(a) Gliricidia sepium
(b) Sesbania grandiflora
(c) Erythrina species
(d) Acacia species

The production of woody plants combined with pasture is referred to silvopasture systems
The trees and shrubs may be used primarily to produce fodder for livestock or they may be grown for timber, fuelwood, and fruit or to improve the soil.

Agroforestry is an integration of trees, crops, and livestock on the named plot of land. The commercial Agroforestry trees are casuarina and Eucalyptus.

(i) Petunia species act as indicators for Nitrate pollution.
(ii) Gladiolus species acts as indicators for Fluoride pollution.

The plant species or plant community acts as a measure of environmental conditions, it is referred to as biological indicators or photo indicators or plant indicators. E.g: Lichens as SO₂ pollution indicator.

The International treaty called the Montreal Protocol (1987) was held in Canada on substances that deplete ozone layer and the main goal of it is gradually eliminating the production and consumption of ozone depleting substances and to limit their damage on the Earth's ozone layer.

The decline in the thickness of the ozone layer over restricted area is called Ozone hole. Chlorofluorocarbons (CFC) damages the ozone layer to a great extent.

Ozone layer is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. The ozone layer is also called as the ozone shield and it acts as a protective shield, cutting the ultra-violet radiation emitted by the sun.

(i) The ozone layer of troposphere is called bad ozone.
(ii) The ozone layer of stratosphere is called good ozone.

Dobson Unit is the unit of measurement for total ozone. One DU is the number of molecules of ozone that would be required to create a layer of pure ozone 0.01 millimeter thick at a temperature of 0° C and a pressure of 1 atmosphere.

Man-made sources include nylon and nitric acid production, use of fertilizers in agriculture, manures cars with catalytic converter and burning of organic matter.

Paddy field, fossil fuel production, bacteria in water bodies, cattle rearing, non-wetland soils, and forest & wildfires.

The increase in mean global temperature due to increased concentration of greenhouse gases 

CO₂, CH₄, N₂O and CFC

The gases that capture heat are called Green House Gases.
Eg : CO₂, methane (CH₄ ), Nitrous oxide N₂O and CFC