At over 65 sites around the world, 100s of international researchers with several long-term monitoring protocols and one common aim are working to understanding how the tundra biome is changing.
The ITEX (International Tundra Experiment) network brings together researchers studying the responses of Arctic and alpine plants and ecosystems to global change, with a particular focus on climate change. This synthesis of observations across the tundra has improved our knowledge of the changing tundra plant communities (Elmendorf et al. 2012a, 2015), their responses to experimental warming (Elmendorf et al. 2012b) and the changes to and climate sensitivity of the phenology – timing of leafing out and flower of tundra plant species (Oberbauer et al. 2013, Prevéy et al. 2017). Here, we give you a taster of the research findings that Team Shrub presented at the meeting.
Earlier in April, the 2018 ITEX meeting in Stirling brought together many of the researchers part of the ITEX network to share key findings of their work on how tundra ecosystems are changing and what that might mean for the planet. The meeting kicked off with a field trip to the Scottish hills near Dollar. Through rain, wind and sunshine, our hike reminded us of the days we’ve spend in the Arctic. Amidst the grasses and mosses, there was another flashback to our Arctic days – Eriophorum vaginatum! Growing in the wetter parts of the hills, we found quite a few cottongrass tussocks, an exciting sight for us tundra flora enthusiasts!
In the woodlands in Dollar, spring was in full swing – singing wood warblers, beds of wild garlic and primroses in bloom. In typical scientist fashion, we made many stops along the way to talk about the different species we encountered.
We made it to the top of the hill, took in the nice view and pondered the landscape around us and how it came to be. How far did the natural treeline used go in Scotland and how have these landscapes changed through time? Has Scotland always looked a bit like the treeless tundra biome?
Next up it was time for some science. Here is a brief summary of the team shrub presentations at the conference.
Gergana presented the key findings of the long-term monitoring on Qikiqtaruk-Herschel Island, among which were increased vegetation cover, less bare ground and a deeper active layer. It was particularly exciting to share the results of the ITEX species pool protocol – Gergana’s absolute favourite protocol! We had a great time during the summer walking around the long-term vegetation plots and recording the different species found across the landscape. Knowing more about the regional species pool can help us predict how local biodiversity trends might change in the future. For example, there are two plant species, Saxifraga nelsoniana and Parrya nudicaulis, that were found within five meters of the vegetation plot, yet they have never been recorded inside it so far.
Haydn presented all about tundra traits and what they are telling us about the rates of change in decomposition with vegetation change in the tundra biome. His take-home message was community-level estimates of tundra decomposition haven’t changed much over time and future change will likely be slow. Anne presented about the changes or lack there off in species and functional diversity over three decades of tundra monitoring. And in some ways it is a similar story – even though there are strong spatial patterns in species diversity from the warm to the cold reaches of the tundra biome, functional diversity doesn’t change as much and species diversity isn’t changing rapidly over time.
Sam presented a poster on his undergraduate dissertation about the amount of carbon stored in the above-ground biomass on Qikiqtaruk. And, Mariana presented a poster about the rates of shrub encroachment across two very different biomes that are experiencing similar changes – the tundra and savanna. It was a lively poster session with lots of interesting discussions that continued on over a delicious fish supper in the down of Bridge of Allan.
The next day, Isla summarized the evidence for the detection and attribution of tundra vegetation change to climate change including: phenology change, vegetation change, climate sensitivity of shrub growth, a warming of the combined thermal niches of plant communities and community-level plant trait change. Taken together, these data syntheses provide compelling evidence for the detection and attribution of tundra vegetation change to climate warming, but the evidence also points to variability in plant responses and the importance of other controlling factors such as soil moisture, topographic context, herbivory and permafrost thaw. Isla also presented on behalf of Jeff Kerby and shared the initial results of the High Latitude Drone Ecology Network and discussed how drones can help us to understand the ecological context and representativeness of long-term ecological monitoring studies like the ITEX network.
Sandra told us all about her findings that temperatures rather than growing season length best explained variation in shrub growth. Her research also suggests that the interpretation of growth ring data is more complex that we first thought with growth rings likely representing an integration of plant responses to climate and other biological factors from both above and below ground. In the same session, Janet made an impassioned plea for tundra ecologists to make their data public emphasizing the power of open and available data and the resulting data syntheses with a focus on the results of the plant phenology syntheses that she has been leading.
And finally, Jakob presented his work on the drivers of tundra phenology changes, looking at snowmelt, temperature and sea-ice. It turns out that snow melt, followed by temperature, best explains variation in plant phenology with localized sea ice not being a significant predictor. Jakob’s excellent talk won best student talk! Congrats Jakob!
The final day of the conference after a Scottish ceilidh dance focused on discussions of what will be next for the ITEX network. What questions should the tundra ecology community tackle in the coming years? How can we integrate new technology into the existing tundra monitoring protocols? What is the future change we can expect to observe in the rapidly warming tundra biome? Stay tuned for the next ITEX conference in a couple of years to find out more about the next stage of tundra ecology research and data synthesis!
By Gergana and Isla