When can we call a plant a true mountain plant? What is the optimal definition to divide plants in two categories; alpine or not? Those questions currently keep me occupied during my working day. I thought to shed some light on the differences here with the help of some fluffy examples.
The alpine zone, the zone above the treeline were the climate is too cold to allow trees to grow, hosts some highly typical plant species. In this harsh environment, you need some special skills to survive, and only the selected few meet these requirements.
Most species that do fit the bill however loose the necessary skills to deal with the conditions downhill. Especially the power to compete with fast-growing lowland species eradicates their chances to grow on lower elevations. Those cold-adapted, slow-growing dwarfs, like the creeping willow, are true alpine species.
Creeping willows stay close to the ground, safely protected against the elements. They grow very slow and stay small during their whole lives. Ideal characteristics in the alpine zone, but a burden to win the everlasting natural selection in warmer environments under the tree line.
The same holds true for the mountain avens, or white dryas. These tiny roselike plants stick together in colonies to stay warm. In the warm summer months, their flowers and fluffy seeds dare to leave the protective air layer at the surface, but otherwise they will always keep close to the ground.
Cottonweed falls to the other side of the alpine/non-alpine balance. Although these fluffy plants love the wetlands and marshes in the alpine environment, their range is much broader. They survive everywhere where extreme conditions and bad drainage erase all other competitors.
Although you can find their cute bunny-tales in between the other alpine species, their optimum lies in the ‘montane’ area, the mountain region underneath the tree line.
They found a way around the strong competition on the lower elevations by choosing a niche where no-one else wants to live: swamps and bogs. Another strategie, resulting in a totally different distribution: when alpine species will be easy to observe on high elevations, but impossible to find when you go lower, cotton weed will have the same – small – chance everywhere along the gradient, as they will be linked to soil moisture instead of elevation.