ORCID Profile
0000-0002-1913-1057
Current Organisation
Heidelberg University
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Publisher: Cold Spring Harbor Laboratory
Date: 20-02-2019
DOI: 10.1101/554170
Abstract: Human land use threatens global bio ersity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by few abundant species or rely on high richness remains unclear. Using a global database from 89 crop systems, we partition the relative importance of abundance and species richness for pollination, biological pest control and final yields in the context of on-going land-use change. Pollinator and enemy richness directly supported ecosystem services independent of abundance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the bio ersity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.
Publisher: The Royal Society
Date: 17-03-2021
Abstract: While an increasing number of studies indicate that the range, ersity and abundance of many wild pollinators has declined, the global area of pollinator-dependent crops has significantly increased over the last few decades. Crop pollination studies to date have mainly focused on either identifying different guilds pollinating various crops, or on factors driving spatial changes and turnover observed in these communities. The mechanisms driving temporal stability for ecosystem functioning and services, however, remain poorly understood. Our study quantifies temporal variability observed in crop pollinators in 21 different crops across multiple years at a global scale. Using data from 43 studies from six continents, we show that (i) higher pollinator ersity confers greater inter-annual stability in pollinator communities, (ii) temporal variation observed in pollinator abundance is primarily driven by the three-most dominant species, and (iii) crops in tropical regions demonstrate higher inter-annual variability in pollinator species richness than crops in temperate regions. We highlight the importance of recognizing wild pollinator ersity in agricultural landscapes to stabilize pollinator persistence across years to protect both bio ersity and crop pollination services. Short-term agricultural management practices aimed at dominant species for stabilizing pollination services need to be considered alongside longer term conservation goals focussed on maintaining and facilitating bio ersity to confer ecological stability.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 28-02-2013
Publisher: Springer Science and Business Media LLC
Date: 18-02-2016
DOI: 10.1038/NCOMMS10841
Abstract: Nature Communications 6: Article number: 7414 (2015) Published: 16 June 2015 Updated: 18 February 2016. The authors inadvertently omitted Kimiora L. Ward, who managed and contributed data, from the author list. This has now been corrected in both the PDF and HTML versions of the Article.
Publisher: Wiley
Date: 22-09-2015
Publisher: Wiley
Date: 02-08-2011
DOI: 10.1111/J.1461-0248.2011.01669.X
Abstract: Sustainable agricultural landscapes by definition provide high magnitude and stability of ecosystem services, bio ersity and crop productivity. However, few studies have considered landscape effects on the stability of ecosystem services. We tested whether isolation from florally erse natural and semi-natural areas reduces the spatial and temporal stability of flower-visitor richness and pollination services in crop fields. We synthesised data from 29 studies with contrasting biomes, crop species and pollinator communities. Stability of flower-visitor richness, visitation rate (all insects except honey bees) and fruit set all decreased with distance from natural areas. At 1 km from adjacent natural areas, spatial stability decreased by 25, 16 and 9% for richness, visitation and fruit set, respectively, while temporal stability decreased by 39% for richness and 13% for visitation. Mean richness, visitation and fruit set also decreased with isolation, by 34, 27 and 16% at 1 km respectively. In contrast, honey bee visitation did not change with isolation and represented > 25% of crop visits in 21 studies. Therefore, wild pollinators are relevant for crop productivity and stability even when honey bees are abundant. Policies to preserve and restore natural areas in agricultural landscapes should enhance levels and reliability of pollination services.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 04-10-2019
Abstract: Bio ersity benefits pollination, pest control, and crop productivity but suffers from land-use intensification.
Publisher: Springer Science and Business Media LLC
Date: 16-06-2015
DOI: 10.1038/NCOMMS8414
Abstract: There is compelling evidence that more erse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for bio ersity conservation. However, it is unclear how much bio ersity 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 ersity of bees therefore requires more than just ecosystem-service-based arguments.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-05-2014
Publisher: Wiley
Date: 11-03-2013
DOI: 10.1111/ELE.12082
Abstract: 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 ersity), and their interactions, on wild bee abundance and richness for 39 crop systems globally. Bee abundance and richness were higher in ersified and organic fields and in landscapes comprising more high-quality habitats bee richness on conventional fields with low ersity 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.
No related grants have been discovered for Kristin Krewenka.