Grundel and his colleagues wanted to find out if the kinds of plants that live in different habitats can predict what kinds of bees will be there or if other factors such as soil type, tree density or even fire -- are more important. To do this, the team surveyed landscapes and collected and identified nearly 5,000 native bees representing at least 175 species in five kinds of habitats at Indiana Dunes National Lakeshore and nearby natural areas around northwestern Indiana. These habitats ranged from dense forests to open fields.
"We had suspected that the closer our collecting sites were to each other the more similar the bees communities we found would be but we were wrong," Grundel said. "In fact, mere physical proximity wasn't a very good predictor of how similar bee communities at different sites would be to each other. Instead, local factors and even the micro-habitats that we often ignore are really important in determining what kinds of bees use an area."
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.
Bee abundance how many bees were captured at a site was lower in areas with a dense tree canopy and higher if a fire had occurred recently in the area. Bee diversity the number of different kinds of bees was higher in a
|Contact: Ralph Grundel|
United States Geological Survey