Dynamics of Silurian Plants as Response to Climate Changes

The most ancient macroscopic plants fossils are Early Silurian cooksonioid sporophytes from the volcanic islands of the peri-Gondwanan palaeoregion (the Barrandian area, Prague Basin, Czech Republic). However, available palynological, phylogenetic and geological evidence indicates that the history of plant terrestrialization is much longer and it is recently accepted that land floras, producing different types of spores, already were established in the Ordovician Period. Here we attempt to correlate Silurian floral development with environmental dynamics based on our data from the Prague Basin, but also to compile known data on a global scale. Spore-assemblage analysis clearly indicates a significant and almost exponential expansion of trilete-spore producing plants starting during the Wenlock Epoch, while cryptospore-producers, which dominated until the Telychian Age, were evolutionarily stagnate. Interestingly cryptospore vs. trilete-spore producers seem to react differentially to Silurian glaciations—trilete-spore producing plants react more sensitively to glacial cooling, showing a reduction in species numbers. Both our own and compiled data indicate highly terrestrialized, advanced Silurian land-plant assemblage/flora types with obviously great ability to resist different dry-land stress conditions. As previously suggested some authors, they seem to evolve on different palaeo continents into quite disjunct specific plant assemblages, certainly reflecting the different geological, geographical and climatic conditions to which they were subject.

Download Full-text

No snow in the mountains: Early Eocene plant fossils from Hotham Heights, Victoria, Australia

Australian Journal of Botany ◽

10.1071/bt04032 ◽

2004 ◽

Vol 52 (6) ◽

pp. 685 ◽

Cited By ~ 31

Author(s):

Raymond J. Carpenter ◽

Robert S. Hill ◽

David R. Greenwood ◽

Alan D. Partridge ◽

Meredith A. Banks

Keyword(s):

Sea Level ◽

Papua New Guinea ◽

Environmental Conditions ◽

New Guinea ◽

Climatic Conditions ◽

Early Eocene ◽

Geological Evidence ◽

Plant Fossils ◽

Plant Assemblage ◽

Tree Ferns

An Early Eocene plant assemblage from near the summit of Mt Hotham, Victoria, is described, using a combination of macro- and microfossils, especially cuticles. This is important since no other Australian macrofossil sites from this time, when environmental conditions are believed to have been the warmest of the Cenozoic, have been described in detail. The nature of the flora and vegetation supports geological evidence that the site was upland (approximately 800 m above sea level) at this time, with climatic conditions similar to those now experienced in regions such as the Atherton Tablelands in Queensland and mid-montane Papua New Guinea. The vegetation was probably a form of rainforest dominated by mesotherm elements, with abundant ferns including Gleicheniaceae and the tree ferns Cnemidaria, Cyathea and Dicksonia. Gymnosperms included Araucariaceae (Agathis) and Podocarpaceae (at least Acmopyle and Dacrydium). Angiosperms were diverse in Lauraceae (at least nine species including probably Cryptocarya, Endiandra and Litsea) and Proteaceae (at least nine species including probably Musgravea and Darlingia). Other angiosperms included Cunoniaceae, Gymnostoma (Casuarinaceae), Diospyros-like Ebenaceae, and the vine Cissocarpus (Vitaceae). Nothofagus was rare or absent from the Mt Hotham region at this time, as no macrofossil evidence was found, and pollen percentages were very low.

Download Full-text

Genetic Diversity Analysis of Salvadora Oleoides Decne: An Evergreen Dry Land Fruit Tree of Rajasthan, India

10.21203/rs.3.rs-198120/v1 ◽

2021 ◽

Author(s):

Juleri M Upendra ◽

Shari Nair ◽

Satyawada R Rao ◽

Harchand R Dagla

Keyword(s):

Genetic Diversity ◽

Random Amplified Polymorphic Dna ◽

Splice Junction ◽

Genetic Distances ◽

Climatic Conditions ◽

Fruit Tree ◽

Group Method ◽

Dry Land ◽

Intron Splice ◽

Semi Arid

Abstract Genetic diversity of Salvadora oleoides Decne is analyzed by cumulative data of 10 Random Amplified Polymorphic DNA (RAPD), 10 Inter Simple Sequence Repeats (ISSR) and 7 Intron Splice Junction (ISJ) markers. The plant is an evergreen fruit tree and well distributed in semi-arid and sub-humid climatic conditions of Rajasthan, India. RAPD, ISSR and ISJ primers accounted for 84.4%, 85.3%, 85.9% polymorphism. Average 0.23 PIC is accounted for RAPD, ISSR and ISJ primers. The genetic similarity ranged between 0.42-0.89. Analysis of molecular variance (AMOVA) revealed higher variation (73%) at intra-population than inter-population (27%) level. Genetic distances based on Un-weighted Pair Group Method with Arithmetic mean (UPGMA) dendrogram and Principal Coordinate Analysis (PCoA) is correlated with physical distances or climatic conditions of Salvadora oleoides Decne in a semi-arid and sub-humid environment of Rajasthan. The present investigation may help in the understanding of gene flow systems between physical distances and environmental heterogeneity of the populations for better management of Salvadora oleoides Decne in the region.

Download Full-text

Reconstructing the initial shape of volcanic islands to quantify long-term coastal erosion

10.5194/egusphere-egu21-8763 ◽

2021 ◽

Author(s):

Rémi Bossis ◽

Vincent Regard ◽

Sébastien Carretier

Keyword(s):

Coastal Erosion ◽

Erosion Rate ◽

Developed Countries ◽

Global Scale ◽

Radial Symmetry ◽

Wave Direction ◽

Initial Shape ◽

Vertical Movements ◽

Volcanic Islands

The global solid flux from continent to ocean is usually reduced to the input of sediments from rivers, and is estimated at approximately 20 Gt/year. Another input of sediments to ocean is coastal erosion, but this flux is difficult to estimate on a global scale and it is often neglected, perhaps wrongly according to regional studies [1,2]. Most studies attempting to quantify coastal erosion have focused on the coasts of developed countries and are limited to the timescale of decades or less [3]. The difficulty in quantifying long-term coastal erosion is that there are still many uncertainties about the factors controlling coastal erosion on this time scale, and it would be necessary to know the initial geometry of coastlines to calculate an eroded volume.Volcanic islands, as geomorphological objects, seem to be very good objects of study to remedy these limitations. Indeed, many young volcanic islands are made of only one central edifice with a strong radial symmetry despite its degradation by erosion [4,5]. By knowing the age of an island and by comparing reconstructed shape with current shape, we can calculate a total eroded volume and an integrated average coastal erosion rate on the age of the island. Moreover, due to their geographical, petrological and tectonic diversity, volcanic islands allow to compare the influence of different factors on long-term coastal erosion, such as climate, wave direction and height, rock resistance or vertical movements. Thus, we will be able to prioritize them to propose coastal erosion laws that would applicable to all rocky coasts.Here we built on previous works that have used aerial geospatial databases to reconstruct the initial shape of these islands [6,7] but we improve this approach by using offshore topographic data to determine the maximum and initial extension of their coasts. From both onshore and offshore topographies, we determine a long-term mean coastal erosion rate and we quantify precisely its uncertainty. Using the example of Corvo Island, in the Azores archipelago, we show how our approach allows us to obtain first estimates of long-term coastal erosion rate around this island.&#160;References&#160;[1] Landemaine V. (2016). Ph.D. thesis, University of Rouen.[2] Rachold V., Grigoriev M.N., Are F.E., Solomon S., Reimnitz E., Kassens H., Antonow M. (2000). International Journal of Earth Sciences, 89(3), 450-460.[3] Pr&#233;maillon M. (2018). Ph.D. thesis, University of Toulouse.[4] Kar&#225;tson D., Favalli M., Tarquini S., Fornaciai A., W&#246;rner G. (2010). Journal of Volcanology and Geothermal Research, 193, 171-181.[5] Favalli M., Kar&#225;tson D., Yepes J., NannipierI L. (2014). Geomorphology, 221, 139-149.[6] Lahitte P., Samper A., Quidelleur X. (2012). Geomorphology, 136, 148-164.[7] Kar&#225;tson D., Yepes J., Favalli M., Rodr&#237;guez-Peces M.J., Fornaciai A. (2016). Geomorphology, 253, 123-134.

Download Full-text

Scavenging in the Anthropocene: Human impact drives vertebrate scavenger species richness at a global scale

10.26686/wgtn.12469334.v1 ◽

2020 ◽

Author(s):

E Sebastián-González ◽

JM Barbosa ◽

JM Pérez-García ◽

Z Morales-Reyes ◽

F Botella ◽

...

Keyword(s):

Species Richness ◽

Human Impact ◽

Large Scale ◽

Diversity Index ◽

Global Scale ◽

Climatic Conditions ◽

Ecosystem Functions ◽

Number Of Species ◽

Terrestrial Vertebrate ◽

Latitudinal Patterns

© 2019 John Wiley & Sons Ltd Understanding the distribution of biodiversity across the Earth is one of the most challenging questions in biology. Much research has been directed at explaining the species latitudinal pattern showing that communities are richer in tropical areas; however, despite decades of research, a general consensus has not yet emerged. In addition, global biodiversity patterns are being rapidly altered by human activities. Here, we aim to describe large-scale patterns of species richness and diversity in terrestrial vertebrate scavenger (carrion-consuming) assemblages, which provide key ecosystem functions and services. We used a worldwide dataset comprising 43 sites, where vertebrate scavenger assemblages were identified using 2,485 carcasses monitored between 1991 and 2018. First, we evaluated how scavenger richness (number of species) and diversity (Shannon diversity index) varied among seasons (cold vs. warm, wet vs. dry). Then, we studied the potential effects of human impact and a set of macroecological variables related to climatic conditions on the scavenger assemblages. Vertebrate scavenger richness ranged from species-poor to species rich assemblages (4–30 species). Both scavenger richness and diversity also showed some seasonal variation. However, in general, climatic variables did not drive latitudinal patterns, as scavenger richness and diversity were not affected by temperature or rainfall. Rainfall seasonality slightly increased the number of species in the community, but its effect was weak. Instead, the human impact index included in our study was the main predictor of scavenger richness. Scavenger assemblages in highly human-impacted areas sustained the smallest number of scavenger species, suggesting human activity may be overriding other macroecological processes in shaping scavenger communities. Our results highlight the effect of human impact at a global scale. As species-rich assemblages tend to be more functional, we warn about possible reductions in ecosystem functions and the services provided by scavengers in human-dominated landscapes in the Anthropocene.

Download Full-text

Tsunami and tephra deposits record interactions between past eruptive activity and landslides at Stromboli volcano, Italy

Geology ◽

10.1130/g47331.1 ◽

2020 ◽

Vol 48 (5) ◽

pp. 436-440 ◽

Cited By ~ 2

Author(s):

Marco Pistolesi ◽

Antonella Bertagnini ◽

Alessio Di Roberto ◽

Maurizio Ripepe ◽

Mauro Rosi

Keyword(s):

Volcanic Activity ◽

Southern Italy ◽

Global Scale ◽

Stromboli Volcano ◽

Close Link ◽

Flank Collapse ◽

Volcanic Events ◽

Volcanic Islands ◽

Volcaniclastic Deposits

Abstract Devastation associated with tsunamis is well known on the global scale. Flank collapse at volcanic islands is among the mechanisms triggering tsunamis, but very few examples document interaction between landslides and volcanic activity. The study of three well-preserved medieval tsunami deposits recently discovered along the coast of Stromboli volcano (Aeolian Islands, southern Italy) enabled a detailed characterization of the tsunami sequences intercalated with volcaniclastic deposits and primary tephra and allowed reconstruction of the likely sequence of volcanic events. In one case, a violent explosion possibly preceded the tsunami, whereas in the youngest event, the lateral collapse of the volcano flank triggered a tsunami wave that was rapidly followed by sustained explosive magmatic activity and ensuing prolonged ash venting. The hypothesized tsunami-triggering dynamics suggests a close link between volcanic activity and flank collapse, further confirming that the persistent activity at Stromboli makes the volcano particularly susceptible to tsunami generation.

Download Full-text

WINTERHARDINESS OF ALFALFA CULTIVARS IN SOUTHERN SASKATCHEWAN

Canadian Journal of Plant Science ◽

10.4141/cjps73-150 ◽

1973 ◽

Vol 53 (4) ◽

pp. 773-777 ◽

Cited By ~ 6

Author(s):

D. H. HEINRICHS

Keyword(s):

North America ◽

Medicago Sativa ◽

Great Plains ◽

Climatic Conditions ◽

Northern Great Plains ◽

Dry Land ◽

The Third ◽

The Usa ◽

Medicago Sativa L

Winter injury occurring at Swift Current, Saskatchewan, was recorded in 17 tests during the period 1962–72. Cultivars developed in the Northern Great Plains Region of the USA and in Canada were generally more winter-hardy than cultivars developed in other regions of North America or in Europe. Cultivars classified as Medicago media Pers. were more winter-hardy than those classified as Medicago sativa L. Very few USA cultivars were more winter-hardy than Vernal, but most Canadian cultivars were. In nonhardy cultivars winter injury never occurred during the first winter, but it often occurred in the second winter and frequently in the third winter. There was considerably more winter injury among alfalfa cultivars on irrigated land than on dry land. Based on results from these tests, 50 cultivars and strains have been classified for relative winterhardiness under climatic conditions in southern Saskatchewan, Canada.

Download Full-text

A dynamic local scale vegetation model for lycophytes (LYCOm)

10.5194/gmd-2021-202 ◽

2021 ◽

Author(s):

Suman Halder ◽

Susanne K. M. Arens ◽

Kai Jensen ◽

Tais Wittchen Dahl ◽

Philipp Porada

Keyword(s):

Soil Carbon ◽

Vascular Plants ◽

Chemical Weathering ◽

Vascular Tissue ◽

Net Primary Production ◽

Soil Microbial Activity ◽

Global Scale ◽

Local Scale ◽

Climatic Conditions ◽

Silicate Weathering

Abstract. Lycophytes (club mosses) represent a distinct lineage of vascular plants with a long evolutionary history including numerous extant and extinct species which started out as herbaceous plants and later evolved into woody plants. They enriched the soil carbon pool through newly developed root-like structures and promoted soil microbial activity by providing organic matter. These plants enhanced soil carbon dioxide (CO2) via root respiration and also modified soil hydrology. These effects had the potential to promote the dissolution of silicate minerals, thus intensifying silicate weathering. The weathering of silicate rocks is considered one of the most significant geochemical regulators of atmospheric CO2 on a long (hundreds of thousands to millions of years) timescale. The motivation for this study is to achieve an increased understanding of the realized impacts of vascular plants, represented by modern relatives to the most basal plants with vascular tissue and shallow root system, on silicate weathering and past climate. To this end, it is necessary to quantify physiological characteristics, spatial distribution, carbon balance, and the hydrological impacts of early lycophytes. These properties, however, cannot be easily derived from proxies such as fossil records, for instance. Hence, as a first step, a process-based model is developed here to estimate net carbon uptake by these organisms at the local scale, considering key features such as biomass distribution above and below ground, root distribution in soil regulating water uptake by plants besides, stomatal regulation of water loss and photosynthesis, and not withholding respiration in roots. The model features ranges of key physiological traits of lycophytes to predict the emerging characteristics of the lycophyte community under any given climate by implicitly simulating the process of selection. In this way, also extinct plant communities can be represented. In addition to physiological properties, the model also simulates weathering rates using a simple limit-based approach and estimates the biotic enhancement of weathering by lycophytes. We run the Lycophyte model, called LYCOm, at seven sites encompassing various climate zones under today’s climatic conditions. LYCOm is able to simulate realistic properties of lycophyte communities at the respective locations and estimates values of Net Primary Production (NPP) ranging from 126 g carbon m−2 year−1 to 245 g carbon m−2 year−1. Our limit-based weathering model predicts a mean chemical weathering rate ranging from 5.3 to 45.1 cm ka−1 rock with lycophytes varying between different sites, as opposed to 0.6–8.3 cm rock ka−1 without lycophytes, thereby highlighting the potential importance of such vegetation at the local scale for enhancing chemical weathering. Our modeling study establishes a basis for assessing biotic enhancement of weathering by lycophytes at the global scale and also for the geological past. Although our method is associated with limitations and uncertainties, it represents a novel, complementary approach towards estimating the impacts of lycophytes on biogeochemistry and climate.

Download Full-text

Development of seed production elements of new grain beans variety Yuzhanka bred by FSBSI Federal Scientific Rice Centre

E3S Web of Conferences ◽

10.1051/e3sconf/202128502041 ◽

2021 ◽

Vol 285 ◽

pp. 02041

Author(s):

Grigory Pischulin ◽

Lybov Esaulova

Keyword(s):

Seed Production ◽

Mineral Nutrition ◽

Morphological Traits ◽

Climatic Conditions ◽

Mineral Fertilizers ◽

Biological Product ◽

Dry Land ◽

Agricultural Method ◽

Cultivation Technology ◽

Krasnodar Region

For the rapid distribution and successful cultivation of beans, it is necessary to develop methods of cultivation technology in accordance with the soil and climatic conditions of Krasnodar region. In this regard, the aim of this work was to study the efficiency of irrigation, various doses of mineral nutrition and the use of the biological product Nitragin KM on grain beans crops. The effect of pre-sowing application of mineral fertilizers under irrigation and rainfed conditions on phenological, morphological traits, yield and productivity of grain beans variety Yuzhanka has been studied. Analysis of the data on the yield of beans seeds showed that the most effective agricultural method for seed production of this crop is the introduction of mineral fertilizers on drip irrigation. With an increase in the level of mineral nutrition, the seed multiplication factor increased from 30 to 45 pcs/pcs on dry land and from 50 to 69 pcs/pcs during irrigation. The application of mineral fertilizers contributed to an increase in yields both in rainfed and irrigated conditions. The highest yield of bean seeds of variety Yuzhanka was obtained with the use of fertilizers at a dose of N30P30K30 (1,77 t/ha on dry land and 3,04 t/ha on irrigated plots).

Download Full-text

A biologically driven directional change in susceptibility to global-scale glaciation during the Precambrian-Cambrian transition

10.1101/359422 ◽

2018 ◽

Author(s):

Richard A. Boyle ◽

Carolin R. Löscher

Keyword(s):

Land Surface ◽

Climate Models ◽

Abiotic Factors ◽

Global Scale ◽

Snowball Earth ◽

Critical Aspect ◽

Geological Evidence ◽

Directional Change ◽

Temperature Window ◽

Tectonic Boundary

Integrated geological evidence suggests that grounded ice sheets occurred at sea level across all latitudes during two intervals within the Neoproterozoic era; the “snowball Earth” (SBE) events. Glacial events at ~730 and ~650 million years ago (Ma) were probably followed by a less severe but nonetheless global-scale glaciation at ~580Ma, immediately preceding the proliferation of the first fossils exhibiting unambiguous animal-like form. Existing modelling identifies weathering-induced CO2 draw-down as a critical aspect of glacial inception, but ultimately attributes the SBE phenomenon to unusual tectonic boundary conditions. Here we suggest that the evident directional decrease in Earth’s susceptibility to a SBE suggests that such a-directional abiotic factors are an insufficient explanation for the lack of SBE events since ~580 Ma. Instead we hypothesize that the terrestrial biosphere’s capacity to sustain a given level of biotic weathering-enhancement under suboptimal/declining temperatures, itself decreased over time: because lichens (with a relatively robust tolerance of sub-optimal temperatures) were gradually displaced on the land surface by more complex photosynthetic life (with a narrower temperature window for growth). We use a simple modelling exercise to highlight the critical (but neglected) importance of the temperature sensitivity of the biotic weathering enhancement factor and discuss the likely values of key parameters in relation to both experiments and the results of complex climate models. We show how the terrestrial biosphere’s capacity to sustain a given level of silicate-weathering-induced CO2 draw-down is critical to the temperature/greenhouse forcing at which SBE initiation is conceivable. We do not dispute the importance of low degassing rate and other tectonic factors, but propose that the unique feature of the Neoproterozoic was biology’s capacity to tip the system over the edge into a runaway ice-albedo feedback; compensating for the self-limiting decline in weathering rate during the temperature decrease on the approach to glaciation. Such compensation was more significant in the Neoproterozoic than the Phanerozoic due, ultimately, to changes in the species composition of the weathering interface over the course of evolutionary time.

Download Full-text

Evolution of Land Plants

Evolutionary Biology ◽

10.1093/obo/9780199941728-0119 ◽

2019 ◽

Author(s):

Charles C. Davis ◽

Sarah Matthews

Keyword(s):

Global Economy ◽

Vascular System ◽

Aquatic Organisms ◽

Land Plant ◽

Climatic Conditions ◽

Land Plants ◽

Late Devonian ◽

Middle Ordovician ◽

Below Ground ◽

Plant Form

The colonization of land by plants was one of the most important events in the earth’s history, setting the stage for the greening of the continents, increased oxygenation of the atmosphere, and the provision of food and habitat for the animals and microorganisms that evolved in parallel—and in many cases, diversified in their shadows. They are the foundation of agriculture and the source of timber, fibers, pharmaceuticals, and psychoactives. Fossilized plants, in particular, drive our global economy, being the source of coal, petroleum, and natural gas. And living plants represent huge above- and below-ground (as roots and microalgae) carbon sinks. Continental colonists who appeared before land plants (embryophytes) included prokaryotic microbes, eukaryotic microalgae, and fungi. The conditions necessary for colonization—sufficient areas of stable land accessible to marine and aquatic organisms, formation of soils, and equable atmospheric and climatic conditions—appear to have been established approximately 540–440 million years ago (ma; Cambrian and Ordovician). By about 470–460 ma (middle Ordovician), plant microfossils first appear in the fossil record, including spores, cuticular fragments, and tracheid cells. Early plant micro- and macrofossils, when considered together, displayed adaptations that facilitated survival on land, including coatings to reduce desiccation, stomata to facilitate gas exchange (in all lineages but liverworts), and specialized cells such as tracheids for the movement of water and nutrients (precursors of a vascular system). By about 410 ma (late Silurian to early Devonian), vegetation comprising small plants with a well-developed vascular system was establishing itself on multiple continents. From about 390–360 ma (middle to late Devonian), the number of species increased rapidly, and by 360 ma the major extant lineages of land plants were established. Major innovations in plant form began to appear, including the capacity to attain great height and size, and in the late Devonian period, the evolution of seeds. The seed provided protection during periods of dormancy and facilitated survival at greater distances from water. These events were followed during the Cretaceous/Cenozoic by one of the most spectacular radiations of any terrestrial clade: the rise of the angiosperms, which in the 21st century constitute about 90 percent of all land plant diversity.

Download Full-text