Name any one green house gas and its possible source of production on a large scale. What are the harmful effects of it?
The common green house gases are $\mathrm{CO}_2, \mathrm{CH}_4, \mathrm{CFC}$, oxide of nitrogen ( $\mathrm{N}_2 \mathrm{O}$ ), water vapour and $\mathrm{O}_3$. The level of $\mathrm{CO}_2$ (green house gas) is increasing due to large scale deforestation, change in land use and unlimited buring of fossils fuel and is leading to global warming.
The source of methane and other main green house gases are garbage dump, incomplete decomposition by anaerobic methanogens, flooded paddy field and marshy land. About 90-95\% of $\mathrm{CH}_4$ is produced/generated by rice fields of Asia.
It is a common practice to plant trees and shrubs near the boundary walls of buildings. What purpose do they serve?
A common practice to grow and maintain trees and shrub near the boundary wall of residential, official building acts as a barrier for sound and check noise pollution. This green belt of tree and shrub also acts as an effective measure to check primary air pollutants like dust, flyash, etc.
Why has the National Forest Commission of India recommended a relatively larger forest cover for hills than for plains?
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 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.
How can slash and burn agriculture become environment friendly?
Slash and burn agriculture can be environment friendly if
(i) small widely scattered plots are used for cultivation as the forest ecosystem will not suffer damage.
(ii) crop rotation is used so that soil does not loose fertility entirely.
(iii) keeping cropping period small and fallow (unplanted) period longer.
What is the main idea behind "Joint Forest Management Concept" introduced by the Government of India?
The main idea behind joint forest management concept introduced by the Government of India was involving the local communities in the forest conservation.
This concept was adopted considering the extraordinary courage and dedication the local people showed in protecting the wildlife through the movements like Bishnoi's is movement in Jodhpur and Chipko Movement in Garhwal Himalayas.