Based on the temperature prevailing in an area, Raunkiaer classified the world's vegetation into the following four types.
(i) Megatherms
(ii) Mesotherms
(iii) Microtherms
(iv) Hekistotherms

It is a technique of encasing seeds in a mixture of clay & soil humus & scattering them on to suitable ground, not planting of trees manually.

1. Sometimes, ants take their shelter on some trees such as mango, litchi, jamun, acacia etc.
2. These ants act as body guards of the plants against any disturbing agent and the plants in turn provide food and shelter to these ants.
3. This phenomenon is known as Myrmecophily.
Example: Acacia and, Acacia ants.

1. The outer bark of trees which extends to the last formed periderm is called rhytidome.
2. It is composed of multiple layers of suberized periderm, cortical & phloem tissues.
3. It protects the stem against fire, water loss, invasion of insects & prevents infection by microorganisms.

Submerged plants are unable to obtain full illumination because a lot of sunlight is absorbed by overlying layers of water this is not the case for exposed floating plants that receive sunlight directly.

The plant, Ophrys orchid, the flower looks like a female insect to attract the make insect to get pollinated by the male insect.

1. Lichen is a mutual association of an alga & a fungus.
2. It is an interaction between two species of organisms in which both are benefitted from the obligate association.

Sandy soil loses water at high rate, These characters along with other parameters such as p^H, mineral composition is also important.

Soil formation is initiated by the weathering process. Biological weathering takes place when organisms like bacteria, fungi, lichens & plants help in the breakdown of rocks through the production of acids & certain chemical substances.

A desert has little or no plant life without plants, there is no organic horizon in the soil leading to a low level of water retention that is unsuitable for plant growth.

Certain plants can also be used to remove cadmium from contaminated soil, this is known as phytoremediation.
Example: Eichhornia

The blue green light have short wavelength & penetrates into the water. Green algae is unable to use that component of light. Blue light can penetrate up to 500 ft depth therefore algae are unlikely to survive below that depth.

1. Eurythermal: Organisms which can tolerate a wide range of temperature fluctuations.
2. Stenohaline: Organisms which can withstand only small range of salinity.
3. These variations the organisms also grow in different environment.

Taxonomically different species occupying similar habitats (Niches) in different geographical regions are called Ecological equivalents.
E.g: Certain species of epiphytic orchids of Western Ghats of India differ from the epiphytic orchids of South America. But they are epiphytes.

The interaction of organisms with their environment results in the establishment of grouping of organisms
Levels of ecological hierarchy

1. It deals with the study of environment in relation to organisms.
2. It can be studied by considering individual organisms, population, community, biome or biosphere and their environment.