Question

(a) What is primary productivity? Why does it vary in different types of ecosystems?
(b) State the relation between gross and net primary productivity.

Answer 1

Hint: We know human beings and animals are dependents on the plants. We take the food made by the plants and consume it to gain energy. It is the reason that they are called the producers. They are producing the food with help of sunlight, chlorophyll, and water.

Complete answer:
(a) The quantity of energy accumulated in the plant body which was involved in the process of photosynthesis as in the form of biomass or organic matter for every unit area over a period of time is called Primary productivity.

(b) It is the fact that it varies in dissimilar sorts of ecologies for the reason that the factors which are unlike influence it.

- The type of soil and a number of environmental factors, their photosynthetic activity, availability of nutrients, availability of sunlight and precipitation, plant species composition, and succession all will differ from ecosystem to ecosystem.
- We know these all are the factors that normally sustain the growth of a plant. Thus, there exists a sort of variability which is normally seen in different ecosystems.
- The rate of creation of organic matter in the duration of the process of photosynthesis is called the Gross primary production of an ecosystem. However, the amount of Gross primary production which is utilized by the plants in respiration is called a considerable amount of GPP.

Note: We should note that the primary productivity subject to diverse plant species present in a given ecology. In addition, each of their photosynthetic efficiency has an influence on these plants. One can say the difference between the gross primary productivity and respiratory losses (R) gives the amount of Net primary productivity or NPP.
$GPP - R = NPP$