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Brunelle A. Interactions Among the Fire, Vegetation, the North American Monsoon and the El Niño-Southern Oscillation in the North American Desert Southwest. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.656462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Millennial-scale environmental histories from North American desert southwest (SW) ciénegas were examined with existing time series for the North American Monsoon (NAM) and El Niño, in concert with published long-term records of desert vegetation and climate. The goal was to better understand the relationships among fire, the seasonality of precipitation, effective moisture levels, and vegetation type. It was determined that without sufficient winter precipitation fires are rare in desert SW ecosystems. However, it was also determined that in addition to winter moisture, summer ignitions are critical for fire in southwestern deserts. A relationship between the abundance of woody fuels and charcoal abundance was identified, although further calibration on charcoal production in woody vs. grassy desert settings in necessary to fully understand this interplay. Finally, the impacts of climate change and invasive species were considered, with both likely increasing the frequency of fire in desert ecosystems.
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Edvardsson J, Helama S, Rundgren M, Nielsen AB. The Integrated Use of Dendrochronological Data and Paleoecological Records From Northwest European Peatlands and Lakes for Understanding Long-Term Ecological and Climatic Changes—A Review. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.781882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Our overall understanding of long-term climate dynamics is largely based on proxy data generated from archives such as ice cores, ocean sediments, tree rings, speleothems, and corals, whereas reconstructions of long-term changes in vegetation and associated climate during the Holocene are largely based on paleoecological records from peat and lake sequences, primarily pollen and plant macrofossil data. However, since no proxy can provide a complete picture of the past, it is important to integrate different types of data, and to use methods that can support the paleoecological and paleoclimatic interpretations. Here we review how tree-ring data and dendrochronological approaches can be integrated with stratigraphic records to provide complementary paleoecological and paleoclimatic information. The review includes multiproxy studies in which dendrochronological data have been either compared or integrated with stratigraphic records, mainly pollen records, with the aim to contribute to a better understanding of long-term ecosystem and climate dynamics. We mainly focus on studies from northwest Europe in which tree-ring data and at least one type of paleoecological proxy record from the same site or area has been either compared or integrated. We find that integration of dendrochronological data and paleoecological records from peat and lake sequences is a powerful but underutilized approach to reconstruct long-term ecological and climatic changes. One likely reason for its limited use is the contrasting character of the two categories of data, including their different time resolution and occurrence, making them difficult to integrate. For example, subfossil wood providing annual dendrochronological data usually only occurs sporadically in peat and lake sediments, and the presence/absence of the trees are normally expected to be recorded in the pollen data with multi-decadal or coarser resolution. Therefore, we also discuss methods to compare and integrate dendrochronological and stratigraphic records, as well as the relevant paleoecological and paleoclimatic information provided by dendrochronology, pollen, and peat stratigraphy, with the aim to facilitate new multi-proxy initiatives that will contribute to a better understanding of long-term ecosystem and climate dynamics and thereby a firmer basis for future nature conservation initiatives.
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Romero IC, Kong S, Fowlkes CC, Jaramillo C, Urban MA, Oboh-Ikuenobe F, D'Apolito C, Punyasena SW. Improving the taxonomy of fossil pollen using convolutional neural networks and superresolution microscopy. Proc Natl Acad Sci U S A 2020; 117:28496-28505. [PMID: 33097671 PMCID: PMC7668113 DOI: 10.1073/pnas.2007324117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Taxonomic resolution is a major challenge in palynology, largely limiting the ecological and evolutionary interpretations possible with deep-time fossil pollen data. We present an approach for fossil pollen analysis that uses optical superresolution microscopy and machine learning to create a quantitative and higher throughput workflow for producing palynological identifications and hypotheses of biological affinity. We developed three convolutional neural network (CNN) classification models: maximum projection (MPM), multislice (MSM), and fused (FM). We trained the models on the pollen of 16 genera of the legume tribe Amherstieae, and then used these models to constrain the biological classifications of 48 fossil Striatopollis specimens from the Paleocene, Eocene, and Miocene of western Africa and northern South America. All models achieved average accuracies of 83 to 90% in the classification of the extant genera, and the majority of fossil identifications (86%) showed consensus among at least two of the three models. Our fossil identifications support the paleobiogeographic hypothesis that Amherstieae originated in Paleocene Africa and dispersed to South America during the Paleocene-Eocene Thermal Maximum (56 Ma). They also raise the possibility that at least three Amherstieae genera (Crudia, Berlinia, and Anthonotha) may have diverged earlier in the Cenozoic than predicted by molecular phylogenies.
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Affiliation(s)
- Ingrid C Romero
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
| | - Shu Kong
- Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213
- Department of Computer Science, University of California, Irvine, CA 92697
| | - Charless C Fowlkes
- Department of Computer Science, University of California, Irvine, CA 92697
| | - Carlos Jaramillo
- Center for Tropical Paleoecology and Archaeology, Smithsonian Tropical Research Institute, Ancon, 0843-03092, Panama
- Institut des Sciences de l'Évolution de Montpellier, Université de Montpellier, CNRS, Ecole Pratique des Hautes Études, Institut de Recherche pour le Développement, Montpellier, 34095, France
- Department of Geology, Faculty of Sciences, University of Salamanca, Salamanca, 37008, Spain
| | - Michael A Urban
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Biology, University of New Brunswick, Fredericton, NB, E3B 5A3, Canada
| | - Francisca Oboh-Ikuenobe
- Department of Geosciences and Geological and Petroleum Engineering, Missouri University of Science and Technology, Rolla, MO 65409
| | - Carlos D'Apolito
- Faculdade de Geociencias, Universidade Federal de Mato Grosso, Cuiaba, 78000, Brazil
| | - Surangi W Punyasena
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
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A new pollen sequence from southern Iberia suggesting coastal Pleistocene phytodiversity hotspot. REVIEW OF PALAEOBOTANY AND PALYNOLOGY 2020. [DOI: 10.1016/j.revpalbo.2020.104281] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Larsen A, Simpson DF. Comment to Rull et al. (2013)—Challenging Easter Island's Collapse: the need for interdisciplinary synergies. Front Ecol Evol 2014. [DOI: 10.3389/fevo.2014.00056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Conservation of Mediterranean wetlands: Interest of historical approach. C R Biol 2011; 334:742-56. [DOI: 10.1016/j.crvi.2011.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 07/13/2011] [Accepted: 07/14/2011] [Indexed: 11/24/2022]
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Willis K, Bailey R, Bhagwat S, Birks H. Biodiversity baselines, thresholds and resilience: testing predictions and assumptions using palaeoecological data. Trends Ecol Evol 2010; 25:583-91. [PMID: 20800315 DOI: 10.1016/j.tree.2010.07.006] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 07/22/2010] [Accepted: 07/22/2010] [Indexed: 11/25/2022]
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SHAFER AARONBA, CULLINGHAM CATHERINEI, CÔTÉ STEEVED, COLTMAN DAVIDW. Of glaciers and refugia: a decade of study sheds new light on the phylogeography of northwestern North America. Mol Ecol 2010; 19:4589-621. [PMID: 20849561 DOI: 10.1111/j.1365-294x.2010.04828.x] [Citation(s) in RCA: 254] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- AARON B. A. SHAFER
- Department of Biological Sciences, CW 405 Biological Sciences Building, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - CATHERINE I. CULLINGHAM
- Department of Biological Sciences, CW 405 Biological Sciences Building, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - STEEVE D. CÔTÉ
- Département de Biologie and Centre for Northern Studies, Université Laval, Québec, Québec G1V 0A6, Canada
| | - DAVID W. COLTMAN
- Department of Biological Sciences, CW 405 Biological Sciences Building, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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Hajar L, François L, Khater C, Jomaa I, Déqué M, Cheddadi R. Cedrus libani (A. Rich) distribution in Lebanon: past, present and future. C R Biol 2010; 333:622-30. [PMID: 20688283 DOI: 10.1016/j.crvi.2010.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 03/02/2010] [Accepted: 05/27/2010] [Indexed: 11/16/2022]
Abstract
Long-term vegetation studies are needed to better predict the impact of future climate change on vegetation structure and distribution. According to the IPCC scenario, the Mediterranean region is expected to undergo significant climatic variability over the course of this century. Cedrus libani (A. Rich), in particular, is currently distributed in limited areas in the Eastern Mediterranean region, which are expected to be affected by such climate change. In order to predict the impact of future global warming, we have used fossil pollen data and model simulations. Palaeobotanical data show that C. libani has been affected by both climate change and human activities. Populations of C. libani survived in refugial zones when climatic conditions were less favourable and its range extended during periods of more suitable climate conditions. Simulations of its future geographical distribution for the year 2100 using a dynamic vegetation model show that only three areas from Mount Lebanon may allow its survival. These results extrapolated for cedar forests for the entire Eastern Mediterranean region show that forests in Syria are also threatened by future global warming. In southern Turkey, cedar forests seem to be less threatened. These results are expected to help in the long-term conservation of cedar forests in the Near East.
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Affiliation(s)
- Lara Hajar
- CNRS-université de Toulouse, LMTG, observatoire Midi-Pyrénées, 14, avenue Edouard-Belin, 31400 Toulouse, France.
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Abstract
AbstractFor nearly forty years, palynologists and other scientists studying the Quaternary have claimed that palynology, when applied in the Arctic, is a “blunt instrument” for analysing environmental change in this region. In this essay, the author explains why this expression should be laid to rest. Limits to palynological resolution are spatial, temporal and taxonomic. These are discussed and examples are shown where both the temporal and spatial resolution of pollen analyses is far higher than previously thought possible. The supposed “bluntness” of Arctic palynology is due to the way this tool has been applied in Arctic environments rather than inherent limits of palynology in Arctic ecosystems.
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Affiliation(s)
- Konrad Gajewski
- Laboratory for Paleoclimatology and Climatology, Department of Geography, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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Odgaard BV. Palaeoecological perspectives on pattern and process in plant diversity and distribution adjustments: a comment on recent developments*. DIVERS DISTRIB 2003. [DOI: 10.1111/j.1472-4642.2001.00110.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Yu Z. Late Quaternary dynamics of tundra and forest vegetation in the southern Niagara Escarpment, Canada. THE NEW PHYTOLOGIST 2003; 157:365-390. [PMID: 33873648 DOI: 10.1046/j.1469-8137.2003.00678.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• Here, paleoecological studies from southern Ontario, Canada, are detailed to reconstruct vegetation history of the last 13 000 14 C year, with emphasis on late-glacial treeless vegetation. • Two sites (Crawford Lake and Twiss Marl Pond) were investigated using combined pollen and plant-macrofossil stratigraphic data. Comparison of multivariate analysis of pollen data with climate variations inferred independently from oxygen isotopes at the same site facilitated systematic evaluations of climate-vegetation interactions during different stages of vegetation development. • Pollen results show a distinctive successional change from Alnus - Dryas -Cyperaceae sparse tundra or periglacial desert to Salix - Juniperus -Cyperaceae dense tundra, with abundant arctic/alpine plant macrofossils, during the first few centuries after ice retreat. The area around the two sites was then dominated by Picea ( c. 12 000-10 000 14 C BP). Vegetation shifts, summarized by log-contrast principal component analysis of the pollen record, indicated a lagged response of forests to deglacial climate warming. The major vegetation shift at c. 7500 14 C BP from coniferous Pinus -dominated to mixed forests probably corresponded to a major shift from deglacial to full postglacial climates. Vegetation during the mid- and late Holocene responded more directly to natural (drought-triggered pathogen-induced Tsuga decline) and human disturbances (aboriginal and EuroCanadian settlements). • This study demonstrates that bedrock basins most faithfully recorded the earliest vegetation change because they usually experienced a short delay in lake formation after ice retreat.
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Affiliation(s)
- Zicheng Yu
- Department of Earth and Environmental Sciences, Lehigh University, 31 Williams Drive, Bethlehem, PA 18015-3188, USA
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Abrupt Climate Change around 2,650 BP in North-West Europe: Evidence for Climatic Teleconnections and a Tentative Explanation. ACTA ACUST UNITED AC 1998. [DOI: 10.1007/978-94-017-3659-6_2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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