ECOLOGIA MEDITERRANEA -T. VIII -1982. Fase. 1/2. Marseille Définition et localisation des Ecosystèmes méditerranéens terrestres. Saint-Maximin 16-20/11/1981.

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Phryganic (east mediterranean) ecosystems and fire

M. ARIANOUTSOU-FARAG-GITAKI*

N.S.MARGARIS*

Introduction

Fire is a very common event in the areas covered by mediterranean type ecosystems, that means countries around the Mediterranean basin, California, Chile, SW. and W Australia and S. Africa. It is considered a natural event incorporated in the information pool of Mediterranean-type Ecosystems (M.T.E.), at least from Californian and Australian scientists. For the old world, fire is accepted as a catastrophic factor which is always attributed to criminal anthropogenic actions. But, the general consideration is changing towards the first aspect, in the Mediterranean countries, because small groups in Israel (NAVEH, 1973), Greece (LIAKOS, 1973 ; ARIA-NOUTSOU and MARGARIS, 1981 a and b) have started accepting fire as a necessary factor included in system’s function.

If the above mentioned hypothesis is true, these ecosystems might have developed response mecha¬ nisms that help them to overcome the action of fire, both in survival and in quick recovery. This is exactly the working hypothesis on which the discussion on behaviour of phrygana after fire is held. For the definition of the term phrygana look to paper by MARGARIS and VOKOU, in this volume.

The phryganic ecosystem under study is located on the Mt Hymettus at a height of 400 m above sea level. It was burned accidentaly in late July 1976. For reasons of comparison an adjacent unbumed area with the same structure is chosen. Data for this unbumed site have already been given by MARGARIS (1976).

I. Ways of survival

Two main types of survival can be discerned and considered as adaptive strategies : resprouting and regeneration by seeds :

A

Resprouting is carried out from dormant buds located at the crown and which are not influenced by fire. It begins during autumn when soil moisture is in satisfactory levels, something that is suggested to be valid for California too (PLUMB, 1963). Some others have attributed it to the carbohydrates available, which are found in the plants at the moment that fire occurs (JONES and LAUDE, 1960).

From the woody species dominating in the area before fire with an above ground biomass of about 1.000 gjn-2 (Phlomis fruticosa 33%, Euphorbia acanthothamnos 24%, Sarcopoterium spinosum 13%, Cistus spp 8% and Thymus capitatus 3%; MARGARIS, 1976), P. fruticosa regenerates by resprouting from such buds staying undisturbed by fire. Most individuals of this species successfully recover by this way. S. spinosum res¬ prouts too, but not in the same degree. Most of its individuals do not survive, especially those which are old ones. The third resprouting species is E. acanthothamnos, which recovers quite enough through this process.