The record is in the rings

Each growing season in the life of a tree leaves its mark in the ring of a layer of cells formed in the trunk that conduct water and minerals from the roots to other parts of the plant.
The growth rings are visible because of differences in the density of the wood produced early in the growing season and that produced late in the season. The early wood has large cells with thin walls; late wood has smaller cells with thicker walls.
Within a given growth layer, the change from early wood to late wood is gradual but a clear change is visible where the small thick-walled cells meet the larger thin-walled cells of the next growing season.
The thickness of the yearly growth layer will vary from year to year. The amount of light, rainfall, temperature, amount of soil water and the number of frost-free days all play their part in altering the appearance of each layer. The width of the growth layer is a fairly accurate indicator of the amount of rainfall in any particular year. If conditions are good and there is ample water the growth rings are wide if water is scarce the rings are narrow.
In arid regions, such as the tundra where the growing season may be only a week or two long the growth rings are almost too close together to count. Some trees in this area may be two feet high and a hundred years old.
Each growth ring is different and a study of the rings tells the story of the area that could go back several centuries. In a year when fire ravaged a forest the event will be recorded in the charred rings. Which side of the tree received the most heat will show as a dip in the yearly rings.
The closer the rings are together the shorter the growing season. Counting the rings will give a fairly accurate time when the event occurred.
Western White Pines are very large trees, 150 feet (50 m) high and 5 feet (150cm) in diameter and will live up to 400 years. When the growth rings of these trees are studied with modern measuring devices they reveal a great deal about the yearly climate conditions on our west coast.
Information provided by growth rings of both evergreens and deciduous trees is being used to reconstruct past weather conditions and to predict future conditions. With more accurate knowledge of past climate conditions, which may go back hundreds of years, than is provided by human records which go back only a few centuries, it will be possible to determine weather patterns and cycles for rainfall and drought. This knowledge will be used to manage and allocate the resource of the future, fresh water.

Speaking of Nature
Jim Ferguson, 5313 River Road, R.R.5, Renfrew, Ontario K7V 3Z8 Phone 613-432-2738 email jamesh@nrtco.net

An exported native species

Pearly Everlasting (Anaphalis margaritacea) was exported to Europe a short time after the first settlers arrived in North America. It was easy to grow and did not require a great deal of care and before too many years was common in English gardens.
The name margaritacea is derived from the Greek margarites, “pearl” and referes to the pearly flower heads. The flower heads can be dried and will remain in perfect condition for many years.
Pearly Everlasting is not much more than green foliage for much of the summer but it is valuable in many gardens of Europe and North America for its late summer display of white flowers. The flower heads are pearly white, about half an inch across with papery petal-like bracts around a cluster of yellow or brownish florets. There may be several florets in dense, flat-topped clusters.
The plants form a bushy mound of silvery-grey leaves, bearing upright, with the clusters of florets on top. They make excellent cut flowers either fresh or dried and present a colourful display for several weeks. In the wild they tolerate a variety of soils and can be found in wet or dry, open or often disturbed sites. Once they are established at a site they are tolerant of drought and will return to flowering when conditions permit.
The blooms are attractive to butterflies and are a favourite haunt for late or second hatching fritillaries in August or September. The plants propagate very quickly and are inclined to spread seed over a wide area. In some locals the plants are so thick that they crowd one another out of a place to grow.
In Canada the plants were added to smoking mixtures both as medicine and as a tobacco substitute. As it turned out the substitute was not a good one and smokers became ill from the so-called medicine. Native Canadians used pearly everlasting tea to treat coughs, colds and digestive upsets.
The fuzzy leaves were used as poultices for sores, burns, bruises, swellings and rheumatism. The leaves, stems and flowers were crushed mixed with animal fat and used as a balm to rub on muscles to increase strength and reduced the effects of injuries. It was sometimes chewed for protection from danger.
Pearly everlasting is a member of a plant family that represents one of the three plant communities and their progression from wet to dry, from dense shade to full sun and from north to south. Forests are not only trees. They are a total of hundreds of competing, dependent and cooperative organisms—herbs, grasses, trees, shrubs, vines and fungi each perfectly adapted for survival of its own species in its own part of the forest.
When we walk through the forest or along any trail or road we may pass several different types of habitat and in each of them we find different species. We should be careful not to disturb the habitat or remove any of its members. They grow in that area because that is where their needs are met.

Speaking of Nature
Jim Ferguson, 5313 River Road, R.R.5, Renfrew, Ontario K7V 3Z8 Phone 613-432-2738 email jamesh@nrtco.net blog address with the Canadian Forestry Association www.canadanaturally.blogspot.com

They are many and ancient

According to fossil records ferns first appeared on earth 400 million years ago. The majority of the 12,000 living species are found in the tropics but many occur in temperate zones.
Ferns are vascular plants (they have vessels that carry liquids to the various parts of the plant) that can usually be distinguished from other plants by their large feathery leaves. Immature ferns develop as a “fiddle head” which looks like the head of a fiddle and which uncoils and spreads as it grows.
The fiddleheads of our most familiar woodlands develop underground for several years. In their final season, they multiply very rapidly, pushing their coiled tops above ground. In a few weeks of growth and uncoiling they become mature fern fronds.
Young fiddleheads, when cooked, look like asparagus and are considered a great delicacy by Maritimers. Fortunately for us they have shared their love of fiddleheads with others across the country.
The stems of ferns are not as complex as the stems of other plants, and are often reduced to a creeping underground root. Although ferns do not display any secondary growth –the type of growth that results in an increase in diameter and the formation of bark and woody parts—some ferns grow very tall. Ostrich ferns which grow along many creeks can reach six or seven feet (1.5-2.0m) tall.
The leaves, known as fronds, are often finally divided into smaller leaves called pinnae; these divided leaves spread widely and therefore collect more sunlight. It is necessary for the ferns to develop this way because they grow on the forest floor where there is dense shade.
Many ferns are almost all leaf, and even in giant tree ferns, the leaf is the main feature, the “stem” being composed of a mass of overlapping leaf bases. The leaf may be bladelike or more often they are finally divided into a regular fringe of smaller leaflets.
The spores of ferns develop on the undersides of the leaves. They are usually clustered; the clusters have a brownish colour and are often mistaken for insect eggs or patches of disease (rust). In a few ferns such as the cinnamon fern only specialized leaves bear the spore sacs, however in most ferns spores develop in all mature leaves.
Some of the spore sacs develop in distinct patterns which help identify the plant. Others are formed around the edges of the leaves. Many ferns including the Christmas fern (gets its name because it stays green all winter) have groups of spore sacs that are covered with a thin scale.
As the spores mature the outside covering dries and shrivels. When the outside ring of the sacs that contain the spores dries out it snaps open sending the powder-like spores into the air. The number of spores produced by a single leaflet may be as high as 52 million. Only a few of these germinate and produce new ferns.

Speaking of Nature
Jim Ferguson, 5313 River Road, R.R.5, Renfrew, Ontario K7V 3Z8 email jamesh@nrtco.net
Many articles from this column are now on the blog at http://www.canadian.naturally.blogspot.com