| 1. |
- Daly, Robert J., et al.
(författare)
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A palynological study of an extinct arctic ecosystem from the Palaeocene of Northern Alaska
- 2011
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Ingår i: Review of Palaeobotany and Palynology. - : Elsevier BV. - 0034-6667. ; 166:1-2, s. 107-116
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Tidskriftsartikel (refereegranskat)abstract
- The Palaeocene arctic supported a vegetation type quite distinct from the tundra and polar desert of today. Here we demonstrate, through the palynological record, the structure of this extinct vegetation and its dynamics over this period. The Late Palaeocene coal-bearing units of the Sagwon Bluffs on Alaska's North Slope (present latitude 69 degrees N) are predominantly fine-grained, non-marine and rich in palynomorph-bearing sediments. From the analysed palynological assemblage we were able to demonstrate, using 'Detrended Correspondence Analysis' (DCA) and 'Fuzzy c-Means Cluster Analysis' (FCM), 1) a complex heterogeneous ecosystem, 2) its major successional states, and 3) its development over an extended period. The climax state of the floodplain was dominated by flood-tolerant, deciduous conifers such as Metasequoia. A more heterogeneous mid-successional assemblage is represented by angiosperm and gymnosperm co-dominance with an angiosperm dominance of Corylus, while early-successional ecological groups, dominated by ferns and bryophytes, are considered to represent riparian and post-disturbance niches. The structure of this vegetation does not remain static over the course of the stratigraphic interval represented. We observe a particularly dramatic ecological change for instance, following the deposition of a large conglomeratic unit. It is hypothesized that this corresponds to altered drainage and/or precipitation on the North Slope. The vegetation examined herein shows marked similarities to that of other palaeobotanical studies from various sites of similar age at high northern latitudes. It is hence considered to represent an extensive and long-lived circumpolar arctic biome. (C) 2011 Elsevier B.V. All rights reserved.
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| 2. |
- Hazra, Taposhi, et al.
(författare)
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New discovery of rare insect damage in the Pliocene of India reinforces the biogeographic history of Eurasian ecosystems
- 2022
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Ingår i: Review of Palaeobotany and Palynology. - Amsterdam : Elsevier. - 0034-6667 .- 1879-0615. ; 298, s. 104589-104589
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Tidskriftsartikel (refereegranskat)abstract
- Plant–insect interactions in the fossil record are, as yet, sparsely known and understudied. Here, we document evidence of a new type of insect skeletonization on Abroma augustum (L.) L. f. (Malvaceae) leaf remains fromthe latest Neogene (Pliocene) sediments of Chotanagpur plateau, Jharkhand, eastern India. This unique skeletonization feeding trace attributable to herbivorous insects occurs all over the surfaces of our recovered Pliocene leaf remains. In the skeletonized area, the interveinal tissues are completely removed leaving behind only the tough leaf veins. This type of insect feeding behaviour is documented for the first time on Indian Cenozoic leaf remains. Based on published data, as well as our survey of modern forests adjacent to the fossil locality, we suggest that probable damage inducers of this skeletonization on Abroma Jacq. fossil leaves might be Chrysomelid (Coleopteran) beetles. This finding also reveals that specific insect feeding damage, such as the one presented here, can reveal similarity of environments despite the difference of plant species observed. Such results strengthen the importance of using plant–insect interactions on leaves as a complementary proxy to others revealing paleoenvironmental conditions.
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| 3. |
- Ellis, Robert P., et al.
(författare)
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Does sex really matter? Explaining intraspecies variation in ocean acidification responses
- 2017
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification (OA) poses a major threat to marine ecosystems globally, having significant ecological and economic importance. The number and complexity of experiments examining the effects of OA has substantially increased over the past decade, in an attempt to address multi-stressor interactions and long-term responses in an increasing range of aquatic organisms. However, differences in the response of males and females to elevated pCO2 have been investigated in fewer than 4% of studies to date, often being precluded by the difficulty of determining sex non-destructively, particularly in early life stages. Herewe highlight that sex can significantly impact organismresponses to OA, differentially affecting physiology, reproduction, biochemistry and ultimately survival. What is more, these impacts do not always conform to ecological theory based on differential resource allocation towards reproduction, which would predict females to be more sensitive to OA owing to the higher production cost of eggs compared with sperm. Therefore, non-sex-specific studies may overlook subtle but ecologically significant differences in the responses of males and females to OA, with consequences for forecasting the fate of natural populations in a near-future ocean.
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| 4. |
- Hofmann, Christa-Charlotte, et al.
(författare)
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Scanning electron microscopy investigation of monads and tetrads of basal core eudicots from the Upper Cretaceous Vilui Basin, Siberia: Evidence for reticulate evolution
- 2011
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Ingår i: Review of Palaeobotany and Palynology. - : Elsevier BV. - 0034-6667. ; 167:3-4, s. 196-211
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Tidskriftsartikel (refereegranskat)abstract
- Non-marine Late Cretaceous sediments from the Vilui Basin, Siberia, yield a diverse palynoflora of over 180 taxa, a third of which had a circum-polar distribution. The Vilui palynoflora belongs generally to the northerly Aquilapollenites Province admixed with minute Normapolles types, and comprises about 36-70% angiosperm pollen forms, indicating a late Campanian/early Maastrichtian age. Using a combination of light and scanning electron microscopy we examined well-known stratigraphic taxa such as Aquilapollenites mtchedlishvilii Srivastava, Aquilapollenites decorus Srivastava Azonia recta Bolkhovitina and Tricerapollis minutus Chlonova. Further we present pollen belonging to early eudicots such as Saxifragales (Cercidiphyllaceae, Altingiaceae and Hamamelidaceae), basal eudicots (? Buxaceae) and basal core eudicots (?Gunnerales) that are preserved as colpate or porate forms, some of which are preserved as obligate tetrads, such as the morphogenera Virgo Ward, Artiopollis (Agasie) Singh, and Senectoteradites Dettmann while others are preserved as single grains or in pollen aggregations, such as Periporopollenites (Potonie) Pflug &Thomson, Retitricolpites (van der Hammen) Pierce and unnamed tricolpate types. The following new species are introduced: Virgo nicholsii, Artiopollis tyungensis, Artiopollis bellus, Periporopollenites sakhaensis, and Senectotetradites viluiensis. Our approach revealed features suggesting that individual grain types exhibit affiliations to more than one extant family. This mirrors trans-familial characters also observed in Late Cretaceous leaf fossils and is typical of reticulate evolution. (C) 2011 Published by Elsevier B.V.
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| 5. |
- Kuang Soh, Wuu, et al.
(författare)
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Rising CO2 drives divergence in water use efficiency of evergreen and deciduous plants
- 2019
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5:12
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Tidskriftsartikel (refereegranskat)abstract
- Intrinsic water use efficiency (iWUE), defined as the ratio of photosynthesis to stomatal conductance, is a key variable in plant physiology and ecology. Yet, how rising atmospheric CO2 concentration affects iWUE at broad species and ecosystem scales is poorly understood. In a field-based study of 244 woody angiosperm species across eight biomes over the past 25 years of increasing atmospheric CO2 (similar to 45 ppm), we show that iWUE in evergreen species has increased more rapidly than in deciduous species. Specifically, the difference in iWUE gain between evergreen and deciduous taxa diverges along a mean annual temperature gradient from tropical to boreal forests and follows similar observed trends in leaf functional traits such as leaf mass per area. Synthesis of multiple lines of evidence supports our findings. This study provides timely insights into the impact of Anthropocene climate change on forest ecosystems and will aid the development of next-generation trait-based vegetation models.
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| 6. |
- Murray, Michelle, et al.
(författare)
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Convergence in Maximum Stomatal Conductance of C-3 Woody Angiosperms in Natural Ecosystems Across Bioclimatic Zones
- 2019
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Stomatal conductance (g(s)) in terrestrial vegetation regulates the uptake of atmospheric carbon dioxide for photosynthesis and water loss through transpiration, closely linking the biosphere and atmosphere and influencing climate. Yet, the range and pattern of g(s) in plants from natural ecosystems across broad geographic, climatic, and taxonomic ranges remains poorly quantified. Furthermore, attempts to characterize g(s) on such scales have predominantly relied upon meta-analyses compiling data from many different studies. This approach may be inherently problematic as it combines data collected using unstandardized protocols, sometimes over decadal time spans, and from different habitat groups. Using a standardized protocol, we measured leaf-level g(s) using porometry in 218 C-3 woody angiosperm species in natural ecosystems representing seven bioclimatic zones. The resulting dataset of 4273 g(s) measurements, which we call STraits (Stomatal Traits), was used to determine patterns in maximum g(s) (g(smax)) across bioclimatic zones and whether there was similarity in the mean g(smax) of C3 woody angiosperms across ecosystem types. We also tested for differential g(smax) in two broadly defined habitat groups - open-canopy and understory-subcanopy - within and across bioclimatic zones. We found strong convergence in mean g(smax) of C3 woody angiosperms in the understory-subcanopy habitats across six bioclimatic zones, but not in open-canopy habitats. Mean g(smax) in open-canopy habitats (266 +/- 100 mmol m(-2) s(-1)) was significantly higher than in understory-subcanopy habitats (233 +/- 86 mmol m(-2) s(-1)). There was also a central tendency in the overall dataset to operate toward a g(smax) of similar to 250 mmol m(-2) s(-1). We suggest that the observed convergence in mean g(smax) of C3 woody angiosperms in the understory-subcanopy is due to a buffering of g(smax) against macroclimate effects which will lead to differential response of C3 woody angiosperm vegetation in these two habitats to future global change. Therefore, it will be important for future studies of g(smax) to categorize vegetation according to habitat group.
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