"So many unknowns": How will the wildfires impact bee populations?
The wildfires still burning across the western United States now cover a total area the size of Hawaii. Only 11% of these active large fires are reported contained at the time of writing. Thirty-five people have been killed, dozens are missing, and thousands have been displaced. Fire resources are stretched to their limits. Images of dystopian orange skies are a stark and pervasive reminder of the destruction – and the heroic efforts – happening in these states.
When massive bushfires raged across southern Australia at the end of last year, there was concern about the impact of the fires on wildlife – including invertebrates and insects – as well as humans. In particular, we were worried about the fate of the endangered green carpenter bee. As our own fiery tragedy continues here in the United States, it’s worth thinking about this same thing: How will the fires affect bee populations living in these western states?
“Historically, fires maintained diversity in many of our forests by creating an opportunity for species that benefit from disturbances – including many flowering plants and pollinators – to thrive in the years following the event,” says Sara Galbraith, an ecologist at Colorado State University who has studied the impact of wildfire on bees. For example, the offspring of ground-nesting bees tend to survive fires because they are insulated in their underground nests and can take advantage of flowering plants that bloom after the fire. These same burned areas might also lack abundant stem-nesting bees in the short term because their above-ground nesting sites were eliminated or overheated.
“After a fire, there is often a pulse of floral resources when the canopy is opened,” says Lauren Ponisio, an assistant professor of entomology at UC Riverside. Her own work has shown that in forests with a historically natural fire pattern that includes frequent, mixed-severity burns, there is an incredible diversity of bees.
But very large, very intense fires may have a very different impact on bees by making more extreme changes to their habitat.
“Where things may go wrong for bees is if the fires are so large and high severity that it is hard for bees to get back into those areas because the remaining bee populations are too far away,” Ponisio says. “We have found evidence that the types of bees supported by these high severity burns are also similar across large distances, so we may see regional diversity of bees decrease if we only see these large, high severity fires and lose our more mixed-severity fires in the future.”
“With forest conditions changing due to all sorts of complex factors, it is possible that more extreme fire events will change the number or type of bees that are ‘winners’ in the short and long term,” Galbraith says. Such factors include: How much bee and flowering plant diversity was present before the event? What plants are waiting in the soil's seed bank? How will climate change influence recolonization in the burned area? How big of a problem will invasive species (like grasses) be in following years?
“These are the kind of things that will determine whether a really diverse, complex plant-pollinator network returns or if there is some ‘harm’ to the system,” says Galbraith.
Of special concern, says Scott Black, executive director of the Xerces Society, are several imperiled bumble bees in the west – some of which have an official conservation status from federal and state agencies. The current wildfires have burned over historic and recent sites for Franklin’s bumble bee (Bombus franklini), the western bumble bee (Bombus occidentalis), and Crotch’s bumble bee (Bombus crotchii). If queens of these species have been affected, it may be difficult for them to recolonize the burned areas if more common bees quickly find and make use of the renewed resources.
“There are so many unknowns here,” Black says. “Will our forests be able to recover from the new era of climate change induced fires? There is emerging data that suggests that some forests just will not recover with warmer temperatures and less precipitation. Only time will tell.”
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Happy anniversary, Grand Staircase-Escalante National Monument!
Twenty-four years ago today, this monument was created to protect and preserve the amazing biodiversity and history in this corner of southern Utah. Just a few years later, an intrepid group of young researchers and volunteers began observing, collecting and cataloging the bees living deep in the backcountry of the new monument.
If you’ve already reserved your “seat” for the virtual premiere of The Bees of Grand Staircase-Escalante next week, thank you! I’m super excited to be sharing this film and looking forward to leading the conversation afterwards about bees, public lands and biodiversity. Can’t wait to see all of your “there”!
Conservation
Will putting honey bees on public lands threaten native bees?
(Yale E360) As suitable sites become scarce, commercial beekeepers are increasingly moving their hives to U.S. public lands. But scientists warn that the millions of introduced honey bees pose a risk to native species, outcompeting them for pollen and altering fragile plant communities.
Newly launched Insect Biodiversity Center to promote insect conservation, healthy ecosystems
(Penn State) The Insect Biodiversity Center at Penn State will create a focal point for the study and conservation of insects and the ecosystems with which they interact. It brings together faculty researchers and educators from eight Penn State colleges.
The world missed a critical deadline to safeguard biodiversity, UN report says
(National Geographic) A decade ago, United Nations members crafted an agreement to curb the loss of biodiversity. We’ve failed miserably, but all hope is not lost.
Science
Meet a bee with a very big brain
(New York Times) Just like mammals or birds, insect species of the same size may have different endowments inside their heads. Researchers have discovered some factors linked to brain size in back-boned animals. But in insects, the drivers of brain size have been more of a mystery. A new study has scrutinized hundreds of bee brains for patterns. Bees with specialized diets seem to have larger brains, while social behavior appears unrelated to brain size. This means when it comes to insects, the rules that have guided brain evolution in other animals may not apply.
Bumble bees benefit from faba bean cultivation
(Georg-August-Universität Göttingen) About one third of the payments received by German farmers are linked to specific “greening measures” to promote biodiversity. The cultivation of nitrogen-fixing legumes is very popular. However, these measures have been criticized because the benefits for biodiversity are unclear. It turns out that bumble bees benefit from the cultivation of faba beans, while all other wild bees depend on the presence of semi-natural habitats.
Heated rivalries for pollinators among arctic plants
(University of Helsinki) Insect pollination is as important to Arctic plants as it is to plants further south. When flowers abound, the plants have to compete for pollinators. Researchers reveal that higher temperatures cause the flowering periods of different plant species to pile up in time. As a consequence, climate change may affect the competitive relationships of plants. The most attractive plant species steal the majority of pollinators, making other plants flowering at the same time suffer from poorer pollination.
One More Thing…
Scientific American endorses Joe Biden. “Scientific American has never endorsed a presidential candidate in its 175-year history. This year we are compelled to do so. We do not do this lightly. The evidence and the science show that Donald Trump has badly damaged the U.S. and its people—because he rejects evidence and science.”