Nuevos datos acerca de la singularidad fitogeográfica de las Sierras de Algeciras (Cádiz): Sphagnum platyphyllum en la Sierra de la Palma

The study of a bryophytes samples from the neighbourhood of Los Barrios (Cádiz) reveals the existence of two species of Sphagnum of the Subsecunda section: S. denticulatum Brid. (= S.lescurii Sull., S.auriculatum Schimp.) and S.platyphyllum (Braith.) Warnst. The first species had been already mentioned in the province of Cádiz, but the second one was unknown in Andalusia. The presence of this latter species with circumpolar distribution (Karlin, 1991) is a peculiar addition to the group of elements which a geobotanical meaning to the southern mountanious area of the province of Cádiz.Al examinar unas muestras de briófitos recolectadas en las proximidades de Los Barrios (Cádiz), identificamos dos especies de Sphagnum de la sección Subsecunda: S.denticulatum Brid. Sull. (= S.lescurii Sull., S.auriculatum Schimp.) y S.platyphyllum (Braithw.) Warnst. El primero ya había sido mencionado en la provincia de Cádiz, no sucediendo lo mismo con el segundo que no se conocía de Andalucía. La presencia de esta especie, de distribución fundamentalmente circumpolar (Karlin, 1991), proporciona un dato florístico más a añadir al conjunto de elementos que hacen de estas serranías meridionales gaditanas una zona de particular significación geobotánica

Abedulares de la Sierra de San Mamede (Orense, España).

En el presente trabajo se aborda el estudio de las formaciones de abedul en el límite meridional de la región galaica. Se describe su estructura, composición florística y se establece su dinamismo tanto progresivo como regresivo. Asi mismo se propone su inclusión en la asociación Luzulo henriquesii-Betuletum (TM/mi-tecle Rivas Martínez 1964.Complementariamente se aportan datos sobre su situación actual y se plantean diversas alternativas para su conservación.In this paper a study of the birch-tree forest along the south limit of the "Galaica" region is done. Their structure and floristic composition is described. It is appointed both their progresive and degradating dynamism. It is also suggested the inclusion of these forest in the phytological association Luzulo henriquesii-Betuletum celtihericae Rivas Martínez 1964. Their actual situation is commented too and several proceeding for their conservation are suggested

Taxonomic differences between Pinus sylvestris and P. uncinata revealed in the stomata and cuticle characters for use in the study of fossil material

Taxonomic differences in the needle epidermis characteristics of Pinus sylvestris L. and Pinus uncinata Ramond ex DC. from two Iberian populations were sought; such information could help identify these species when pollen analysis and the inspection of wood anatomy fails. The features of the cuticle are commonly well preserved in the fossil record. Although the epidermal patterns of the examined taxa were similar, qualitative differences were seen in the subsidiary and guard cells. P. sylvestris showed small subsidiary cells homogenously arranged around the opening of the epistomatal chamber, while P. uncinata showed small, lateral subsidiary cells and non-differentiated subsidiary cells in the polar position. The aperture of the epistomatic chamber of P. uncinata was also larger in diameter (15.1 ± 1.8 µm P. sylvestris; 21.1 ± 2.8 µm P. uncinata). Principal components analysis and discriminant analysis was performed on the features of the guard cells characterising the size and shape of the cuticular thickenings — all the variables analysed can be measured in disperse stomata in microscope preparations for pollen analysis. Significant differences were found in the upper woody lamellae width and the coefficient associated with the shape of the medial lamellae borders (discriminant analysis weighting 0.739 and 0.826 respectively). Other significant parameters included the coefficient associated with the relative size of the medial lamellae border width of the guard cells with respect to the distance between the external limits of the medial lamellae borders, and the length of the upper woody lamella. Different light regimens appeared not to significantly affect the variability of the studied features

A taxonomic tool for identifying needle remains of south-western European Pinus species of the Late Quaternary

This work provides a tool whereby the needle remains of native, south-western European Pinus spp. can be easily identified from species-specific epidermal features. To construct this tool, the needles of P. uncinata, P. sylvestris, P. nigra, P. pinaster, P. pinea and P. halepensis were gathered across the Northern Hemisphere range of each taxon and compared with non-indigenous trees growing in two South Australian Botanic Gardens. Three needles from each of these species were taken from three adult trees growing at three different localities. Light microscopy was used to observe the key epidermal and stomatal features of the needles. To improve interpretation, additional scanning electron microscopy samples were prepared. Epidermal features, including variation in the diameter of the epistomatal chamber aperture (pore), are described. A taxonomic key based on the size, shape and arrangement of the subsidiary cells of the stomatal complexes was constructed. This key enables the identification of pine needle fragments at the species level (except those belonging to the group P. gr. nigra-uncinata). Despite their overlapping range, pore size was helpful in distinguishing between P. nigra and P. uncinata and between three groups of species. Isolated stomata were also observed. Cluster and discriminant analyses of stomatal variables described in earlier studies were performed. Overlap in guard cell variables hampers species-level identification of isolated stomata. Species discrimination is improved if groups of ecological affinity are considered

A taxonomic tool for identifying needle remains of south-western European Pinus species of the Late Quaternary

Primer trabajo a nivel mundial sobre la diferenciación de especies de Pinus con clave dicotómica a través de la estructura cuticula

Floristic changes in the Iberian Peninsula and Balearic Islands (south-west Europe) during the Cenozoic

AIM  The aim of this work was to identify the main changes in the flora and vegetation of the Iberian Peninsula over the Cenozoic Era, to record the disappearance of taxa associated with these changes and to determine the influence of climate and human activity on these events. Location  The Iberian Peninsula and Balearic Islands. METHODS  A critical review was made of the palaeobotanical literature with the aims of detecting patterns of floristic change and extracting information on the disappearance of different taxa over the Cenozoic. These data are viewed alongside the most recent data for the climate of this period. A critical analysis is made of the role of Palaeotropical and Arctotertiary taxa in the forest communities of the Iberian Peninsula throughout the Cenozoic. RESULTS  Although the Eocene–Oligocene transition was a time when many taxa disappeared, the most outstanding events occurred between the end of the Oligocene and throughout the Miocene. Substantial floristic changes took place over this period, including the disappearance of 177 Palaeotropical taxa. This was probably related to acute cooling and aridification; no evidence exists that the Messinian Salinity Crisis had any important effect in the Iberian Peninsula. The last great disappearance of Palaeotropical taxa (36 in total) ended in the Middle–Late Piacenzian; Arctotertiary taxa were most affected during the Pleistocene. The Lower–Middle Pleistocene transition, best represented by marine isotopic stages (MIS) 36–34 and 20–18 and characterized by a change in glacial cyclicity, was the time of the last notable disappearance of taxa. MAIN CONCLUSIONS  This work provides the first chronogram of extinctions for the Iberian flora, and records the disappearance of 277 taxa during the Cenozoic. A clear relationship was detected between the main climatic events and the latest appearances of the different taxa

Late Holocene vegetation dynamics in response to human activities in the Teleno Mountain Range (NW Iberia)

Teleno Mountains are a good area to address these questions. Today are almost completely deforested, and it is commonly assumed that Romans were the culture responsible of this situation, as they developed important mining activities all over this mountains. Our main aim has been to track human impact on the landscape of this Iberian mountainous area along the second half of the Holocene and confirm the role of Roman culture in this process. For this purpose, we have obtained a new palaeoecological record from the Teleno Mountain

Los bosques en la provincia de Toledo a finales del siglo XVII según las relaciones topográficas de Felipe II

A finales del siglo XVI bajo el auspicio del rey Felipe II, se inicia una amplia encuesta en el reino de Castilla con la intención de reunir datos históricos y económicos para un mejor conocimiento de su territorio. Los resultados quedan recogidos en las llamadas Relaciones Topográficas de Felipe II. Algunas de las preguntas recogen información sobre la fuente energética, la leña, y la madera que se utilizaba en la construcción. Estos datos nos permiten tener una idea de la ocupación del territorio y la composición de los ecosistemas en el entorno de los pueblos que responden a las preguntas. En este trabajo nos hemos circunscrito a los datos aportados por los pueblos de la provincia de Toledo recogidos y transcritos a mediados del siglo XX por Viñas Rey. La imagen que nos devuelven estas respuestas no diferiría mucho de la que vemos en la actualidad, la misma composición florística de bosques, terrenos baldíos ocupados por matorral y extensiones cultivadas por cereal, olivos o viñas. El paisaje parecen extenderse sin variación a lo largo del tiempo hasta nuestros días, únicamente cambiaría la superficie ocupada por el bosque

Long-term persistence of Mediterranean pine forests in the Duero Basin (central Spain) during the Holocene: The case of Pinus pinaster Aiton

In the southern Duero Basin of central Spain, there are vast areas of aeolian sand sheets and dune fields. A comprehensive survey of the sand quarries in this area identified a number of palaeosols in sedimentary sequences. The identification and AMS radiocarbon dating of soil charcoal fragments collected in these palaeosols indicate the persistence of Pinus pinaster in this area throughout most of the Holocene. Although potential natural vegetation models have usually considered the Pinus pinaster forests in this inland area of artificial origin, soil charcoal analysis provides firm evidence of a natural origin. Our data fit perfectly with the pattern of Holocene vegetation development for inland areas of Iberia, which are characterised by stability of pine forests throughout the Holocene. Finally, the growing body of palaeobotanical evidence from Iberia (macrofossils and pollen) is contributing to improve our knowledge of P. pinaster ecology, showing that this species has been present in most Iberian regions during the Holocene, where it has inhabited areas characterised by a very diverse set of climatic and soil conditions

Taxonomic composition of the Holocene forests of the northern of Spain, as determined from their macroremains

Eight sites distributed over a distance of some 400 km of the Cantabrian coast (northern Spain) provided 153 wood, 50 fruit and over 350 leaf remains belonging to the area’s Holocene forests. The high taxonomic precision with which these macroremains were identified (in many cases at the species level), plus the accurate information available regarding the original growth locations of these plants, provide new geobotanical insights into the history of northern Spain’s Atlantic forests. Radiocarbon dating of the wood samples showed the collected material to have lived between 8550 and 800 cal. BP. Analysis of the macroremains showed the deciduous mixed forests of the Holocene to contain a majority of Quercus robur and Corylus avellana, accompanied by Acer pseudoplatanus, Ulmus minor, Castanea sp., and hygro-thermophilous taxa (Arbutus, Laurus and Vitis vinifera). The remains of hygrophilous communities, dominated by Salix atrocinerea, Alnus glutinosa and Fraxinus sp., show these to have expanded during the Holocene. The absence of conifer macroremains is interpreted as reflecting the disappearance of Würmian conifer populations at the beginning of the Holocene. The different taxa (eg, Ilex spp. and V. vinifera) that survived the last glaciation in the refugia offered by Spain’s northern coast persisted in the same areas during the Holocene. A leaf sample of Ulmus minor dating to 3950 ± 120 cal. BP reveals for the first time the natural occurrence of this species on the northern coast of Spai