Cycles in NatureEssential Knowledge for Naturalists
The Cyclical Nature of reality
A cycle is a series of events that recurrs, with some observable repeating pattern. Some definitions of a cycle include the concept of returning to the beginning state. For example, the cycle of the seasons runs from winter to spring to summer to fall and then, a year later, back to the beginning, winter. This is, of course, one of the most apparent cycles.
Nature, and the individual components of Nature, such as plants and animals, also tend to follow cyclical patterns, just like the seasons. If you are attuned to it, you will see cycles, patterns, and fluctuations everywhere in Nature.
Learning this one little fact can go a long way toward helping you live a more balanced life. When things get you down, just remember: the essence of life is change; things change, then change yet again. Be happy with that, that's the nature of things here. Sometimes things are ahead of where you would like them to be, sometimes they are behind.
Here a a few examples of cycles in Nature:
Seasons of the Year
Because the sun is Eath's energy source, the distance we are from the sun can make a big difference in our temperature. Like when you stand too close to a camp fire, you get a little toasty? When you take two steps back, what happens? Too cold? One step forward again and it is just right. Seasons are like that. Almost.
When it is winter in the Northern Hemisphere (above the equator), it is summer in the Southern Hemisphere (below the equator). If we were further from the sun in the winter, wouldn't the other half of the world also be further away? It isn't the distance that makes the difference in seasons. In fact, the Earth is closer to the sun during winter in the Northern Hemisphere. Think about that for a moment. Closer to the fire makes it colder?
It is the angle that accounts for the drastic temperature difference. You see, the earth doesn't rotate from a truly horizontal position. The axis (the imaginary line running from the North to the South Pole) is on a tilt of about 23 and a half degrees from vertical. The axis always points in the same direction. As the Earth circles the sun, during the northern summer, the axis orients the Northern Hemisphere to intercept the sun's light and heat more directly, while in the Sothern Hemisphere's summer, that portion of the glode is situated to get more direct solar energy.
The tilt of the Earth thus causes the seasons. As we know, life on Earth is attuned to the seasons. Trees and bears hibernate in winter and come out again in the spring. Crops grow during the spring, and summer, and are harvested during the fall. The never-ending seasons are part of a fundamental cycle that touches almost every aspect of nature.
Just as there are seasons through the course of a year, there are cycles in the lives of each type of plant and animal on earth. For example, Butterflies. A butterfly is only a butterfly at a certain point in its life cycle.
An adult butterfly lays its eggs on a host plant, thus beginning a new cycle for the eggs. The eggs develop into caterpillars. This is the larval stage of buterfly development. the caterpillars eat plant material and store it until they are ready to pupate, or enter the next stage of their life cycle, known as the chrysalis. This is what most of us refer to a a cocoon. In this stage, the chrysalis undergoes metamorphosis and becomes the adult butterfly.
Similar cycles occur in each species. Many plants form seeds which over-winter in the ground, then grow into a plant, convert energy into nutrients, produce flowers, set seeds and die. Their active life cycle runs from spring to fall, with the seed lying dormant unti l conditions are just right.
The timing of each life cycle is different. To learn a bit more about life cycles, visit the Franklin Institute's web page
Water is one of the most precious resources on Earth. Some have even said that many of our future wars may be fought over it. While we all hope that does not happen, one thing is for sure. We need to take care of our precious water supplies. In order to do that, we each need a basic understanding of how water flows though Nature.
There is no clear starting or ending point of the water cycle. Arbitrarily, let's choose water in the ocean as the beginning of this description. Ocean water, which covers three quarters of the Earth, is heated by the sun. Some of this water becomes water vapor, which rises to become clouds. Clouds can travel on wind currents, and as they move, the water contained in the clouds may fall back to the ocean as rain, or it may fall over land.
If rain, snow, or other precipitation falls on land, gravity and topography will conspire to direct the water to flow in certain patterns. Some of the rain will be absorbed by the ground, where it will filter through plant roots, soil, and rock until it reaches a layer of groundwater. Some ofthe water reaching the surface as precipitation will run off and make its way to a stream, flow into a river, and then into a lake, sea, or ocean to start the cycle again. Groundwater may seep out in springs and seeps, be taken up through wells for human use, or enter the roots of plants and be released back to the water cycle in that way.
Some precipitation may be stored for prolonged periods as ice and snow, or in lakes. Glaciers, and snow caps on mountains are places where vast quantities of Earth's water are stored as ice. Eventually though, it will all re-enter the water cycle, and move through its phases of solid, liquid and gas again and again, supporting life on Earth as it does.
For more information about the water cycle, visit the United States Geological Survey's Water Cycle page.
Like water, nutrients move through the environment in set, fairly predictable ways. For simplicity, we'll just describe one such cycle, the nitrogen cycle. Be aware, however, that each nutrient has a different set of properties, and is used differently in the environment.
The Earth's atmosphere is mostly nitrogen. Some of this atmospheric nitrogen is taken into the soil by plants such as beans, known as legumes. These nitrogen fixing plants, as well as commercial fertilizer companies, take atmospheric nitrogen and turn it into either organic nitrogen, ammonium, or nitrates that can be used by plants as nutrients.
Some of these nitrogen containing compounds leach, or run off from the soil, and enter a water stream, where they are moved with the water until entering a water body or being reabsorbed by soil. others of these compounds may undergo chemical or biological decomposition and are released back into the atmosphere.
Others of these compounds are actually taken up into the roots of plants, and become the building blocks of plants. The dead residues of these plants rot and re-enter the soil, returning the nitrogen to the soil for another cycle. Other plants may be eaten by animals. The nitrogen in the plants eaten by animals gets returned to the soil at the animals death, or in the form of animal wastes.
This nitrogen is then the raw material for fresh plant growth, enering the cycle yet again.
For more information about nutrient cycles, visit the International Institute For Plant Nutrition's web site.