It all started with a group of ecologists trying to understand the effects of nutrients such as nitrogen and phosphorus on the Earth’s ecosystems. Use of fossil fuels and fertilizer has more than doubled the amount of these nutrients flowing into Earth’s ecosystems, but measuring the effects is difficult because every experiment is done a little bit differently.
“A frustrated team member asked, ‘Why don’t scientists all do things the same way?’” recalls Elizabeth Borer, professor of Ecology, Evolution, and Behavior in the College of Biological Sciences. The “aha moment” came when they realized, “‘Oh, wait — we’re scientists and we should do this.”
From that conversation in 2007 emerged the Nutrient Network (NutNet), a global collaboration of independent research groups whose common thread is the study of human impacts on grasslands. A decade later NutNet, as it’s known, has grown into what could be the most extensive ecological research collaborative in the world, involving scientists from six continents, 25 countries, and more than 100 sites, including CBS’s Cedar Creek Ecosystem Science Reserve. Over the years, it has yielded remarkable insights into how grassland ecosystems function and how that might be changing as human influences intervene.
“It’s a cultural shift in how we do science,” says Borer, who was part of the original visioning team and now co-directs NutNet with CBS colleague Eric Seabloom.
Grasslands are a valuable focus of study, Seabloom says, because they play a critical role in global carbon cycles and also are among the ecosystems that have been most altered by humans as we’ve plowed prairies and brought in grazing animals and invasive species.
“Grasslands are also very important to humans,” he says. “Many of our most important crops like corn, wheat, rice, and oats are grasses, as are many of our most problematic weeds and invasive plants.” And, he adds, grasslands are ripe for a global collaboration like NutNet, because they are found all around the world, from high in the mountains to along ocean shores.
The collaboration brings together under one research umbrella a variety of grassland types, ranging from tundra to desert. Its unique value as a research approach lies in the standardization of procedures, such as how to add nutrients and keep out grazing animals, across sites. And because it’s designed to be low budget, even scientists from countries where little support for such research is available can participate.
“The grassroots NutNet model has empowered scientists,” Seabloom says. “Historically, conducting global-scale research has been a big-budget endeavor. NutNet has demonstrated that high-impact, global-scale research is within the reach of scientists who do not have global-scale budgets by leveraging creativity and science's social networks.”
Broadly, NutNet focuses on characterizing relationships among various traits of grasslands, such as how many pounds of plants grow each year, the diversity of the plants and animals they support, and how plants help store carbon and control movement of nutrients like nitrogen and phosphorus. Among other things, past NutNet studies have revealed that grasslands that support a more diverse community of species are also more stable and productive. They also have shown that increased nutrient supplies lead to the extinction of native plants and a higher abundance of non-native, invasive species.
As NutNet begins its second decade, researchers plan to continue to gather data, increasing the opportunity to discover effects that only occur after long periods of time. They’re also aiming to look at what determines plant diversity at scale ranging from a few inches to the entire planet, and to further explore how human alteration of Earth’s ecosystems affects the ability of grassland ecosystems to support native species and control the movement of elements like carbon, nitrogen, and phosphorus that affect the earth’s climate, soil fertility, and water quality. Borer also is planning an intriguing project aimed at understanding why plants sequester salt in their tissues, despite the fact it’s not an essential nutrient for them and might make them tastier for the animals that eat them. With these studies and many others, the scientists will provide perspectives valuable for understanding how global change will affect ecosystems in the future.
In addition to continuing to grow its own grassland network to include new sites in China, the Arctic, and elsewhere around the world, NutNet also is inspiring and informing the use of a similar research approach in other fields.
“Collaborative experimental science is gaining traction,” Borer says. “What we have done with NutNet is to empower scientists by putting a new tool in the toolbox used to study planetary-scale problems.” –Mary Hoff