In scientists' eyes, each leaf of the northern pitcher plant is a small ecosystem.
Credit: Aaron Ellison
Whether small carnivorous plant or huge lake, both are subject to the same ecological "tipping points," of concern on Earth Day--and every day, say scientists.
The findings are published in this week's issue of the journal Proceedings of the National Academy of Sciences.
In the paper, ecologists affiliated with the National Science Foundation (NSF) Harvard Forest Long-Term Ecological Research site in Massachusetts offer new insights about how such tipping points happen.
"Human societies, financial markets and ecosystems all may shift abruptly and unpredictably from one, often favored, state to another less desirable one," says Saran Twombly, program director in NSF's Division of Environmental Biology, which funded the research.
"These researchers have looked at the minute ecosystems that thrive in pitcher plant leaves to determine early warning signals and to find ways of predicting and possibly forestalling such 'tipping points.'"
Life in lakes and ponds of all sizes can be disrupted when too many nutrients--such as in fertilizers and pollution--overload the system.
When that happens, these aquatic ecosystems can cross "tipping points" and change drastically. Excess nutrients cause algae to bloom. Bacteria eating the algae use up oxygen in the water. The result is a murky green lake.
"The first step to preventing tipping points is understanding what causes them," says Aaron Ellison, an ecologist at Harvard Forest and co-author of the paper. "For that, you need an experiment where you can demonstrate cause-and-effect."
Ellison and other scientists demonstrated how to reliably trigger a tipping point.
They continually added a set amount of organic matter--comparable to decomposing algae in a lake--to a small aquatic ecosystem: the tiny confines of a pitcher plant, a carnivorous plant native to eastern North America.
Each pitcher-shaped leaf holds about a quarter of an ounce of rainwater. Inside is a complex, multi-level food web of fly larvae and bacteria.
"The pitcher plant is its own little ecosystem," says Jennie Sirota, a researcher at North Dakota State University and lead author of the paper.
Similar to lake ecosystems, oxygen levels inside the water of a pitcher plant are controlled by photosynthesis and the behavior of resident organisms--in this case, mostly bacteria.
Ellison says that conducting an experiment with bacteria is like fast-forwarding through a video.
"A bacterial generation is 20 minutes, maybe an hour," he says. "In contrast, fish in a lake have generation times of a year or more.
"We would need to study a lake for 100 years to get the same information we can get from a pitcher plant in less than a week."
The same mathematical models, Ellison and colleagues discovered, can be used to describe a pitcher plant or a lake ecosystem.
To approximate an overload of nutrients in pitcher-plant water, the team fed set amounts of ground-up wasps to the plants.
"That's equivalent to a 200-pound person eating one or two McDonald's quarter-pounders every day for four days," says Ellison.
In pitcher plants with enough added wasps, an ecosystem tipping point reliably occurred about 45 hours after the start of feeding.
The scientists now have a way of creating tipping points. Their next step will be to identify the early warning signs.
"Tipping points may be easy to prevent," says Ellison, "if we know what to look for."
Other authors of the paper are Benjamin Baiser of Harvard Forest and Nicholas Gotelli of the University of Vermont.Media Contacts
Cheryl Dybas | EurekAlert!
Scientists team up on study to save endangered African penguins
16.11.2017 | Florida Atlantic University
Climate change: Urban trees are growing faster worldwide
13.11.2017 | Technische Universität München
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses