Human activities on natural resources – Cont’d
LAST WEEK, we began our study of the impact of human activities on the environment by looking at how these activities impacted two of the four resources that were listed for study. Do you remember what these resources are? Of course you do! Did you say energy, minerals, forests and the resources of the seas and the oceans? If you did, you are correct. Now, which ones did we look at last week? If your answer was energy and minerals, then you are, again, correct! This week we will continue our study by looking at the remaining two, forests and the resources of the oceans and seas.
FORESTS
The human population depends on the trees in the forests to maintain the balance of carbon dioxide in the atmosphere. Do you know how the trees are able to do this? The trees take in carbon dioxide which they use in the process of photosynthesis. This continuous removal of carbon dioxide from the atmosphere serves to keep the level of carbon dioxide at 0.03%. Remember that carbon dioxide is being continuously returned to the atmosphere due to respiration, so if it is not removed the levels would increase.
WHAT ARE THE CONSEQUENCES OF DESTROYING THE FORESTS?
The destruction of the forest is known as deforestation. Many Caribbean countries are suffering from the effects of rapid rates of deforestation.
■ As said before, trees help to maintain the carbon dioxide levels in the atmosphere, so if the trees are cut down then the amount of carbon dioxide in the atmosphere will increase. Carbon dioxide is a greenhouse gas and increased levels will contribute to global warming.
■ Deforestation can contribute to soil erosion. The roots of trees help to bind the soil together, preventing soil erosion.
■ If trees are growing close together, their leaves will form a canopy which will serve to break the force of the water when there is heavy rain. This also helps to prevent erosion of the soil and flooding.
■ Transpiration from the leaves helps to maintain the transpiration stream so when deforestation occurs, it can lead to a reduction in the amount of water vapour going to form clouds. Transpiration plays a role in the water cycle.
■ Trees provide food and shelter for many organisms, so deforestation can endanger the survival of these organisms.
■ Many endemic organisms live in areas such as tropical rainforests; destruction of these forests can lead to their extinction. These include animals like the giant citrus swallowtail butterfly in Jamaica, the parrots of St Lucia and Jamaica, and the Iguana which used to be found in large numbers in many Caribbean islands but whose numbers have now dwindled.
If trees are so important, why then are we trying our best to get rid of them? Well, unfortunately, man is not known for thinking long term, so we continue to use what we want, when we want to, without spending much time to think of the consequences.
Let us look now at some of the reasons why forests are destroyed.
■ We use lumber to make houses and furniture and as populations increase, the need for lumber grows.
■ Trees provide pulp to make paper for newsprint, photocopiers, printers and general uses in offices, homes and schools.
■ Trees are removed to provide land for farming and cattle ranching.
■ Trees are removed to provide for the construction of roads and housing schemes.
■ Trees are also used to provide fuel, either as charcoal or as firewood. In some areas of the world this is the only source of fuel.
MARINE RESOURCES
Most times when we think of the seas and the oceans, we think only of the fish, large and small, that are found there; but these two vast expanses of the earth’s surface are much more than providers of fish, and their ecosystems are also threatened by human activity.
We are going to look briefly at the impact of human activities on the coral reefs that form an
important part of our lives as island states.
■ Coral reefs are vibrant, delicate structures that provide food such as fish, shrimp, lobsters, sea urchins and sea weeds for humans, and shelter for a wide array of organisms.
■ They also provide avenues for recreational activities such as swimming, snorkeling and scuba diving for tourists; and don’t forget that they were the providers of the beautiful, white sand beaches that form the coastline of many Caribbean states.
■ The reefs protect the island coastlines from erosion, since they act as breakers for the waves coming to shore.
■ It follows, then, that we ought to take care of them; unfortunately, it does not always happen, as with the forests, we use and abuse.
The following gives a list of the destructive activities that are carried out on the reefs.
■ Divers collect the living corals which they then sell to tourists – corals take a very long time to grow; it takes approximately one thousand years for a reef to grow one metre.
■ Fishing for reef fishes has caused a lot of damage to the reefs. Some fishermen use traps that damage the structure of the reef. These traps catch fish indiscriminately, i.e., young and mature, small and large. Populations of conch, sea urchin and lobsters have been depleted and some island states have had to restrict the periods when they can be fished for.
■ Unsupervised ecotourism activities can also cause damage to the reefs, e.g., if humans are allowed to walk and snorkel on them freely.
■ Dredging of lagoons and the destruction of reefs to create harbours for ocean vessels, reclaiming of land to build coastal roads and hotels all serve to destroy the reefs.
■ Discharge of untreated sewage into the sea provides excessive supplies of nutrients which lead to algal blooms, causing the deaths of other marine organisms due to oxygen depletion.
■ Run-off of fertiliser into the sea also causes algal blooms, resulting in the death of other organisms.
Interesting, isn’t it? See you next week! Take care!
“What you do makes a difference and you have to decide what kind of difference you want to make.”
– Jane Goodall