Increasing crop heterogeneity enhances multitrophic diversity across agricultural regions

International audienceAgricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter “crop heterogeneity”) can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production

Comparing social representations of the landscape: a methodology

International audienceSocial representations (SRs) are systems of values, ideas, and practices that characterize individuals' and social groups' relationships to both their social and natural environment. Comparing SRs between places, social groups, and through time is critical to understanding how social-ecological systems (SESs) and their diverse uses are perceived, interpreted, and understood. This knowledge needs to be taken into account to achieve efficient land use management of SESs such as agricultural landscapes. People's perceptions of the landscape are increasingly studied in sustainability sciences and a growing number of studies use the SR framework for analyzing differences in SRs between stakeholders and localities or for detecting changes over time. Robust methodologies able to compare SRs are required for this purpose. In this paper, we propose a modular approach to studying SRs from words collected from free listing tasks. This approach relies on standardizing definitions of frequency thresholds commonly used to assess SR content, consensus level, and structure. We then illustrate the value of this methodological approach through a comparative study of farmers' social representations of the agricultural landscape among four contrasted social-ecological contexts in France. We show how our comparative method allows for characterizing spatial variations in SRs and identifying social-ecological factors that influence the structuration and content of SRs. Finally, we discuss our methodological progress and the implications of our results for public policies aimed at managing SESs and in particular agricultural landscapes for conservation

Of people and trees: exploring the spatio-temporal dynamics of urban and periurban dwellers’ social representations of trees.

Almost 40 years ago, Pyle [1] started to warn the scientific community about the progressive disconnection between urban dwellers and nature. This so-called "extinction of experience" may affect individual relationships toward elements of nature in the everyday life, such as knowledge, emotions, attitudes and practices. It may also affect social representations (SRs) of these elements of nature, i.e., collective elaborations "of a social object by the community for the purpose of behaving and communicating" [2]. In turn, varying SRs are linked with different prioritization in conservation policies. Here, we explored the hypothesis of "extinction of experience" regarding such a valued component of urban nature (e.g. [3]), by characterizing individual relationships with, and social representations of trees, in varying urbanization contexts and for different generations of people, in Paris area (France). We computed a questionnaire comprising: (1) a free-listing task and three open-ended questions to elicit the SRs of "tree"; (2) closed-ended questions to evaluate individual relationship to them; (3) socio-demographic variables. We adminstrated the questionnaire face-to-face with 80 people from 8 to 93 years old in the city of Dugny, and online with 454 people from 18 to 85 years old living in urban and sub-urban areas. We analyzed the words elicited through the free-listing task with rank-frequency analyses to elicit the content and structure of the social representation. Individual relationships to trees were characterized using a multivariate analysis and a classification algorithm. We then extracted the main lexical worlds used by respondents from a lexical analysis of the open-ended questions. We showed three main dimensions in the social representations of urban trees: (1) trees are considered as key components of nature through their perceived function of providing oxygen, (2) they are perceived through an aesthetic dimension; (3) they hold important symbolic and affective representations. Multivariate analyses showed that urban people closer to trees associated them more frequently to their ecological functions. By comparing the SR of younger and older people in our sample, we studied the temporal dynamics of the social representations of trees. Combining qualitative and quantitative analyses allowed us to suggest a loss of autonomy of the concept of trees vis-à-vis the broader and less specific concept of "nature" that dominate the social representation, together with a decreasing association between trees and "forest" through time. These results invite us to question the ways to integrate trees in cities and sub-urban agricultural landscapes in a way that promotes physical and emotional experiences with trees. [1] Pyle R.M. 1978. Horticulture 56: 64-67. [2] Moscovici S. 1963. Annual Review of Psychology 14: 231-260. [3] Vesely E.T. 2007. Ecological Economics 63:605-615peerReviewe

Ways of farming and ways of thinking: do farmers' mental models of the landscape relate to their land management practices?

The efficiency of the European Union's Common Agricultural Policy in mitigating the negative effects of agricultural intensification on the landscape and biodiversity is increasingly being questioned. Enhancing a reciprocal understanding of various stakeholders' mental models of agro-social-ecosystems has been proposed to trigger changes in both policy design and farmers' behaviors. However, the relationship between farmers' mental models and practices is rarely considered. Here, we explore the relationship between farmers' individual mental models (IMMs) of the agricultural landscape and their land management practices. To do so, we developed a theoretical and methodological framework grounded in cognitive psychology and farming system research for eliciting and comparing IMMs and land management practices. We applied this framework in the Coteaux de Gascogne territory, a hilly crop-livestock region in southern France. We identified groups of farmers according to their cropland and semi-natural habitat management practices. The results of our quantitative and qualitative comparisons of mental models between farmer groups showed that the way of farming partly relates to farmers' ways of thinking about the landscape and highlighted the heterogeneity of IMMs between and within farmer groups. We found evidence that path-dependent factors that constrain farmers' practices can modify their mental models, e.g., the role of agricultural machinery. Our study illustrates how an interdisciplinary framework coupling mental models and farming systems approaches provides an opportunity to enhance our understanding of the relationships between farmers' world views and their practices. Moreover, our results challenge current ways of thinking and designing biodiversity conservation policies in farmed landscapes

Convergences and divergences in understanding the word biodiversity among citizens: A French case study

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