Introduced Species – Effect on Biodiversity

Introduction of an exotic, non-native species into the distributional range, either deliberately or accidentally by human activity many-a-times poses a serious threat to the local habitat. A habitat containing all indigenous varieties tries to balance and control each species living within its limits. An introduced species has no enemies to control it; hence they slowly out number the native species and compete with them for the available resources.

Threats to biodiversity are many like habitat destruction by forest clearing, release of poisonous gasses due to industrialization etc. Out of all these threats introduction of exotic species ranks second. In fact, native biodiversity is affected more by introduced species rather than by pollution, harvest, and disease combined.

Some of these species are also being used as biological weapons as they cause mass destruction of ecosystem.

Examples of Damage to Biodiversity

Species are habitat-specific and can thrive only in a particular habitat but introduced species change the entire habitat and cause a major threat to biodiversity.

• Australian paperbark tree was introduced which replaced native plants, such as sawgrass, over a wide range of about 400,000 acres of south Florida. Australian paperbark tree had a combination of traits like flammable leaves, spongy outer bark and litter which can increase fire frequency and intensity. The uncontrolled spread of paperbark made many birds and mammals extinct as they were adapted to the native plant community.

Some other invasive species, do not change a habitat, but pose a threat to a single species. Sometimes they even destroy the entire groups of them in various ways.

• Brown tree-snake, is a predator which was introduced from Admiralty Islands in cargo. This brown tree snake has affected forests of Guam by eliminating ten of the eleven native bird species.

Some times the impact of invaders is subtle but destroys the native species at the same time.

• In North America native red squirrels are being driven to extinction by gray squirrels. Both these species compete for nuts and gray squirrels are more efficient than the native species. Such competition for resources is difficult to observe, but loss of a native species is the end result.

An interesting example amongst plants is that of acacia and the eucalyptus. These species were brought from Australia as a part of afforestation programmes. These are quick growing plants and were encouraged as the demand for wood had also increased. But these plants are known for their large number of disadvantages like:

• These trees shade the ground and the leaves that are shed do not allow other plants to grow.
• These trees do not decompose easily
• During the rains there is heavy erosion and poor percolation in the areas rich in these trees.

Only a few Introduced species are beneficial. Like most of our food crops (rice), onion, chilies and pets. The statistics of damaging introduced species is startling. The solution to this problem is stringent quarantine rules at all entry and exit points like airports, harbours, border crossing areas etc. 

Such proactive measures to check this problem will allow the existing plants and animals to flourish in their natural surroundings and habitat.

Control Measures of Soil Pollution

The natural resource, soil, is the thin layer of organic and inorganic materials that covers the Earth's rocky surface. Soil formation involves a large number of factors and is a time taking process. Mechanical weathering of rocks due to temperature changes, wind, moving water, lichens are a few of the contributing factors.

Pollutants like toxic compounds, radioactive materials, salts, chemicals, when added to the soil, deteriorate the quality, texture and mineral content of the soil. This leads to soil pollution. Soil pollutants disturb the biological balance of the organisms in the soil. The adverse effect of this contamination is reduced soil fertility affecting plant and animal growth.

Major causes of soil pollution are:

• Random use of fertilizers
• Random use of pesticides, insecticides and herbicides
• Disposal of large quantities of solid waste
• Deforestation and soil erosion
• Addition of industrial contaminants
• Dumping of radioactive wastes

Control of soil pollution

Various steps suggested in order to control soil pollution are as follows:

Reducing chemical fertilizer and pesticide use

As the soil erosion has become a major cause of concern we need to adopt the three R's: Reduce, Reuse, and Recycle in order to minimize the usage of fertilizers and pesticides.

Biofertilizers are the best alternatives for chemical fertilizers. They are microorganisms which are used to increase the fertility and growth capacity of soil. This process of Biofertilization also reduces the need for pesticides and fungicides.

Practice of crop rotation – Leguminous plants can fix atmospheric nitrogen and hence enhance the soil fertility. These plants can be grown in between the crops which absorb a lot of soil nutrients.

Recycling of materials

Recycling and reusing of materials such as glass containers, plastic bags, paper, cloth etc. at domestic levels rather than disposing, reduces the solid waste pollution. Use of plastic bags has increased drastically. Paper bags or jute bags can be a good alternative for them. Toys made up of clay can be a good source of amusement for kids. A complete ban on the use of plastics is advisable.

Reforestation

Wastelands, soil erosion and floods can be controlled by reforestation. Huge forests have become prey to man’s greed. It takes years together to reform a forest. Every individual on earth should decide to plant trees to save our planet earth.

Treatment of waste

Biological treatment of the waste using anaerobic microorganisms, such as methanogens and acetogens is advisable as it helps to break down the soil wastes into a less toxic and biodegradable form. Industrial and radioactive wastes should be properly treated before leaving them to soil.

It is high time the man realizes the importance of the rich top soil and takes necessary steps to protect it from pollutants. Soil is an asset and there is no substitute for this. Wide stretches of desserts created by human beings are laughing at us. When we cannot create tanks and tanks of natural fertile soil should we not stop destroying it?

The Cry of a Hungry Child

Food is the basic necessity of human being and it is sad to know that at least 925 million people across the world are deprived of it. According to the statistics provided by worldhunger.org among these 925 million people, at least 578 million people are from Asian and Pacific region. A maximum number of people suffering from undernourishment are from developing countries.

It is sad that children are most liable victims of malnourishment. Children deprived from food for a sufficiently long span of time suffer from serious forms of Protein Energy Malnutrition. This situation arises due to the insufficient supply of nutrients especially proteins and energy to the body to meet its demands. A malnourished or undernourished child falls prey to many diseases like malaria, measles, diarrhea etc. Most of the deaths of children below 5 years of age are reported to be due to Protein Energy Malnutrition.

Reasons behind hunger from the economic point of view are many, like poverty and uneven distribution of money which is a primary cause of hunger. Poverty means lack of resources and ability to purchase food. Since ages it has been seen the rich people have access to all resources and tend to become further rich whereas the poor become poorer.

Some other reasons include economic crisis across the world and inadequate supply of food due to neglect towards agriculture. Another major factor which adds to all these is the wastage of food across the world. Food wastage statistics are quite saddening. The trend of wasting food has crept slowly from rich countries like America to developing countries.

Wastage of food begins at the producer level (farmer) and continues through the distribution channel till the house hold level. If we add up the wastage at each level it shows a considerable amount which can perhaps save many children from malnourishment. Vegetables are stored to increase the price in the market and if in this process they are spoilt they are simply thrown away. A vegetable seller throws away huge quantities of vegetables at the end of day rather than selling them at a lower price just because he has to maintain the market price. Similarly distribution channels, publicize the damage to stored food to artificially increase the prices. Tons and tons of packed food just go as waste. The reason behind this is the expiry date. How nice it would have been if they could have planned and distributed them amongst the people living in slums just before reaching their expiry date.

Did you ever think before throwing food into the dustbin at the restaurant or at home? Now-a-days it is common to see heaps of wasted food dumped outside a reception hall or a restaurant. Food wastage at the house hold level has also become common these days. The wasted food is not only a problem to the environment but it also increases the number of street dogs, rats, bacteria etc thus spoiling the balance of ecosystem. Are we not contributing to hunger and imbalance in ecosystem?

Back in the olden days our grandparents used to teach us not to leave even a single particle of food. Evidence of this can be found in one of our great epics Mahabharata where Lord Krishna fills up his stomach with a single rice grain and asks Draupadi not to waste that. Social and moral values have vanished away as the earning capacity of a few people has increased. Can we not take steps to stop food wastage and save a child who is crying because of hunger?