N. S. Margaris

EFFECTS OF VOLATILE OILS FROM AROMATIC SHRUBS ON SOIL MICROORGANISMS

Abstract Volatile oils from Thymus capitatus, Satureja thymbra and, to a lesser extent, Rosmarinus officinalis stimulate soil respiration. The S. thymbra oil is fungistatic to the germination of Penicillium citrinum spores in soil, and to mycelial growth of Mucor hiemalis in liquid culture. Addition of the S. thymbra oil and, to a lesser extent, R. officinalis oil to soil result in increased bacterial numbers. Bacteria appear to use the oils as carbon and energy sources. Thus the oils appear to have an ecological effect by shifting the soil population balance from fungi to bacteria.

Volatile Oils as Allelopathic Agents

The term allelopathy was introduced by Molisch (1937) to cover all kinds of biochemical interactions among plants (microorganisms included) both of detrimental and beneficial effect. Later on the meaning of this term was restricted so as to refer only to harmful interferences.

Latex producing plants in Greece

Abstract The occurrence of energy rich plants, due to their content of stored hydrocarbons, provides the possibility of their exploitation as alternative and renewable energy sources. The contribution of a great number of latex producing plants in the native Greek flora favours experimental work in this direction. Data on the occurrence of Euphorbiaceae in Greece and special growth characteristics of two species, namely E. acanthothamnos and E. dendroides , are provided.

Leaf Morphology of Thymus capitatus (Labiatae) by Scanning Electron Microscopy

Thymus capitatus (L.) Hoffmann & Link, a common mediterranean plant of Labiatae (12), rich in essential oil (5), represents in Greece an important element of the phryganic flora.

Microbial decomposition of smog organic pollutants

Athens, the capital of Greece, has been experiencing smog at least during the last five years. Situated at a site favoring temperature inversions with full sunlight most of the time, it concentrates in its major area most of the country industrial activity and almost half of the population of Greece. Since the natural systems in and around Athens are mediterranean-type ecosystems with many aromatic plants emitting volatile compounds, decomposable by the soil bacteria, the authors decided to study the effect of photochemical smog on soil microorganisms.

Desertification in northwestern Greece; the case of Kella

The mountainous area in the northwestern Greece near the Vegoritis lake is characterized by extremely low plant cover. According to the climatic conditions prevailing and taking into account the vegetation of adjacent areas it seems that the type of system favoured there is that of deciduous trees mixed with evergreen sclerophylls. Nevertheless, the vegetation is very sparse dominated exclusively by Juniperus oxycedrus; under such conditions,soil erosion is very strong. The soil bareness is attributed to overgrazing pressure acting for long in the area.

The Mining Factor in the Desertification Process

Land disturoance due to surface mining of the lignite deposits in the Ptolemais-Amideon area (N. Greece) has resulted to desert-like conditions. The surface disturbed at present is approximately 30 km2 and is estimated to cover 135 km2 by 2020 when depletion of deposits is predicted. Though the exploitation of lignite started in 1955 no serious efforts of rehabilitation have been undertaken up to now