A paleoecological context to assess the development of oak forest in Colombia: A comment on Zorilla-Azcué, S., Gonzalez-Rodríguez, A., Oyama, K., González, M.A., & Rodríguez-Correa, H., The DNA history of a lonely oak: Quercus humboldtii phylogeography in the Colombian Andes. Ecology and Evolution 2021, doi: 10.100-2/ ece3.7529

The present “comment” on Zorilla-Azcué et al.’s paper “The DNA history of a lonely oak: Quercus humboldtii phylogeography in the Colombian Andes. Ecology and Evolution 2021, doi:10.100-2/ece3.7529” provides the paleoecological understanding of oak forest since Quercus became apparent in the Northern Andes three glacial–interglacial cycles ago. The interpretation of phylogeographical data is placed in an up-to-date paleoecological context. We arrived at sharper conclusions how genetic diversity between Q. humboldtii populations might have been driven by the dynamic environmental theatre of the recent Pleistocene. This paleoecological context also serves the potential future analyses of other arboreal taxa from the Andean montane forest belt. We show that hypotheses to be tested should grow out of phylogenetic analysis and paleoecological understanding together.publishedVersio

60 years of scientific deep drilling in Colombia: The north Andean guide to the Quaternary

We sketch the initial history of collecting deep cores in terrestrial and marine sedimentary basins and ice cores to study environmental and climate change. Subsequently, we focus on the development of long records from the Northern Andes. The 586 m long pollen record from ancient Lake Bogotá reflects the last 2.25 × 106 years with ∼ 1.2 kyr resolution, whereas the sediment core reflects almost the complete Quaternary. The 58 m long composite core from Lake Fúquene covers the last 284 ka with ∼ 60 years resolution. We address the various challenges and limitations of working with deep continental cores. For the tropics, the presence of these deep cores has made the Northern Andes a key area in developing and testing hypotheses in the fields of ecology, paleobiogeography, and climate change. We summarize the results in the figures, and for details on the paleoenvironmental reconstructions, we refer to the corresponding literature. We provide an overview of the literature on long continental records from all continents (see the Supplement). Based on our 50 years of experience in continental core drilling, developing a research capacity to analyze the large amounts of samples, and keeping a team together to publish the results, we listed suggestions in support of deep continental records aimed at studying environmental and climate change over long intervals of time.publishedVersio

Вулиця Басейна у Києві

Challenges and pitfalls for developing age models for long lacustrine sedimentary records are discussed and a comparison is made between radiocarbon dating, visual curve matching, and frequency analysis in the depth domain in combination with cyclostratigraphy. A core section of the high resolution 284-ka long temperature record developed from Lake Fuquene in the Northern Andes is used to explore four different age models (a-d). (a) A model based on 46 AMS C-14 dates of bulk sediment is hampered by low concentrations of organic carbon. (b) A model based on the comparison of the radiocarbon dated pollen record to the well-established record from Cariaco Basin using curve matching and visual tie points. For the upper 26 m of the core this approach yields an age interval of 28-59.5 ka. (c) Another age model is based on curve matching and the Intcal09 radiocarbon calibration curve, yielding an age range of 22.5-80.4 ka for the same core interval. (d) Finally, a model is developed based on spectral analysis in the depth domain of the temperature-related altitudinal migrations of the upper forest line. This method identifies periodicities without a pre-conceived idea of age. The main frequency of 9.07 m appears to reflect the 41-kyr orbital signal of obliquity, which is tuned to the filtered 41-kyr temperature signal from the well-constrained LRO4 marine benthic delta O-18 stack record (Lisiecki and Raymo, 2005). Using this last age-modelling approach, the upper 26 m of core Fq-9C yields a temporal interval of 27-133 ka. Problems arising from radiocarbon dating carbon poor sediments from a large lake are addressed and the visual curve matching approach is compared to the analysis of cyclic changes in sediment records in developing an age model. We conclude that the frequency analysis and cyclostratigraphy model is the most reliable one of the four approaches. These results show that cyclostratigraphy may provide a useful method for developing an age model for long terrestrial records including multiple orbital cycles. (C) 2014 Elsevier B.V. Al! rights reserved

Colombian dry moist forest transitions in the Llanos Orientales—Acomparison of model and pollen-based biome reconstructions

Colombian vegetation, at the ecological level of the biome, is reconstructed at six sites using pollen data assigned a priori to plant functional types and biomes. The chosen sites incorporate four savanna sites (Laguna Sardinas, Laguna Angel, El Pin˜al and Laguna Carimagua), a site on the transition between savanna and Amazon rainforest (Loma Linda) and a site within the Amazon rainforest (Pantano de Monica). The areal extent of tropical moist forest, tropical dry forest and steppe have been subject to significant change: differential responses of the vegetation to climatic shifts are related to changes in plant available moisture, duration of dry season and edaphic controls on the vegetation. The record from El Pin˜al shows that the present-day savanna vegetation, dominated by steppe (Poaceae) with little occurrence of woody savanna taxa (e.g. Curatella, Byrsonima), was present since the last glacial period of the northern hemisphere. Unfortunately, El Pin˜al is located on an edaphic savanna and is not particularly responsive to registering change. Most records cover the early Holocene; one site records the El Abra stadial (Younger Dryas equivalent), when forest expansion reflects more humid climatic conditions and higher plant available moisture. During the early and middle Holocene, the maximum expansion of steppe and tropical dry forest occurred, indicating that dry climatic conditions continued to around 4000 CBP. The following period, from shortly before 4000 C BP, is characterised by an increase in forest and gallery forests, reflecting a wetter period probably with a shorter annual dry season. Anthropogenic influence on the vegetation is recorded by all the records over the last millennial, particularly characterised by a reduction in forest cover and high amplitude changes in vegetation. Biome transitions from one type to another, and the environmental controls on this shift, are investigated by applying a vegetation model (BIOME-3). The model uses climatic data from six meteorological stations that, encompass a range of environments within lowland Colombia, which are similar to the pollen data. The signals of vegetation change can be translated to the main environmental controls of temperature and moisture to indicate the degree of change needed in these parameters to record the vegetation change depicted by the pollen data. Moisture balance is the dominant control on driving vegetation change whether under seasonal or annual control. The combined reconstruction from pollen data and model output of biome-scale vegetation dynamics for lowland Colombia allows an understanding of the environmental controls to be developed

Colobanthus quitensis (h.b.k.) bartl. (caryophyllaceae) en los andes colombianos

Colobantbus quitensis y Deschampsia antarctica son las dos únicas fanerogamas nativas presentes hoy dia en el continente antártico (Green, 1970). La primera tiene una distribución amplia en regiones templadas y frías de América Latina, desde la Tierra del Fuego hasta México (Moore, 1972).  En noviembre de 1978 se realizó una exploración geobotánica corta al Páramo Alto del Almorzadero en la Cordillera Oriental, Departamento de Santander; en el piso pantanoso de un vallecito a 3.900 m (El Tutal) se encontraron algunas maticas dispersas de Colobanthus quitensis (biótipo laxa) cerca de una corriente lenta de agua. El hallazgo anterior de Colobanthus quitensis en la región del Nevado del Ruiz en la Cordillera Central motivó la elaboración del presente trabajo, con el fin de dar a conocer los caracteres morfológicos, palinológicos y sociológicos de esta interesante especie