Photo: Kishor Kumar Dash
The author walking down, in the backdrop of the Balimela Reservoir.

The author is working as a freelance correspondent with G & Y from Orissa.

Term Power

What is ...

It is the study of the harmful effects of chemicals in ecosystems. This includes the way in which the chemicals enter the ecosystem, how they are distributed through the food webs and then metabolised. Population changes are monitored with any development of resistance - for example, pests becoming resistant to pesticides.

One of the alternative forms of a gene. In diploid cells, each gene is present as two alleles, one of which is dominant (expressed) and the other recessive (not expressed).

Describing two populations or species that cannot interbreed because the regions they occupy are too far apart.

The study of the relationship between a single species and its environment.

An area of marsh with sluggish or stagnant water that occurs in the southeastern USA at the outflow of a lake or in a river estuary.

A plant community that develops in wet, acid areas. Decomposition is slow, favouring the development of peat. In temperate climates, typical bog plants include bogmosses, heathers and sundews. Different plants occur in tropical bogs.

The idea that the earth’s living and non-living systems form a single system regulated principally by the activities of living organisms themselves. These maintain conditions of temperature and chemical composition that are favourable to life. The Gaia hypothesis was first outlined in the 1970s by the British scientist James Lovelock, who has proposed that the study of the Earth from a Gaian perspective be called “geophysiology”.

A method of cultivating plants without soil. It allows increased planting density and a year round growing season. The plants are grown in peat or gravel, through which a solution of artificial nutrients is circulated. Hydroponics is best suited to small scale greenhouse cultivation and is often used in arid climates or in crowded countries with little land to spare for agriculture.

A plant or animal whose presence or absence in an area indicates certain environmental conditions, such as soil type, or low levels of dissolved oxygen in rivers. Many plants prefer either alkaline or acid soil, and certain trees are found only in soils with high concentrations of aluminum. Some lichens are sensitive to sulphur dioxide in the air and their absence indicates atmospheric pollution.

Describing plants that inhabit rubbish heaps, wasteland, old fields or waysides.

Describing any organism that feeds on dead or decaying animal or plant matter; for example, house fly larvae (maggots) and fungi. Saprotrophs cannot make food for themselves, so they are considered to be a type of heterotroph.

A series of plant communities (succession) that develop in a particular habitat. A litho-sere is a succession starting on the surface of bare rock. A hydrosere is a succession in shallow fresh water, beginning with planktonic vegetation and ending with the development of swamp. A halosere is a succession beginning in saline conditions. A plagiosere is the sequence of communities that follows clearing of existing vegetation.

It is the study of the physical phenomena associated with lakes and other bodies of fresh water. Limnographic data can be useful in dating recent geological events in understanding climatic changes and in paleontology.

An isotope of an element produced by the radioactive decay of another isotope.

A type of volcanic outbreak produced by vapourisations of liquid nitrogen or methane at very low temperatures. It is the type of volcanism developed on outer planet moons, such as Neptune’s moon Triton, on which geyser like activity appears to have occurred.

Bulbous vertical body of igneous rock that rises into the earth’s crust because of its lower density compared to the surrounding rocks. Salt domes are also diapiric in nature – that is, they rise because they are lighter than the surrounding rocks.

A coarse grained igneous rock which is chemically equivalent to basalt. Essential minerals found in Gabbro are calcium rich plagioclase feldspar and pyroxene, usually the variety augite.

A highly deformed and brecciated mass of rock usually associated with the convergence of two lithospheric plates. Sedimentary and volcanic rocks that have accumulated at the toe of an advancing plate margin, particularly one containing an island arc, become ‘scraped’ up into an imbricate wedge of mélange as collision progresses. Ancient mélange deposits have been identified within the geological succession and enable geologists to estab-lish positions of ancient plate margins.

The vast super continent that came together on earth during the latter part of Paleozoic time. It comprised all of the present day continents. It finally fragmented in Mesozoic times.

The lower, denser, regions of the earth’s continental crust and the crust that forms the floors of the oceans. It is relatively rich in the elements silicon and magnesium.