How trees in agricultural landscapes structure pollinator communities ?

Technology adoption has often been a key constraint on improving productivity, income and yields in farming, particularly in developing countries where market-based systems of production are not well developed, the subsistence economy remains strong, land is held under communal tenure and family labour is the backbone of production. This session welcomes papers that explore socio-cultural and economic factors that constrain or limit the adoption of new technologies in agroforestry systems. We interpret technology in its broad sense to include non-material technologies such as new farm management techniques, labour arrangements, changing gender relations, new regimes of land tenure, etc., as well as material technologies like new processing machinery, inorganic fertiliser and so on. We anticipate that together the presentations will provide an overview of the key constraints on technology adoption and smallholder productivity in much of the developing world and point to potential solutions and strategies to address such constraints

0357 : Platypnea orthodeoxia syndrome: focus on predisposing anatomical factors

Platypnea orthodeoxia syndrome (POS) is a rare situation with hypoxia and breathlessness in the upright position recovering in the recumbent position. A mechanical inter-atrial septum distortion, causing redirection of flow from the right to the left atrium through a patent foramen ovale (PFO), despite normal pulmonary pressure, is suggested to explain POS. Prevalence of predisposing anatomical factors remain little knownMethodsAll patients who underwent a PFO closure for a POS were retrospectively included from 2 CHU. Predisposing anatomical factors were investigated.Results67 patients (Median age 72 y.o., interquartile range 61-80; 58.2% men) were included. All patients had dyspnea (76.2% NYHA III or IV, 53.7% under oxygen-therapy). The remaining patients had a refractory hypoxemia (38.2%) without POS. Most frequent predisposing anatomical factor was an enlarged or unwound aorta (n=29, 43.3% 95CI 31.2-56.0) with an aortic aneurysm in 25 patients (37.3%, 95CI 25.8-50.0). Other factors identified were pneumonectomy (n=8, 11.9% CI95 5.3-22.2), a history of cardiac surgery (n=7, 10.5%, 95CI 4.3-20.3), mechanical ventilation (n=6, 9.0% 95CI 3.4-18.5), kyphoscoliosis (n=4, 6.0% 95CI 1.7-14.6), hepatomegaly (n=4, 6.0% 95CI 1.7-14.6, 2 patients with hepato-renal polycystic disease, one hemochromatosis and one cirrhosis), right ventricle failure (n=2,3.0% 95CI 0.4-10.4), pericardial effusions (n=2,3.0% 95CI 0.4-10.4), right ventricle arrhythmogenic dysplasia (n=2,3.0% 95CI 0.4-10.4), diaphragmatic paralysis (n=1, 1.5% 95CI 0.1-8.0), carcinoid syndrome with tricuspid regurgitation (n=1, 1.5% 95CI 0.1-8.0), a right atrium pace-maker lead (n=1, 1.5% 95CI 0.1-8.0) and a tako-tsubo syndrome (n=1, 1.5% 95CI 0.1-8.0).ConclusionAortic aneurysm and pneumonectomy are the most frequent situation leading to a POS. Other causes were observed such as hepato-renal polycystic kidney, or atrial pacemaker probe that may be underdiagnosed in clinical practice

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

Hétérogénéité des paysages et des pratiques agricoles : effets sur la diversité des abeilles sauvages et la pollinisation

The ecological and agricultural importance of wild bees in farmlands stresses the needs for management strategies for these insect pollinators. Wild bees use multiple habitats in agricultural landscapes, such as semi -natural habitats (woodlands, hedgerows, permanent grasslands) and crop fields. This study aims to characterize the community structure of wild bees and assess pollination delivery along gradients of landscape heterogeneity based on the composition and configuration of semi-natural habitats and landscape-wide intensity of farming practices. Using a trait-based approach, based on traits determining resource-use by wild bee species, we showed that i) the least mobile species, solitary bees and ground-nesting species were more abundant in crop fields surrounded by large amounts of little-fragmented permanent grasslands, ii) crop fields surrounded by high amount of woodland edges supported a greater abundance of little-mobile bee species, late-emerging bees, social bees and polylectic bees, iii) oligolectic bee species were filtered out in highly forested landscapes , because these species could thrive on resources provided by the crop mosaic. We also found that the positive effect of the proportion of semi-natural habitats on bee diversity was greater in landscapes with intensively managed crop mosaic. Moreover, we showed that the local intensity of farming practices had as much influence on bee diversity as the proportion of semi-natural habitats. Finally, we showed that, depending on situations, the abundance fluctuations of dominant bee species or the occurrence of an assemblage of uncommon bee species can explain variations in pollination success. In the cases where pollination success responded to the occurrence of uncommon species, the proportion of semi-natural habitats had a positive influence on pollination delivery provided by wild bees. This study shows the importance of some uncommon species, dependent on semi-natural habitats, for pollination delivery but also the positive relationship between the abundance of some species groups and the proportion of semi-natural habitats. This work therefore confirms the hypothesis that semi-natural habitats sustain the diversity of wild bee communities and pollination delivery. However, the positive effect of semi-natural habitats on bee diversity depends on farming practices at the local and landscape scale. Therefore, recommendations on the management of landscape heterogeneity and changes in farming practices cannot be given independently from each other.L’importance écologique et agronomique des abeilles sauvages dans les paysages agricoles rend cruciale la gestion de ces insectes pollinisateurs. Les abeilles sauvages utilisent plusieurs habitats dans les paysages agricoles, comme les milieux semi-naturels (bois, haies, prairies permanentes), mais aussi les parcelles agricoles. L’objectif de ce travail est de caractériser la structure des communautés de pollinisateurs et le succès de pollinisation le long de gradients de composition et de configuration des milieux semi-naturels ainsi que d’intensité des pratiques agricoles à l’échelle paysagère. Par une approche basée sur les trais écologiques, traduisant des différences d’utilisation des ressources par les abeilles sauvages, nous avons mis en évidence que i) les abeilles sauvages peu mobiles, les espèces solitaires mais aussi les espèces terricoles (nids souterrains) sont plus abondantes dans des parcelles agricoles entourées d’une forte proportion de prairies permanentes faiblement fragmentées, ii) les parcelles entourées d’une forte quantité de lisières forestières présentent une abondance plus importante d’espèces peu mobiles, d’espèces tardives, sociales et polylectiques, iii) les espèces oligolectiques sont filtrées (exclues) dans les paysages fortement boisés car ce sont des espèces profitant de ressources fournies par la mosaïque cultivée. Nous avons aussi mis en évidence que l’effet positif de la proportion en milieux semi-naturels sur la diversité des abeilles sauvages était plus important dans des paysages à la mosaïque agricole gérée de façon intensive. Nous montrons par ailleurs que l’intensité locale des pratiques agricoles peut autant influencer la diversité des abeilles sauvages que la proportion de milieux semi-naturels environnants. Enfin, nous montrons que, suivant les situations, l’abondance des espèces d’abeilles sauvages dominantes ou la présence d’un assemblage d’espèces peu communes peut expliquer le succès de pollinisation. Il semblerait que, dans le cas où le succès de pollinisation répond à l’occurrence d’espèces peu communes, la proportion de milieux semi-naturels aurait une influence positive sur le succès de pollinisation par les abeilles sauvages. Ce travail de thèse démontre l’importance d’espèces peu communes, dépendantes des milieux semi-naturels, pour le succès de pollinisation mais aussi la relation positive entre l’abondance de certains groupes d’espèces et la proportion de milieux semi-naturels. Ce travail permet donc de soutenir l’hypothèse selon laquelle les milieux semi-naturels sont garants du maintien de la diversité des abeilles sauvages et des services rendus par ces dernières. Cependant, l’effet positif des milieux semi-naturels sur la diversité des abeilles sauvages est variable, puisque il dépend des pratiques agricoles à l’échelle locale et paysagère. Les préconisations d’aménagement paysager et de modifications des pratiques ne peuvent donc être faites indépendamment les unes des autres

Organic farming improves the spatiotemporal stability of pollinator species richness

The spatiotemporal stability of the biodiversity of service providers such as insect pollinators is critical to guarantee high and stable levels of ecosystem services in agroecosystems. The proportion of semi-natural habitats (SNH) in the landscapes has been shown to stabilize the species richness of pollinators but the effect of farming intensity has not yet been studied. In this study, we compared the temporal and spatial stability of two groups of pollinating insects (butterflies and bumblebees) between nine conventional and ten organic farms, distributed along a gradient of landscape complexity. We surveyed pollinator communities and local flower cover during the growing season, along three years and in several habitat types per landscape (cereal fields, ley fields and semi-natural grasslands). At the plot scale we found that within-year stability of bumblebee species richness was higher in organic than in conventional ley fields, and that it was due to higher continuity of in-field flower resources. Our results also suggested that late-season flower resources in organic ley fields were critical to maintain a high within-year stability of bumblebee richness by reducing resource bottleneck during that period. The long term (among-years) stability of bumblebee richness was also higher in organic than in conventional cereal fields. The temporal stability of butterfly richness was not influenced by farming system. On the farm scale we also found that the spatial stability of butterfly and bumblebee species richness was higher in organic than in conventional farms, but that it was not explained by a greater spatial continuity of flower resources. Our study therefore suggest that organic farming can help to maintain the short-term stability of bumblebee species richness, due to practices that favor flower resources in ley fields (no mineral fertilizers, late mowing, etc.). Other practices, such as the non-use of insecticides, might be responsible for higher long-term stability of bumblebee richness in cereal fields, or landscape-scale spatial stability of both bumblebee and butterfly richness.peerReviewe

Quelle biodiversité des abeilles sauvages favorise la pollinisation ?

National audienc

Selection of floral resources to optimise conservation of agriculturally-functional insect groups

Non-crop vegetation in agricultural landscapes can provide a means of conserving insects in farmed landscapes and optimising on-farm ecosystem services as a result. Inclusion of floral resources may be particularly useful in conserving many beneficial insects, where groups including pollinators and pest natural enemies often rely on nectar and pollen during (at least part of) their life-cycle. As not all flowers are equally suited to all beneficial insects, selection of appropriate flowering plants is key to ensuring that conservation targets are met and benefits to ecosystems services realised as a result. This short paper describes an experiment conducted to assess the ‘total temporal attractiveness’ of a range of British wildflowers to selected functional insect groups. The results obtained demonstrate that flowering period alone is a poor indicator of plant suitability to insects, where no relationship existed between this and attraction to insects overall. Data also suggest that, based on attraction over a season, certain flowering plants are more likely to be of general insect conservation value and/or benefit to functional insect groups than others. Attraction to pest insects was also considered, with relatively high catches of thrips and pollen beetles observed in flowering stands of some plants

Flowering forbs for field margins: selecting species that optimise ecosystem services

The aim of this study was to assess the attractiveness of flowers to target groups of beneficial insects. Water trap samples were taken throughout the entire period of inflorescence and were accompanied by sweep net sampling in early summer. Samples were assessed for target insect groups (predatory beetles, true bugs, aphids, hoverflies and Parasitica) that are known to provide ecosystem services in farm landscapes (such as pollination, conservation and pest control). Yarrow and Oxeye daisy were the most promising flowering plants, attracting multiple beneficial target groups. These species seem to be the most promising for use in flowering field margins

Sensitivity to agricultural inputs and dispersal limitation determine the response of arable plants to time since transition to organic farming

Transitioning to low-input agricultural systems such as organic farming has been acknowledged as a way to mitigate negative effects of agriculture on biodiversity. However, the speed, magnitude and context dependence of biodiversity recovery after converting to organic farming remain uncertain. In this study, we explored the response of plant communities to time since transition to organic farming in a variety of production contexts. Using a spatially replicated space-for-time substitution design, we surveyed plant communities in small-grain cereal and ley fields in conventional and organic farms, distributed along independent gradients of time since transition to organic farming and proportion of seminatural grasslands in the landscapes. We selected a set of response traits to explore the mechanism of potential time lag in that response to conversion. These traits were selected to characterize the sensitivity of plant species to agricultural inputs and their ability to respond swiftly to environmental changes. We found an increase in plant species richness and evenness in cereal fields with increasing time since transition to organic farming, and a similar but less pronounced pattern in leys. After 30 years of continuous organic farming, organic cereal fields harboured more than twice the number of plant species than newly converted fields. Importantly, we found that the dependence on insect pollination, sensitivity to herbicides and dispersal capacity of plants modulated the effects of time since transition on plant communities in cereal fields. This suggests that both management and biotic interactions shape plant community structure in response to organic practices over time. Policy implications. Our study highlights that benefits of organic farming for plant diversity are likely to take decades to become substantial after conversion. We found this slow recovery of plant communities to be driven by both the gradual improvement of habitat quality after conversion and species' dispersal limitation. Assessments of biodiversity benefits of organic farming should therefore consider this time delay to avoid underestimating its environmental performance. Farmers should also be supported during this ecological transitional phase during which yield-enhancing ecosystem services reliant on plant diversity might build up.Peer reviewe

Organic farming supports spatiotemporal stability in species richness of bumblebees and butterflies

The spatiotemporal stability of wild organisms, such as flower-visiting insects, is critical to guarantee high levels of biodiversity in agroecosystems. Whereas the proportion of semi-natural habitats in the landscapes has been shown to stabilize the species richness of flower visitors, the effect of farming intensity has not yet been studied. In this study, we compared the temporal and spatial stability (continuity of species richness in space and time) of two groups of flower-visiting insects (butterflies and bumblebees) between nine conventional and ten organic farms, distributed along a gradient of semi-natural grassland proportion. We surveyed bumblebees, butterflies and local flower cover during the growing season, covering multiple years and several habitat types per farm (cereal fields, temporary grasslands and semi-natural grasslands). At the field scale we found that within-year stability of bumblebee species richness was higher in organic than in conventional temporary grasslands (leys), because of a higher continuity of in-field flower resources. Further analyses showed that late-season flower resources in organic ley fields were critical to maintain a high within-year stability of bumblebee species richness by reducing resource bottlenecks during that period, when most bumblebee colonies produce new queens. The among-year stability of bumblebee species richness was higher in organic than in conventional cereal fields, whereas the within and among-year stability of butterfly species richness was not influenced by farming system. On the farm scale, we found that the spatial stability of butterfly and bumblebee species richness was higher in organic than in conventional farms, but this was not explained by a greater spatial continuity of flower resources. Our study shows that organic farming reduces the spatiotemporal fluctuations in bumblebee and butterfly species richness. In addition, increasing floral resources as such benefits bumblebees and butterflies irrespective of farming system. Organic farming and increasing availability in floral resources therefore contribute to maintaining the within and between-year stability of bumblebees and butterflies in agricultural landscapes