The health of rangelands carry a large importance in the agricultural industry and in effort to improve and educate, Leduc County and West-Central Forage Association held a pasture and feed resources seminar on April 19.
Keynote speakers Ed Bork, range ecology and management, University of Alberta and Grant Lastwika, livestock and forage business specialist, Alberta Agriculture and Forestry, both spoke on a variety of rangeland health subjects and good grazing management practices.
Bork’s presentation leaned heavily toward carbon storage and he tied many other aspects of grazing management back to the subject.
Right from the beginning Bork told those who attended the seminar he was disappointed with the lack of value being placed on grasslands as a carbon sink, as there are many other far-reaching benefits stemming from that potential.
Bork was part of a research team conducting an extensive study regarding how grasslands can serve as a net uptake for the gasses. Across several provinces, up to 114 grassland sites managed by Alberta Environment and Parks were studied under different tests and variables.
Bork says the sites, ranging from 15 to 70 years old, were observed for carbon and grazing management and the links between the two.
Grasslands store between 10 to 30 per cent of the world’s organic carbon pool, and temperate grasslands cover eight per cent of the Earth’s surface, says Bork. “And they store more than 300 gigatonnes of carbon. Nine gigatonnes of this is basically in plants. The majority is below ground, in soil.”
In the prairie region, native grasslands were found to store 80 tonnes per hectare while cropland stores 60 tonnes per hectare. In the parkland region, 120 tonnes per hectare was found in the grassland and 70 tonnes under the cropping system.
“Where is that carbon today? It’s back in the atmosphere, contributing to rising CO2. So I would argue this represents a very significant benefit to society,” said Bork. “When people think about global warming they only think about the burning of fossil fuels,” he added.
Along with helping to keep moisture retained in the soil — which is crucial during drought periods — Bork says minimal and no tilling procedures help maintain ground carbon levels.
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“It’s amazing how many people that are living in our cites and towns do not understand this stuff … When we look at a picture of a perennial grassland they just see something that’s wasteland, there’s nothing out there. It’s not true at all,” said Bork.
“There’s a whole plethora of environmental goods and services that they are benefiting from … we haven’t done a good job getting that message across to those people,” he added.
Within the study, plant diversity peaked in areas with moderate to high rainfall and regions such as parkland and foothills; continuing to reveal a higher diversity when there was more grazing on their grasslands. “This is not surprising … If you remove grazing for a long period of time you find stagnation in the plant community,” said Bork.
In the areas with moderate to high rainfall, grazing also helped introduce new plants to the grasslands. The increased diversity leads to boosted plant production and carbon storage. Bork added drier lands were more resistant to plant introduction.
“Grazing is actually critical to help maintain the ongoing function of these areas including providing forage production. Without it you actually lose productivity,” said Bork.
Long-term grazing exposure also helps protect the sustainability of grasses growing on the grasslands by reducing shrubbery. “Cattle are a natural biological control agent to keep shrub encroachment in check,” said Bork.
Grazing without over grazing was found to promote plant health and root growth of plants, which is critical in maintaining the grasslands systems; once again suggesting a link between grazing and carbon storage, says Bork.
“Grasslands provide far more than just forage production,” he added. Along with carbon storage they also serve as a water purification system, flood mitigation, wildlife habitats and encourage pollination.
“Grazing is a full functioning system and as a full functioning system, everything relates,” said Lastwika. He explained a healthy system can be broken up into individual variables: 40 per cent management, 40 per cent environment and 20 per cent species.
When it comes to grazing management, Lastwika says there needs to be a balance between forage supply and animals needs. “The balance really focuses on biological rest.”
Over-grazing reduces pasture productivity in the long-term; by leaving more than 50 per cent of a plant’s above ground mass there is almost no negative impact to the root systems. “That’s why it’s important when we graze these plants, our frequency and severity are considered.”