Bio-monitoring is monitoring the quality of the environment by using all living organisms as indicators to see whether they live in a certain place and time under the same environmental conditions.

Plants and vegetation communities are natural indicators of environmental conditions and their changes, provided they have happened under natural and anthropogenic influences. They indicate and reflect specific intentional and unintentional activities of mankind (drying of vegetation along rivers where sand is exploited without control, burning the remaining part of the wheat after harvest, burning bushes for creating pastures, building motoways, construction of facilities, irrigational systems etc.). In such cases specific bio-genic factors are changed and the balance between the quality and quantity of the vegetaion is disturbed. Vegatation is an "instrument" that responds to pollutants quickly, even to most insignificant quantities. How badly the vegatation will be damaged will depend upon the emission of pollutants in specific environments. Physiological changes occur first, followed by morphological that result with slow development, changes on leaves and barks caused by structural reactions, drying of the bark, and eventually extinction of the plant and vegetation communities.

Lichen and moss in central residential environments or in industrial zones are not prominent, i.e. their absence is due to the presence of Sulphur Dioxide and Carbon dust discharged from energy plants (carbon, crude oil, oil etc.), thus they are the indicators that Sulphur Dioxide is present in the envionment. Sulphur Dioxide damages the leaves of the beeches, blackberries, pines, lindens etc.while fluorhydrogene damages the leaves of willows, pears and black and red currents, and lead damages cabbage.

The quaility of the water can be determined from the ground waters (rivers, streams, springs etc.), especially if the river flows in different environments (residential areas, industrial zones, meadows) on the basis of vegetation diversity. Thus, upstream, the relatively clean part, microphytic and macrophytic vegetation can be noticed, while in the middle part, that is usually polluted from the small agricultural settlements, another type of vegetation can be found, and finally, downstream, where the water is polluted from industrial waste waters, a specific type of vegetation can be found.

The vegetation component illustrates the quality of the water.