Ground- and cavity-nesting native bees: Pollinators’ habitat defined more by supply of dead wood than plant species available

Blue Orchard Mason Bee

U.S. Geological Survey June 21, 2011, press release:

Native bees – often small, stingless, solitary and unnoticed in the flashier world of stinging honeybees – are quite discriminating about where they live, according to U.S. Geological Survey research.

The study found that, overall, composition of a plant community is a weak predictor of the composition of a bee community, which may seem counterintuitive at first, said USGS scientist and study lead Ralph Grundel. This may be because specialized plant-bee interactions, in which a given bee species only pollinates one plant species and that plant species is only pollinated by that bee species are not common.  More common is for a plant species to be pollinated by many pollinator species and each pollinator species pollinating many species of plants.

Given this complex network of interaction between plants and their pollinators, it is not surprising that knowing which plants occur in an area does not necessarily allow us to predict which bees will occur in that area, Grundel said.

Because many native bees are ground- and cavity-nesters, the scientists weren’t surprised to find that an abundant supply of dead wood, such as woody debris and dead tree limbs, was essential in determining what kinds of bees lived where. They were surprised, however, at how important other factors were, including bee preferences for specific soil characteristics and for areas that had burned in the previous two years.

Read more here.

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