April 10th, 9am
Today I am returning to one of my favorite topics before the warmth and lack of rain alters them so much that we don’t even notice them anymore, the mosses. Right now, they are spectacular lush green carpets of soft velvet, reaching up with their sporophytes, taking advantage of the morning fog and dew. The last wonderful rain we had helped to increase their potential for successful reproduction, and they have put out many capsules or sporangiums, as Bryologists call them.
It seems that I have been fascinated with mosses since I was a small child. It is like an underwater world in the forest. The more you peer into it the more you can see.
Mosses are part of a group of non-vascular plants called Bryophytes, which also include liverworts and hornworts. Bryophytes are the earliest group to diverge from land plants around 400 million years ago. There are approximately 12,000 species of moss worldwide, and 650 different moss species residing in California. That is a lot of different mosses! They lack flowers, fruits, and seeds and have no roots. In the book “Gathering Mosses” by Robin Wall Kimmerer, she states beautifully my feelings about these amazing plant forms. “They are the most simple of plants, and in their simplicity, elegant… Each one (species) is a variation on a theme, a unique creation designed for success in tiny niches in virtually every ecosystem.”
Most people just think there are only a few species of them around, yet around where I live in Willits, I have found over 70 species. They are not always easy to identify because a dissecting scope and a microscope are needed to tell many species apart, but there are 20 to 25 of them that can be identified to species with close inspection using a hand lens or close-up binoculars. Another 20 or more mosses can at least be identified down to genus using a dissecting scope. It is endlessly entertaining to spend time looking at mosses up closely. They dry up without moisture but all you need is a spray bottle with water, and they will come to life right under your eyes.
Mosses are found in most habitats from hot deserts to the Arctic and Antarctic. Friends have brought me back mosses from Iceland, Nepal, and Japan. They prefer and thrive in cooler, moister climates such as temperate rain forests, or Mendocino county! This is a fabulous place for mosses and out on the mitigation lands the oak woodlands and ash forests are good habitats for many species of mosses. The Plasma forest, our upland site, has an abundance of mosses to show you.
You might ask, why do mosses or bryophytes matter? Don’t they harm the trees? My friend and a wonderful Botanist, Kerry Heise, made a list of the reasons why they matter:
- Mosses contribute significantly to local plant diversity.
- They hold and regulate large amounts of water, influencing local site conditions.
- They are good colonizers of exposed sites, aiding in stabilization of scoured banks and landslides.
- Mosses are good indicators of water quality, physical disturbance, and substrate moisture regime.
- They play a role in the formation of soil.
- They increase soil fertility.
- Aquatic species slow down fast-moving sediment and provide important habitat for macroinvertebrates.
- Peat mosses are important carbon sinks.
- Then the answer to the question do they harm the trees is simply no. They are epiphytes that grow on the bark on the tree or shrub and can easily be scraped off by a squirrel climbing up the trunk or a woodpecker looking for food. When they fall to the ground, they provide nutrients to the soil and then of course to the tree.
As I walk through the woodland admiring the green carpets of mosses everywhere, I begin to see that the variety is astounding. On some of the older large valley oak trees there are three very distinct mosses growing. The first one is a common associate of oak trees that is called Tree or Feather moss, Dendraolsia abietica. This moss is a large feathery moss that covers the bark of trees like a gown, slowing rainwater as it streams down the trunks of the trees. This enables the water to gather nutrients as it passes through and eventually reaches the soil below. Right next to this feather moss is another bright green moss with shiny undulate leaves that also grow on valley oaks and rock walls. The leaves are fun to look at with a hand lens because they reflect an iridescence like tiny rainbows. This moss is Neckera menziesii. See if you can find it next to the feather moss. These two mosses are called pleurocarpous mosses because they produce sporophytes from the side of the main stem. The third moss I want to point out is called an acrocarpous moss because it produces sporophytes from the apex of the main stem. This moss is called Orthodicranum tauricum. Another distinguishing characteristic is that the leaves look like little needles standing up. This species has a feature that helps me identify it easily and that is that the tips of the needle-like leaves break off easily, a reproductive property. The leaves can easily be observed with a hand-lens. It was fun finding this moss today. There are many more species which I will not talk about today, I will just leave you with the photos to look at. Try to find different species. Remember when you are out in your yard to notice the mosses and take a close look for yourself!