- , Ecomare, Sytske Dijksen
Ecology of moss
The presence or absence of a specific moss says something about the environment. A number of moss species are used as a bio-indicator. That usually means if the moss is found, then the conditions are good. However, bio-indicators can also be a warning for pollution. Everything a moss needs is directly absorbed from the air or ground via its leaves. Therefore, it reacts more quickly to changes in the environment than plants with roots, which lie relatively deep in the ground and delay any reaction.
On Texel
- , Foto Fitis, www.fotofitis.nl
The Texel dunes are poor in calcium, just like all dunes in the wadden region. Only the beach ridges are richer, thanks to fresh sand blown from the beach. Most of the moss species growing on the island are those found in calcium-poor dunes. However along the shell paths, you will also find species for calcium-rich habitats, such as sand-hill screw-moss.
- Use and ecological functions of moss
- Clumps of moss upturned by birds, Sytske Dijksen, www.fotofitis.nl
Moss usually grows in large, sometimes impenetrable clumps, thereby protecting the ground from erosion caused by wind and rain. Because moss retains lots of moisture, it is very suitable for various germinating seeds and spores. However for many other seed plants, the carpets of moss are too dense to penetrate and germinate. As for animals, moss offers an excellent habitat for spiders, mites, insects, worms and other small creatures. Mice eat the spore capsules and birds peck the mats for the creatures hiding underneath. Those torn up mats of moss are evidence of foraging birds.
- Habitat
- Glass hairs on heath star moss, Foto Fitis, www.fotofitis.nl
Just like plants, moss species have a preference for where they grow. The humidity level, acidity of the soil, availability of nutrients and the quality of the air are important factors.
The dunes have many different habitats that vary in calcium content, light intensity, moisture and nutrients. The effect of these factors on the presence of certain moss species becomes clearer when you take a walk through the dunes and look at the differences between the northern and southern slopes. Should a species of moss grow on the southern slopes it appears grayish. The grayness comes from the glass hairs that reflect the sun and thereby protect the moss from dehydration. Those species growing on the northern slopes and in damp dune slacks are more sheltered from direct sunlight. They don't dry out as easily and often have a fresh green color. - Calcium richness
- , Sytske Dijksen, www.fotofitis.nl
If you have moss in your grassy yard, you often throw on lime to kill it. However, some moss species actually profit from the lime and spread even more.
In addition to the differences between calcium-rich and calcium-poor dunes, there is also a difference in the calcium content between more inland and seaward dunes. Due to percipitation, rain leaches out calcium in the dunes. However, dunes situated closer to the sea constantly receive a new supply of sand. The calcium content has direct influence on the acidity of the soil. The soil is acidic when the content is low so that mainly acidic species, such as Aulacomnium androgynum (photo). In soils with lots of calcium, you find moss species such as calliergonella moss.
- Humidity
- , Ecomare, Sytske Dijksen
Since it has no roots for absorbing water, the humidity of the air has a greater influence on moss than the dampness in the soil. The humidity in the dunes can vary greatly from place to place. Those species that don't require much water grow on the southern slopes, which is always exposed to the sun if it shines. Because the sun is not directly overhead in the Netherlands but on an angle, the northern slope doesn't generally receive direct sunlight and therefore remains damper.
- Light intensity
- Moss as indicators
- Bristly haircap, Sytske Dijksen, www.fotofitis.nl
Some moss species are real pioneers. Bristly haircap is one of the first moss species to appear on newly formed dunes, where it holds down wind-blown sand. There are other species that prefer freshly burned or even heavily polluted soil, such as common cord-moss and common liverwort. Screw-moss species often grow in areas with lots of wind while feather-mosses prefer the shelter of bushes or other less exposed areas.
- Overview
