation and food production, I then ask which forms of agricultural intensification can best feed the world now and in the future. On the basis of my review, I suggest that the dichotomy of the land‐sparing/land‐sharing framework limits the realm of future possibilities to two, largely undesirable, options for conservation. Both large, protected regions and favorable surrounding matrices are needed to promote biodiversity conservation; they work synergistically and are not mutually exclusive. A “both‐and” framing of large protected areas surrounded by a wildlife‐friendly matrix suggests different research priorities from the “either‐or” framing of sparing versus sharing. Furthermore, wildlife‐friendly farming methods such as agroecology may be best adapted to provide food for the world's hungry people.
Given widespread declines in pollinator communities and increasing global reliance on pollinator-dependent crops, there is an acute need to develop a mechanistic understanding of native pollinator ...population and foraging biology. Using a population genetics approach, we determine the impact of habitat and floral resource distributions on nesting and foraging patterns of a critical native pollinator, Bombus vosnesenskii . Our findings demonstrate that native bee foraging is far more plastic and extensive than previously believed and does not follow a simple optimal foraging strategy. Rather, bumble bees forage further in pursuit of species-rich floral patches and in landscapes where patch-to-patch variation in floral resources is less, regardless of habitat composition. Thus, our results reveal extreme foraging plasticity and demonstrate that floral diversity, not density, drives bee foraging distance. Furthermore, we find a negative impact of paved habitat and a positive impact of natural woodland on bumble bee nesting densities. Overall, this study reveals that natural and human-altered landscapes can be managed for increased native bee nesting and extended foraging, dually enhancing biodiversity and the spatial extent of pollination services.
We hypothesize that biological diversification across ecological, spatial, and temporal scales maintains and regenerates the ecosystem services that provide critical inputs—such as maintenance of ...soil quality, nitrogen fixation, pollination, and pest control—to agriculture. Agrobiodiversity is sustained by diversified farming practices and it also supplies multiple ecosystem services to agriculture, thus reducing environmental externalities and the need for off-farm inputs. We reviewed the literature that compares biologically diversified farming systems with conventional farming systems, and we examined 12 ecosystem services: biodiversity; soil quality; nutrient management; water-holding capacity; control of weeds, diseases, and pests; pollination services; carbon sequestration; energy efficiency and reduction of warming potential; resistance and resilience to climate change; and crop productivity. We found that compared with conventional farming systems, diversified farming systems support substantially greater biodiversity, soil quality, carbon sequestration, and water-holding capacity in surface soils, energy-use efficiency, and resistance and resilience to climate change. Relative to conventional monocultures, diversified farming systems also enhance control of weeds, diseases, and arthropod pests and they increase pollination services; however, available evidence suggests that these practices may often be insufficient to control pests and diseases or provide sufficient pollination. Significantly less public funding has been applied to agroecological research and the improvement of diversified farming systems than to conventional systems. Despite this lack of support, diversified farming systems have only somewhat reduced mean crop productivity relative to conventional farming systems, but they produce far fewer environmental and social harms. We recommend that more research and crop breeding be conducted to improve diversified farming systems and reduce yield gaps when they occur. Because single diversified farming system practices, such as crop rotation, influence multiple ecosystem services, such research should be holistic and integrated across many components of the farming system. Detailed agroecological research especially is needed to develop crop- and region-specific approaches to control of weeds, diseases, and pests.
Diversified Farming Systems Kremen, Claire; Iles, Alastair; Bacon, Christopher
Ecology and society,
01/2012, Letnik:
17, Številka:
4
Journal Article
Recenzirano
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This Special Issue on Diversified Farming Systems is motivated by a desire to understand how agriculture designed according to whole systems, agroecological principles can contribute to creating a ...more sustainable, socially just, and secure global food system. We first define Diversified Farming Systems (DFS) as farming practices and landscapes that intentionally include functional biodiversity at multiple spatial and/or temporal scales in order to maintain ecosystem services that provide critical inputs to agriculture, such as soil fertility, pest and disease control, water use efficiency, and pollination. We explore to what extent DFS overlap or are differentiated from existing concepts such as sustainable, multifunctional, organic or ecoagriculture. DFS are components of social-ecological systems that depend on certain combinations of traditional and contemporary knowledge, cultures, practices, and governance structures. Further, as ecosystem services are generated and regenerated within a DFS, the resulting social benefits in turn support the maintenance of the DFS, enhancing its ability to provision these services sustainably. We explore how social institutions, particularly alternative agri-food networks and agrarian movements, may serve to promote DFS approaches, but note that such networks and movements have other primary goals and are not always explicitly connected to the environmental and agroecological concerns embodied within the DFS concept. We examine global trends in agriculture to investigate to what extent industrialized forms of agriculture are replacing former DFS, assess the current and potential contributions of DFS to food security, food sovereignty and the global food supply, and determine where and under what circumstances DFS are expanding rather than contracting.
The eighteenth-century Malthusian prediction of population growth outstripping food production has not yet come to bear. Unprecedented agricultural land expansions since 1700, and technological ...innovations that began in the 1930s, have enabled more calorie production per capita than was ever available before in history. This remarkable success, however, has come at a great cost. Agriculture is a major cause of global environmental degradation. Malnutrition persists among large sections of the population, and a new epidemic of obesity is on the rise. We review both the successes and failures of the global food system, addressing ongoing debates on pathways to environmental health and food security. To deal with these challenges, a new coordinated research program blending modern breeding with agro-ecological methods is needed. We call on plant biologists to lead this effort and help steer humanity toward a safe operating space for agriculture.
Biological diversity could enhance ecosystem service provision by increasing the mean level of services provided, and/or by providing more consistent (stable) services over space and time. Ecological ...theory predicts that when an ecosystem service is provided by many species, it will be stabilized against disturbance by a variety of 'stabilizing mechanisms.' However, few studies have investigated whether stabilizing mechanisms occur in real landscapes affected by human disturbance. We used two datasets on crop pollination by wild native bees to screen for and differentiate among three stabilizing mechanisms: density compensation (negative co-variance among species' abundances); response diversity (differential response to environmental variables among species); and cross-scale resilience (response to the same environmental variable at different scales by different species). In both datasets, we found response diversity and cross-scale resilience, but not density compensation. We conclude that stabilizing mechanisms may contribute to the stability of pollination services in our study areas, emphasizing the insurance value of seemingly 'redundant' species. Furthermore, the absence of density compensation that we found at the landscape scale contrasts with findings of previous small-scale experimental and modelling work, suggesting that we should not assume that density compensation will stabilize ecosystem services in real landscapes.
A hypothesized underlying principle of the diversity‐functioning relationship is that functional groups respond differently to environmental change. Over 3 years, we investigated how pollinator ...diversity contributes to the magnitude of pollination service through spatial complementarity and differential response to high winds in California almond orchards. We found honey bees preferentially visited the top sections of the tree. Where wild pollinators were present, they showed spatial complementarity to honey bees and visited the bottom tree sections more frequently. As wind speed increased, honey bees' spatial preference shifted toward the bottom tree sections. In high winds (>2.5 m s−1), orchards with low pollinator diversity (honey bees only) received almost no flower visits. In orchards with high pollinator diversity, visitation decreased to a lesser extent as wild bee visitation was unaffected by high winds. Our results demonstrate how spatial complementarity in diverse communities can help buffer pollination services to environmental changes like wind speed.
Farms benefit from pest control services provided by nature, but management of these services requires an understanding of how habitat complexity within and around the farm impacts the relationship ...between agricultural pests and their enemies. Using cage experiments, this study measures the effect of habitat complexity across scales on pest suppression of the cabbage aphid
Brevicoryne brassicae
in broccoli. Our results reveal that proportional reduction of pest density increases with complexity both at the landscape scale (measured by natural habitat cover in the 1 km around the farm) and at the local scale (plant diversity). While high local complexity can compensate for low complexity at landscape scales and vice versa, a delay in natural enemy arrival to locally complex sites in simple landscapes may compromise the enemies' ability to provide adequate control. Local complexity in simplified landscapes may only provide adequate top-down pest control in cooler microclimates with relatively low aphid colonization rates. Even so, strong natural enemy function can be overwhelmed by high rates of pest reproduction or colonization from nearby source habitat.
Many major corporations and countries have made commitments to purchase or produce only “sustainable” palm oil, a commodity responsible for substantial tropical forest loss. Sustainability ...certification is the tool most used to fulfill these procurement policies, and around 20% of global palm oil production was certified by the Roundtable on Sustainable Palm Oil (RSPO) in 2017. However, the effect of certification on deforestation in oil palm plantations remains unclear. Here, we use a comprehensive dataset of RSPO-certified and noncertified oil palm plantations (∼188,000 km²) in Indonesia, the leading producer of palm oil, as well as annual remotely sensed metrics of tree cover loss and fire occurrence, to evaluate the impact of certification on deforestation and fire from 2001 to 2015. While forest loss and fire continued after RSPO certification, certified palm oil was associated with reduced deforestation. Certification lowered deforestation by 33% from a counterfactual of 9.8 to 6.6% y−1. Nevertheless, most plantations contained little residual forest when they received certification. As a result, by 2015, certified areas held less than 1% of forests remaining within Indonesian oil palm plantations. Moreover, certification had no causal impact on forest loss in peatlands or active fire detection rates. Broader adoption of certification in forested regions, strict requirements to avoid all peat, and routine monitoring of clearly defined forest cover loss in certified and RSPO member-held plantations appear necessary if the RSPO is to yield conservation and climate benefits from reductions in tropical deforestation.
Ecology Letters (2011) 14: 922–932
Many studies in recent years have investigated the relationship between landscape complexity and pests, natural enemies and/or pest control. However, no ...quantitative synthesis of this literature beyond simple vote‐count methods yet exists. We conducted a meta‐analysis of 46 landscape‐level studies, and found that natural enemies have a strong positive response to landscape complexity. Generalist enemies show consistent positive responses to landscape complexity across all scales measured, while specialist enemies respond more strongly to landscape complexity at smaller scales. Generalist enemy response to natural habitat also tends to occur at larger spatial scales than for specialist enemies, suggesting that land management strategies to enhance natural pest control should differ depending on whether the dominant enemies are generalists or specialists. The positive response of natural enemies does not necessarily translate into pest control, since pest abundances show no significant response to landscape complexity. Very few landscape‐scale studies have estimated enemy impact on pest populations, however, limiting our understanding of the effects of landscape on pest control. We suggest focusing future research efforts on measuring population dynamics rather than static counts to better characterise the relationship between landscape complexity and pest control services from natural enemies.
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