Suchergebnisse

[Questions] North African dry woodlands constitute mediterranean climatic ecotone ecosystems of vital importance for human livelihoods and local biodiversity. To improve the basis for managing these key ecosystems, we selected a Tertiary relict woodland (Argania spinosa) in order to clarify the sensitivity to long‐term climate change (the present, the past glacial‐interglacial cycle and under future scenarios). We also discuss the impact of long‐term human land use for the distribution of dry woodlands in North Africa. ; [Methods] To assess whether the argan woodland is in equilibrium with current climate, we used species distribution modelling (SDM) to estimate its potential range. Then, SDM was used to estimate its potential distribution during the Last Glacial Maximum (LGM; 21,000 BP) and the Middle Holocene (Mid‐Holocene; 6,000 BP). Model predictions for past scenarios were compared with Quaternary palaeorecords to evaluate their accuracy. Finally, we forecasted changes in the potential range to year 2080 to assess its likely future range dynamics. ; [Results] At the LGM, suitable areas occurred at more southern latitudes, where the Sahara Desert currently lies, while suitable areas in the Mid‐Holocene shifted northwards, occupying areas similar to those of today. The estimated past distributions are consistent with palaeorecords, providing evidence for the important role of Quaternary climate changes in driving dry woodland range dynamics. The current range‐filling constitutes 44% of the potential distribution, probably primarily reflecting anthropic land‐use effects. Future climate change is forecast not to cause latitudinal/altitudinal range shifts, but rather an overall range contraction. ; [Conclusions] The models reflect the high sensitivity of the dry woodland ecosystem to past climate changes, in agreement with palaeorecords. The estimated climatic sensitivity also predicts severe range contraction during future climate change. Consequently, management strategies for dry woodlands should be developed to facilitate their in situ survival, particularly by reducing the currently intensive human pressure. ; We are indebted to the Spanish Consolider Program (CSD2007-00058), Excellence Research Projects' Program from Andalusian government (RNM-7033), Research Projects Plan from UGR (PP2012-PI02) as well as HAR2008-06477-C03-03/HIST and CGL2011-30512-C02-01 projects (Plan Nacional I + D + i) for financial and technical support. We also thank Universidad de Granada (Spain) by supporting Diego Nieto-Lugilde postdoc position at the Ecoinformatics and Biodiversity Group, Aarhus University. JCS was supported by the European Research Council (ERC-2012-StG-310886-HISTFUNC) and the Danish Council for Independent Research | Natural Sciences (12-125079) ; Peer reviewed

Peer reviewed ; The paucity of modern pollen-rain data from the Iberian Peninsula is a significant barrier to understanding the Late Quaternary vegetation history of this globally important southwestern mediterranean region. The relationships between current vegetation, the available environmental data and modern pollen are examined in Central Spain for both natural and human-induced vegetation types, as an aid for palaeoenvironmental reconstructions. A set of 60 surface moss polsters was sampled from different vegetation and land-use types in the Madrid autonomous region, and analysed to obtain modern pollen analogues of ancient cultural landscapes. Hierarchical cluster analysis (HCA) was used to divide the main pollen taxa into two major groups and ten subgroups representing the anthropic and natural vegetation types and the main communities within them. Statistically distinctive taxa were identified using principal components analysis (PCA). The results indicate that human-influenced communities have pollen assemblages that are different from those of natural vegetation types. When modern pollen assemblages are compared, the three Holm oak (Quercus rotundifolia) communities of Madrid, representing two phytogeographical provinces and three subprovinces, are easily distinguishable by their pollen spectra. This research was funded by the Technology Research 'Consolider' Program (TCP-CSD2007 – 00058), by the R&D National Plan of the Spanish Government (HAR2008 – 06477-C03 – 03/HIST project), and by the CSICCAM Consolidation project (CCG07-CSIC/HUM-1924). ; 16 páginas, 5 figuras, 1 tabla.

16 páginas, 5 figuras, 1 tabla. ; The paucity of modern pollen-rain data from the Iberian Peninsula is a significant barrier to understanding the Late Quaternary vegetation history of this globally important southwestern mediterranean region. The relationships between current vegetation, the available environmental data and modern pollen are examined in Central Spain for both natural and human-induced vegetation types, as an aid for palaeoenvironmental reconstructions. A set of 60 surface moss polsters was sampled from different vegetation and land-use types in the Madrid autonomous region, and analysed to obtain modern pollen analogues of ancient cultural landscapes. Hierarchical cluster analysis (HCA) was used to divide the main pollen taxa into two major groups and ten subgroups representing the anthropic and natural vegetation types and the main communities within them. Statistically distinctive taxa were identified using principal components analysis (PCA). The results indicate that human-influenced communities have pollen assemblages that are different from those of natural vegetation types. When modern pollen assemblages are compared, the three Holm oak (Quercus rotundifolia) communities of Madrid, representing two phytogeographical provinces and three subprovinces, are easily distinguishable by their pollen spectra. ; This research was funded by the Technology Research 'Consolider' Program (TCP-CSD2007 – 00058), by the R&D National Plan of the Spanish Government (HAR2008 – 06477-C03 – 03/HIST project), and by the CSICCAM Consolidation project (CCG07-CSIC/HUM-1924). ; Peer reviewed

[EN] Salt exploitation in the Villafáfila lagoon complex (Tierra de Campos, Zamora) is one of the most important events since Prehistory in the northern plateau of the Iberian Peninsula. Salt production is documented from the Bell Beaker (ca. 2450 cal BC). In 2013, a core drilling was performed in the salty swamp of the Laguna de las Salinas. The analysis of pollen and non-pollen palynomorphs of this record suggests the origin of the lagoon eight thousand years ago linked to the 8,2 ky cal BP climatic event, a very anthropized environment from the beginning of the Chalcolithic period ca. 3300 cal BC and the subsequent exploitation of salt, the gradual and definitive degradation of the holm oak forest from the Bronze Age onwards, and, in general, a wide climatic variability, with alternate humid and arid phases throughout the palaeoenvironmental sequence ; [ES] La explotación de la sal en el complejo lagunar de Villafáfila (Tierra de Campos, Zamora) es uno de los eventos más importantes de la meseta norte de la península ibérica desde la Prehistoria. La producción de sal se documenta a partir del periodo Campaniforme (ca. 2450 cal BC). En 2013, se efectuó un sondeo mecánico en los pastizales húmedos anexos a la Laguna de las Salinas. El análisis de polen y microfósiles no polínicos de este registro sugiere el origen de la laguna hace al menos ocho mil años vinculado al evento climático 8,2 ka cal BP, un ambiente muy antropizado desde los inicios del Calcolítico ca. 3300 cal BC y la posterior explotación de la sal, la degradación paulatina y definitiva del bosque de encinas a partir de la Edad del Bronce, y, en general, una amplia variabilidad climática alternando fases húmedas y áridas a lo largo de toda la secuencia paleoambiental. Los autores agradecen al organismo gestor de la Reserva Natural Lagunas de Villafáfila, dependiente de la Fundación Patrimonio Natural de la Junta de Castilla y León, las facilidades ofrecidas para el desarrollo de este trabajo. Éste ha sido financiado por una ayuda de investigación ...

Persistence of relict tree species in Mediterranean environments is becoming increasingly unlikely in view of ongoing and future global change. The variability in the Holocene climate and more recent anthropogenic impacts have driven many populations to fragmentation and isolation, and even to extinction. However, some have persisted to the present day. The understanding of their evolution requires long-term studies, in which pollen analysis is a key approach both for formulating hypotheses and supporting results from other disciplines. Mountain ranges have played and still play an essential role as both glacial and interglacial refugia during the Quaternary. The Spanish Central System harbors an exceptional diversity due to its geographical location and complex topography. Some cold-adapted species have survived here with significant proportions of their southernmost populations, often displaying striking adaptations to their changing environments. This work contains a comprehensive review of the palynological investigations conducted in the Spanish Central System, and reveals the distribution of genera such as Taxus, Betula, Fagus, Carpinus and Tilia throughout the Holocene. We also highlight the scarcity of well-dated and high-resolution works, which may contribute to a better understanding of their recent and future evolution. ; This paper is part of the research carried our within the project "Dinámicas socio-ecológicas, resiliencia y vulnerabilidad en un paisaje de montaña: el Sistema Central (9000 cal. BC-1850 cal. AD) " (R&D National Plan of the Spanish Government, HAR2013-43701-P).