7,190 research outputs found
Alexandra Klein: work, inspiration, and tips from her time as a guest researcher at BECC
No full textBECC regularly welcomes guest researchers to work in areas within its scientific framework, with the aim to further strengthen the research and research groups. Prof. Dr. Alexandra-Maria Klein is head of the Chair of Nature Conservation and Landscape Ecology at the University of Freiburg in Germany, who recently finished her timer as a BECC guest researcher
Pollinator shortage and global crop yield
No full textFil: Garibaldi, Lucas Alejandro. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio Ecotono; Argentina.Fil: Aizen, Marcelo A. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio Ecotono; Argentina.Fil: Cunningham, Saul A. CSIRO Entomology; Australia.Fil: Klein, Alexandra M. University of California; USA.Fil: Klein, Alexandra M. University of Goettingen; Alemania.Fil: Aizen, Marcelo A. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Aizen, Marcelo A. Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA); Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.A pollinator decline caused by environmental degradation might be compromising the production of pollinator-dependent crops. In a recent article, we compared 45 year series (1961–2006) in yield, production, and cultivated area of pollinator-dependent and nondependent crop around the world. If pollinator shortage is occurring globally, we expected a lower annual growth rate in yield for pollinator-dependent than nondependent crops, but a higher growth in cultivated area to compensate the lower yield. We have found little evidence for the first “yield” prediction but strong evidence for the second “area” prediction. Here, we present an additional analysis to show that the first and second predictions are both supported for crops that vary in dependency levels from nondependent to moderate dependence (i.e. up to 65% average yield reduction without pollinators). However, those crops for which animal pollination is essential (i.e. 95% average yield reduction without pollinators) showed higher growth in yield and lower expansion in area than expected in a pollination shortage scenario. We propose that pollination management for highly pollinator-dependent crops, such us renting hives or hand pollination, might have compensated for pollinator limitation of yield
How much does agriculture depend on pollinators? Lessons from long-term trends in crop production
No full textFil: Aizen, Marcelo A. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio Ecotono; Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio Ecotono; Argentina.Fil: Cunningham, Saul A. CSIRO Entomology; Australia.Fil: Klein, Alexandra M. University of California; USA.Fil: Aizen, Marcelo A. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Aizen, Marcelo A. Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA); Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Fil: Klein, Alexandra M. University of Goettingen; Alemania.Abstract
Background and Aims
Productivity of many crops benefits from the presence of pollinating insects, so a decline in pollinator abundance should compromise global agricultural production. Motivated by the lack of accurate estimates of the size of this threat, we quantified the effect of total loss of pollinators on global agricultural production and crop production diversity. The change in pollinator dependency over 46 years was also evaluated, considering the developed and developing world separately.
Methods
Using the extensive FAO dataset, yearly data were compiled for 1961–2006 on production and cultivated area of 87 important crops, which we classified into five categories of pollinator dependency. Based on measures of the aggregate effect of differential pollinator dependence, the consequences of a complete loss of pollinators in terms of reductions in total agricultural production and diversity were calculated. An estimate was also made of the increase in total cultivated area that would be required to compensate for the decrease in production of every single crop in the absence of pollinators.
Key Results
The expected direct reduction in total agricultural production in the absence of animal pollination ranged from 3 to 8 %, with smaller impacts on agricultural production diversity. The percentage increase in cultivated area needed to compensate for these deficits was several times higher, particularly in the developing world, which comprises two-thirds of the land devoted to crop cultivation globally. Crops with lower yield growth tended to have undergone greater expansion in cultivated area. Agriculture has become more pollinator-dependent over time, and this trend is more pronounced in the developing than developed world.
Conclusions
We propose that pollination shortage will intensify demand for agricultural land, a trend that will be more pronounced in the developing world. This increasing pressure on supply of agricultural land could significantly contribute to global environmental change
Nearby rainforest promotes coffee pollination by increasing spatio-temporal stability in bee species richness
No full textNatural tropical forests are highly diverse and are known to contribute to forest-based services such as pollination of nearby crops. Landscape changes cause spatial and temporal bee community changes, but consequences how the community changes affect pollination is not well analyzed. This paper addresses the effects of rainforest distance and on site flower resources in agro-forests on spatial and temporal variation in pollinator communities and the consequences for coffee pollination. The Study was conducted in 24 agro-forests dominated by coffee and cacao in Sulawesi, Indonesia differing in their distance to rainforest margin of the Lore-Lindu National Park and in flower density and its temporal variation. In all agro-forests, (1) transect surveys of the understory were obtained over a five-month period to assess bee community compositional similarity, bee diversity, and the temporal variation in bee diversity; and (2) coffee flower visitors were observed and open and bagged pollination treatments conducted over one week of coffee blooming to assess bee diversity and the spatial variation in bee diversity and coffee pollination. Mean number of shared species of the understory ranged between 40 and 60% per agro-forest and was higher in agro-forests nearby the rainforest than in agro-forests with a minimal distance of 500 m isolated from the rainforest. Mean species richness in the understory and in coffee flowers decreased with rainforest isolation and increased with flower resource availability. Temporal variation in bee species richness of the understory and spatial variation of the coffee flower-visiting bee species richness per agro-forest increased with forest distance. The variation in bee species richness decreased the mean and increased the spatial variation in bee-pollinated coffee fruit set per agro-forest. In conclusion, crops grown near intact rainforests and which profit from the pollination by many species may fluctuate less in bee-pollinated fruit set across crop plants than crop plants in isolated agriculture that receive low or even single species pollination services (C) 2009 Elsevier B.V. All rights reserved
Functional complementarity and specialisation: The role of biodiversity in plant–pollinator interactions
No full textEcological niche breadth (specialisation) and niche differentiation (complementarity) play a key role for species coexistence and hence biodiversity. Some niche dimensions of a species represent ecosystem functions or services such as pollination (functional niche). When species differ in their contribution to some collective function (functional complementarity), this implies that functions from several species are required for a high overall functional performance level. Applied to plant pollinator interactions, functional complementary suggests that a higher diversity of pollinators contributes to an increased pollination success of the plants or, in turn, that a higher diversity of flowers may better sustain the consumers' requirements. Complementarity can affect functioning at different scales: the collective functioning of the target community, a single species, an individual or even a part of the individual, e.g. a single flower. Recent network analyses revealed that plant pollinator interactions display a relatively high extent of complementary specialisation at the community scale. We propose several mechanisms that generate complementarity. From the consumers' viewpoint, differences in flowering phenology and/or nutritional variation in floral resources (nectar, pollen) may explain a complementary role of different flower species. From the plant's viewpoint, temporal or environmental variation in the pollinator species' activities may contribute to complementary effects on pollination of plant communities. In addition, different species may also pollinate either more exposed or more sheltered flowers from the same plant individual, or vary in their functions within single flowers. So far, empirical evidence for complementary effects in general, and particularly mechanistic explanations of such effects are scant and will require comparative investigations at multiple scales in the future. Such studies will help us to understand if and how biodiversity maintains the quality and quantity of plant pollinator functional relationships
Landscape context and management effects on an important insect pest and its natural enemies in almond
No full textEilers E, Klein A-M. Landscape context and management effects on an important insect pest and its natural enemies in almond. Biological Control. 2009;51(3):388-394.Pest control mediated by organisms such as parasitoids is a valuable ecosystem service, particularly with regard to high costs, low effectiveness, and detrimental effects of some agrochemicals. This study examined infestation rates and abundance of pests and their natural enemies in organic and conventional almond orchards in California, differing in landscape context, understory plant cover, and plant species richness. Parasitoids of the commercially most important insect pest of almond, the Navel Orangeworm (NOW) were studied by rearing NOW in collected overwintering nuts. The indirect impact of vertebrate natural enemies of NOW were estimated by counting empty nut shells with feeding marks by wild birds and various mammals, found at the orchard floor. Mean nut infestation by NOW ranged from 0.8% to 37% per orchard and was reduced by parasitism rates, ranging from 0% to 22%, and vertebrate nut damage, ranging from 2% to 96% per orchard. The parasitoids were facilitated by a high proportion of natural habitat surrounding the orchards and high proportion of understory ground cover with vegetation. The vertebrate natural enemies were facilitated by a high proportion of natural habitat surrounding the orchards and plant species richness in the orchard understory. In conclusion, this study shows that pest control mediated by vertebrates and invertebrates promoted by near natural habitats can lower pest pressure by NOW larvae in overwintering almond. In case of the vertebrate nut damage this service might only be temporal and turn into a dis-service during and after harvest because the vertebrates continue to feed on the nuts and may also cause injuries to the trees
Author, Philosopher Alexandra Stoddard to Speak March 2 at Williams Library
No full textOXFORD, Miss. – Contemporary philosopher, author, interior designer and speaker Alexandra Stoddard gives an inspirational lecture and reading March 2 at the University of Mississippi
Stages for the More Sustainable Farm
No full textCurrently, agricultural farm units are faced with a double and most times contradictory challenge, in order to be successful: on the one hand the invested capital has to be profitable and the economic performance has to be maximised. On the other hand, given the socio-environmental situation, it is necessary to preserve and to protect the environment and natural resources. Given the potential conflict of the two aims, since the satisfaction of one implies the underperformance of the other (and vice versa), the question then is: which is the solution to choose? We intend, in this work, to formulate a farm plan with the purpose of reconciling the criteria of environmental sustainability with that of economic competitiveness. For this achievement we proceed to the comparative study of sustainability of different groups of farms identified in the study area (first evaluation cycle) through MESMIS (“Marco para la Evaluación de Sistemas de Manejo de Recursos Naturales Mediante Indicadores de Sustentabilidad” - Framework for Evaluation of Natural-Resource Systems Handling through Sustainability Indicators) methodology, that allowed to select the more sustainable group of farms. Based on the found potentialities and weakness on these production systems, we stepped to the planning of a production unit of bovine meat, which obeys simultaneously to economic and environmental objectives, using Multicriteria Decision. We finished the work with the sustainability evaluation between groups of farms identified previously and the planned farms (second evaluation cycle), based, again, in the MESMIS methodology, to confirm (or not) the greatest sustainability of the last ones. Analyses of the results allow us to confirm the greatest relative sustainability of the planned farm, for the diverse traced scenarios.Decision taking, planning, sustainability, Environmental Economics and Policy, Farm Management,
Plant–flower visitor interaction webs: Temporal stability and pollinator specialization increases along an experimental plant diversity gradient
No full textAlthough most plants benefit from pollen vectors, very little information exists about how plant diversity structures the interactions between plants and their flower visitors. The structure of such interaction webs holds information about specialization and effectiveness of flower visitors in flower resource use. Here, we analyzed 52 plant–flower visitor interaction webs along a gradient of experimentally manipulated plant species richness in a European grassland. The gradient allows testing for effects of the number of flowering plant species per se. Linkage density and interaction diversity between flowering plant species and their visiting insect species increased with higher richness of flowering species. Increased interaction diversity led to smaller temporal variability in the frequency of flower visits. These results suggest higher temporal stability of pollination provided for plants integrated in complex interaction webs with a high number of flowering plant species.Flower resource specialization of solitary bees, but not of honey and bumble bees, increased with increasing flowering plant species richness. Conservation of diverse grasslands can result in high flower specialization and may promote effectiveness of pollination services. Die meisten Pflanzen werden durch Pollenüberträger begünstigt, jedoch ist wenig bekannt über die Auswirkungen von Pflanzendiversität auf die Interaktionen zwischen Pflanzen und ihren Blütenbesuchern. Die Struktur dieser Interaktionsnetze liefert wichtige Informationen über Spezialisierung und Effektivität der Blütenbesucher in ihrer Resourcennutzung. Wir untersuchten 52 Pflanze–Blütenbesucher-Interaktionsnetze eines europäischen Graslandes entlang eines experimentellen Gradienten in der Anzahl von Pflanzenarten. Der experimentelle Gradient bietet uns die Möglichkeit den Einfluss der Anzahl der blühenden Pflanzenarten per se zu untersuchen. Linkdichte (linkage density) und Interaktionsdiversität (interaction diversity) zwischen den blühenden Pflanzenarten und ihren Blütenbesuchern nahmen mit der Anzahl der blühenden Pflanzenarten zu. Ein Anstieg in der Interaktionsdiversität führte wiederum zu einer Abnahme in der zeitlichen Variabilität. Die Ergebnisse lassen auf höhere zeitliche Stabilität in der Bestäubung von Pflanzen schließen, die von einer hohen Anzahl an blühenden Pflanzenarten umgeben sind und somit in ein komplexes Interaktionsnetz integriert sind. Die Spezialisierung auf Blütenresourcen nahm bei den solitären Bienen mit zunehmender Anzahl an blühenden Pflanzenarten zu, nicht jedoch bei Honigbienen und Hummeln. Der Schutz von diversen Graslandflächen führt demnach zu höherer Resourcenspezialiserung, und kann somit eventuell eine Zunahme in der Bestäubungsleistung fördern
Contrasting responses of bee communities to coffee flowering at different spatial scales
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