The Ecotypes Project Returns for a New Game of Tundra Chess

April 5, 2022

Haley Dunleavy
907-474-6407

In the Arctic鈥檚 short summer growing season, timing is everything. From snowmelt to senescence, tundra plants race to send out their annual set of leaves, flowers, and fruit while producing enough energy to support their dormancy through the winter months. But as climate change extends Arctic summers, some plants appear to be better able to respond, staying green鈥攁nd fixing carbon鈥攆or longer. Researchers at Toolik Field Station want to know how well Eriophorum vaginatum, commonly known as tussock cottongrass, can adjust to the longer growing season鈥攁nd what that may mean for the tundra at large.

Last fall, Ned Fetcher, Michael Moody, Gus Shaver, and Jim Tang were to study the ties between phenology and genetics as Eriophorum, the foundational namesake in 有料盒子视频鈥檚 moist acidic tussock tundra, responds to a warming Arctic. Known as the Ecotypes project, the researchers鈥 previous work has been a staple at Toolik since the station鈥檚 early development. Its roots trace back to 1979, when Fetcher, now a plant ecologist at Wilkes University, was interested in the classic ecological question: does a plant鈥檚 environment or its genetics carry more weight in determining variation within a species? 

Open Top Chambers warm the tundra at the Ecotypes experimental sites.
Amanda Young
The Ecotypes experiment uses open top chambers to passively warm the tundra near Toolik Field Station.
A field of seeding Eriophorum vaginatum
Amanda Young
Eriophorum vaginatum, also known as 有料盒子视频 cottongrass, fills the tundra with its fluffy white tuffs of seeds.

To explore this question, Fetcher and colleagues, including Shaver, across a latitudinal temperature gradient from Eagle Creek up to Prudhoe Bay. Shaver was studying variation in tundra plants along the Dalton Highway and invited Fetcher along for the drive. During that trip, Fetcher said they got the idea to transplant tussocks in hopes of better identifying some of the drivers of variation within Eriophorum. In total, six reciprocal transplant gardens were initially established, the success of which Fetcher said was partly due to Eriophorum鈥檚 annual root system. 鈥淵ou could slice off the tussock without disturbing the soil, without digging up roots, without going through all that business,鈥 Fetcher said. 鈥淛ust slice off the tussocks and move them around like you would pieces on a chessboard.鈥

Researcher juggling tussocks
Ned Fetcher
Knut Kielland, a researcher at the University of 有料盒子视频 Fairbanks, juggles cottongrass while transplanting tussocks in 1980 across the North Slope of the Brooks Range.

Since the start of the first Ecotypes experiment, Fetcher and his collaborators have played a lot of Eriophorum chess, establishing between Coldfoot, Toolik, and Sagwon and tracking tussock growth, survival, and senescence in . Though the researchers鈥 initial goal was to among ecotypes, Fetcher said that the focus of Ecotypes shifted as climate change moved to the forefront of ecologists鈥 concerns. 鈥淚 speculated that these differences that we found in the response of these ecotypes could affect what happens with Arctic change,鈥 he said. 鈥淚f something stays green longer or stays green later, that's going to affect ecosystem properties, like nutrient retention or primary productivity,鈥 Fetcher added. Because tussocks are a key player in the 有料盒子视频n tundra, 鈥渢his is a case where ecotypic variation could actually make a difference.鈥

The researchers have indeed found strong evidence that climate change interacts with ecotypic differences. For instance, : one northern and the other southern, geographically separated latitudinal treeline, near the Chandalar Shelf. Fetcher and collaborators found differences between the two ecotypes that can persist for at least 30 years after transplanting. Southern tussocks are larger and have a longer growing season than northern tussocks, even when experimentally transplanted to northern regions like Toolik. In contrast, northern populations don鈥檛 seem to extend their growing season when either transplanted south or artificially warmed in the north. This might mean that northern ecotypes lose out in a hotter Arctic despite the lengthened potential growing season. And though to living in a warmer climate, their ability to thrive in northern locations ultimately depends on whether or not they could migrate northward. Fetcher and colleagues suspect that鈥檚 unlikely at a pace that matches that of climate change, leaving Eriophorum鈥檚 future in a state of uncertainty.

Re-examining Core Drivers

The Ecotypes group has largely centered their efforts on the role that temperature plays in differences among Eriophorum populations. But, Fetcher said, their research has missed a key factor: light. 鈥淭here have been lots of studies of phenology in the Arctic,鈥 he said. 鈥淏asically they find that when spring comes, things start to grow and then they start to senesce in the fall in August. [These studies conclude] that it's tied with temperature, but very few studies really considered light regime.鈥

Researchers measure tussock gas exchange
Ned Fetcher
Steve Unger, a research assistant, and Tom Parker, a postdoctoral researcher, measure gas exchange on a transplanted tussock in the Ecotypes experimental plots.

When tussocks are transplanted, they鈥檙e not just entering a new temperature regime. They also experience a different photoperiod. Southern ecotypes in northern common gardens suddenly enter an area with longer daylight hours while northern ecotypes that are transferred to southern gardens experience darkness earlier into the season. Fetcher found in preliminary greenhouse experiments that tussocks exposed to three hours of darkness senesced earlier compared to tussocks grown in 24 hours of light. In the field, Eriophorum鈥檚 response to light might interact with its response to warming. 鈥淎s things warm up, the southern ecotype may be able to migrate north,鈥 he said. 鈥淏ut then it's going to be in a different photoperiod and may not be able to respond.鈥 

In the next round of the Ecotypes project, the research group is returning to their initial question of what鈥檚 driving differences鈥攖he environment or genetics鈥攁nd asking how light factors into Eriophorum鈥檚 phenology between Coldfoot and Toolik. Michael Moody, an associate professor at University of Texas at El Paso, said their new research aims to disentangle the extent to which temperature, light quantity and quality, and genetics play a role in phenology and photosynthetic rates. 鈥淭hat's the exciting aspect,鈥 Moody said, 鈥淲hat else is causing [these differences]? Is there an interaction between light, temperature, and other environmental factors?鈥

To address these questions, the researchers plan to manipulate photoperiod in the field with help from mechanical engineering students at Fetcher鈥檚 Wilkes University. He鈥檚 working with students to build automated 鈥渂lackout boxes鈥 that encapsulate tussocks at the transplant gardens in Toolik in a few hours of darkness during the never-setting summer sun of the Arctic. At Coldfoot, the team plans to simulate 24 hours of light even into the late summer months, when dark nights begin to reappear. The light manipulations will help determine the extent to which photoperiod controls phenological differences between northern and southern ecotypes. 

Two researchers return to tussock transplant experiment
Ned Fetcher
Ecotypes researcher Jim McGraw and field technician Alana Thurston examine transplanted tussocks near Toolik Field Station on a rainy summer day.

The researchers won鈥檛 just track phenology and photosynthetic rates in these new transplant and light experiments. Moody, a plant geneticist, also plans to explore the genetic controls on Eriophorum鈥檚 phenology more. His past research has shown that the two ecotypes are distinct in both their genome and . Moody said in addition to examining the importance of photoperiod in determining senescence, their new grant will also allow them to 鈥渓ink to what's happening at the genetic level and figure out which genes are signaling when to shut down鈥 via transcriptomics.

鈥淲e can look at phenology and see that 鈥榶eah the phenology is different鈥. But by looking at the genes and transcriptome, we can start finding finer scale patterns of what really is reacting to these differences,鈥 Moody said. This could prove useful for models projecting future tundra vegetation shifts. He added: 鈥淢ost research to this point really has been treating species as one entity that doesn't have any real difference.鈥 The Ecotypes researchers know from their previous studies that this assumed uniformity isn鈥檛 the case for Eriophorum. To better predict whether tussocks will persist in a future Arctic, Moody said, 鈥渨e're going to have to think of not treating Eriophorum vaginatum as one single entity, but as multiple entities.鈥

Expanding in a Changing Field

Understanding the environmental and genetic controls on 贰谤颈辞辫丑辞谤耻尘鈥檚 phenology is one move in the chess problem of Eriophorum and climate change. Also on the board is what these drivers mean in a tundra that鈥檚 not only warmer, but also shrubbier. The Ecotypes team will address this unknown by comparing responses of Eriophorum with the region鈥檚 dominant deciduous shrubs, Betula nana and Salix pulchra, two plants that are expanding across tundra ecosystems and could outcompete Eriophorum in the future.

This latest development to the grant鈥攖he added factor of shrub expansion鈥攊s just one of the ways the Ecotypes project has evolved over its decades-long run. 鈥淚t's amazing where science has come over [those years since the project began],鈥 said Moody. Take the pair鈥檚 collaborative effort to link genetics and ecology. 鈥淏ack when Ned was first getting started, evolutionary biologists and ecologists never really worked together,鈥 said Moody, who teamed up with Fetcher after they met in 2013. 鈥淚t really is a history of science in a way of the project where it started to what we can do today with teams of people working on very different aspects of the science,鈥 he added.

Toolik tussock at Eagle Creek
Ned Fetcher
An Eriophorum vaginatum tussock, transplanted from Toolik Lake in 1979, continues to grow in the southerly site of Eagle Creek, 有料盒子视频 roughly 4 years later.

Fetcher said Toolik Field Station helped support the project鈥檚 development as well. During the project鈥檚 early start at Eagle Creek, Fetcher said he and others were living in tents, using snow banks for refrigeration, and spending lots of time cooking or making grocery runs back down to Fairbanks. Over the years, Toolik has grown to better provide for those logistics, opening up more time for science and more infrastructure for advancements in technology. 鈥淲ithout Toolik, I don't think we could do the kinds of experiments that we've done,鈥 Fetcher said. 

Moody shared that same sentiment for Toolik. His connections at Toolik, he said, have given him opportunities to think of ecosystem dynamics under a genomics context. Moody added, 鈥淓verybody鈥檚 thinking about different aspects of what affects the Arctic, especially under climate change. It really makes it possible for you to approach new avenues of research and different ways to think about it.鈥

Look out for a new game of Eriophorum chess when the Ecotypes project returns to Toolik this coming summer.