Aaseesh Preetam

Jhum (Shifting) cultivation is a primitive practice of cultivation in States of North Eastern Hill Region of India and people involved in such cultivation are called Jhumia. The practice involves clearing vegetative/forest cover on land/slopes of hills, drying and burning it before onset of monsoon and cropping on it thereafter. After harvest, this land is left fallow and vegetative regeneration is allowed on it till the plot becomes reusable for same purpose in a cycle. Meanwhile, the process is repeated in a new plot designated for Jhum cultivation during next year. Initially, when Jhum cycle was long and ranged from 20 to 30 years, the process worked well. However, with increase in human population and increasing pressure on land, Jhum cycle reduced progressively (5-6 years) causing problem of land degradation and threat to ecology of the region at large.

OZONE LAYER:- The ozone layer is a deep layer in the stratosphere, encircling the Earth, that has large amounts of ozone in it. The layer shields the entire Earth from much of the harmful ultraviolet radiation that comes from the sun. Interestingly, it is also this ultraviolet radiation that forms the ozone in the first place. Ozone is a special form of oxygen, made up of three oxygen atoms rather than the usual two oxygen atoms. It usually forms when some type of radiation or electrical discharge separates the two atoms in an oxygen molecule (O2), which can then individually recombine with other oxygen molecules to form ozone (O3). OZONE HOLE:- Excessive thinning of ozone layer when more than half of the ozone gas in a particular area is depleted, and harmful ultraviolet rays can pass through to reach the earth's surface.