René van der Wal, has just revisited an area in Svalbard where he began to study the vegetation 25 years ago. What is happening to the plants in an environment that is warming faster than any other terrestrial ecosystem? Where the primary herbivore – Svalbard reindeer – have tripped in numbers. And where the pink-footed goose now has firmly embedded itself.
“One sees glaciers and other (deemed) ‘permanent’ snow and ice patches disappear, at quite a staggering rate. However, despite the rapid warming, large part of the tundra remains ‘as was’… with over the whole rather subtle changes. And it’s not the changing climate that pulls the ‘vegetation strings’ hardest, but …. geese!”
Why is that?
"The geese have engineered much of the wetlands, and in fact created a new kind of habitat dominated by a sedge, Carex subspathacea. Large areas of that anoxia-tolerant saltmarsh plant, moving inland because of the geese effectively lowering the tundra when digging for roots in spring. It took a few years before the reindeer ‘understood’ the value of this plant, and initially avoided eating it, but now it’s an important part of their diet."
Do you see any effect of climate on the vegetation?
"A big winner in the system is field horse-tail, Equisetum arvense, turning the damper parts into lush radiant-green swards. It is also promoted by the geese, in part because it can ‘hide’ its roots better than other plants. Men en annan trolig faktor är att den så kallade aktiva lagret - den del av tundran som tinar under sommaren för att sedan frysa till igen på hösten - blir djupare. But another likely factor is that the so-called active layer - the part of the tundra that thaws out during summer to then freeze up again in autumn - is getting deeper. A more subtle change is that the ridges have gained an aromatic grass, Hierochloë alpina, meaning these high parts in the landscape smell of caramel. This is likely a climate change signal, reflecting higher levels of nitrogen available to plant growth in these skeletal soils."