Detailed research efforts will help inform reforestation efforts
It is easy to think of trees as part of the landscape. But what if the trees were the landscape?
That’s what a new study by a University of Georgia researcher brings to us. By viewing each tree as a world that hosts its own populations of insects and fungi—and looking at the genetic variation that supports those communities—we can better understand the role trees play in the larger ecosystem.
But then the study took the concept a step further, broadening the perspective to examine the impact of tree genetics on communities across much of the North American Southwest. It is the first time researchers have linked tree genetic variation to community biodiversity on a continental scale.
Helen Bothwell
“Understanding this relationship between tree genotypes and the organisms they support provides a more comprehensive roadmap for reforestation efforts that also support healthy ecosystems,” said Helen Bothwell, assistant professor at the UGA Warnell School of Forestry and Natural Resources and lead author of the study.
“Diversity breeds diversity. We know that different communities gather on different tree genotypes, and we can now show that this relationship has implications for biodiversity conservation even at very large scales. Planting diverse reforestation stocks is critical to maintaining abundance of pollinators and predators, which in turn provide valuable services to our agricultural systems and serve as a food source for bird and wildlife populations.”
The study focused on poplars
Bothwell and her collaborators collected hundreds of samples from trees at more than 50 sites in California, Nevada, Utah, Arizona and northern Mexico. They focused on poplars, a fundamental species of riparian ecosystems in this region. These river corridors are oases, hotspots of biodiversity in the surrounding arid, rocky landscape. But these green patches are among the most threatened in the United States, with less than 3% of their pre-20th-century range remaining.
Development requirements, water consumption and stress from climate change also threaten the habitat of the poplars. But the findings from the study, published in the journal Forests in May, may help support reforestation efforts and create more resilient cottonwood groves in the future.
Many previous studies have documented strong relationships between tree genotypes and invertebrate and fungal communities at the level of individual trees in community gardens, she said. Community gardens are a valuable tool for studying genetic effects. When growing plants in a common environment, any remaining variation is due to genetic effects. But now the researchers wanted to know whether insects and fungi can still recognize this variation outside the manicured boundaries of the garden, where nature’s disorder reigns supreme.
“We wanted to see how these insect and fungal communities translate into truly comprehensive species management at a continental scale. For example, do communities still respond to differences between entire tree populations? Different watersheds? Or even broad geographic regions, roughly the scale of the entire North American Southwest?” Bothwell said.
After collecting samples of trees, insects and fungi, the researchers began to see patterns – for example, the characteristics of certain trees corresponded to certain insect or fungus populations.
“And so we correlated the patterns in genetics with the patterns in community members; Those relationships were very strong at a local level, but as we scaled up, environmental fluctuations had a larger effect,” she said.
The influence of trees on regional biodiversity
But despite increasing environmental noise, she was still able to identify the impact of tree genetics on communities at very large scales throughout the US Southwest and Mexico. That’s surprising, she said, and underscores the importance of considering the impact of trees when it comes to preserving regional biodiversity.
This knowledge could inform future reforestation and conservation efforts in these vanishing cottonwood ecosystems, she added. Rather than just gathering seeds from nearby forests, land managers can draw on nearby regions to boost tree genetics.
“With climate change, you realize that local growing may not be the best – trees may not be ‘locally’ adapted to where they settled 50 or 100 years ago,” Bothwell said. “So if you want to plant for future climate change, one option is to take a stepping stone approach and collect seeds both on-site and from nearby regions that have temperatures similar to those predicted by climate models for 50 years, for example. By.” a blended approach, you get local genetic variation while also incorporating trees that may be better able to withstand future climate stresses.”
Losing a tree like the cottonwood would be devastating to the Southwest landscape, Bothwell added, as it is home to an abundance of undergrowth plants, fungi, insects and wildlife. By better understanding the forces acting on trees, land managers can also better protect the plants and animals that live around them.
The communities that use trees for habitat are mindful of the diversity they host. In short, says Bothwell, planting diverse trees supports diverse communities.
“It’s a powerful conservation model; you can think of it like an umbrella,” she added. “By understanding forest systems and working to conserve them, we can also provide conservation benefits to whole communities of organisms that we don’t have the time or resources to focus on individually. You get more protection for your money if you focus on conserving the genetic management of foundation species — species that have a major impact on their ecosystems, such as trees.”
news.uga.edu
https://news.uga.edu/study-links-tree-genetics-to-biodiversity-patterns/
