Juul Limpens, plant ecologist at Wageningen University & Research and specialized in mosses, stands with her nose close to the bark of an old ash tree. “This is the perfect place for mosses to bond,” says Limpens. “On the north side it is a bit cooler and more humid, they love this.”
With her nose she moves close to the orange stems with yellow balls on them that tower above the moss. The species: a common hair cap (Orthotrichum affine). The moss looks brown and dead. “Watch out,” says Limpens. She puts her finger in her mouth and wets the moss with a dollop of saliva. Within seconds the moss turns green again. “Magical, right? Mosses can sometimes go months without water and then they come back to life with just a few drops.”
Limpens’s fascination with mosses is no coincidence, she explains. In her research, she mainly looks at how plants can influence their environment. “Moss often play an indispensable role in this.”
What is the role of mosses?
“They are true pioneers. Take a mountain landscape. There you see all kinds of mosses without seeing higher plant species. Mosses make less demands on a landscape, have no roots and filter their food from the air. They are also almost indestructible, so they can do their thing in many different climates. At the same time, they make the soil richer in fungi and nutrients, which higher plants can benefit from later on. A perfect example of how plants influence their environment.”
So, no plants without mosses?
“Well, that is a bit too firm, but mosses in many ecosystems ensure that it is really a lot easier for other plants to establish themselves. They are really paving the way.”
Peat areas are part of the historic Netherlands
Where exactly do you research mosses?
“I mainly look at processes in areas that are on the verge of imminent change. At the moment I mainly work in raised bogs. These consist of eighty percent peat mosses.
“Three thousand years ago, half of the Netherlands was covered with peat, new mosses grow on their dead predecessors and over the years a thick layer of peat was created. Now only a few stamps remain. Nature organizations want to preserve and restore that, just like we refurbish old churches because they are heritage. Peat areas are part of the historic Netherlands.
“Besides the historical value, peat areas are also of value for nature and climate. After all, because of all those dead mosses, a lot of carbon is stored in them. Moist soil prevents the release of all this carbon. But the current drought means that peat areas already emit carbon from the top layer in the form of CO2.
“In addition, peat areas are sensitive to ashes due to drought – a kind of smoldering fires – such as three years ago in nature reserve De Peel. This not only affects top layers, but can also affect deeper prehistoric layers, which means that much more CO2 is released. So if the drought continues and we do nothing, we will not only lose our peatlands, but tons of greenhouse gases will also be released into the atmosphere.”
Read about the fire in De Peel: ‘The Netherlands’ largest wildfire ever’ shook nature managers awake. What lessons have been learned since then?
They can suck up and hold 30 to 40 times their own weight in water
And mosses can prevent that?
“Of course. Peat mosses are a kind of sponge that cover the soil like mats. They can suck up and hold 30 to 40 times their own weight in water. In principle, the more mosses, the wetter an area is. That in turn is beneficial for your underlying soil life, and in the case of raised moor areas for the preservation of old peat layers and stopping the CO2emissions. After all, it prevents dehydration.”
Is it really that simple?
“Haha, it’s nature, isn’t it, so no. We have another problem in the Netherlands and that is nitrogen. When plants grow too quickly due to a too high nitrogen deposition, they tower over the moss and eventually outcompete the mosses, which in turn increases the risk of your peat areas drying out. So it’s really a balance that we have to continuously consider in our research and during peat restoration. But I have high hopes that it will work!”
Mosses are therefore true pioneers who can edit a landscape and also keep it alive. Yet in science there is much more attention for higher plants.
“Yes, sin. Moss is a bit of a neglected child. I think it is simply because they are not as tangible and visible as higher plants. In addition, mosses are not food crops, so they are not very interesting in terms of commercial use.”
I call it a bit the dinosaurs among the plants
But do mosses still intrigue you?
“Absolute. But that wasn’t right away. I used to have nothing to do with moss. I thought they were way too small and didn’t have a magnifying glass to look at them. At one point I went with Heinjo During, an ecologist at Utrecht University, and I was completely sold. He showed me how many colors and shapes mosses could have. I immediately bought a second-hand microscope and was completely amazed. A world opened up for me.”
What did you see in that world?
“Well, what is very nice, for example, are the cell structures. Mosses have leaflets that are only one cell layer thick. This allows them to absorb nutrients directly without complex root systems. Through that single cell layer, I saw the chloroplasts that photosynthesize more clearly than ever. That microscopic world came to life for me. As a hobby I also started drawing the mosses, so I could remember many species. I was just totally obsessed, in a good way.
“Now that I know a little more about it, I realize that that obsession was justified. They are great plants. I call it a bit the dinosaurs among the plants. They have hardly evolved in the past millions of years because they are so strong and can handle so many circumstances. That’s just really cool.
“They do not grow through seeds, but through spores that are transported through the atmosphere. For example, the mosses I research here can also be found in China or Canada. They grow everywhere, they are real world travelers.”