Why has the National Forest Commission of India recommended a relatively larger forest cover for hills than for plains?

Explanation

It is our moral duty to protect, restore and conserve/preserve forest as they are highly beneficial for mankind in India, around `30%` of land was covered by forest in early 20th century, which has been reduced to `18-19%` by the year 2000. National Forest Commission of India (1988) recommended a relatively large forest cover `(67%)` for the hills and `33%` for the plains.
Recommendation a large forest area for hills is due to due to its properties like checking soil erosion, percolation and recharging ground water , checking landslide and other natural calamities and to maintain the original flora and fauna of hills.