Scientists from the University of Freiburg surveyed the German Black Forest National Park to determine the number of tree species, how the trees are scattered, the heights of individual tree crowns and if there are fallen trees or hollowed-out tree trunks. They found that creating deadwood in coniferous forests is a promising restoration measure to promote an abundance of aboveground nesting bees. Their findings, “Wild Bees Benefit from Structural Complexity Enhancement in a Forest Restoration Experiment,” were published in the journal Forest Ecology and Management.

As part of an experiment, structural richness was artificially created in 2016 on several sample plots by felling and uprooting 20 spruce trees per plot, creating deadwood and small gaps. Six other plots were left in their natural state as a control group. The researchers compared how many wild bees were in the different plots in June 2018 and 2019. Results show that deadwood increases the abundance and biodiversity of wild bees. Professor Dr. Alexandra Klein, head of the Chair of Nature Conservation and Landscape Ecology, says, “In the course of climate change, forest areas will be increasingly characterized by deadwood and sparse areas caused by storms, droughts or bark beetles. As a result, forest habitat will increase in importance for wild bees.”