Mar 062013
 

african-lionafrican lionA report from Washington said that over next 20-40 years, nearly half of Africa’s wild lion populations may decline if the urgent conservation measures are taken.

The report entitled “Conserving large carnivores: dollars and fence” which has been recently published in the scientific Ecology Letters, said that the situation of many lion populations is so worse which is very difficult to recover. The report also concludes that fencing them in, and fencing humans out, may be their only hope for survival.

The report has been prepared by the University of Minnesota’s Professor Craig Packer and co-authored by a large team of lion biologists, including Panthera’s President, Dr. Luke Hunter, and Lion Program Director, Dr. Guy Balme.


Craig Packer, who is the advisor on Panthera’s Cat Advisory Council said, “it is clear that fences work and unfenced populations are extremely expensive to maintain.

The report also proved that there is significant increase in lion population sizes and densities in reserves secured by wildlife-proof fences compared to unfenced ecosystems. Meanwhile such conservation costs are also lowered.

Those populations which are in unfenced reserves were subject to a higher degree of threats from human communities including retaliatory killing by herders, habitat loss and fragmentation and over hunting of lion prey.

It is very necessary to separate lion and human population for the survival. For that, fencing or some alternative physical boundary such as intensely managed buffer zones should be made.

According to the report, at present, it is estimated that fewer than 30,000 lions remain in Africa in just 25 percent of the species’ original natural habitat.

Jan 312013
 

In terms of biology, productivity can be defined as the rate of production of amount of organic matter (food) which is accumulated in the living components of the ecosystem in unit area and time. We can classify productivity in two types. They are:

1. Primary Productivity
2. Secondary Productivity


1. Primary Productivity: Primary productivity is associated with the producers which are autotrophic. The autotrophic producers include both chemoautotrophs and photoautotrophs. Primary productivity is defined as the rate at which radiant energy of the sun is stored or used by producers to form organic matter, i.e. food. Primary productivity can also be classified into two different types which are described below:

    • Gross Primary Productivity (G.P.P): Gross Primary Productivity is the total organic matter synthesized by producers during photosynthesis. It can also be defined as the total rate of photosynthesis including the organic matter used up in the process of respiration during the period of measurement. This is also called total photosynthesis or total assimilation.
    • Net Primary Productivity (N.P.P): Net Primary Productivity can be defined as the rate of storage of organic matter by producers, excluding the organic matter which is used up in respiration process during the period of measurement. This is also called apparent photosynthesis or net assimilation. For calculating Net Primary Productivity, we can use the following formula:

Net Primary Productivity = Gross Primary Productivity – Rate of respiration

2. Secondary Productivity: Secondary productivity is the productivity which is associated with consumers or heterotrophs. Consumers feed on other organisms for their survival. They use the organic matter which is present in food for the resynthesis of new organic matter. The resynthesis of organic matter by consumers is called secondary productivity. Secondary productivity can also be defined as the rate of energy storage at consumers’ level for the resynthesis of new organic matter. It can be calculated by using the following formula:

Secondary Productivity = Net Primary Productivity – Heterotrophic consumption