Introduction

Background

Bees serve an important role in maintaining terrestrial ecosystems through pollination services. They are especially important for pollinating flowering crops and therefore contributing to agricultural yields (Winfree, 2010). However, native bees across the globe are in decline predominantly due to habitat loss, largely in the form of conversion of land to agriculture (Winfree, 2010). Also, to a lesser extent, pesticides, pathogens and climate change are negatively affecting wild bee abundance (Winfree, 2010).

Alberta is home to about 370 species of native wild bees (figure 2), which is about 47% of Canadas wild bee species (ANBC, 2024). In Alberta roughly 10% of wild bee species are declining (or rare). However, there is a severe lack of understanding regarding the full picture of the status of native bees in Alberta making it difficult to assign conservation rankings to all species (ANBC, 2024). The Alberta Native Bee Council (figure 1) began a project in 2018 to better understand the status of native bees across the province and monitor their changes over time. My aim is to better understand how landcover and climate impact Alberta's native bee communties and at what spatial scale to inform conservation efforts.

Figure 1. Alberta Native Bee Council logo.

Figure 2. Snapshot of the diversity of native bees within Alberta (ANBC, n.d.)

Bees can fly anywhere from 200m to 2000m from their nest to a foraging site depending on their body size, only larger bodied bees have to ability to travel as far as 2km to forage (Gathmann & Tscharntke, 2002). Due to this wide foraging distance, the landcover surrounding bees nesting site will impact a bees ability to survive. If bees are predominantly impacted by land cover at small scales (250-500m) conservation efforts can prioritize site-level habitat enhancement. Efforts that could be done by landowners and municipalities. Whereas if larger spatial scales are found to be the most influential to wild bees, more landscape scale habitat retention in the from of preserved and protected areas may be necessary for conservation of wild bees. Additionally, by understanding the spatial scale at which landcover affects native bees, agricultural endeavors can better plan where and how much natural area to provide surrounding crops to better utilize pollination services from wild bees. Currently, restoration efforts surrounding agriculture tend to in the form of 2-6m buffer strips (Winfree, 2010), results from this study could inform whether that is the most effective use of space.

Current research generally suggests that bees are more strongly influenced by smaller scale habitat but it can be extremely variable depending on species, location and land cover type. Saturni et al. (2016) found that native bee abundance, richness and diversity were much more influenced by land cover at smaller scales (300m radius) rather than at larger landscape scales (1-2km radius). However, this study was conducted in Brazil where the ecology differs significantly from Alberta therefore, my results could tell a different story. Benjamin et al. (2013) conducted a study in New Jersey similarly looking at the effect of landcover at differing spatial scales, but specifically looking at agricultural land. Benjamin et al. (2013) found that overall, bees were more strongly affected by smaller scale land cover. However, the spatial scale effect varied depending on bee body size, larger bees were negatively affected by agriculture but more so at a landscape scale while smaller bodies bees were also negatively affected by nearby agriculture but only at a smaller field scale. Again, my results could be different from these findings since I am looking at multiple different land cover types as opposed to solely focusing on the effects of Agriculture. Alberta also spans a large climatic gradient meaning bee communities across the province may be structured differently and vary in their response to habitat types.

Objectives

1.) Identify the spatial scale at which surrounding land cover most strongly shapes native beecommunities in Alberta to determine whether conservation efforts should focus on local habitat enhancement or landscape-scale habitat protection.

2.) Identify which land cover types are most strongly associated with differences in native bee community composition across Alberta to help prioritize habitats for bee conservation.

3.) Evaluate how broad climatic gradients across Alberta shape native bee communities, and whether bee communities occurring under different climatic conditions may require different habitat priorities for conservation.

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