Visions from nature

Mountain avens and limestone

By Anders L Kolstad

In the Scandinavian mountains there lives a plant named after the leaves of oak, due to the similarities in the leaves. These ones are considerably smaller though, perhaps 1 cm, suitable for a life in the wind and the cold. Dryas octopetala is its name, and as the specific epithet signifies, it has eight (octo) petals (petala). There are lots of other plant also growing next to it, but Dryas is the best known, and the name is spoken with respect by botanists and hill climbers alike. The last group is perhaps most taken by its large white flowers that light up the apparently barren mountain side. Botanists are not without aesthetic sense, but they do react differently, perhaps because they know what is coming next. The mountain avens is what we call an indicator species, and what it indicates is limestone. This mineral is a sporadic resource in the mountain. That mean that the plant species that are adapted to lime are in a way squeezed together into a small area. Here we can find species that are rare, and that makes it an interesting place for botanists. The mountain avens is like a lantern in the mountain, showing the way to high diversity areas.

Reinrose er en vakker plante i fjellet som også indikerer for botanikere at det kan finnes sjeldne arter knyttet til kalkforekomster i bakken.
Mountain avens is a beautiful plant in the Scandinavian mountains, which also indicates to botanists that there could be rarer plant around which are also associated with the high limestone content of the soil. Photo: Anders L. Kolstad NTNU University museum CC BY-SA 4.0.


På Svalbard er det generelt mye kalk og høy pH i bakken. Her vokser reinrose overalt og kan ikke sies å være indikator for spesielt artsrike plantesamfunn.
On Svalbard there is generally much limestone and a high pH in the soil. Here mountain avens grows just about everywhere and cannot be said to indicate anything more then that you are outdoors. Photo: Anders L. Kolstad NTNU University museum CC BY-SA 4.0.

What is lime?

First, it is not a sour fruit. Lime, or calcium carbonate (CaCO3) is a mineral, commonly found in limestone. It consists of Calsium (Ca), carbon (C) and three oxygen (O). Calcium is of interest to plants since it is a macro nutrient, meaning plants need considerable amounts of it in order to grow and live. It is taken up through the roots and used in the building of cells and organic molecules inside the plant. The other implication of lime in the soil is that it raises the pH and makes the soil less acidic. This happens because the carbonate (CO3, or carbon and oxygen together) bind protons (H+) and form CO2 and water. The pH of the soil has a large indirect effect on plant growth by affecting microbial activity and the solubility of nutrients and toxic metals such as aluminium.


This post is part of a series of shorter plant stories.


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