Sebastián Pérez-Díaz

Modern pollen analysis: a reliable tool for discriminating Quercus rotundifolia communities in Central Spain

The paucity of modern pollen-rain data from the Iberian Peninsula is a signifi cant 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 identifi ed using principal components analysis (PCA). The results indicate that human-infl uenced 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.

Exploring seven hundred years of transhumance, climate dynamic, fire and human activity through a historical mountain pass in central Spain

A high-altitude peat sequence from the heart of the Spanish Central System (Gredos range) was analysed through a multi-proxy approach to determine the sensitivity of high-mountain habitats to climate, fire and land use changes during the last seven hundred years, providing valuable insight into our understanding of the vegetation history and environmental changes in a mountain pass close to a traditional route of transhumance. The pollen data indicate that the vegetation was dominated by shrublands and grasslands with scattered pines in high-mountain areas, while in the valleys cereals, chestnut and olive trees were cultivated. Strong declines of high-mountain pines percentages are recorded at 1540, 1675, 1765, 1835 and 1925 cal AD, which may be related to increasing grazing activities and/or the occurrence of anthropogenic fires. The practice of mountain summer farming and transhumance deeply changed and redesigned the landscape of the high altitudes in central Spain (Gredos range) since the Middle Ages, although its dynamics was influenced in some way by climate variability of the past seven centuries.

Are Cedrus atlantica forests in the Rif Mountains of Morocco heading towards local extinction

Cedrus atlantica (Atlas cedar) is a relict and endemic endangered species from northwestern African mountains, whose distribution range has undergone a dramatic reduction over recent decades. Long-term studies are needed for a better understanding of the development of its range as well as for assisting in the implementation of sustainable conservation measures. The multi-proxy analysis of a high-resolution fossil record of 180 cm depth allowed us to depict the final demise of an Atlas cedar population from the western Rif Mountains (Jbel Khesana), despite its high resilience during the last ~4000 years. Currently, Atlas cedar trees are not observed in Jbel Khesana but they still occur in the nearby area as scattered populations on a few mountain tops at altitudes higher than 1400 m a.s.l. Our data show an initial relatively stable period (~4000–2400 cal. yr BP) followed by a phase where both climatic and human-induced disturbances cause an alternate dominance of oaks and Atlas cedars (2400~1550 cal. yr BP). Then, the increasing aridity and human activities favoured the depletion of Atlas cedar forests (~1550–800 cal. yr BP). Our record shows that Atlas cedar forests have recovered after each deforestation event, which reveals a high resilience of the species until the mid-20th century, when they became extinct in the study area. The main driver of their local extinction may be attributed to the strong human pressure. Management measures of Atlas cedar in the Rif Mountains should aim at limiting intensive loggings and protecting the existing populations for their local regeneration.

39. Las Lanchas, Toledo Mountains (central Spain)

Las Lanchas bog (39° 35′ 8.76ʺ N, 4o 53′ 39.47ʺ W; 800 m above sea level [a.s.l.]) lies on the north-eastern slope of the ‘Sierra de Sevilleja’ in the western part of the Toledo Mountains (La Jara district, Robledo del Mazo, Toledo). The peat-bog extends over an area of 0.18 ha and it is a ‘special protected habitat’ in accordance with Law 9/1999 of Castilla-La Mancha on Nature Conservation. It was designated an ‘environmental micro-reserve’ in 2003 by the Decree 319/2003 (Martín-Herrero et al. 2004). The area experiences a Mediterranean climate with dry and warm summers, influenced by the Atlantic winds from the southwest. The average annual temperature is 14–15 °C and the annual precipitation is 600–700 mm. Precipitation is irregular along the year with maximum values during the winter. Themost representative plant communities of the area are holm oak (Quercus ilex L. subsp. ballota [Desf.] Samp.) and cork oak (Q. suber L.) woodlands of the meso-mediterranean foothills in sunny areas and shady valleys, the first associated with mesothermophilous taxa (Arbutus unedo L.) and the second with deciduous trees (Q. faginea Lam. subsp. broteroi [Cout.] A. Camus, Acer monspessulanum L. and Sorbus torminalis [L.] Crantz). Deciduous oak forests of Q. pyrenaica Willd. and chestnuts trees (Castanea sativa Mill.) occupy the supra-mediterranean bioclimatic belt and north-eastern oriented slopes (Perea & Perea 2008). Riparian forests are dominated by Salix atrocinerea Brot., S. salviifolia Broth., Frangula alnus Mill., Fraxinus angustifolia Vahl. and Betula pendula Roth. subsp. fontqueri (Rothm.) G. Moreno et Peinado, accompanied by Ilex aquifolium L., Taxus baccata L. and Prunus lusitanica L. The bog vegetation is composed mainly of Sphagnum sp., Drosera rotundifolia L., Pinguicula lusitanica L., Erica tetralix L., E. lusitanica Rudolphi, Dactylorhiza elata subsp. sesquipedalis (Willd.) Soó, Genista anglica L., Lobelia urens L. and Molinia caerulea (L.) Moench. (LópezSáez et al. 2014). The bedrock is an old siliceous basement made up mainly of Lower Ordovician Armorican quartzites and slates (Muñoz-Jiménez 1976).

40. Botija, Toledo Mountains (central Spain)

Botija bog (39o 36ʹ 5.97′′ N, 4o 41ʹ 46.45′′ W; 755 m above sea level [a.s.l.]) lies on the northeastern slope of the Sierra de la Botija in the western part of the Toledo Mountains, extending over an area of 0.07 ha next to the right margin of the Pusa River. The area experiences a Mediterranean climate with dry and warm summers, influenced by the Atlantic winds from the southwest. The average annual temperature is 15–16 oC and the annual precipitation is 700–800 mm. Rainfall occurs irregularly with maximum values during winter. The most representative plant communities of the area are holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.) woodlands of the meso-mediterranean foothills in sunny areas and shade bottoms, associated with mesothermophilous taxa (Arbutus unedo L., Cistus ladanifer L.). Deciduous oak forests of Quercus pyrenaica Willd. occupy the supra-mediterranean bioclimatic belt and north-eastern oriented slopes (Perea & Perea 2008). Riparian forests are dominated by Salix atrocinerea Brot., S. salviifolia Broth., Frangula alnus Mill., Fraxinus angustifolia Vahl. and Betula pendula Roth. subsp. fontqueri (Rothm.) G. Moreno & Peinado. The bog vegetation is composed mainly of Sphagnum palustre L., Drosera rotundifolia L., Calluna vulgaris (L.) Hull., Pinguicula lusitanica L., Erica tetralix L., Dactylorhiza elata subsp. sesquipedalis (Willd.) Soó, Genista anglica L., Lobelia urens L. and Molinia caerulea (L.) Moench. (López-Sáez et al. 2014). The bedrock is an old siliceous basement made up mainly of Lower Ordovician Armorican quartzites and slates (Muñoz-Jiménez 1976). Sediment description

A Late Antique Vegetation History of the Western Mediterranean in Context

Fossil pollen records from 70 sites with reliable chronologies and high-resolution data in the western Mediterranean, were synthesised to document Late Holocene vegetation and climate change. The key elements of vegetation dynamics and landscape construction during Late Antiquity are clear in the light of the fossil pollen records. These are: fire events (natural or anthropogenically induced); grazing activities in high-mountain areas; agriculture; arboriculture; and human settlement in the lowlands. In terms of anthropogenic pressure, the differences recorded between highlands and lowlands suggest an imbalance in land use. Such practices were related to three main types of activities: wood exploitation and management, cultivation, and pastoralism. In lowland areas there seems to be some synchronism in vegetation dynamics during the late antique period, since most of the territories of the western Mediterranean had been deforested by the Early Roman period. However, in mountainous regions, pollen records document a clear asynchrony.

Paleobiogeografía de Abies spp. y Cedrus atlantica en el Mediterráneo occidental (península ibérica y Marruecos)

Delgado L.A. 2018. Landscape Heterogeneity and tree species diversity in a tropical forest. Development and validation of a methodological proposal. Ecosistemas 27(1): 105-115. Doi.: 10.7818/ECOS.1475 Many landscapes exist as unstable spatial-temporal mosaics where changes in patterns of biodiversity are affected by nature processes and the dynamic interaction between social and ecological factors. It is a consequence of the natural dynamics of socio-economic systems that regulate man-made tropical forests. However, a significant proportion of studies have made generalizations about the relative values of biodiversity, without taking into account the high levels of internal heterogeneity in the biophysical properties and land uses of each site. The purpose of this study is to propose and validate a methodology to delimit the heterogeneity of the landscape based on criteria that integrate the coupling of human-ecological systems such as: space-time dynamics of deforestation and fragmentation; complexity of the landscape structure; current and historical land use and biophysical variability. For this, the use of satellite images, landscape metrics, field work, documentary review and multivariate analysis were combined. The proposed methodology is intended to help guide the empirical delimitation of landscape heterogeneity as a prerequisite for the selection of similar landscapes and forest patches in studies of the diversity of tree species, in order to provide an opportunity to control the possible difficulties caused by variability in the proportion of forests, landscape configuration and successional states, in estimating its effects on forest richness and floristic composition.

Resilience, vulnerability and conservation strategies in high-mountain pine forests in the Gredos Range, central Spain

Abstract Background: High-mountain pine forests and broom communities in central Spain today have led to contrasting interpretations of their natural or human-induced origin. Aims: We evaluated the vulnerability and resilience of high-mountain Pinus sylvestris/P. nigra forests and derived Cytisus broom scrub communities to climate and anthropogenic disturbances. Methods: We assessed historical transitions from forest to scrub and their relation to climate and human influences, using a multi-proxy paleoenvironmental study (pollen, non-pollen palynomorphs, charcoal, magnetic susceptibility) in three mires in the Gredos Range, western Iberian Central System. Results: High percentages of Pinus sylvestris/nigra pollen and the identification of their macro remains demonstrated that high-mountain pine forests have been present in the oromediterranean bioclimatic belt of the Gredos Range since the mid-Holocene. After that, a major human-induced decline, enhanced by climate conditions, has led to their gradual replacement by broom communities. Conclusions: Broom communities are derived from ancient pine forests that were intensively transformed by human activities after 700 cal year BP, and largely disappeared by ca. 500 cal yr BP. Today’s landscape, dominated by broom scrub and grasslands with scattered stands of pines, shows high resilience and provides suitable refugia for a rich mountain biodiversity which deserves a further protection.

Late Antique Environment and Economy in the North of the Iberian Peninsula: The Site of La Tabacalera (Asturias, Spain)

The exceptional preservation of organic remains in a well-reservoir at the site of La Tabacalera (Asturias, Spain) is the subject of an interdisciplinary study regarding past human-environmental interaction. The feature, dated to Late Antiquity, corresponds to a large well containing a wide range of organic material (animal bones, pollen, non-pollen palynomorphs ( NPP s), mites, seeds, wood and wooden artefacts, etc.). This article examines both plant micro (pollen and NPP s) and macro-remains (seeds and wood) dated between the late 5th–8th c. AD . The palynological evidence suggests that the structure investigated was colonised by different species dominated by ivy, while the surrounding anthropised area was characterised by the presence of open areas, probably occupied by meadows and pastures. A mixed deciduous forest was also present not far from the site. The abundant plant macro-remains include the presence of water-loving woody species, which inform us about the vegetation growing around the well-reservoir. The seed record comprises cultivated plants, and a wide range of wild species typical of humid environments. Among the remains there are also some wooden artefacts. Plant remains have provided significant information, not only to reconstruct the landscape around the site, but also on the formation of the feature’s backfill. Moreover, the remains offer us information regarding objects of daily life and the maintenance of the feature.

36. Praillos de Boissier mire, Tejeda Natural Park (Baetic Range, southern Spain)

This work was supported by the Excellence Research Projects Programme from the Andalusian Government, Sevilla, Spain [Project Relictflora-P11-RNM-7033].