The fifth stage of the Tour takes us up into the Vosges Mountains passing on the way Le Plateau des Mille Étangs — the Plateau of a Thousand Ponds.
We saw another land of many lakes last year when the sprinters raced into the Parc des Oiseaux in Villars-les-Dombes, but while those ponds were man-made fish ponds, the ponds of the Plateau were carved by glaciers as they retreated. I’ve seen this landscape referred to as a fjeld, a Scandinavian word for a high glacial plateau, and Matthew Keenan called it the Finland of France during the broadcast today.
Many of the small ponds are surrounded by wetlands, and it’s possible to find ponds in various stages of the hydrosere succession. The edges of the ponds are colonized by emergent marsh plants. As the marsh plants die, the dead plant matter is incorporated into the soil and forms peat. As the peat builds up, sedges move in. Eventually the pond fills up with peat, and forests can establish on top of the peat.
Now the existence of true hydroseres has been questioned in the ecological literature. Lee Klinger makes the argument that very rarely do we actually see a pond turn into a forest over time. More often, we make inferences from the spatial patterns of vegetation that we see on the ground now. Instead, you might have many different possible progressions of vegetation. You might end up with a bog that stays a bog and never turns into a forest.
My impression is that the consensus among ecologists is that succession is a lot more complicated than a linear progression from one state to another. So the hydrosere model may not be the most scientifically sound one to explain the diversity of landscapes we find on the Plateau. I think it is helpful to remember though, that when you see a bog on the Plateau, that could very well have been a pond in the past. And when you see a pond, it probably won’t stay a pond forever.
Up the mountain it was Fabio Aru leading the big names of the Tour. Starting to see the GC shake out, but we have a few more days of sprint finishes before we can see how much damage the Vosges did.