Qikiqtaruk is a beautiful and inspirational place – science chats are particularly special when you can see, feel, hear and even smell your study system change as the growing season progresses. Out during phenology data collection yesterday, we saw that the spring flowers are fading and seed dispersal is beginning… summer is well under way. And this year, in addition spotting awesome wildlife, admiring magnificent sunsets and informally chatting about science in our remote Arctic field site, we have also started a book club!
Living among the flowers
Over the past year, Mark Vellend’s “The Theory of Ecological Communities” prompted the start of several book clubs around the world. Mark is a collaborator of ours and Isla’s former postdoc advisor, so we have been eagerly awaiting our chance to read and discuss his book. We didn’t initially join the book club, but we did manage to stay away from major spoilers and now that we are on Qikiqtaruk and away from the distractions of the world beyond the island (and as close to the plant communities we study as could be) this seems like just the right time to start our very own book club!
We read the first two chapters of Mark’s book after a day of putting hundreds of tea bags in the ground for a decomposition experiment out across the landscape in the different ecological communities here on the island from flood plain willows to dry grass and tussock sedge, and here are our thoughts!
What is decomposition like in this wet tangle of leaves?
The first question that Mark asks in his book is:
“What is community ecology and how does one define an ecological community?”
Gergana has also been concurrently reading Anne Magurran’s “Measuring Biological Diversity”, which also discusses the definition of an ecological community or species assemblage, so taking what we learned from the two books, there are many ways to define a community, and it’s rarely clear where are community ends and another begins…
Unless you are on a remote Arctic island! Here on Qikiqtaruk, there are several very distinct ecological communities – in particular the so-called Herschel and Komakuk vegetation types. They are very easy to spot when you are out walking around across the landscape or from a drones-eye view from 50 – 100 metres in the air. The ecological communities are so distinct up here that it is the only place that Isla has been to where she truly believes vegetation classification is possible.
The Herschel (left) and Komakuk (right) vegetation types
The Herschel communities are older landforms (we think) and dominated by tussocks of the sedge Eriophorum vaginatum, whereas the Komakuk communities likely have undergone disturbances such as active layer detachments, more active cryoturbation and erosion and are dominated by forb species, grasses and the dwarf willow Salix arctica. There are very few species shared between them, and it’s virtually impossible to confuse the two. But why are there such distinct ecological communities in the same extreme Arctic environment occupying the same upland soils with the same overall species pool that are undergoing the same types of selection pressures? This remains a mystery to us.
Sedge and willow dominated Herschel
Grass and dryas dominated Komakuk
Point framing in the Herschel and Komakuk vegetation types. The two locations are about 200m apart
How did these two communities come to be? We think that perhaps it was the different disturbance facilitated the establishment of the younger Komakuk community. But what is keeping the communities separate today? As demonstrated by the abundance of bare ground patches in Komakuk, some level of disturbance continues, but there are a few, not many, but still some areas of Komakuk where Eriophorum tussocks are making a comeback – we probably won’t live to see it in these long-lived and slow growing plant communities, but maybe at some point, the Herschel community will again dominate over Komakuk in less disturbed parts of the landscape. But on the other hand, with longer growing seasons and warming autumn and winter temperatures perhaps different disturbances are on the increase in this part of the climate-limited tundra biome.
Grins and bare ground in the Komakuk vegetation community
Mark Vellend would have us believe that four factors alone shape the ecological communities that we see on the landscape including: 1) selection, 2) drift, 3) speciation and 4) dispersal. And that within these four factors are many other forces at play such as biological interactions such as competition, mutualisms, herbivory, disease, etc.
On Qikiqtaruk we have found evidence of biotic interactions such as plant-plant competition and allelopathy potentially influencing the growth and germination of seeds and see signs of herbivory from the muskox and caribou, lemmings and voles down to insects, but it must be more than just biotic interactions creating these super distinct ecological communities up here in the Canadian Arctic. Can the following chapters of the book “Theory of Ecological Communities” shed light on the ecological mystery that is the plant communities of Qikiqtaruk? We shall see, so stay tuned.
How does competition affect seed germination in the tundra?
We are looking forward to our next book club meeting. Until then, we will be collecting data and thinking about how the four high-level processes central to the Theory of Ecological Communities (selection, drift, speciation and dispersal) are influencing the patterns we see in the Herschel and Komakuk communities at our remote Arctic field site.
By Gergana and Isla
p.s. Gergana also found the acknowledgements section very inspirational – it’s always great to read about a community (of people) that supports one another and collectively works to advance science! The University of Queensland, in the sub tropics of the city of Brisbane Australia where the majority of the book was written, was also where Gergana spent a year of her undergrad – such a great place to think and write about ecology! And such a different place ecologically from Qikiqtaruk in the Canadian Arctic.
This blog post was written on Qikiqtaruk-Herschel Island in the Western Canadian Arctic and sent via satellite phone to be posted to the Team Shrub blog. Team Shrub are a group of plant ecologists who often work in high latitude tundra ecosystems on topics in community ecology.