In studies of individual organisation levels of organisms, the requirement of hollistic expression of structure and function is traditional despite the fact that structural direction prevails in studies. Less attention is paid to the place where function activity occurs in connection with the structure. This place is the surface - the medium where physical, chemical, biological and synergic processes interact. These surfaces are called ecologically active surfaces (EAS). From this standpoint, the surface is a place for energy exchange, which appears as mean studies of function and structural properties of the biological object.
The quantification of these areas taking into account the functional activities - (developed surface, the functional characteristics) to the desktop, or to the volume is the methodological starting point in the assessment of the country, or of its componens after the assessment of the energy potential of the environment. This ratio can be considered as the degree of heterogeneity of the conditions after taking into account the gradient of the environment.
We have achieved partial results related to EAS during the solution of tasks connected with the environmental evaluation of biotic components of a landscape, mainly during the investigation of aquatic biotopes, which are demonstrated on some examples.