Northland Nature: Mosses begin greening in woods
When it comes to weather, April is a month that can run the gamut. Temperatures early in the month may be near zero degrees, as seen in April 2018, or can rise to 70 or 80 late in the month — more typical are mild days, chilly nights.
We can, and often do, get snows, some rather substantial (nearly 51 inches in April 2013) or none (April 2010). We do get the expected April showers, which can morph into thunderstorms accompanied with hail. Strong east winds can make us think that this spring month feels more like one of winter.
And when the snow melts, we may need to deal with two opposing factors. The demise of the snowpack can lead to floods. Or the dried grasses now freed from snow cover can become a fire hazard. Among some, April is known as the fire month.
With all of these changes, a constant component of this month is the lengthening of sunlight each day. We begin with about 13 hours of light, becoming more than 14 by the time we exit April and enter May.
This growing amount of light starts another happening of this month: the beginning of green leaves. We notice the initial greening usually as grass in bright hotspots put forth new blades. From these starting sites in plenty of sunlight, the lawns begin to take on a more complete green look. In the woods, the greening also begins low near the ground.
During a recent woods walk, I noted patches of snow still left from winter and spring snowfalls; mostly seen on the north-facing hillsides, but also in the shade of the forest.
In many ways, the woods of April looks like what we saw in early November, before the snow cover. (I like to refer to that period of time in autumn as "AutWin" — after the leaves fall and before a snow cover. The converse now is "WinSprin" — after the snow melts and before the new growth of leaves in the trees.)
But greening is beginning here. Like the lawn, greening starts low and goes up. Soon we'll see the green leaves (and flowers) of spring wildflowers (often called ephemerals). Wild leeks (ramps) can grow profusely on the floor of deciduous woods of late April.
Soon, shrubs like gooseberry, fly honeysuckle and elderberry will be unfolding their new set of leaves. But it all begins with very small plants that we are likely to walk right by; the mosses.
Unlike most of the forest flora, mosses retain their green leaves all winter. In the arid air of the cold season, they may shrivel and curl, but they remain green. With more sunlight and moisture from the melted snow, they will open their leaves for growth, before leaves form overhead.
Walking here now, I see an abundance of these miniature plants at the bases of trees, on rocks and on the ground. Soon all these low sites will be shaded and so, the mosses set the pace of greening by growing now. Some kinds form new leaves, other develop stalks that stick up from the plant. These thin growths will later hold spore capsules on the top.
Taking a closer look, I find these reproductive stalks are numerous on some mosses. Most are on a leafy species of moss called plagiomnium. Once detected, more can be found and we see that despite the cold and late snows, the diminutive mosses show us that the woods are beginning to green now in April.