Browsing Gund Institute for Ecological Economics by Subject "abundance"

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Browsing Gund Institute for Ecological Economics by Subject "abundance"

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  • Kleijn, D.; Winfree, R.; Bartomeus, I.; Carvalheiro, L. G.; Henry, M.; Isaacs, R.; Klein, A. M.; Kremen, C.; M'Gonigle, L. K.; Rader, R.; Ricketts, T. H.; Williams, N. M.; Adamson, N. L.; Ascher, J. S.; Baldi, A.; Batary, P.; Benjamin, F.; Biesmeijer, J. C.; Blitzer, E. J.; Bommarco, R.; Brand, M. R.; Bretagnolle, V.; Button, L.; Cariveau, D. P.; Chifflet, R.; Colville, J. F.; Danforth, B. N.; Elle, E.; Garratt, M. P. D.; Herzog, F.; Holzschuh, A.; Howlett, B. G.; Jauker, F.; Jha, S.; Knop, E.; Krewenka, K. M.; Le Feon, V.; Mandelik, Y.; May, E. A.; Park, M. G.; Pisanty, G.; Reemer, M.; Riedinger, V.; Rollin, O.; Rundlof, M.; Sardinas, H. S.; Scheper, J.; Sciligo, A. R.; Smith, H. G.; Steffan-Dewenter, I.; Thorp, R.; Tscharntke, T.; Verhulst, J.; Viana, B. F.; Vaissiere, B. E.; Veldtman, R.; Westphal, C.; Potts, S. G. (Nature CommunicationsNat. Commun., 2015
      There is compelling evidence that more diverse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for biodiversity conservation. However, it is unclear how much biodiversity is needed to deliver ecosystem services in a cost- effective way. Here we show that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species. Across crops, years and biogeographical regions, crop-visiting wild bee communities are dominated by a small number of common species, and threatened species are rarely observed on crops. Dominant crop pollinators persist under agricultural expansion and many are easily enhanced by simple conservation measures, suggesting that cost- effective management strategies to promote crop pollination should target a different set of species than management strategies to promote threatened bees. Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments.
  • Aburto-Oropeza, O.; Ezcurra, E.; Moxley, J.; Sanchez-Rodriguez, A.; Mascarenas-Osorio, I.; Sanchez-Ortiz, C.; Erisman, B.; Ricketts, T. (Ecological Indicators, 2015
      The recovery of historic community assemblages on reefs is a primary objective for the management of marine ecosystems. Working under the overall hypothesis that, as fishing pressure increases, the abundance in upper trophic levels decreases followed by intermediate levels, we develop an index that characterizes the comparative health of rocky reefs. Using underwater visual transects to sample rocky reefs in the Gulf of California, Mexico, we sampled 147 reefs across 1200 km to test this reef health index (IRH). Five-indicators described 88% of the variation among the reefs along this fishing-intensity gradient: the biomass of piscivores and carnivores were positively associated with reef health; while the relative abundances of zooplanktivores, sea stars, and sea urchins, were negatively correlated with degraded reefs health. The average size of commercial macro-invertebrates and the absolute fish biomass increased significantly with increasing values of the IRE. Higher total fish biomass was found on reefs with complex geomorphology compared to reefs with simple geomorphology (r(2) = 0.14, F = 44.05, P<0.0001) and the trophic biomass pyramid also changed, which supports the evidence of the inversion of biomass pyramids along the gradient of reefs' health. Our findings introduce a novel approach to classify the health of rocky reefs under different fishing regimes and therefore resultant community structures. Additionally, our IRH provides insight regarding the potential gains in total fish biomass that may result from the conservation and protection of reefs with more complex geomorphology. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.
  • Garibaldi, L. A.; Bartomeus, I.; Bommarco, R.; Klein, A. M.; Cunningham, S. A.; Aizen, M. A.; Boreux, V.; Garratt, M. P. D.; Carvalheiro, L. G.; Kremen, C.; Morales, C. L.; Schuepp, C.; Chacoff, N. P.; Freitas, B. M.; Gagic, V.; Holzschuh, A.; Klatt, B. K.; Krewenka, K. M.; Krishnan, S.; Mayfield, M. M.; Motzke, I.; Otieno, M.; Petersen, J.; Potts, S. G.; Ricketts, T. H.; Rundlof, M.; Sciligo, A.; Sinu, P. A.; Steffan-Dewenter, I.; Taki, H.; Tscharntke, T.; Vergara, C. H.; Viana, B. F.; Woyciechowski, M. (Journal of Applied Ecology, 2015
      Understanding the relationships between trait diversity, species diversity and ecosystem functioning is essential for sustainable management. For functions comprising two trophic levels, trait matching between interacting partners should also drive functioning. However, the predictive ability of trait diversity and matching is unclear for most functions, particularly for crop pollination, where interacting partners did not necessarily co-evolve. World-wide, we collected data on traits of flower visitors and crops, visitation rates to crop flowers per insect species and fruit set in 469 fields of 33 crop systems. Through hierarchical mixed-effects models, we tested whether flower visitor trait diversity and/or trait matching between flower visitors and crops improve the prediction of crop fruit set (functioning) beyond flower visitor species diversity and abundance. Flower visitor trait diversity was positively related to fruit set, but surprisingly did not explain more variation than flower visitor species diversity. The best prediction of fruit set was obtained by matching traits of flower visitors (body size and mouthpart length) and crops (nectar accessibility of flowers) in addition to flower visitor abundance, species richness and species evenness. Fruit set increased with species richness, and more so in assemblages with high evenness, indicating that additional species of flower visitors contribute more to crop pollination when species abundances are similar.Synthesis and applications. Despite contrasting floral traits for crops world-wide, only the abundance of a few pollinator species is commonly managed for greater yield. Our results suggest that the identification and enhancement of pollinator species with traits matching those of the focal crop, as well as the enhancement of pollinator richness and evenness, will increase crop yield beyond current practices. Furthermore, we show that field practitioners can predict and manage agroecosystems for pollination services based on knowledge of just a few traits that are known for a wide range of flower visitor species. Despite contrasting floral traits for crops world-wide, only the abundance of a few pollinator species is commonly managed for greater yield. Our results suggest that the identification and enhancement of pollinator species with traits matching those of the focal crop, as well as the enhancement of pollinator richness and evenness, will increase crop yield beyond current practices. Furthermore, we show that field practitioners can predict and manage agroecosystems for pollination services based on knowledge of just a few traits that are known for a wide range of flower visitor species. Editor's Choice

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