Plant diversity of Alberta rangelands little affected by intensive livestock grazing management, study finds

How ranchers graze their cattle doesn’t make much difference to plant diversity on earth, says U of A study.

That’s important because plant diversity is a useful metric for assessing the resilience of a landscape, including the rangelands used by cattle ranchers, says Jessica Grenke, the study’s first author.

The researchers compared multi-pen adaptive grazing, called AMP, with other more common grazing systems in the northern Great Plains. AMP is a specialized rotational grazing practice that aims to mimic historic grazing patterns of large herds of animals moving rapidly across the landscape, allowing a long recovery period before being grazed again.

The MPA is more management intensive, employs greater inputs such as fencing and labor, and uses much higher livestock densities compared to ranches that use typical regional management.

“Multi-pen adaptive grazing has been studied and experimented with in more controlled environments for many years, and the scientific community has been left with conflicting results about its ecological impacts,” says Grenke, a PhD student at Department of Biological Sciences.

“In this study, we were able to see what is actually happening on the ground.”

The results suggest that MPA grazing is not an ideal solution to promote plant diversity.

Plant diversity is only one piece of the puzzle when it comes to rangeland (and ranch) management. Additional studies conducted by U of A researchers as part of this project found that ranches using AMP grazing practices lead to greater water infiltration and therefore can help grasslands resist drought. Additional studies have focused on the diversity of soil microbes and the presence of carbon deposition in the soil, all adding crucial context to the pros and cons of various grazing practices on various ecosystem goods and services.

AMP grazing has been around since the 1950s, according to Grenke. However, many studies investigating its ecological effects have had limitations, such as the lack of control ranches for comparison or concentration in a small locality not offering conclusive information.

There are many practical and financial challenges to adopting the broader approach used by this study, says Grenke, who worked with Edward Bork, Cameron Carlyle, Mark Boyce and his supervisor, James Cahill on the project.

“It’s really difficult logistically. To be able to go to all of these operational ranches, to sample these ranches equally, in the same season, using the same breeding methodologies and procedures, takes a ton of work,” says Grenke.

A grant from Agriculture Canada made it possible to carry out the work. The team traveled almost 30,000 km to visit ranches in the prairie provinces in a single season. The study looked at 18 ranch pairs. One ranch in each pair used AMP grazing while the other used grazing practices typical of the region to serve as a control.

To assess plant diversity, they sampled vegetation in pastures with at least 10 years of stable grazing practices, using 15 areas of 0.25 square meters per ranch. They also carefully examined the areas where the samples were taken, making sure the soil type was the same, there were no bodies of water nearby, and there were no nothing that can potentially act as fertilizer, like grazing bullets.

“It was just another step we took to make sure our findings were the results of management and not the underlying ecology of the sampling site,” says Grenke.

Grazed lands cover about half of Earth’s land area and are crucial sources of a wide variety of ecological goods and services, says Grenke.

“There are so many services they provide and it’s the least protected ecosystem in the world – and they’re declining at an alarming rate.”

This team’s research has demonstrated that MPA grazing can be a useful tool for achieving other ecological goods and services objectives, such as soil carbon sequestration and water infiltration. The most recent results indicate that these goals can be achieved with little impact on overall plant diversity. The only negative effect was a small reduction in the total number of native plant species found on each ranch, which may reflect an intolerance of endemic plant species to MPA grazing.

Studies like this provide critical information on how grazing systems and other ranch management practices can potentially affect these grassland ecosystems and offer clues as to what could be done to conserve these areas for the future. ‘coming.

“We’re going to have to increase the sophistication of how we use these landscapes in order to satisfy the plethora of different goods and services that we need on these lands,” says Grenke.

“A better and more accurate understanding of the impact of grazing management on landscapes is key to achieving this. »

/Release from the University of Alberta. This material from the original organization/authors may be ad hoc in nature, edited for clarity, style and length. The views and opinions expressed are those of the author or authors.View Full here.

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