I recently worked with some colleagues on the boundaries between plant communities. It is interesting to note that the soils professionals look at the plants to help them identify changes in soils, and the plant ecologists look at the change in soils to help identify changes in plant communities. By the way, it might surprise you, but the resulting maps are the same. Soils reflects vegetation, and vegetation reflects soils.
The work I and my colleagues were doing involved a saline lowland. Saline lowlands are often areas of natural vegetation where salts come to the soil surface. In cropland these areas are commonly known as alkali spots. I suspect that most North Dakotans are familiar with foxtail barley and its prominence on these alkaline or saline soils. It may even give them the impression that this species is adapted to these soils. But that is not true in this case, as well as the distribution of many other plants and animals.
Foxtail barley is a plant that is not particularly well adapted to saline lowlands. If you were to plant it in a fertile garden and weeded it regularly to keep the competition down, it would do well. But without that constant weeding, the competing plants would soon out compete it. It just couldn’t keep up. Foxtail barley is a competitive wimp!
But all is not lost! Foxtail barley is one of a very small group of plants that can tolerant the high salt concentrations in these soils. As a result, foxtail barley often finds a home in saline lowlands and alkali spots. It can do well there because of the limited competition from other plants. So we see foxtail barley mainly on saline soils, not because it is particularly well adapted to saline conditions, but because it just cannot compete with the other species on more hospitable sites. That is not a particularly rare phenomenon for a species distribution.
So the next time you see some foxtail barley, give some consideration not only to the tolerance the plant has that enables it to exist in those highly alkaline sites, but also how competition with other species influences species distribution.
~Chuck Lura
