Farmers cultivate or maintain riparian buffers for a variety of purposes, including enhancing water quality, preventing soil loss, and supporting hunting grounds. Recent research from the University of Illinois Urbana-Champaign highlights another advantage of riparian buffers: their contribution to terrestrial biodiversity. The study reveals that a 10% rise in forest cover correlates with the presence of one more species.
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Raccoon and common snapping turtle DNA were ubiquitous in our samples,” stated Eric Larson, the study’s lead author and an associate professor in the Department of Natural Resources and Environmental Sciences (NRES) within the College of Agricultural, Consumer and Environmental Sciences at the University of Illinois. “However, discovering bobcats and big brown bats using our technique was thrilling, highlighting the vibrant activity within those riparian buffer zones.
Uncovering biodiversity through environmental DNA.
Larson is talking about this particular sampling technique:environmental DNAMetabarcoding is a technique that he and other ecologists have increasingly relied on in recent years to identify species that are uncommon or difficult to observe directly. By isolating DNA snippets from sources like water, soil, snow, or even the atmosphere, researchers can determine which animals have passed through the surrounding area, whether by walking, swimming, or flying.
Larson and Olivia Reves, the lead author of the study, were aware of the advantages of tree canopies for aquatic life when they chose to investigate biodiversity in riparian buffers. They knew, for instance, that shade from trees along the banks helps keep water temperatures stable and provides better living conditions for fish. However, the advantages of riparian buffers for land animals in farming regions were less clear.
Research approaches and results in Illinois.
To address this deficiency, Reves and Larson employed eDNA metabarcoding to determine the terrestrial species present in water samples collected near farmland at 47 locations in Central Illinois, which differed in the amount of forestation.
Reves, a recent graduate student under Larson, stated that this monitoring tool hasn’t been utilized enough to determine the positive impacts of agricultural conservation efforts, such as riparian buffers, on land-based biodiversity.
However, what’s the reason for taking water samples to find land-based creatures?
Larson stated that analyzing these samples for fish would undoubtedly reveal fish DNA. He elaborated that the water in streams and rivers gathers DNA from all creatures interacting with the nearby environment. Taking a drink from a stream, for example, leaves behind traces of your own DNA that can be detected further down the waterway.
How forest cover affects wildlife.
Once the researchers had separated and determined the identity of all the DNA pieces from the water samples, they were able to investigate the links between land-based biodiversity and the extent of forest. They discovered that for each 10% rise in forest cover, there was an additional species present. Furthermore, locations with total forest cover sustained three times as many land vertebrate species as areas without any trees. The makeup of the community also shifted in areas with greater forest cover.
Reves stated that they observed a shift in animal populations that correlated with the amount of forest cover. “On one extreme, we identified grassland species, such as mice, ground squirrels, and killdeer, which thrive in more disrupted habitats. In areas with dense forest cover, we encountered a completely different array of species. The observation that we sawforest-dependent species, like southern two-lined salamanders, North American river otters, and ruby-throated hummingbirds, truly emphasizes how valuable riparian buffers are in farming areas.”
Challenges and future of riparian buffers
Reves added that despite the biodiversity benefits, not all agricultural landowners are sold on riparian buffers.
“Some landowners see them as unkempt or think they bring pests to their fields. But we found a lot of species, like bats, that actually draw pests away or prey on those pests. In addition, riparian buffers can help with soil erosion and water quality,” she said. “I hope our study informs the voluntary and regulatory implementation of forested riparian buffers across the Midwest.”
More information: Environmental DNA quantifies the terrestrial biodiversity co-benefit of forested riparian buffers in agricultural landscapes, Journal of Applied Ecology (2025).
Provided by University of Illinois at Urbana-Champaign
This story was originally published on Alpine Times.
