In Fire-Prone West, Pollinators Need Their Plants — and Vice Versa

Fireweed (Chamerion angustifolium) blooms in Yellowstone National Park, Montana. New research highlights the importance of plant-pollinator interactions in restoring ecosystems in which natural wildfire regimes have been altered or suppressed by human activities. (Photo by Jonathan Myers, Washington University in St. Louis)

(CN) — In the wake of the worst year on record for wildfire destruction, scientists are racing to learn more about how fire impacts the environments they burn, specifically the dynamic between plants and their pollinators.

A new study, focusing on the northern Rockies in Montana, has found that like most things, there are benefits within a careful balance.

Details of the study are published Wednesday in the Journal of Ecology, where researchers from Washington University in St. Louis, Marquette University, Montana State University and The Wilderness Society conducted important research on this interaction that can’t come a moment too soon.

“A large number of studies have looked at how fire affects plants, or how fire affects animals. But what is largely understudied is the question of how fire affects both, and about how linkages within those ecological networks might respond to fire disturbance,” said study co-author Jonathan Myers, associate professor of biology in Arts & Sciences at Washington University, in a statement accompanying the study.

According to their findings, wildfires and the relationships between the plants and pollinators are important factors in determining both of their presence in an area. When a landscape has been burned, healthy plant-pollinator relationships are needed more than ever, and largely determine the fauna of the area.

Furthermore, the researchers found that following a wildfire, the local pollinators will depend heavily on successful flowering plants, which can impact their population sizes accordingly. This relationship goes both ways, as the presence of these pollinators can determine how many and what kind of plants will thrive.

“Clearly, pollinators perform a valuable ecosystem service for humans by pollinating all our crops. In intact natural ecosystems, they perform an equally valuable service,” said lead author Joseph LaManna, assistant professor of biological sciences at Marquette University, in the statement. “What we are seeing is that plant and pollinator linkages become even more important in disturbed or burned landscapes. These connections are important for restoring ecosystems in which natural wildfire regimes have been altered or suppressed by human activities.

“And as climate change increases the frequency and intensity of wildfires, the potential for biodiversity loss — for losses of individual plant or pollinator species — is going to be even more profound than we anticipated,” he said.

Normally, wildfires would have hotter and cooler spots and leave regions with varying levels of fire disturbance. However, climate change has played a role in upsetting this trend and increasing global temperatures have caused many fire-quelling plants and materials to disappear. In turn, we see unprecedented damage from disastrous wildfires.

For the study, co-author Laura Burkle at Montana State University and a team of researchers observed plant and pollinator populations in 152 selected plots in Montana. Together, all the plots represented different levels of wildfire disturbance ranging from untouched, mixed-severity and high-severity.

After analyzing the data, they found the areas that had experienced wildfire disturbances had more pollinators like bees, flies and butterflies, as well as the plants pollinators love. But areas of mixed-severity wildfire disturbances that left some vegetation alive fared better than high-severity wildfire areas where the landscape can be decimated. Burned landscapes also showed nine to ten times greater biodiversity than unburned areas, and in total the team accounted for 329 pollinator species and 193 flowering-plant species.

“Oftentimes, the public perception about fire in general is that it is bad. But it was impressive how much higher the abundances of both plants and pollinators were — as well as the number of species — in the burned landscapes compared with the unburned landscapes,” Myers said.

These results provide hope that something positive can come from this year of horrific wildfires, but the benefits entirely depend on the severity of the blazes. Mixed-severity is ideal for the biggest rewards, as they leave room to promote plant growth and pollinator activity.

“Thanks to this project, we now have very in-depth knowledge of local pollinator communities, especially the bee communities,” Burkle said, commenting on the decline of the pollinators. “One of the benefits of these data is to be able to provide expert knowledge about declining pollinator species and species of concern, like the western bumblebee, which is currently being considered for federal listing under the Endangered Species Act.

“When we think about patterns of biodiversity across space, we typically consider different groups of species separately,” she continued. “In our case, we might consider patterns of plant diversity separately from patterns of pollinator diversity. But our study provides solid evidence that — above and beyond the influence of disturbances like wildfires — the relationships that plants have with pollinators are strong contributors to these patterns of biodiversity.”

The authors note that it is becoming more popular for land managers to invest in “controlled burn” approaches to replenish their land, though it has been met with pushback. Although there is always a risk with wildfires, controlled burns prevent flammable material from building up and maintains the overall natural health of landscapes.

Burkle hopes the study will encourage changes in conservation efforts to keep the relationship between wildfires and plants and pollinators in mind, especially with the looming threat of climate change. And she hopes with the new arsenal of wildfire knowledge that we can act preemptively to protect landscapes and vulnerable species, as the loss of even one pollinator can set off a chain reaction among dependent species.

“By sharing our findings with federal land managers across the region, we hope to contribute to management plans, with the dual aim of maintaining biodiversity of plants and pollinators while restoring environmental complexity representative of historical fire regimes,” Myers said.

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