Question

What is primary productivity? Give brief description of factors that affect primary productivity.

Answer 1

Primary productivity:it's described as the quantity of organic be counted or biomass produced by producers according to unit location overerio a time period. it is expressed as in terms of weight(g/ m^-2 yr ^-1).It is of two types: gross primary productivity and net primary productivity. Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP).

Factors affecting primary productivity:                

(i) Solar radiation: Maximum light is available in tropics. Poles receive minimum light. Due to this, photosynthesis is maximum and net primary productivity (NPP) is highest (> 20 t ^ha^-1 year^1) in tropics against (about 8 t ha^-1 year^-1) in temperate forests.                

(ii) Temperature: Temperate forests have lesser productivity than tropical rain forests due to cold climate.                 (iii) Moisture: Rain and humidity increase productivity of the ecosystem.               

(iv) Nutrients: Nutrients are essential for producers? growth. Desert soils are deficient in nutrients and therefore, are less productive.

(v) Photosynthetic efficiency of producers: C4 plants are more productive than C3 plants.