Invasive plants can be as serious a threat to the environment as climate change. Discover how a new study shows that combined factors like drought, fire and invasive species start a vicious cycle that makes matters even worse.
When I discuss climate change with some people, their response is sceptical. “We’re only talking about a degree or two,” they may say. “What possible difference could that make?”
What I don’t think people with this mindset have grasped is that our ecosphere is an interdependent web of life. There’s a mysterious symmetry at work in Nature that we don’t yet fully understand.
I was reminded of this again this week by a long-term study that the journal Ecology Letters published this week. For quite a while now, ecologists have believed that when climate change aggravates conditions life fires or droughts, it can trigger invasive species to spread.
Do Invasive Species Make Climate Change Worse?
The researchers set up an experiment to learn if invasive plants make the impacts of climate change even worse. Working at the University of Florida’s Biven’s Arm Research Site, they exposed small plots of long-leaf pine trees to three possible climate conditions.
Those conditions were drought, invasive species, or a combination of both. Using a weed called cogongrass, they allowed the trees to grow under each of these scenarios for about six years.
They simulated droughts by building shelters over the young trees. The shelters reduced the rainfall that could reach them.
Congrass – Fast Growing Plant From Southeast Asia
The cogongrass they planted is a fast growing, adaptable plant that belongs in Southeast Asia. It’s been taking over forests and pastures throughout the region.
Finally, to complete their research, they also introduced fire into the equation. The scientists started controlled burns to study how that extra stressor would affect the results.
After the fires died down, the team found that trees that had endured both drought and cogongrass infestation were the least likely to survive the fires. Luke Flory is a professor of ecology at the University of Florida’s Institute of Food and Agricultural Sciences.
Cogongrass Provided Extra Fuel to the Fire
“Less water meant the trees didn’t grow as tall,” Professor Flory explained. At the same time, the cogongrass, which is drought-tolerant, provided extra fuel to the fire, making it burn hotter and increasing the height of flames.”
The results show a vicious cycle involving the drought, the fire, and the presence of the cogongrass. The drought made the trees shorter and the cogongrass made the flames higher.
It wasn’t any one of these three influences on its own that harmed the trees. It was the interaction of the natural connections between all three.
Interplay between Climate Change and Invasive Plants
The study offers some helpful hints for forest managers. Understanding the interplay between climate change and invasive plants will help them conserve habitats in fire-prone regions.
However, these results also remind of of a larger understanding. As Professor Flory put it, “These findings are one more reason why managing invasive plants is so important to conserving native ecosystems.”
In the past, science tended to look at living organisms in isolation, like machines. As ecology has progressed, we’re coming to see the natural world as an interconnected ecosphere.
Natural World as an Interconnected Ecosphere
Looking at climate change in isolation doesn’t provide a perspective on its full impact. When we consider organisms like the long leaf pine tree in the context of their habitats, we discover cycles of synergy that can work for or against the existing natural balance.
That’s what makes the consequences of climate change so potentially devastating. Until humanity rediscovers that our works like a single, integrated being, we’ll continue to underestimate the consequences of our industrial emissions and our exploitation of natural resources.
Professor Flory’s lab conducted this experiment as part of a project called Drought-Net. This is a global network of scientists researching the effects of extreme drought on various ecosystems.
We always have more to learn if we dare to know.
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