When the arctic is covered in snow, we turn our scientific interests to the other side of the world: the (sub)antarctic. Our goal is to see if the patterns in the vegetation we observe at one part of the globe – the subarctic world of Lapland – hold true at the completely opposite side as well.
With this idea in mind, we go to the city of Punta Arenas, on the absolute southernmost point of the American continent. There we study the possibilities of exotic plant invasion in extreme environments. With these trips to the south we hope to come up with a comparison of the limits for common Western European weeds on this far away location with what we know and learn in Northern Scandinavia.
Our last field trip has been in April, when summer on the southern hemisphere disappeared and made way for snowy autumn storms. This intermediate season presented us with true roller-coaster weather, with freezing lows and icy storms right before the clearest blue skies.
The results of this last trip to the south look very promising at first sight. The climatic gradient in the mountains around the city of Punta Arenas turns out to be a pretty drastic one. In the city itself, the ocean buffers temperatures and weather is cold but mild, in fact more a borderline temperate climate than a true subantarctic one.
The nonnative European species, like the well-known dandelion and white and red clover, profit from these mild circumstances and flourish sometimes even more than in their native range!
Several hundred meters above the city, however, you arrive in a different place. The howling winds that already torture the city of Punta Arenas all year round, can blow even more freely up here, and temperatures drop to zero almost every night during the whole summer season. This environment feels much more like Antarctica, the icy continent that is so close-by.
Plants see their growing season reduced to less than half of the months they have at sea level. The negative effects on plant performance are inevitable. Where the nonnative species seemed to be unimpressed by the climate within the safe boundaries of the city, their survival and growth is reduced to virtually zero on the highest elevations.
Interestingly, the interactions of our invaders with the established vegetation seem to change as fast as the weather. However, we have to dig in the data first to get those patterns clear. Hopefully soon more news about that!
And afterwards, it is back to the Arctic, where summer is finally on its way again!