AZUL, ANABELA MARISA & FREITAS, HELENA.
Department of Botany, Coimbra University, 3049 Coimbra Codex, PORTUGAL.
Quercus suber L. is an ecologically important specie representing 21% of the portuguese cover in Portugal, specially in areas where summer drought is more intense. This specie is now in decline. The study of mycorrhizas in Mediterranean ecosystems under disturbance is essential to understand the degree of colonization of the soil symbiotic microorganisms and to implment restoration programmes. In this work two populations of Q. suber L. were examined in regard to their association with ectomycorrhizal fungi in Southern Portugal (Grândola and Santiago do Cacém). Biodiversity was evaluated together with relation between the relative abundance of a certain morphotype (form) and its carpophore, and with physical factors such as climate and soil characteristics (pH, P, organic matter). Root, rhizospheric soil and carpophore samples were collected bimonthly during one year. Determination of mycorrhizas was based on mantle morphology, biochemical tests and carpophore presence. Results show that 1) the number of colonizing species is correlated to the type of vegetation, 2) relative abundance of some species is dependent on the physical factors, specially climate, 3) carpophores are not always indicators of high mycorrhizal colonization.