The rate of decomposition of detritus is affected by the abiotic factors like availability of oxygen, pH of the soil substratum, temperature etc. Discuss.
Decomposition of dead remain or matter of animal and plant is carried out by microorganisms like bacteria, fungi etc. The growth rate of these decomposers is affected by abiotic factors like temperature, humidity, pH of soil and light etc.
The soil pH affect the composition of acidophilic and basophilic microorganisms. In absence or presence of oxygen aerobic and anaerobic processes occurs.
In presence of oxygen, complete degradation of substance occureds while in absence of oxygen, there will be an incomplete degradation. Similarly, at high temperature microbes can not grow optimally but high or low temperature favours the growth of stress tolerant microorganisms.
A farmer harvests his crop and expresses his harvest in three different ways.
(a) I have harvested 10 quintals of wheat.
(b) I have harvested 10 quintals of wheat today in one acre of land.
(c) I have harvested 10 quintals of wheat in one acre of land, 6 months after sowing.
Do the above statements mean one and the same thing. If your answer is 'yes', give reasons. And if your answer is 'no' explain the meaning of each expression.
(a) Farmer's expression for his crop harvestation (a) he has harvested 10 quintal of wheat, (b); He has harvested 10 quintals of wheat in one acre of land (c), six, months after sowing mean one and the same thing. Because crop an artificial ecosystem can be prepared with inclusion of bitoic and abiotic component in a given area.
Here abiotic components like water, is given by the farmer, while climatic factor like light, humidity, air is supplied naturally. The living component is wheat plant, which are obtained on harvestation by farmer.
Justify the following statement in terms of ecosystem dynamics. "Nature tends to increase the gross primary productivity, while man tends to increase the net primary productivity".
In term of ecsosystem dynamics, flow of energy takes place from one trophic level to the next trophic level and occured in unidirectional way. About $50 \%$ of solar energy incident over earth is present in Photosynthetic Active Radiation (PAR) and only 2-10\% of this PAR is utilised by green plants to form chemical energy (Gross Primary Productivity) (GPP).
Out of $90 \%$ of gross primary productivity is lost maximum during respiration and other vital activities. GPP utilised by plants in respiration minus respiration losses is the net primary productivity and is available to the organism of next trophic level (herbivore and decomposers) for consumption.
Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis.
So nature tend to increase gross primary productivity through supporting the large number of plant (producers) in an ecosystem.
Net primary productivity is the available biomass for the consumption to heterotrophs (human and animals) man tries to increase net primary productivity by cultivating food and other crops which the depend on to fullfil their needs.
Formula to genrate NPP is
$$ \mathrm{NPP} \rightleftharpoons \mathrm{GPP}-\mathrm{R} $$
Which of the following ecosystems will be more productive in terms of primary productivity? Justify your answer. A young forest, a natural old forest, a shallow polluted lake, alpine meadow.
Primary Productivity can be defind as the rate at which primary producers (Green plants) traps and store solar radiation in form of biomass. This is measured in term of weight $\left(\mathrm{g}^{-2}\right)$ and in term of energy ( $\mathrm{Kcal} \mathrm{m}^{-2}$ ) per year in given time.
So, primary productivity varies from ecosystem to ecosystem and the ecosystem which possess more producer will be more productive in term of primary productivity. So young forest grow quicker than older, mature forest and are more productive in terms of productivity. The shallow polluted lake and alpins meadow will be less productive because of less number of producers and high amount of dead matter.
What are the three types of ecological pyramids. What information is conveyed by each pyramid with regard to structure, function and energy in the ecosystem.
Ecological Pyramids An ecological pyramid is a graphical representation of an ecological parameter as number of individual present in various trophic level of food chain.
Properties of ecological pyramid
(i) The trophic structure of an ecosystem is represented in the form of ecological pyramids.
(ii) The base of each pyramid represents the producers or the first trophic level, while the apex represents tertiary or top level consumer.
The three types of ecological pyramids are
(a) Pyramid of number shows relationship between producers and consumers in an ecosystem in terms of numbers. It may be inverted or upright pyramid.
(b) Pyramid of biomass shows relationship between producers and consumers in an ecosystem terms of biomass. It can be
(a) Upright, e.g., in case of grass land ecosystem.
(b) Inverted, e.g., in case of pond ecosystem.
Inverted pyramid of biomass.
Small standing crop of phytoplankton supports large standing crop of zooplankton
(c) Pyramid of energy is the relationship between producers and consumers in an ecosystem in terms of flow of energy. It is always upright because energy is always lost as heat at each step.
An ideal pyramid of energy. Observe that primary producers convert only $1 \%$ of the energy of the sunlight available to them into Net Primery Productivity.