Exploring an Eastern Woodland
Healthy woodlands play an important part of maintaining biodiversity in the environment. They provide a habitat for all manner of species, flora and fauna. If that woodland dies off, from natural causes or removed by man, then the birds, bees, mammals, varieties of ferns and mosses must all establish new colonies, if such places exist. Healthy forests are important for all.
How do forest soils provide enough nutrients to support such a quantity of trees over the years?
Leaf litter, twigs and pieces of bark that fall to the forest floor accumulate as organic matter. Within months this litter begins to become part of the soil during the process of decomposition.
Decomposition is the process of decay that takes place when a living thing changes chemically after dying.
Decomposition in soils is a key ecosystem function that in part determines the productivity and health of the plants that grow there.
There are thousands of types single celled fungi and bacteria in the soil. When an organism dies, fungi and bacteria begin breaking it down into its simplest components: carbon dioxide, water and nutrients. As rot sets in on these organisms insects, worms and other invertebrates inhabit the organism and aid in the decomposition. This process of decomposition releases large quantities of essential nutrients to the soil solution, thereby making them available to plant roots.
There was a time in Earth’s distant past when organic matter did not rot. The Carboniferous Period (358.9 million yrs. ago – 298.9 million yrs. ago) was a time when fantastic trees with delicate fern like leaves and pencil thin trunks grew to 160′ tall in dense swamp forests. Vast areas of the landmass EuroAmerica was covered in marsh and swamp, the air warm and humid. Plants gave off so much oxygen into the atmosphere that plants, insects and animals reached sizes not known in today’s atmosphere.
At that distant time bacteria, fungi and microorganisms that initiate decomposition of organic matter did not exist. Microbes that could ingest lignin and cellulose – key wood eaters – had yet to evolve. The result was that as leaf litter accumulated and trees died and fell they remained intact. They did not rot. All this dead material piled over the other in damp swamps. Dead material would compress from the weight piled above, and be submerged in the moist soils eventually turning to peat. Heat and pressure compressed the mud and carbon holding matter over millions of years. When dead matter builds up faster than the rate of decay, layers of organic carbon become natural gas, oil, coal.
If bacteria had been around devouring wood they would have broken carbon bonds, releasing carbon and oxygen into the air, but instead the carbon stayed in the fibers of the wood. Ninety percent of all coal mined on Earth today is from deposits formed in the Carboniferous Period.
The Carbon Cycle begins with plants. In the presence of sunlight, green plants combine carbon dioxide from the air with water. This process (photosynthesis) creates the simple sugar glucose, nothing more than carbon, oxygen and hydrogen. The glucose and other sugars are the fuel for building plant structure, plant growth and reproduction. When plants die, carbon and other nutrients stay in the fibers. The stored carbon is released back into the atmosphere through a chemical reaction after death. Decomposition releases carbon into the air, soil and water. Living things capture this liberated carbon to build new life. This is the Carbon Cycle.
The release of carbon dioxide from soil has global implications. It occurs in ecosystems worldwide and contributes significantly to the greenhouse effect. The greenhouse effect is a natural property of the atmosphere in which greenhouse gases prevent the transfer of heat from the Earth’s surface to outer space. A warming atmosphere will lead to a cascade of environmental impacts. Impacts such as global warming, sea level rise, alteration of precipitation patterns and increased storm activity can be expected. The rapid increase of greenhouse gases in the atmosphere began at the time of the industrial revolution. Coal and other fossil fuels are a convenient source of energy but when burned, the stored carbon is released into the atmosphere. This alters the balance of the carbon cycle and is changing the Earth’s climate.
Decomposition is a biological process carried out by bacteria and fungi. Bacteria and fungi are very sensitive to temperature. Colonies of microorganisms will face unknown threats in a warming environment. Climate change will also affect decomposition rates. As precipitation patterns are altered to very dry or very wet conditions, decomposition rates will decrease.
The meltdown of the nuclear reactor core at the Chernobyl power plant on the 26th of April, 1986 was an environmental disaster that had never been seen before. Because of high radiation levels an exclusion zone was established around the epicenter and the reactor was covered with a concrete dome in an attempt at containment. It wasn’t just people, animals and trees that were affected by radiation exposure at Chernobyl, but also decomposers: insects, microbes and fungi.
Scientists and researchers continue to study the compounding effects on the environment within the exclusion zone. What they have found is a significant accumulation of forest litter. This poses a fire threat that could spread contaminated material to a far wider area. Scientists have also noted that there has been very little plant decay in the 20 to 30 years after the disaster. Trees are not rotting. Studies are now being done at Fukushima in Japan to see if similar conditions with decomposers are evident.
The carbon cycle is so tightly tied to plant life that the growing season can be seen by the way carbon dioxide fluctuates in the atmosphere. In the northern hemisphere during winter, when few plants are growing and many are decaying, atmospheric carbon dioxide concentrations climb. During the spring, when plants start growing again, concentrations drop.
The intricate bonds that bind the of the web of life are beyond my imagination. In our solar system there is nothing like it. A small blue marble in the darkness of space. Everything needed to support life is here. Nature has filled every niche with life. Even in death nature has provided a way to recycle elements that induce new life. Decomposition plays a vital role in keeping a balance of Earth’s natural systems and cycles. In death there is life.
Human activity is disrupting the Earth’s systems of balance with dire consequences. I encourage all to learn more about the web of life, the environment and the ecosystems that exist where you live. Learn to love the planet.