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We have studied Juniperus oxycedrus L. subsp. badia (H.Gay) Debeaux in the central and southern Iberian Peninsula, where the macrobioclimate ranges from Mediterranean-pluviseasonal-oceanic to Mediterranean-pluviseasonal-continental, and the thermotype from the thermo- to the supramediterranean. The relevés were taken following the Braun-Blanquet phytosociological methodology. A statistical treatment was applied to establish a separation among Juniperus communities. To understand the presence of Juniperus communities in territories dominated by species in the Quercus genus, we applied Thornthwaite's formula to calculate potential evapotranspiration. The general cluster analysis clearly distinguishes two groups of plant communities and separates the different associations in each group. All the plant communities growing on rocky crests and in extremely steep sloping areas are significantly influenced by the soil. The ombroclimatic index does not explain the presence of plant communities influenced by substrate, so we proposed a new ombroedaphoxeric index which explains the presence of Juniperus communities in territories with a thermotype between the thermo- and supramediterranean. The areas of distribution of Juniperus species are expanding due to the spread of rocky areas; this phenomenon causes an increase in edaphoxerophilous areas and a decrease in climatophilous ones. We propose four new plant associations, with updated structures and floristic compositions. Efficient conservation is possible in both the territories studied (Spain and Portugal) through the implementation of specific cross-border cooperation projects.

[EN] This field guide was developed as part of the XIII International Seminar Management and Biodiversity Conservation – Vale do Lobo, Loulé (Algarve – Portugal), that aims to contribute for the scientific knowledge of the flora and vegetation of the Algarvian territories. The itinerary of the geobotanical excursion have been chosen to present the remarkable floristic richness and plant communities of three different landscape subunits: i) Faixa Litoral (dunes and saltmarshes of the Ancão Peninsula); ii) Barrocal (Nave do Barão); and, iii) Serra Algarvia (Caldeirão and Monchique mountains). For each sites the plant communities are briefly stated, as well as the vascular flora observed, including species with special conservation interest. Finally, we present the syntaxonomic scheme, and the floristic catalog of the field trip., [PO] No âmbito das atividades do XIII Seminário Internacional de Gestão e Conservação da Biodiversidade – Vale do Lobo, Loulé (Algarve – Portugal), desenvolveu-se o presente trabalho, com o objetivo de aprofundar o conhecimento da flora e vegetação dos locais a visitar no contexto do itinerário da excursão geobotânica aos territórios algarvios. Assim, a seleção dos locais de paragem procurou evidenciar a originalidade florística e fitocenótica de três sub-unidades paisagísticas de carácter e identidade distintas: i) Faixa Litoral (dunas e sapais da Península do Ancão); ii) Barrocal (Nave do Barão); e, iii) Serra Algarvia (Serra do Caldeirão e Serra de Monchique). Após uma breve descrição dos aspetos litológicos, das condições bioclimáticas e do enquadramento biogeográfico, evidenciam-se as associações vegetais e espécies presentes nas paragens realizadas, com identificação dos elementos florísticos com interesse para a conservação. Por último, tendo por base a descrição da vegetação, apresenta-se o esquema sintaxonómico, e um elenco florístico dos locais percorridos.

The plant variability in the southern Iberian Peninsula consists of around 3500 different taxa due to its high bioclimatic, geographic, and geological diversity. The deciduous forests in the southern Iberian Peninsula are located in regions with topographies and specific bioclimatic conditions that allow for the survival of taxa that are typical of cooler and wetter bioclimatic regions and therefore represent the relict evidence of colder and more humid paleoclimatic conditions. The floristic composition of 421 samples of deciduous forests in the south-central part of the Iberian Peninsula were analyzed. The ecological importance index (IVI) was calculated, where the most important tree species were Quercus pyrenaica, Acer opalus subsp. Granatensis, and Corylus avellana. These species are uncommon in the south-central part of the Iberian Peninsula, forming forests of little extension. An analysis of the vertical distribution of the species (stratum) shows that the majority of the species of stratum 3 (hemicriptophics, camephytes, geophites, and nanophanerophytes) are characteristic of deciduous forests, and their presence is positively correlated with high values of bioclimatic variables related to humidity and presence of water in the soil (nemoral environments), while they are negatively correlated with high values of bioclimatic variables related to high temperatures, evapotranspiration, and aridity. This work demonstrates that several characteristic deciduous forest taxa are more vulnerable to disappearance due to the loss of their nemoral conditions caused by gaps in the tree or shrub canopy. These gaps lead to an increase in evapotranspiration, excess insolation, and a consequent loss of water and humidity in the microclimatic conditions.