Bio-Diversity & Its Convervation - Part 2

 BIO – DIVERSITY & ITS CONSERVATION

PART 2

GRADIENTS OF BIODIVERSITY :
•    Biodiversity is not uniform on the earth. It varies with change in latitude or altitude.
•    Biodiversity increase, when we move from high to low latitude (i.e. from the poles to the equator). The temperate region has severe climate with short growing period for plants.
•    On the other hand tropical region has favourable conditions for the growth throughout the year. The favourable environmental conditions favour speciation (i.e. origin of new species) and make it possible for a larger number of species to occur and grow.
•    Therefore, tropical regions are rich in biodiversity.
•    Similarly, the species diversity decreases from lower to higher altitude on a mountain.
•    The temperature drops about 6.5oC with increase in altitude by 1000 m. The drop in temperature and greater seasonal variability at higher altitudes are the two major factors that reduce diversity.
•    It should not be confused with complexity and heterogenecity of the physical environment which tends to increase complexity and diversity of flora and fauna of an area.

BENEFITS OF BIODIVERSITY :
•    Biodiversity provides numerous direct and indirect services to human beings, e.g., :
1.    Diversity of plants and animals provide a vast variety of foods and fabrics.
2.    Maintenance of ecological balance or ecosystems stability.
3.    Preserving biodiversity provides economic benefits which include improving the desirable characteristics of crops, making plants more pest resistant, providing medicines to treat and curve illness, supporting ecotourism and providing enjoyment to individuals.
4.    Biodiversity enriches the lives of people in industrialized world and developed countries provides the means of survival to people in developing countries.

THREATS TO BIODIVERSITY

1.    DESTRUCTION OF HABITATS :
•    Destruction of natural habitat is the primary threat to the biodiversity.
•    Natural habitats, which protect natural flora and fauna are being converted to human settlements, harbours, dams, reservoirs, crop-lands, grazing grounds and mining sites.
•    Deforestation deprive animal life of shelter and food.
•    This decreases the population of many species. Migratory animals are also affected by deforestation because of the disturbance in their routes.
•    Some of the dams are blocking, spawning and migration of fishes by inundating the habitats and by changing the physical environment.
•    Sometimes human cleanliness destroy the habitat of scavengers such as vultures, kites, etc.
•    The California condor (Cathartes californianus) a shy scavanger, which is the largest flying bird of today, has been severely affected by human cleanliness.

2.    DISTURBANCE AND DEGRADATION OF HABITATS :
•    They are of two types, natural and man-made. Natural disturbance and degradation are caused by spontaneous jungle fire, pest infestation, defoliation by insects, locust attack, etc. Man-made disturbance and degradation are more severe.
•    They include felling of trees, use of fire for clearing forest areas, collection of litter, and over-exploitation for other economically important products.
•    Disturbance and degradation result in loss of biodiversity.

3.    POLLUTION :
•    The most subtle form of habitat degradation is environmental pollution.
•    Pollution may reduce and eliminate populations of sensitive species.
•    The populations of fish eating birds and falcons have declined due to excessive use of pesticides in crop fields.
•    Lead poisoning is another major cause of mortality of many aquatic birds like ducks, swans and cranes.
•    These birds often swallow the spent shotgun pellets that fall into lakes and marshes. The nutrient enrichments (eutrophication) also drastically reduce biodiversity.

4.    INTRODUCTION OF EXOTIC SPECIES :
•    New species entering a geographical region are called exotic or alien species.
•    Introduction of exotic species may cause significant loss to the biological communities.
•    The great majority of the exotic species do not become established in the introduced new places.
•    However, some of the species are able to establish in new area. Such successful exotic species may kill or eat native species to the point of extinction, or may so alter the habitat that many natives are no longer able to persist.
•    Island ecosystems are most vulnerable due to small size and small number of species.

Examples of introduction of exotic species and their effects are :
•    Introduction of Nile perch (an exotic predatory fish) into lake Victoria (South Africa) threatened the entire ecosystem of the lake by eliminating several native species of the small Cichlid fish species that were endemic to this fresh water ecosystem.
•    In several tropical countries including India, water hyacinth (A free floating exotic water weed) clogs rivers and lakes, and threatens the survival of many aquatic species in lakes and rivers.
•    Lantana camara (An exotic shrub) strongly competes with the native species and eliminate many of them. The exotic shrub has invaded many forests in different parts of our country.

To be Continued in Part 3