Ana Maria Abarzúa

The Río San Pedro Formation, located northwest of Valdivia in south‐central Chile (∼39°S), preserves a fossil‐rich stratigraphic succession that provides new insights into the sedimentary, floristic, and climatic dynamics of southern South America during the Late Eocene. Integrated stratigraphic, sedimentological, and U–Pb LA‐ICP‐MS geochronological analyses indicate that the formation was deposited within a meandering fluvial system and constrain its maximum depositional age to ∼39.9 Ma. Leaf‐bearing strata accumulated primarily in floodplain settings, as indicated by lithofacies associations. The taphoflora comprises a heterogeneous mix of Gondwanan, Neotropical, Pantropical, and endemic elements, dominated by taxa indicative of tropical and subtropical climates. Leaf physiognomic analyses suggest a mesothermal climate, with a mean annual temperature of ∼14–17°C and a mean annual precipitation of ∼1,200 mm. These estimates are broadly consistent with global Late Eocene climate simulations (HadCM3L model, pCO ₂ proxies) and align with contemporaneous Paleogene floras from Patagonia and central Chile. Collectively, our findings underscore the persistence of warm and humid conditions across southern South America during this interval and provide an important baseline for understanding subsequent floristic and climatic transitions.

This project in southern Chile's Lake Region analysed late Pleistocene human–environment interactions. Two field seasons in 2020 and 2022 provided a new lithic collection dating to around 17 300–12 800 cal BP, which indicates human presence in north-western Patagonia prior to the Younger Dryas period.

Multiproxy reconstructions of fire regimes in forest ecosystems can provide a clearer understanding of past fire activity and circumvent some limitations of single proxy reconstructions. While inferring fire history from scars in trees is the most precise method to reconstruct temporal fire patterns, this method is limited in Araucaria araucana forests by rot after fire injuries, successive fires that destroy the evidence and the prohibition of sample extraction from living Araucaria trees. In this context, dendrochemical studies in Araucaria trees and charcoal analysis from sediment cores can complement and extend the time perspective of the fire history in the relictual Araucaria-Nothofagus forests of the coastal range. We used dendrochemical, fire scar and charcoal records from the Nahuelbuta Coastal Range (37.8° S; 73° W) spanning the last 1000 years to reconstruct the fire history. The results indicate that periods with higher fire activity occurred between 1400 and 1650 AD. Long-term changes in the fire regime are related to increased climate variability over the last 1000 years, and especially with the arrival of settlers to the area after 1860 CE. The most severe fire events in the Nothofagus and Araucaria forests occurred when suitable fire-prone conditions were superimposed with high human densities.

Aim: Climate change is expected to impact mountain biodiversity by shifting species ranges and the biomes they shape. The extent and regional variation in these impacts are still poorly understood, particularly in the highly biodiverse Andes. Regional syntheses of climate change impacts on vegetation are pivotal to identify and guide research priorities. Here we review current data, knowledge and uncertainties in past, present and future climate change impacts on vegetation in the Andes.Location: Andes.Taxon: Plants.Methods: We (i) conducted a literature review on Andean vegetation responses to past and contemporary climatic change, (ii) analysed future climate projections for different elevations and slope orientations at 19 Andean locations using an ensemble of model outputs from the Coupled Model Intercomparison Project 5, and (iii) calculated changes in the suitable climate envelope area of Andean biomes and compared these results to studies that used species distribution models.Results: Future climatic changes (2040–2070) are projected to be stronger at high‐elevation areas in the tropical Andes (up to 4°C under RCP 8.5), while in the temperate Andes temperature increases are projected to be up to 2°C. Under this worst‐case scenario, temperate deciduous forests and the grasslands/steppes from the Central and Southern Andes are predicted to show the greatest losses of suitable climatic space (30% and 17%–23%, respectively). The high vulnerability of these biomes contrasts with the low attention from researchers modelling Andean species distributions. Critical knowledge gaps include a lack of an Andean wide plant checklist, insufficient density of weather stations at high‐elevation areas, a lack of high‐resolution climatologies that accommodates the Andes' complex topography and climatic processes, insufficient data to model demographic and ecological processes, and low use of palaeo data for distribution modelling.Main conclusions: Climate change is likely to profoundly affect the extent and composition of Andean biomes. Temperate Andean biomes in particular are susceptible to substantial area contractions. There are, however, considerable challenges and uncertainties in modelling species and biome responses and a pressing need for a region‐wide approach to address knowledge gaps and improve understanding and monitoring of climate change impacts in these globally important biomes.

A new podocarpaceous conifer is described from the early Danian Salamanca Formation (southern Chubut, Patagonia, Argentina) based on compressions of leafy branches with cuticular remains. Kirketapel salamanquensis gen. et sp. nov. has amphistomatic, scale-like leaves with marginal frills distinguishable at the apex; stomata oriented randomly in relation to the major axis of the leaf with four to five subsidiary cells and extremely reduced Florin rings; and irregularly shaped epidermal cells. We compare K. salamanquensis with extant and extinct members of the imbricate-leaved podocarps, among which it closely resembles Florin’s Dacrydium group C genera (i.e., Lagarostrobos, Manoao, Lepidothamnus and Halocarpus). Among these genera, only Lepidothamnus has a living representative in South America, the Chilean L. fonkii, whose leaf macro- and micromorphological characters are described in detail for comparison. Overall, the Patagonian fossil species is most similar to the extant and extinct members of Lagarostrobos in its cuticular micromorphology; however, macromorphological characters, such as the leaf size, apex curvature and mode of flattening, clearly differentiate it from all four genera of Dacrydium group C. We include Kirketapel salamanquensis in a combined molecular and morphological phylogenetic analysis conducted under the maximum parsimony criterion. The new, early Paleocene fossil taxon is confidently recovered as part of the scale-leaved clade as defined herein, which also includes Halocarpus, Phyllocladus, Lepidothamnus, Parasitaxus, Lagarostrobos and Manoao, and it constitutes the oldest record known for the group by at least 17 million years as well as its first fossil occurrence outside Australasia, establishing a widespread Gondwanan history. Furthermore, based on its oldest locality of occurrence, K. salamanquensis shows that the divergence of the total group of the scale-leaved podocarps occurred by at least 65 million years ago, adding to the growing systematic knowledge of earliest Cenozoic macrofloras in the Southern Hemisphere. Ana Andruchow-Colombo [aandruchow@mef.org.ar] and Ignacio Escapa [iescapa@mef.org.ar] CONICET, Museo Paleontológico Egidio Feruglio Av. Fontana 140, Trelew 9100, Chubut, Argentina; Raymond J. Carpenter* [raymond.carpenter@adelaide.edu.au] School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tas. 7001, Australia; Robert S. Hill [bob.hill@adelaide.edu.au] School of Biological Sciences and Environment Institute, University of Adelaide, Adelaide, SA 5005, Australia; Ari Iglesias [ari_iglesias@yahoo.com.ar] CONICET, Instituto de Investigaciones en Biodiversidad y Medioambiente INIBIOMA-CONICET, Universidad Nacional del COMAHUE, Quintral 1250, San Carlos de Bariloche 8400, Río Negro, Argentina; Ana Abarzua [anaabarzua@uach.cl] Instituto de Ciencias de la Tierra, Facultad de Ciencias, Universidad Austral de Chile, Av. Rector Eduardo Morales Miranda 23, Valdivia 5090000, Región de los Ríos, Chile; Peter Wilf [pwilf@psu.edu] Department of Geosciences, Pennsylvania State University, University Park, PA 16802, USA. *Also affiliated with: School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia. Received 28.2.2018; revised 22.8.2018; accepted 24.8.2018.