Plants are everywhere. As my last semester’s biology teacher put it, you don’t look down from space and see the animals running around; all that green you see is from plants. It is plants. Like this:
So in this week’s science post, I want to talk about plants, but not those plants in the picture above. Instead, I want to talk about these:
These “plants” are all examples of boreal feather mosses. And I am here today to tell you a bit about their ecology, in order to illustrate why mosses like these beauties are sadly underrated.
In the northern boreal forest (like the Canadian one shown above), these mosses have to compete with various vascular plants (which have internal water- and nutrient-carrying systems, a bit like an animal’s veins and arteries). But the mere fact that mosses have no vascular systems gives them an edge over vascular plants when it comes to photosynthesis (which is how a plant makes its own food). Let me explain.
If you picked a leaf off a vascular plant (like one of the trees shown above) and looked at it under the microscope, you would find a whole bunch of tiny little holes, called stomata. Stomata open and close to allow the plant to absorb the carbon dioxide it needs for photosynthesis without losing much of the water it also needs for photosynthesis.
But mosses have no stomata; their entire bodies can just absorb as much carbon dioxide and water as they need. So a moss that lives in a “sunfleck” on the forest floor, one of those shifting spots of sunlight amidst the shade cast by the trees, can react better when the sun moves and casts light (also needed for photosynthesis) across that spot than a vascular plant, which has to take the effort of opening its stomata, could.
Boreal mosses are also important for succession; this is when something disturbs the ecological community and the members of the community (the different species that live there) must react. When a tree falls down, for example, it disturbs the plant community around it. Mosses and their relatives have been found to move back in sooner than other plants. This is probably because they have more varied reproduction methods than vascular plants; they readily reproduce asexually, which makes them able to colonize new areas quickly. Here, again, they have an advantage over vascular plants.
Mosses can also compete with vascular plants in a more direct way than those described above. In New Zealand, eleven moss species have been found to have allelopathic effects on plants, including native trees. (In allelopathy, one plant secretes chemicals that actually inhibit the growth of another plant.) Specifically, these mosses’ secreted chemicals inhibit the germination and root growth of other plants. This makes them better able to compete in the crowded New Zealand forest.
So, to wrap up this long blog post, mosses are both pretty and interesting. They’ve adapted in ways that allow them to compete with vascular plants, such as speedy photosynthesis and growth-inhibiting chemicals. They’re also important for succession after forest disturbances like treefall. Altogether, these simple plants are interesting, important, and very underappreciated.
Tell me in the comments: What did you think of mosses before? What do you think now? Do you find these snippets of moss biology as interesting as I do? Did you understand everything I said, or did I use too many technical terms?
Also, if you are curious enough to brave a couple peer-reviewed articles today, here are my references!
Jonsson, B.G., and P.-A. Esseen. 1998. Plant colonisation in small forest-floor patches: importance of plant group and disturbance traits. Ecography 21: 518-526.
Kubásek, J., T. Hájek, and J.M. Glime. 2014. Bryophyte photosynthesis in sunflecks: greater relative induction rate than in tracheophytes. Journal of Bryology 36(2): 110-117.
Michel, P., D.J. Burritt, and W.G. Lee. 2011. Bryophytes display allelopathic interactions with tree species in native forest ecosystems. Oikos 120: 1272-1280.