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Pollinator Eco-Services and Causes for the Pollinator Decline

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Pollinator Eco-Services and Causes for the Pollinator Decline Part 6-B: Pollinator Eco-Services and CAUSES for the Decline in Pollinators The Contribution of Bees to our Eco System Native bees are considered a 'keystone' species for almost all terrestrial ecosystems: • Most wild plants depend on pollination by insects for reproduction. • Bee pollinators contribute to seed set and plant diversity. • These insects form the basis of an energy-rich food web. • Plants and their native pollinators have co-evolved over millions of years. • Certain native bees (Bumblebees / Bombus species) are more efficient pollinators than honeybees. • Specialist native bumble bees can buzz pollinate certain crops, such as squashes, tomatoes, peppers, melons and cucumbers. Honey bees can not pollinate these crops. It is estimated that in 2009 bees contributed to 11% of the nation's agricultural value, roughly $14.6 billion per year. Of this, at least 20% ($3.07 billion) is provided by wild pollinators. These important native pollinators need suitable land for nesting and foraging near the cultivated fields. Related Research: • Kearns et al. 1998. Endangered mutualisms: the conservation of plant-pollinator interaactions. Annual Review of Ecology and Systematics 29:83-112 • Losey JE, Vaughan M. 2006. The economic value of ecological services provided by insects. BioScience 56(4):311– 323. The Causes for Native Pollinator Decline ONE: Land Use Intensification / Urbanization / Habitat Loss These practices contribute to the decline in pollinators: • growth of mega-scale agricultural operations; • loss of hedge rows and field borders; • excessive use of herbicides, and drift from the application of these chemicals; • large monocultures of food crops that lack habitat refuge for native bees; • overgrazing; • lawns and fields with mowing that prevents plants from flowering. Related Research related to loss of floral diversity: • Blaauw, BR; Isaacs, R. Flower plantings increase wild bee abundance and the pollination services provided to a pollination-dependent crop. Journal of Applied Ecology 2014, 51, 890–898 A study of blueberry seed- set. From the Abstract: " Crop pollination parameters including percentage fruit set, berry weight and mature seeds per berry were significantly greater in fields adjacent to wildflower plantings 3 and 4 years after seeding, leading to higher crop yields and with the associated revenue exceeding the cost of wildflower establishment and maintenance. ...... provision of forage habitat for bees adjacent to pollinator-dependent crops can conserve wild pollinators in otherwise resource-poor agricultural landscapes. Over time, these plantings can support higher crop yields and bring a return on the initial investment in wildflower seed and planting establishment, also insuring against loss of managed pollinators". • Garibaldi, LA et al: Stability of pollination services decreases with isolation from natural areas despite honey bee visits. Ecology Letters, (2011) 14: 1062–1072 From the abstract: " 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." • Kleijn, D et al. 2015 Delivery of crop pollination services is an insufficient argument for wild pollinator conservation. Nature Communications DOI: 10.1038/ncomms8414 From the Abstract: "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." • Koh, Insu et al. Modeling the status, trends, and impacts of wild bee abundance in the United States. PNAS 2016 January, 113 (1) 140-145. From the Abstract: " ... Between 2008 and 2013, modeled bee abundance declined across 23% of US land area. This decline was generally associated with conversion of natural habitats to row crops. We identify 139 counties where low bee abundances correspond to large areas of pollinator-dependent crops. These areas of mismatch between supply (wild bee abundance) and demand (cultivated area) for pollination comprise 39% of the pollinator-dependent crop area in the United States. Further, we find that the crops most highly dependent on pollinators tend to experience more severe mismatches between declining supply and increasing demand. These trends, should they continue, may increase costs for US farmers and may even destabilize crop production over time." NOTE: much of this land was converted to corn for biofuel. • Potts, SG et al. 2010. Global pollinator declines: trends, impacts and drivers Trends in Ecology and Evolution Vol.25 No.6 From the Abstract: " Pollinators are a key component of global biodiversity, providing vital ecosystem services to crops and wild plants. There is clear evidence of recent declines in both wild and domesticated pollinators, and parallel declines in the plants that rely upon them. Here we describe the nature and extent of reported declines, and review the potential drivers of pollinator loss, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them. Pollinator declines can result in loss of pollination services, which have important negative ecological and economic impacts that could significantly affect the maintenance of wild plant diversity, wider ecosystem stability, crop production, food security and human welfare." • Ricketts, TH et al. Economic value of tropical forest to coffee production. PNAS 2004 , vol. 101 no. 34 pp 12579–12582 Researchers have found that growing coffee near native forest ecosystems increases coffee bean yield by 20% within 1 km of forest edge and reduced the number of 'peaberries' [small misshapen beans] by 27%/ Thus, from the Abstract: "Conservation investments in human-dominated landscapes can therefore yield double benefits: for biodiversity and agriculture". Excessive Lawn Care: Lawns comprise 50% of urban land. At the Pollinator Partners' June 2017 field trip where her experiments with suburban ecosystems were discussed, Susannah Lerman of U Mass gave a talk titled Mow Less for More Buzz. She has surprising results from experiments in Springfield MA, where homeowners committed to less mowing and no chemicals for lawn care (pesticides / herbicide / fertilizers) for two years. Several articles have resulted from these experiments that suggest less lawn care contributes to a remarkable boost in the biodiversity of bees and plants, creating an oasis in what was believed to be a pollinator desert! • Lerman, SB; Milam, J. 2016. Bee Fauna and Floral Abundance Within Lawn-Dominated Suburban Yards in Springfield, MA , Annals of the Entomological Society of America, Volume 109, Issue 5, Pages 713–723 • Lerman, SB et al. 2018. To mow or to mow less: Lawn mowing frequency affects bee abundance and diversity in suburban yards. 'Biological Conservation Volume 221, Pages 160–174. This article suggests we should be a 'lazy lawnmower' -- from the Abstract: 'Lawns mowed every three weeks had as much as 2.5 times more lawn flowers than the other frequencies. Interestingly, lawns mowed every two weeks supported the highest bee abundance yet the lowest bee richness and evenness.' .... 'Mowing less frequently is practical, economical, and a timesaving alternative to lawn replacement or even planting pollinator gardens. Given the pervasiveness of lawns coupled with habitat loss, our findings provide immediate solutions for individual households to contribute to urban conservation.' The researchers counted 93 species of bees, accounting for about a quarter of all bee species in Massachusetts. They suggest this demonstrates that urban environments, if managed properly, can provide suitable habitat for high diversity N.H. Wildlife Action Plaandn abundancecontinu ofe bees.d Neonicotinoids [“neonics”TWO:] are br oad Over spec Reliancetrum insec tOnicid eChemicalss applied both to foliage and Someto seeds insecticides which abs areor worseb them than int oothers: Certain chemicals can be used conservatively, with few side effects. Others have wide-ranging secondary impacts. Organic gardening and the growing plant. The inseagriculturalcticide acc measuresumulates are in nimportantectar an ind protecting the health and variety of pollinators. pollen, which bumble bees consume. Neonicotinoids create many problems: These chemicals are fairly new, with use starting in 1994 and one, Imidacloprid, is now the Exposure causes increased most commonly used insecticide in agriculture in the US and elsewhere, with queen mortality, reduced billions of pounds used each year. Nearly movements in workers and 95% of corn and canola crops are grown reduced
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