Q.14. What are the essentials of a desert ecosystem? (2007-08 I Sem.)
Ans. Desert Ecosystem: -
Essentials: -
Deserts occupy about 17% of the land area. They occur where rainfall is extremely low (less than 50 cm per year) and evaporation rate is high. Even the water from the meager rainfall is not available to plants due to its fast run-off rate.
The deserts are characterized by extremely hot days and clod nights. Further, the seasonal fluctuations of temperature are also very wide. The deserts of the world are mainly located in the south-western United State, Mexico, coastal areas of Chile and Peru, North Africa (Sahara), central-western Australia, Asia (Thar, Gobi, Tibet and West Asia). And most of these deserts are situated in the rain shadow areas. Soils of these deserts often have abundant nutrients but little or no organic matter and need only water to become very productive.
Q.15. What is ecological succession? Describe the causes and basic types of ecological succession. (AKTU. - 2004-05)
Related Questions -
Q. Define ecological succession. Give an account of general process of succession in nature. (AKTU. - 2007-08 Ist Sem.)
Ans. Ecological Succession: -
Over the course of years it is observed that in nature one biotic community gradually gives way to a second, the second perhaps to a third, and even the third to a fourth. This phenomenon of transition from one biotic community to another is called ecological or natural succession. A typical ecological community (or ecosystem) maintains itself more or less in equilibrium with the prevailing conditions of the environment; but in nature this is hardly true.
Causes Of Ecological Succession: -
Broadly, there are three main types of causes:
(i) Initial Causes: -
Initial or Initiating causes are climatic as well as biotic. Climatic causes include factors, such as, wind, fire, erosion and deposits, etc.; while the biotic causes include the various activities of organisms. These causes are responsible in the production of bare areas or in the destruction of the existing population in an area.
(ii) Ecesis Causes: -
Ecesis or continuing causes are the processes that include migration, ecesis, aggregation, competition, reaction, and so on which cause successive waves of population as a result of changes, mainly in the edaphic features of the area.
(iii) Stabilising Causes: -
These are responsible for the stabilization of the community. According to Clements, “climate of the area is the chief cause of stabilization, other factors are of secondary value.”
Types Of Ecological Succession: -
There are two basic kinds of succession: primary and secondary.
(i) Primary Succession: -
Primary succession is the initial development of an ecosystem. It occurs when a community begins to develop on a site previously unoccupied by living organisms, such as an island, a sand or silt bed, a body of water, or a new volcanic flow.
(ii) Secondary Succession: -
Secondary succession is a reestablishment of an ecosystem. In secondary succession, there are remnants of a previous biological community, including such things, as organic matter and seeds in the soil of a forest. It occurs when an existing community is disrupted and a new one subsequently develops at the site.
Q.16. What is meant by Eutrophication? (AKTU. - 2011 - 12)
Related Question -
Q. Define the term Eutrophication. (AKTU. - 2012 - 13)
Ans. Excessive use of chemical fertilizer has a detrimental effect on soil health. The introduction of untreated or partially treated sewage into a water body could lead to an increase in the amount of organic matter in it. The decaying organic matter provides nutrients for the growth of algae and other aquatic plants. This accumulation of excess nutrients is called eutrophication. Eutrophication also occurs when excess fertilizer nutrients (mainly nitrogen and phosphorus) accumulate in the water body. It usually results in an overgrowth of phytoplankton (small plant algae). Once these die, they begin to decompose. Their decomposition cause the depletion of dissolve oxygen, which is very important for the life of fish and other aquatic life. This may ultimately lead to the death of fish and other aquatic organism due to suffocation.
Q.17. Write an explanatory note on the issue of food and shelter security. (AKTU. - 2008-09)
Ans. Food security refers to the availability of food and one’s access to it. A household is considered food secure when its occupants do not live in hunger or fear of starvation. According to the World Resources Institute, global per capita food production has been increasing substantially for the past several decades. In 2006, MSNBC reported that globally, the number of people who are overweight has surpassed the number who is undernourished - the world had more than one billion people who were overweight, and an estimated 800 million who were undernourished. Two commonly used definitions of food security come from the UN’s Food and agriculture Organization (FAO) and the United States Department of Agriculture (USDA):
- Food security exists when all people, at all times, have physical and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life. (FAO)
- Food security for a household means access by all members at all times to enough food for an active, healthy life. Food security includes at a minimum (1) the ready availability of nutritionally adequate and safe foods, and (2) an assured ability to acquire acceptable foods in socially acceptable ways (that is, without resorting to emergency food supplies, scavenging, stealing, or other coping strategies). (USDA)
Shelter is a basic structure or building that provides protection. Protection includes protection from weather and places of refuge.
The number of homeless people world wide has grown steadily in recent years. Approximate 100 million people are homeless in world wide.
Homelessness is the condition and social category of people who lack housing because they can’t afford or are otherwise unable to maintain regular, safe and adequate shelter.
Causes of homelessness
1. Unavailability or lack of affordable housing.
2. Unemployment.
3. Poverty.
4. Domestic violence.
5. Natural disaster.
Problems faced by Homeless people:
1. Reduced access to health case
2. Discrimination
3. Limited access to education
4. Increased risk of suffering from violence and abuse.
