The question of how to meet rising food demand at the least cost to biodiversity requires the evaluation of two contrasting alternatives: land sharing, which integrates both objectives on the same ...land; and land sparing, in which high-yield farming is combined with protecting natural habitats from conversion to agriculture. To test these alternatives, we compared crop yields and densities of bird and tree species across gradients of agricultural intensity in southwest Ghana and northern India. More species were negatively affected by agriculture than benefited from it, particularly among species with small global ranges. For both taxa in both countries, land sparing is a more promising strategy for minimizing negative impacts of food production, at both current and anticipated future levels of production.
Bees provide essential pollination services that are potentially affected both by local farm management and the surrounding landscape. To better understand these different factors, we modelled the ...relative effects of landscape composition (nesting and floral resources within foraging distances), landscape configuration (patch shape, interpatch connectivity and habitat aggregation) and farm management (organic vs. conventional and local‐scale field diversity), and their interactions, on wild bee abundance and richness for 39 crop systems globally. Bee abundance and richness were higher in diversified and organic fields and in landscapes comprising more high‐quality habitats; bee richness on conventional fields with low diversity benefited most from high‐quality surrounding land cover. Landscape configuration effects were weak. Bee responses varied slightly by biome. Our synthesis reveals that pollinator persistence will depend on both the maintenance of high‐quality habitats around farms and on local management practices that may offset impacts of intensive monoculture agriculture.
Farm-level decisions affect the level of productivity and the character of smallholder agriculture landscapes. Landscape crop diversity (LCD) results from farmer decisions and provides information ...about the broader impacts of human-environment interactions. Here, we analyzed the LCD and assessed the influence of local agri-food actors on farmers’ decisions and LCD using semi-structured interviews (N=24) for an agroecological intervention and a comparable control area. We analyzed crop types and computed LCD from remote sensing data using Simpson’s Index of Diversity. With insights from systems perspectives and Vroom’s expectancy theory of motivation, we explored the driving factors of farmers’ cropping decisions and the influential role of local actors in these decisions. We found LCD to be higher in the intervention area than in the control area – indicating that intervention farmers primarily practiced intercropping and crop rotation, creating heterogeneous landscapes. In contrast, control area landscapes were relatively homogeneous due largely to maize cultures. Intervention farmers were motivated by reasons of ecological resilience and the desire to adapt to environmental change because of their instrumentality – enhanced knowledge, expectancy – the expectation of higher productivity from practicing crop diversity, and valence – the value placed on the ecological importance of crop diversity to the environment and economic gain. These motivations emanated from years of work with a local agricultural non-governmental organization and farmer-to-farmer knowledge sharing. The economic value of a crop and seed access through contract farming deals mainly motivated control farmers’ decisions. Thus, strategies designed to draw linkages between agriculture and landscape structure for environmental sustainability must consider the central role of local actors in influencing farmers’ decisions.
•Knowledge and practice of agroecology increase adoption of crop diversity.•Landscapes crop diversity is higher where agroecological farming predominates.•Farmers’ instrumentality, valence, and expectancy motivate crop diversity adoption.•Collaborative knowledge creation and sharing facilitates crop diversity.•Diverse satellite data improves crop diversity mapping in small farms.
•Presents the first estimate of sustainable productivity of Brazil's pasturelands.•Current productivity of Brazilian cultivated pasturelands is 32–34% of potential.•Increasing productivity to 49–52% ...of the potential suffices to meet demands.•The area of 18 million hectares could be spared for Atlantic Rainforest restoration.•Up to 14.3Gt CO2 Eq could be mitigated in relation to deforestation projections.
Providing food and other products to a growing human population while safeguarding natural ecosystems and the provision of their services is a significant scientific, social and political challenge. With food demand likely to double over the next four decades, anthropization is already driving climate change and is the principal force behind species extinction, among other environmental impacts. The sustainable intensification of production on current agricultural lands has been suggested as a key solution to the competition for land between agriculture and natural ecosystems. However, few investigations have shown the extent to which these lands can meet projected demands while considering biophysical constraints. Here we investigate the improved use of existing agricultural lands and present insights into avoiding future competition for land. We focus on Brazil, a country projected to experience the largest increase in agricultural production over the next four decades and the richest nation in terrestrial carbon and biodiversity. Using various models and climatic datasets, we produced the first estimate of the carrying capacity of Brazil's 115 million hectares of cultivated pasturelands. We then investigated if the improved use of cultivated pasturelands would free enough land for the expansion of meat, crops, wood and biofuel, respecting biophysical constraints (i.e., terrain, climate) and including climate change impacts. We found that the current productivity of Brazilian cultivated pasturelands is 32–34% of its potential and that increasing productivity to 49–52% of the potential would suffice to meet demands for meat, crops, wood products and biofuels until at least 2040, without further conversion of natural ecosystems. As a result up to 14.3Gt CO2 Eq could be mitigated. The fact that the country poised to undergo the largest expansion of agricultural production over the coming decades can do so without further conversion of natural habitats provokes the question whether the same can be true in other regional contexts and, ultimately, at the global scale.
To truly understand the current status of tropical diversity and to forecast future trends, we need to increase emphasis on the study of biodiversity in rural landscapes that are actively managed or ...modified by people. We present an integrated landscape approach to promote research in human-modified landscapes that includes the effects of landscape structure and dynamics on conservation of biodiversity, provision of ecosystem services, and sustainability of rural livelihoods. We propose research priorities encompassing three major areas: biodiversity, human-environment interactions, and restoration ecology. We highlight key areas where we lack knowledge and where additional understanding is most urgent for promoting conservation and sustaining rural livelihoods. Finally, we recommend participatory and multidisciplinary approaches in research and management. Lasting conservation efforts demand new alliances among conservation biologists, agroecologists, agronomists, farmers, indigenous peoples, rural social movements, foresters, social scientists, and land managers to collaborate in research, co-design conservation programs and policies, and manage human-modified landscapes in ways that enhance biodiversity conservation and promote sustainable livelihoods.
Between 1990 and 2000, farmland birds showed a significant decline across Europe, a trend not shared by bird assemblages of other habitats over the same period. Mean trends for each farmland species ...in the period 1990–2000 were positively correlated with trends over the period 1970–1990, and there was little change in population trajectory for most species over the 30-year period. Of the 58 species classed by an independent assessment as being primarily birds of farmland, 41 showed negative overall mean trends across Europe in 1990–2000, 19 of them significant. There was a significant negative correlation between mean national trends of all farmland species and indices of national agricultural intensity. This relationship strengthened when the 19 declining species were considered alone, and was not apparent when only non-declining species were considered. Population trends of terrestrial non-farmland bird species over the same period were unrelated to agricultural intensity. Trends in farmland bird populations were independent of the proportion of farmland under agri-environment prescriptions. The results support earlier evidence that population trends of farmland birds across Europe can be predicted from gross national agricultural statistics. Substantial changes in agricultural policy, particularly the removal of economic incentives that lead to agricultural intensification, are required if 2010 targets for halting loss of biodiversity are to be met in an enlarged European Union
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Antimicrobials, parasiticides, feed additives and probiotics are used in Asian aquaculture to improve the health status of the cultured organisms and to prevent or treat disease outbreaks. Detailed ...information on the use of such chemicals in Asian aquaculture is limited, but of crucial importance for the evaluation of their potential human health and environmental risks. This study reports the outcomes of a survey on the use of chemical and biological products in 252 grow-out aquaculture farms and 56 farm supply shops in four countries in Asia. The survey was conducted between 2011 and 2012, and included nine aquaculture farm groups: Penaeid shrimp farms in Bangladesh, China, Thailand and Vietnam; Macrobrachium prawn farms, and farms producing both Penaeid shrimps and Macrobrachium prawns in Bangladesh; tilapia farms in China and Thailand; and Pangasius catfish farms in Vietnam. Results were analysed with regard to the frequencies of use of active ingredients and chemical classes, reported dosages, and calculated applied mass relative to production. A range of farm management and farm characteristics were used as independent variables to explain observed chemical use patterns reported by farmers within each group. Sixty different veterinary medicinal ingredients were recorded (26 antibiotics, 19 disinfectants, and 15 parasiticides). The use of antibiotic treatments was found to be significantly higher in the Vietnamese Pangasius farms. However, total quantities of antibiotics, relative to production, applied by the Pangasius farmers were comparable or even lower than those reported for other animal production commodities. Semi-intensive and intensive shrimp farms in China, Thailand and Vietnam showed a decrease in the use of antibiotic treatments. These farm groups utilised the largest amount of chemicals relative to production, with feed additives and plant extracts, probiotics, and disinfectants, being the most used chemical classes, mainly for disease prevention. The surveyed farmers generally did not exceed recommended dosages of veterinary medicines, and nationally or internationally banned compounds were (with one exception) reported neither by the surveyed farmers, nor by the surveyed chemical sellers. Factors underlying the observed differences in chemical use patterns differed widely amongst farm groups, and geographical location was found to be the only factor influencing chemical ingredient application patterns in the majority of the studied farm groups.
•We assessed the use of chemicals in 252 aquaculture grow-out farms from Asia.•The use of antibiotics was significantly higher in the Vietnamese Pangasius farms.•Chemical use practices varied according to the species and production intensity.•Applied chemical volumes are comparable to other food producing commodities.
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.
We examine the potential role of perennial woody food-producing species (“food trees”) in cities in the context of urban sustainable development and propose a multifunctional approach that combines ...elements of urban agriculture, urban forestry, and agroforestry into what we call “urban food forestry” (UFF). We used four approaches at different scales to gauge the potential of UFF to enhance urban sustainability and contribute to food security in the context of urbanization and climate change. First, we identified 37 current initiatives based around urban food trees, and analyzed their activities in three categories: planting, mapping, and harvesting, finding that the majority (73 %) only performed one activity, and only 8 % performed all three. Second, we analyzed 30 urban forestry master plans, finding that only 13 % included human food security among their objectives, while 77 % included habitat for wildlife. Third, we used Burlington, Vermont as a case study to quantify the potential fruit yield of publicly accessible open space if planted with
Malus domestica
(the common apple) under nine different planting and yield scenarios. We found that 108 % of the daily recommended minimum intake of fruit for the entire city’s population could be met under the most ambitious planting scenario, with substantial potential to contribute to food security even under more modest scenarios. Finally, we developed a Climate–Food–Species Matrix of potential food trees appropriate for temperate urban environments as a decision-making tool. We identified a total of 70 species, 30 of which we deemed “highly suitable” for urban food forestry based on their cold hardiness, drought tolerance, and edibility. We conclude that substantial untapped potential exists for urban food forestry to contribute to urban sustainability via increased food security and landscape multifunctionality.
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