Landscape Pattern and Wild Bee Communities in Maine

Commercial production of lowbush blueberry (Vaccinium angustifolium Aiton) in Maine relies primarily on managed honeybee hives; however, naturally occurring wild bees are more efficient pollinators of the crop. Wild bees have short foraging distances and must nest near crop fields to provide pollination services. After crop bloom, the surrounding landscape must provide sufficient forage to maintain wild bee populations for the remainder of the growing season. Lowbush blueberries in Maine are produced in a mixed-use landscape with two distinct landscape contexts. Here, we document bee communities and habitat resources (nesting and floral) in power line rights-of-way and eight land cover types including and surrounding lowbush blueberry fields. We assess landscape pattern surrounding crop fields in the two contrasting contexts and determine any effect of arrangement of habitat patches on wild bee abundance or diversity. Additionally, we use our field data to inform and validate predictions of wild bee abundance from a spatial model applied to the lowbush blueberry production landscape and assess any influence of landscape pattern on prediction accuracy. Finally, we describe a collaboration with lowbush blueberry growers to develop an interactive web mapping tool that provides maps of habitat resources and predicted wild bee abundance. We documented 168 wild bee species across 72 study sites; three bee species had not been previously recorded in Maine. Power line rights-of-way had diverse and abundant bee communities owing to high habitat quality, especially within resource-poor landscapes near lowbush blueberry fields. We observed abundant floral resources in lowbush blueberry fields, forest edges, and small towns and found ample nesting resources in lowbush blueberry fields and shrubby wetlands. Bees were less abundant and diverse in a homogeneous landscape context; however, that homogeneity led to more accurate model predictions of bee abundance in crop fields. We improved prediction accuracy in a mixed-use landscape and produced accurate predictions in non-crop land cover types in a heterogeneous landscape context; however, we found that predictions of wild bee abundance in crop fields are influenced by landscape heterogeneity. The maps we share through the web tool aid growers and other stakeholders in developing pollination management and conservation plans

MR448: Bees and Their Habitats in Four New England States

Bees are crucial to pollination in unmanaged ecosystems and some crops, and their roles are increasingly understood in four states in the Northeastern U.S., abbreviated “NNE” in this paper: Maine (ME), Massachusetts (MA), New Hampshire (NH), and Vermont (VT). The four states have in common many native bee and plant species, forest types, and natural communities. They share drought events and risk of wildfire (Irland 2013). They are exposed to many of the same major storms (e.g., hurricanes, Foster 1988), pollution events (Hand et al. 2014), and effects ascribed to climate change (Hayhoe et al. 2008). Beekeeping enterprises (the western honey bee, Apis mellifera, an introduced species) of various sizes exist in each of the states. By including the four states in this review, we hope to better understand wild bee distributions, inspire the expansion of floral resources to support bee populations in a strategic manner, reduce use of pesticides, create pollinator corridors, and protect subtle habitat features such as ground nest sites for solitary bees and patches of native vegetation that are free of invasive plants. Our objective in this review is to synthesize from a conservation standpoint the state of knowledge regarding bees in NNE, including their diversity, and biology especially as it relates to climate change. We review foraging and nutrition, nest ecology, parasites and parasitoids, native vs. managed bees, and interactions with plants. We then turn our focus to bee habitats, and identify 15 habitat types we find useful for recognizing essential bee resources. We discuss habitat aspects including forest succession, invasive plants, land use alterations, and agriculture including impacts of pesticides, and cover economic aspects of crop-related pollination reservoirs in NNE that demonstrate cost-effectiveness at various scales. We present habitat improvement strategies including passive and active approaches, based on the literature and our experiences in NNE, and we suggest plants for pollinator plantings. Wherever pertinent throughout the text, we highlight threats to bees in our region such as pests and pathogens, pesticides, and habitat loss. Finally, we identify gaps in knowledge that could help in prioritizing directions for future research. We hope this review will be useful to anyone seeking to protect bees and their habitats.https://digitalcommons.library.umaine.edu/aes_miscreports/1029/thumbnail.jp

Coupling spatial pollination supply models with local demand mapping to support collaborative management of ecosystem services

UID/AMB/04085/2019 UIDB/04085/2020Mapping of ecosystem services (ES) is a powerful tool for communication and knowledge sharing about the implications of ecosystem management practices for human wellbeing. This research aimed to show the usefulness of ES mapping for decision-making by combining modelling of ES supply with ES demand mapping in a participatory process with the engagement of relevant stakeholders. We used the ESTIMAP-pollination model to map wild bee abundance and pollination supply in the Sudoeste Alentejano and Costa Vicentina Natural Park (PNSACV) in Portugal. The model was modified by adding a behavioural component that distributes pollinator visits according to floral availability. Balancing pollination supply with crop dependency levels allowed visualising potential areas of satisfied and unsatisfied demand and testing the effectiveness of ecosystem management interventions. The discussion of these results in two participatory workshops triggered the first collective debate about pollination in the PNSACV. This engagement enabled the development of a shared understanding about this ES and highlighted the role of ES maps as tools to support collaborative natural resources management.publishersversionpublishe

As green infrastructure, linear semi-natural habitats boost regulating ecosystem services supply in agriculturally-dominated landscapes

Semi-natural linear landscape elements, such as hedgerows, are vital structures within agricultural landscapes that have an impact on ecosystem processes and support biodiversity. However, they are typically omitted from green infrastructure planning, which could lead to significant undervaluing of landscapes and their multifunctionality in terms of ecosystem service supply. Using the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model suite, we tested the effects of additionally including semi-natural linear landscape elements on the model outcomes for crop pollination, nutrient regulation, erosion regulation and water flow regulation ecosystem services supply. The results showed that linear semi-natural landscape elements contribute positively to the landscape's multifunctionality. Small changes have been identified for water flow regulation, whereas, considering both spatial extent and magnitude of the changes, the greatest changes have been found with respect to the supply of pollination and nutrient regulation. Direct proximity of the linear elements had the greatest effect on ecosystem service supply, in particular with regard to pollination. Based on our results, a more pronounced consideration of semi-natural linear landscape elements as an important element of green infrastructure is advisable

Modeling Threats To Honey Bees In North Dakota From Land-Use Change And Pesticide Applications

North Dakota supports the highest number of honey bee colonies in the US due to its abundance of floral resources, but threats from land-use change and pesticide applications have altered the quantity and quality of those resources in recent years. This thesis explored landscape scale pesticide use trends from both spray applied and seed treated insecticides on lands within 1.6km of ~13,000 registered apiaries North Dakota from 2001 to 2015. The regional application of five spray applied insecticides was collectively modeled using InVEST’s Habitat Quality Model during years of heightened land-use change. In these models, regional application rates were converted and normalized to relative risk values which degrade the quality of pixels adjacent to where applications occurred. Results from 2006 to 2014 suggest decreases in the quantity and quality of beneficial natural land covers such as grasslands surrounding apiary sites due to shifting land-use and changing spatial pesticide applications. Conservation scenarios were designed to better understand the effectiveness of strategic placement of conservation land within apiary site buffers by utilizing apiary density as a guide in the year 2014. Comparing baseline and scenario outputs led to the discussion of policy at regional and field levels to improve quantity and quality of resources for honey bees. More generalized modeling of neonicotinoid use from corn and soybeans resulted in spatial outputs that mirrored those from spray applied insecticides. Threats to apiaries in the forms of pesticide use and land-use change occurred collectively east of the Missouri River where land-use change has been most pronounced. The ecosystem service benefits of grassland as sources of forage and as a refuge from pesticide exposure were discussed

Spatial modelling of insect-delivered ecosystem services

Insects are integral to many ecosystem services, including pollination of crops by insect pollinators and control of pests by natural enemies (i.e. predators and parasites). These beneficial insects are suffering widespread declines, partly due to agricultural expansion and intensification. We must therefore change the management of agricultural landscapes to preserve these ecosystem services and the resilience of the systems that depend on them. To make such changes, we first need to understand the relationships between landscapes, beneficial insect communities and the delivery of the services they provide. This thesis focuses on analysing novel combinations of large-scale spatial datasets to explore these relationships. Firstly, a ten-year time-series of wheat yield data was analysed in conjunction with satellite�derived land cover data to explore national-scale relationships between crop yield resilience and landscape structure. Whilst relative yield was highest in landscapes dominated by arable land, stability and resistance were promoted by semi-natural habitats. Secondly, data from biological recording schemes were used to construct potential plant-pollinator networks across Great Britain and explore relationships between network structure and land cover. Networks were most robust to simulated extinctions in highly agricultural landscapes, because they supported distinctive, generalist pollinator communities. Finally, data on land cover and cropping patterns were used to develop a range of scenarios of agricultural change. These were linked to beneficial insect richness and functional diversity using species distribution models based on biological records. Scenarios involving restoration of semi-natural grasslands increased the richness and functional diversity of beneficial insects, even if cropped land remained intensive. The findings presented in this thesis demonstrate the value of combining and modelling spatial data in exploring insect-delivered ecosystem services. Whilst there is much scope for further work, including integration with experimental data, spatial modelling remains key to providing the large-scale evidence required by policy makers and agricultural land managers

The impact of agri-environment schemes on pollination services in England

Agri-environment schemes fund landholders to manage land to achieve environmental objectives and other public goods. Previous research has shown that individual scheme interventions can boost wild pollinator populations locally. However, the effect of an entire scheme at a national scale has never previously been assessed. The location of every intervention implemented in England during 2016 was mapped and schemes’ predicted impact on bee abundance and pollination services was modelled using a validated, processbased spatial model (poll4pop), which simulates foraging and population dynamics. The study considered four wild bee guilds (incorporating bumblebees and solitary bees) and their visitation rates to four pollinator-dependent crops (oilseed rape, field beans, orchard fruit and strawberries). The modelling predicted that the scheme significantly increased ground-nesting (but not tree/cavitynesting) bee populations nationally. There were no significant increases in crop visitation at national scale, but some locally significant increases in ground-nesting bumblebee visitation to oilseed rape and field beans were predicted. Linear regression at 10 km scale was used to determine which interventions were driving increased oilseed rape and field bean visitation and found that hedgerow/woodland edge management dominated, due to high resource quality. Floral margins were estimated to provide more limited benefit, due to later resource phenology and low uptake. Fallow also had a strong effect, despite lower relative resource quality, implying effective placement with respect to crops. Finally, the effect of additional tree-planting interventions (hedgerows, agroforestry, and woodland) on bumblebee abundance and crop visitation (oilseed rape, field beans) was studied. This showed that hedgerow planting would deliver the greatest increase in bumblebee abundance, whereas fruit or willow agroforestry would increase crop visitation the most, due to higher co-location. Based on these findings, recommendations are set out for design of future schemes to help deliver greater and more resilient crop pollination services in arable landscapes