Erica's Original Notes Ecology is the study of the interrelationship of all life forms ('oikos' is Greek for house). It is dependent on many conditions such as climate, soil, altitude, dryness, wet, light and shade, sun (length of hours and position), rainfall (amount and when), the ocean and its proximity.
Action of man and animals: If it were not for man who cleared land for crops and grazing, we would have mostly forests. Weedkillers destroy a great many meadow flowers; road allowances prevent many flowers from reseeding; and highway and subdivision development is responsible for destroying acres of farmland annually.
Climatic changes can be seen all over the world when forests are felled without any replanting schemes; one example is the African Sahel Desert. This makes the climate dryer and enables the weeds to colonize.
Acid rain: Rain is normally slightly acidic, which is important as it helps dissolve minerals in the soil that are needed by plants. This normal proportion has now been increased alarmingly over the past few years, by the burning of oil and coal from smelters and power stations, sulphur from pulp mills and emissions from cars adding to the problem. Acid rain destroys aquatic life and stunts vegetation and forests; it erodes buildings made of limestone, marble and sandstone.
Pollution: Lichens are being used in Britain and the Ruhr as early warning indicators of sulphur dioxide pollution. Nicotiana is used in the US to check ozone levels, and Pinus ponderosa needles turn yellow to indicate smog pollution.
From a provincial museum lecture: Our province was not in existence until 160 million years ago. Revelstoke was on the coast, but land was gradually built up by movement of the tectonic plates in two series: first the Rockies were formed, followed by the Coastal Range. The land mass of BC is growing gradually west; gradually meaning six centimetres per annum, much like the growth of one's nails! Glacier formation lowered the level of the Pacific Ocean, thus providing a land bridge from Asia, and some refugia were left when the water levels rose, such as on the Queen Charlotte Islands [2013 update: now called Haida Gwaii]. One ice sheet was formed in the west and one in the east of Canada, with an ice-free corridor between which allowed for passage to the lower part of the continent and to South America. Animals that came were the musk ox, moose, caribou, wolf, and the horrific, short faced bear which may have impeded settlement by man. Cedar was first found 5,000-6,000 years ago and was common 2,000-3,000 years ago. People came about 10,000 years ago by the land bridge. 1863 was the height of the otter Trade, when three-quarters of the First Nations died of disease. 1858 saw the Gold Rush.
Heaths grow in poor dry acid soil; found in Europe (not North America).
Bogs have acid soil, but are less dry. They may be waterlogged and have peat bogs; these are the result of generations of plant remains saturated with water, decaying slowly but not completely; bogs are found in hilly country with rocky substrate from which the water cannot escape.
Forests were formed after the last Ice Age. Deciduous forests have better soil than those of conifers. Tree harvesting may be done by clear cutting for shade-intolerant trees or by selective cutting for shade-tolerant trees. The forest floor has an insect population four times per square foot to that of humans per square mile; and over two tons of debris is deposited per acre on the forest floor in one year. In regard to rain, the canopy and understorey provide a two-tiered porous roof with leaves and twigs acting as interceptors so that less than one percent of rain reaches the soil; rain is also a great equalizer of temperature in the forest, with the soil having the least temperature change and the least amount of wind. Diseases are of great economic importance and may alter the composition of a forest since they usually affect one species only; therefore, pure stands may be wiped out, often due to viruses, transmitted by insects to the phloem; or they may be due to parasitic fungi affecting cambium, leaves and roots (as in the American Elm disease). For instance, mistletoe has clusters of cells in the cambium which absorb water and minerals from the tree; after two years, leafless aerial shoots are formed upon which berries are borne to explode with sticky seeds which are transferred by birds.
Alpine plants usually form rounded cushions or mat plants, offering the least wind resistance and adapted to withstand dryness, with reduced stems. The leaves are packed together and usually covered with hairs or a wax coat to reduce evaporation; they have roots that are deep and wide-spreading, acting as stabilizers. Plant progression in mountains depends on latitude and, to some extent, longitude: at 2,000 metres one finds deciduous trees; at 2,500 metres, conifers; at 3,500 metres, small shrubs; and at 4,000 metres, only herbaceous plants.
Tropical Alpines: Where it is winter every night and summer every day, we find 'nightbuds' to protect tender shoots, a thick felt covering the underside of leaves to protect stomata, and a plumbing system protected by self-lagging from the persistent dead leaves or corky bark.
Arctic tundra subsoil is always frozen as opposed to alpine tundra. Arctic tundra is dominated by wind, ice and snow with temperature fluctuations. There are no annuals here, and the greening of plant life coincides with the birth of animals. Insects and plants tend to be of a dark colour in order to absorb more solar energy, the anthocyanin pigment protecting against the intense light; hairs also trap heat and reflect light; the metabolic warmth of the plants can melt the snow. Growth is slow here because of the short nights, the time for plants to grow; they spend the day photosynthesizing.
Grasslands develop in areas of intermediate precipitation; they may be a) tall grasses, or prairies, as found in the pampas of the Argentine and in European Russia, or b) ranches, as in the steppes of Southeast Europe and adjoining Asia. The savannahs in Africa are really forests held back by grazing and fire. Grasslands are misused by overgrazing on public lands; ungulates are heavy feeders, especially in alpine meadows. It has been found more beneficial on grasslands to graze sheep in a loose-knit flock. The numbers of cattle and sheep in the US has increased dramatically; from 1870 to 1990, cattle increased from 4-1/2 million to 26 million and sheep from 7-1/2 million to 20 million.
Uses of grass: a) ornamental; b) sports' surfaces - golf ski slopes, etc.; c) orchards; d) prevention of soil erosion such as dike stabilization, roadside banks (a wet mixture of cellulose fibre and grass seed is sprayed on); e) economic grasses, such as wheat, barley, rye, oats, corn, all very important for man and could be said to represent our meat, butter and eggs! Historically, the first grasses grown as a crop were barley and wheat in Southwest Asia in 7,000 B.C.
Deserts are habitats where one sees adaptation to a lessening of water supply by a variety of means, including water-storing stems, such as the saquero cactus which is capable of storing up to a ton of water in its fluted stem and is able to contract and expand depending on water content. Roots on the desert surface may radiate as far as 50 feet in order to make the most of any rainfall and may go very deep in their search for this precious liquid. When the Suez Canal was being dug, the roots of tamarisk were found at 50 metres below ground level. Leaves may be covered with a wax or hairs to help with insulation, or they may become spines, thus having a smaller evaporating surface. And in times of severe drought, the leaves may drop off. They have few stomata, which are sunken in pits and may open only at night when carbon dioxide will be taken in and turned into sugar during the day. Cacti sometimes have ephemeral leaves, a reminder of primitive origins, rather like gills on mammals. Desert plants are widely spaced in order to survive.
FreshWater: The world's water is, and always has been, recycled; your drinking water of today may be the same that a dinosaur bathed in eons ago! It is the threshold between two worlds, the surface and the depths. There is a surface film which is very important and a matter of life and death for many creatures. The film is created by tension between one molecule and another, providing a surface for insects to crawl on top and for snails to slide on underneath. Many larvae come equipped to enable them to pierce this film from below in order to obtain a vital air supply. Plants are found in both shallow and deep water. There are many more plants in shallow still water anchored in the mud; when the water is moving, the leaves tend to be divided to avoid damage. Water lilies are typical aquatic plants with reduced roots, needed only as an anchor, because the whole plant is in a solution of nourishing minerals! The stems are hollow, acting as ventilating pipes to provide the extra oxygen needed, and stomata are on the upper side of the leaves for breathing. Aquatic ferns have waterproof spores released in a bubble of air. Water plants work extra hard in hot, sunny weather and one may see bubbles of oxygen being released. Ice as frozen water becomes lighter and, therefore, does not sink.
Seaside: All plants in this habitat are salt-loving, otherwise known as halophytes. Here we have a variety of habitats: salt marshes, where the river meets the sea; sand dunes, stable or shifting; and the shore, which may be sandy or with shingle and washed or above the high tides; and, lastly, the rocks. Ocean currents are conveyors of long-range climates, picked up by winds and delivered to the land.
Seaweeds: Eighty-five percent of earth's greenery is found in the ocean. Seaweeds have a remarkable response to lessening of light intensity depending on their location; the surface seaweeds receive the maximum of all coloured light, especially from the red spectrum and are therefore green, while those deeper receive the blue and green lights which makes them red to our eyes.