A series of landmark studies have shown grazing strategies which best protect biodiversity are also the most profitable for cattle farmers, in a win-win outcome that shows how these farms can complement the conservation work already done by Australia’s national parks.
Scientists at James Cook University were granted access to the Queensland Department of Agriculture and Fisheries’ Wambiana Grazing Trial. This allowed the researchers to conduct Australia’s first dual profitability and biodiversity analysis comparing different grazing strategies used by farmers in Queensland and their effects on mammals, birds, reptiles and invertebrates, and ultimately publish eight papers between 2016 and 2020.
The overall outcome was that the heavy grazing strategy, where more cattle are placed in a paddock than can optimally be supported, was not only worse for biodiversity but actually brought in less profit for farmers than more moderate and variable strategies.
“We were interested in determining the financial cost of maintaining biodiversity. As it turned out, the most profitable grazing strategies long-term were also the best for biodiversity, so the cost of maintaining biodiversity in this system was nil. It is a great outcome for wildlife and land holders,” said senior author of the studies, Professor Lin Schwarzkopf of the College of Science and Engineering at JCU.
While it seems obvious that well-managed properties better protected biodiversity, Schwarzkopf told Lab Down Under that actually quantifying these results was important. The win-win outcome showed precisely how livestock grazing, which currently takes up over 25 per cent of global land use1, could be managed to better assist with conservation, she said.
Maximising biodiversity for every land use
The research commenced with a paper published in Rangeland Ecology & Management in 20162 which explained why rangelands used for livestock grazing had the potential to complement protected areas such as national parks when it came to conserving biodiversity.
Because cattle grazing takes up such an enormous percentage of land use worldwide, doing a “little something” on these agricultural properties could aid biodiversity of plants and animals, including those not found in national parks, Professor Schwarzkopf said.
“We have national parks and their job is to maintain biodiversity. However we also have other land uses that are moderately good for maintaining biodiversity. I actually believe that we should maximise biodiversity on every kind of land use. No matter how bad a particular land use is for biodiversity, you could still manage to maximise biodiversity in that place,” she told Lab Down Under.
According to a report submitted to the Federal Government in 2006 on the funding and resourcing of Australia’s national parks and protected areas3, only around four per cent of the country is national parkland with a further six per cent designated as protected regions such as conservation areas, nature reserves, and indigenous protected areas.
In-the-field studies of cattle grazing
The JCU studies looked at different grazing strategies, determining the relationship between the biodiversity of mammals, reptiles, birds and invertebrates and overall profitability.
The following four grazing strategies were examined at Wambiana, a privately-run working cattle station located in North Queensland:
- Heavy grazing: Each paddock contains a number of cattle twice the long-term carrying capacity
- Moderate grazing: Each paddock contains a number of cattle equal to the long-term carrying capacity
- Variable grazing: The number of cattle on each paddock was varied depending on the amount of feed at the end of each wet season
- Rotational grazing: A third of each paddock was spelled, or fenced off to cattle, each wet season
The long-term carrying capacity is defined as the average number of animals a paddock can support over a defined period4. The actual capacity depends on a number of variables including land types, land condition, climate and feed accessibility.
The grazing strategies were examined at the 1,000 hectare experimental site at Wambiana where 10 paddocks were used with five grazing strategies replicated twice.
A fifth grazing strategy used at Wambiana, varying the number of cattle based on the southern oscillation index predictions for rainfall, was not examined in the JCU papers however.
Wambiana rents 1,000 hectares to DAF, which has conducted controlled grazing experiments there on the profitability of different grazing strategies for the past 18 years.
Video 1: A tour of Wambiana showing the onsite learning opportunities available.
Trading out the trade-off
Professor Schwarzkopf told Lab Down Under that the research was commenced with the expectation that there would be some kind of trade-off such that grazing strategies that were good for biodiversity would be less profitable for farmers.
However, the final outcome was a win-win for both cattle farmers and conservationists with the moderate, variable and rotational grazing strategies beating out the heavy grazing strategy in both conservation and financial goals.
“We thought maybe one of the intermediate strategies would have the best biodiversity and we could tell farmers that if they lost this much profit, there would be this benefit to biodiversity, so this is how much it would cost to maintain high biodiversity,” Professor Schwarzkopf said.
“But instead we found that the best, most profitable grazing strategies — three out of the four — were also the best for biodiversity. The three varied a little bit, so the variable strategy was a bit worse for biodiversity than the rotational and moderate, but the profitability was almost indistinguishable between them. So basically it works out that three of the strategies were good.”
The finding that heavy grazing was the worst in both areas contradicted a common farming belief that overgrazing was required to make money.
“Grazing heavily had the lowest profitability. And it’s because when there’s drought, the farmers have to feed the cattle. That costs a fortune and they don’t recover from that,” Professor Schwarzkopf said.
A complex web of animal responses
While the research found that biodiversity overall was high for anything other than heavy grazing, how particular types of animals responded varied across the different classes.
For instance, heavy grazing generally impacted reptile biodiversity, with this effect being more pronounced during drought years5. However, the resilience of reptiles to grazing depended on whether the species lived on the ground or in trees6 with tree-dwelling species being more resilient.
The response of birds to each grazing strategy was more complicated7. Ground-dwelling birds were in general more negatively impacted by heavy grazing. However, this effect varied from species to species with numbers of red-backed fairy-wrens decreasing in heavy grazing treatments while numbers of Australian magpies increased for example.
Two different mammal studies were also conducted. One found that the tree-dwelling common brushtail possum was resistant to the heavy grazing strategy but preferred certain vegetation types8. The other paper looked at the rufous bettong9, which the study found avoided heavy grazing areas.
When examining invertebrates, the JCU researchers discovered that ants dramatically increased their numbers in response to heavy grazing10.
Bridging barriers for conversation
A major barrier to conservation on rangelands was the view of both farmers and conservationists that the only way to have good wildlife outcomes was to reduce profitability, Professor Schwarzkopf said.
A further hurdle is that most prior studies examined the difference between ungrazed and grazed land, which was not particularly useful when having a conservation with farmers, she added.
“Grazing unquestionably is bad for biodiversity. It’s much better to have a national park than a grazed property. But if you’re a farmer and you have a grazed property, you want to make a profit from it, possibly in addition to conserving biodiversity. So if you want farmers to encourage biodiversity, you have to be able to talk about a grazing strategy that will encourage biodiversity while keeping in mind, and being able to explain, profitability.”
In addition to the particular grazing strategy used, there were a number of ways rangeland managers could improve biodiversity, Professor Schwarzkopf said. This includes not clearing the native trees away and having a distributed water supply to prevent cattle destroying the vegetation next to water holes.
“Rangelands are grazing on natural vegetation when the land hasn’t been improved or planted out by anything. So it’s just grazing in a natural ecosystem. And because it’s in a natural ecosystem, it maintains a lot of biodiversity.”
Professor Schwarzkopf said that further research was needed to test grazing strategies elsewhere in Australia to see if the same trends could be seen in farms across the country.
The papers were funded by Meat and Livestock Australia and the Holsworth Wildlife Research Endowment with support from the Queensland Department of Agriculture and Fisheries.
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1 Asner G, Elmore A, Olander L, Martin R, Thomas Harris A. Grazing Systems, Ecosystem Responses and Global Change. Annual Review of Environment and Resources, November 2004, Volume 29, 261-299.
2 Neilly H, Vanderwal J, Schwarzkopf L. Balancing Biodiversity and Food Production: a Better Understanding of Wildlife Response to Grazing Will Inform Off-Reserve Conservation on Rangelands. Rangeland Ecology & Management, Volume 69 (2016) 430-436.
3 Conserving Australia: Australia’s national parks, conservation reserves and marine protected areas. Environment, Communications, Information Technology and the Arts Reference Committee. November 30, 2006.
4 Utilisation and carrying capacity. Meat and Livestock Australia.
5 Neilly H, O’Reagain P, Vanderwal J, Schwarzkopf L. Profitable and Sustainable Cattle Grazing Strategies Support Reptiles in Tropical Savanna Rangeland. Rangeland Ecology & Management, Volume 71, Issue 2, March 2018, Pages 205-212.
6 Neilly H, Nordberg E, VanDerWal J, Schwarzkopf L. Arboreality increases reptile community resistance to disturbance from livestock grazing. Journal of Applied Ecology, July 2017.
7 Neilly H, Schwarzkopf L. The impact of cattle grazing regimes on tropical savanna bird assemblages. Austral Ecology (2019), Volume 44, 187-198.
8 Neilly H, Schwarzkopf L. The response of an arboreal mammal to livestock grazing is habitat dependant. Scientific Reports, Volume 7, Article number: 17382 (2017).
9 Neilly H, Schwarzkopf L. Heavy livestock grazing negatively impacts a marsupial ecosystem engineer. Journal of Zoology, January 2018.
10 Neilly H, Jones H, Schwarzkopf L. Ants drive invertebrate community response to cattle grazing. Agriculture, Ecosystems and Environment, Volume 290 (2020) 106742.
Featured image: Limousin cattle. Picture by PXFuel. Free for commercial use.