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The Quaternary plant fossil record from the volcanic Azores Archipelago (Portugal, North Atlantic Ocean): a review

Publication . Góis-Marques, Carlos A.; Nascimento, Lea de; Sequeira, Miguel Menezes de; Fernández-Palacios, José María; Madeira, José

Plant fossils are known from the Azores Islands, yet poorly studied. We present a comprehensive bibliographical review for the archipelago. A first pre-scientific reference dates from late fifteenth century, while the first scientific description was reported in 1821, accounting for trunks in pyroclastic units and silicified plants within hydrothermal deposits. Throughout the second-half of the nineteenth century and the first-half of the twentieth century, prospection by naturalists and geological mapping work, led to the discovery and description of plant fossils in most islands. From the 1970s onwards, the taxonomic interest ceased, and plant fossils were used mainly for 14C dating. Recently, sediment cores from lakes and peatlands were used for palaeoecological reconstructions and to measure anthropogenic impacts. Generally, plant fossils are younger than 50 ka, although older fossils may exist. Azorean plant fossils include somatofossils of leaves, stems, logs and seeds preserved as impressions, compressions, adpressions, permineralizations, lava tree casts and mummifications. The taphonomy of macrofloral elements is usually related to explosive volcanic activity, while palynological record is associated with lake sediments and peat bogs. The persistence in palaeobotanical and palaeopalynological studies will decisively contribute to disentangle the paleodiversity, palaeoecology, and add crucial information on insular plant phylogeny and biogeography.

2018Journal article

Open access

Oceanic Island forests buried by Holocene (Meghalayan) explosive eruptions: palaeobiodiversity in pre-anthropic volcanic charcoal from Faial Island (Azores, Portugal) and its palaeoecological implications

Publication . Góis-Marques, C. A.; Rubiales, J. M.; Nascimento, L.; Sequeira, Miguel Menezes de; Fernández-Palacios, J. M.; Madeira, J.

In Faial Island (Azores Archipelago, North Atlantic Ocean), charcoalified and mummified wood fossils have been reported within late Holocene (Meghalayan) pyroclastic deposits from the Caldeira Formation. Due to their re cent age, a detailed study conveys a snapshot into Azorean palaeophytodiversity and palaeovegetation, ca. 7–5 centuries before the arrival of Portuguese settlers to the Azores Islands. Here we provide the first detailed ana tomical and taxonomical study of these wood fossils. In total, 41 samples were collected from seven localities, mainly from a ~1200 yr BP ignimbrite. Field work revealed autochthonous and paraautochthonous assemblages, with tree trunks in upright position. The anatomical study of the fossil woods resulted in the identification of Juniperus brevifolia, Laurus azorica, Myrsine retusa, Morella faya, Picconia azorica, Prunus lusitanica subsp. azorica, and Vaccinium cylindraceum. Two fossil assemblages are comparable to the proposed potential natural vegetation (PNV) for the Azores. Surprisingly, P. lusitanica subsp. azorica was the second most abundant fossil wood suggest ing that this tree was more abundant in a recent past in Faial Island and probably in the archipelago. This is cor roborated by historical accounts, and its modern scarcity was certainly anthropically driven. Identifying Holocene plant macrofossils is essential to properly reconstruct oceanic islands terrestrial palaeoecosystems, especially where forests with high percentage of entomophilous taxa are underrepresented in palaeopalynological limnic record. Further work is necessary to reconstruct Faial Island and Azores archipelago palaeovegetation which is essential to provide an ecosystem base-line for restoration and management.

2020Journal article

Open access