Terracing is done in

Soil erosion is greater when

$UV-$rays are non-ionizing type and are lethal due to their inactivation ability of:

Jhum cultivation:
$I.$ Also called as slash and burn agriculture,is the farming practice in North Eastern states of India.
$II.$ Farmers cut down the trees of forest and burn the plant remains.
$III.$ The ash is used as a fertilizer and the land is then used for farming or cattle grazing.
$IV.$ After cultivation,the land is left for several years,so as to allow its recovery.
Which of the statements given above are correct about Jhum cultivation?

The $Chipko$ movement was started for the protection of .........

Which of the following statements is correct?