The value of leaf cuticle characteristics in the identification and classification of Iberian Mediterranean members of the genus Pinus

This study reports the value of leaf cuticle characteristics in the identification and classification of Iberian Mediterranean species of the genus Pinus (P. nigra subsp. salzmannii, P. pinaster, P. pinea and P. halepensis), with the aim of using these characters to identify isolated cuticles and stomata in palynology slides. Preparations were made of the cuticles of pine needles belonging to one natural Iberian population of each of the above species. A number of epidermal morphological characteristics were then recorded with the aim of distinguishing these species from one another. The structure of the stomatal complex (the shape and arrangement of the subsidiary cells) was different in each species. The aperture of the epistomatal chamber was significantly smaller in P. pinea than in the other species examined, and the variables recorded for the thickening of the guard cells provided relationships that clearly distinguished all four taxa. The width and length of the stomata and the upper woody lamellae, the central distance between the external limits of the medial lamellae borders and the length of the stem were the most useful variables in this respect. The present results contribute to the ongoing discussion regarding the taxonomic classification of the members of Pinus, and provide valuable clues for the identification of Iberian Mediterranean pine species from small pine needle fragments or isolated stomata. After validation of the present results for multiple populations, these results could also be used to help identify fossil leaf macroremains and the scattered/ isolated stomata commonly observed in palaeopalynological samples

Interactive comment on CO2 radiative forcing during the Holocene Thermal Maximum revealed by stomatal frequency of Iberian oak leaves (2)

Here we analyse radiocarbon-dated Quercus leaf assemblages from northern Spain to obtain past atmospheric CO2 mixing ratios for the time period 9000–1100 cal BP by means of stomatal frequency analysis. Normalized, stomata based CO2 records show fluctuations of 20 ppmv during the Holocene that parallel Northern 5 Hemisphere palaeotemperature reconstructions. The calculated radiative forcing of CO2 indicates a CO2 contribution of +0.1_C to the Holocene Thermal Maximum from 7 to 5 kyr BP, and −0.05_C to the Neoglacial cooling around 4 kyr BP. Derived northern hemispheric air-temperature anomalies forced by atmospheric CO2 variation suggest an active role 10 of this trace gas as an amplifier of initial orbital forcing of Holocene climate

Palaeobiogeographical perspectives on pinus pinea, a controversial and enigmatic mediterranean pine

The origins of some species of economic importance occurring over the Mediterranean Basin have been a traditional matter of debate that has important implications for land management. The case of Pinus pinea L. (Stone pine) is probably one of the most controversial, due to its documented long-term interaction with humans and its presence as a symbolic tree in certain areas of the Mediterranean (e.g., southwestern Iberia and Tuscany). Among the rest of the Mediterranean pines, several features make this pine unique (it has a characteristic crown shape, an edible kernel, cones that require three years to mature, and a very depauperate genetic diversity across its range). In addition, its palaeoecological information is rather limited, as the taxonomic precision attained by pollen analysts is insufficient for this tree and macroremains (such as kernels or anatomically well preserved wood) are needed to unequivocally detect the species in the fossil record. Recent findings of macrofossils of Pinus pinea in inland Iberia (Duero Basin) extend the late- Holocene range of the species, but the palaeobiogeographical information and the exhaustive genetic data available still suggest a very limited natural area (but still not sufficiently well defined) and a long and intense history of linkage to humans

Paleofitogeografía de los pinares en las montañas periféricas de la cuenca del Duero

En las dos últimas décadas se han obtenido numerosos resultados procedentes de diferentes trabajos paleobotánicos (Cuaternario final) realizados en los territorios montanos periféricos de la depresión del Duero. Las metodologías empleadas han sido diversas y tienen que ver con los diferentes tipos de yacimientos y de muestras biológicas seleccionadas para su estudio; entre ellas destacan las técnicas de microscopía óptica para la identificación de maderas subfósiles, la morfología comparada de macrorrestos y los estudios dendrocronológicos en árboles longevos y maderas subfósiles. En esta comunicación se reúnen y resumen los trabajos más importantes, haciéndose una síntesis de las conclusiones obtenidas en los trabajos paleofitogeográficos realizados hasta el momento; se hace hincapié en la información proporcionada por los macrorrestos (maderas, estróbilos) así como por la recogida en los registros dendrocronológicos (con extensión a la dendroecología). Otro de los objetivos de la comunicación es la síntesis de las conclusiones obtenidas en los trabajos paleofitogeográficos realizados hasta el momento. Uno de esos resultados es que el comportamiento de los pinares a lo largo del Holoceno presenta diferentes modalidades en cada una de las cordilleras que bordean la cuenca del Duero; desde casos con marcada estabilidad a otros en que se muestran variaciones temporales apreciables (con patrones de heterogeneidad en función de un eje N-S y/o O-E

Assessing the effects of complexity in cross-temporal transferability of species distribution modelling predictions using palaeobotanical data

Valoración de la transferencia temporal de los modelos de distribución de especies para su aplicación en nuestros días utilizando datos paleobotánicos Corilus avellana y Alnus glutinosa

Combining Remote Sensing and Species Distribution Modelling to Assess Pinus hartwegii Response to Climate Change and Land Use from Izta-Popo National Park, Mexico

A detailed analysis of distribution shifts in Pinus hartwegii Lindl. is provided across time for Izta-Popo National Park (México). Combining satellite images, species distribution models, and connectivity analysis we disentangled the effect of climate change and anthropogenic land use on the habitat availability. Twenty-four Maxent habitat suitability models with varying complexity were combined with insights on vegetation and land cover change derived from two Landsat satellite images at 30-m resolution from 1993 and 2013. To evaluate effects of climate change on Izta-Popo’s P. hartwegii forest, projections for future climatic conditions (averaged for 2050 and 2070) were derived using two General Circulation Models under three Representative CO2 concentration pathways (RCPs). Calculated fragmentation and connectivity indexes (Equivalent Connected Area and Probability of Connectivity metrics) showed significant habitat loss and habitat fragmentation that weakens P. hartwegii dispersion flux and the strength of connections. Projections of future climate conditions showed a reduction of P. hartwegii habitat suitability as populations would have to migrate to higher altitudes. However, the impact of anthropogenic land use change documented over the 20 years masks the predicted impact of climate change in Izta-Popo National Par

Anthracological evidence suggests naturalness of Pinus pinaster in inland southwestern Iberia

The study of well-preserved archaeological charcoals in the pre-Roman Iron Age settlement of Castillejos II (Badajoz, Spain) is used to reconstruct environmental conditions and land-use practices in vegetation landscapes in the southwest of the Iberian Peninsula before the arrival of Roman civilization. The results support that, while evergreen Quercus forests dominated during the Holocene, Pinus pinaster existed as a natural element of southwestern Iberian Peninsula vegetation. Although its presence could be linked to anthropogenic disturbance or fire history, it is suggested that P. pinaster populations survived during the Holocene in the region, mixed with oaks or in monospecific stands in mountain enclaves. This hypothesis contrasts with previous assumptions that P. pinaster was not autochthonous in the area