Question

Define :
a) Stratification
b) Gross primary productivity
c) leaching
d) Humification

Answer 1

Hint: The definitions of the first two terms can be told by understanding the meanings of the word strata which means layers and productivity which means the effectiveness. Leach means minerals or chemicals drain away from soil. The fourth word can be defined by knowing the meaning of the word humus.

Complete answer:
a) Stratification:
Stratification in the field of environmental biology or ecology is the vertical layering of a habitat or the arrangement of different vegetation in layers in a habitat. The layers are classified mainly based on the different heights to which the plants grow in that particular habitat. The different layers are root layer, moss layer, herb layer, shrub layer and the tree layer.

b) Gross primary productivity:
Gross primary productivity of an ecosystem can be defined as the amount of carbon that is fixed during photosynthesis in the form of carbon dioxide. It does not take into account the carbon utilized by the plants for growth and maintenance.

c) Leaching:
Leaching in biology or agronomy is the loss of vital nutrients especially the water-soluble plant nutrients from the soil due to various reasons such as excessive irrigation and floods (rain). It can also be referred to the process of using excess irrigation to wash off excess salts in the soil.

d) Humification:
Humification is a process of formation of humus by microorganisms. Humus is a dark amorphous product formed when these microbes degrade dead and decaying organic matter.

Note: Net primary productivity is the gross primary productivity after removing the carbon used up for growth and maintenance. Humification differs from mineralisation. In the latter inorganic nutrients are recycled but in the former only organic matter is converted to organic polymers which are quite stable and cannot be recycled further.