Fossil woods from the Eocene of Corcovado, Argentinean Patagonia: geological setting and conifer diversity

IAWA Journal ◽  
2021 ◽  
pp. 1-15
Author(s):  
Roberto R. Pujana ◽  
Inés Aramendía ◽  
Juan L. García Massini ◽  
Sol Noetinger
Keyword(s):  
Species Richness ◽  
Fossil Wood ◽  
Conifer Species ◽  
Stratigraphic Unit ◽  
Geological Setting ◽  
Argentinean Patagonia ◽  
Conifer Wood

Abstract Eocene paleofloras of Patagonia are diverse and increasingly known. A new assemblage of fossil wood has been recovered from Eocene sediments in Corcovado, western Argentinean Patagonia. The lithological succession (formerly Arroyo Lyn Formation sensu Pesce 1979) is correlated with the Huitrera Formation. The specimens were mostly found embedded in sandstones and conglomerates. One-third of the assemblage are conifers and studied herein. We found four taxonomic types: Agathoxylon cf. antarcticum (Araucariaceae), Phyllocladoxylon antarcticum (Podocarpaceae), Podocarpoxylon dusenii (Podocarpaceae), and Cupressinoxylon hallei (Cupressaceae or Podocarpaceae). The presence of four taxonomic units among only 7 specimens suggests a significant conifer species richness in the assemblage. Araucariaceae and dominant Podocarpaceae are usually found in previously described conifer wood assemblages from the Eocene of Patagonia andAntarctica. The diversity of the conifer assemblage in Corcovado is very similar to that found at Laguna del Hunco (these two localities are 170 km distant), also from the Huitrera Formation. This is consistent with the proposal that the bearing sediments of both localities are from the same stratigraphic unit.

scholarly journals Conifer wood assemblage dominated by Podocarpaceae, early Eocene of Laguna del Hunco, central Argentinean Patagonia

PhytoKeys ◽  
2020 ◽  
Vol 156 ◽  
pp. 81-102
Author(s):  
Roberto R. Pujana ◽  
Peter Wilf ◽  
Maria A. Gandolfo
Keyword(s):  
Growth Ring ◽  
Light Availability ◽  
Pollen Grains ◽  
Early Eocene ◽  
Single Specimen ◽  
Uniform Temperature ◽  
Mature Trees ◽  
Argentinean Patagonia ◽  
Extinct Group ◽  
Conifer Wood

During the early Eocene, Patagonia had highly diverse floras that are primarily known from compression and pollen fossils. Fossil wood studies from this epoch are scarce in the region and largely absent from the Laguna del Hunco flora, which has a highly diverse and excellently preserved compression assemblage. A collection of 26 conifer woods from the Laguna del Hunco fossil-lake beds (early Eocene, ca. 52 Ma) from central-western Patagonia was studied, of which 12 could be identified to genus. The dominant species is Phyllocladoxylon antarcticum, which has affinity with early-diverging Podocarpaceae such as Phyllocladus and Prumnnopitys. A single specimen of Protophyllocladoxylon francisiae probably represents an extinct group of Podocarpaceae. In addition, two taxonomic units of cf. Cupressinoxylon with putative affinity to Podocarpaceae were found. Diverse Podocarpaceae taxa consistent with the affinities of these woods were previously reported from vegetative and reproductive macrofossils as well as pollen grains from the same source unit. Some of the woods have galleries filled with frass. Distinct growth ring boundaries indicate seasonality, inferred to represent seasonal light availability. Growth ring widths suggest that the woods came from mature trees, whereas the widths and types of some rings denote near-uniform temperature and water availability conditions.

Fossil woods from the Eocene–Oligocene (Río Turbio Formation) of southwestern Patagonia (Santa Cruz province, Argentina)

IAWA Journal ◽  
2019 ◽  
Vol 40 (3) ◽  
pp. 596-S3 ◽  
Author(s):  
Roberto R. Pujana ◽  
Daniela P. Ruiz
Keyword(s):  
New Species ◽  
Taxonomic Composition ◽  
Fossil Wood ◽  
Age Difference ◽  
Santa Cruz ◽  
Isotopic Dating ◽  
Stratigraphic Unit ◽  
Genus Level ◽  
Fossil Leaves ◽  
A New Species

ABSTRACTOver 80 samples of fossil woods were collected from numerous outcrops of the Río Turbio Formation, southwestern Patagonia. Preservation of the woods is variable and only about half of these samples could be identified to genus level. The assemblage consists of six types of conifers and four types of dicotyledons, one of them a new species of Caldcluvioxylon (Cunoniaceae). We provide an emended diagnosis of Caldcluvioxylon. A previously described fossil wood from this stratigraphic unit, thought to have affinity with Proteaceae, was re-examined and is described herein as Scalarixylon romeroi sp.nov. Other families recognized in the Río Turbio Formation wood assemblage are Araucariaceae, Podocarpaceae, and Nothofagaceae. Differences in the taxonomic composition of the upper and lower members of the Río Turbio Formation are consistent with the age difference between them according to recent isotopic dating. The diversity of fossil wood is also consistent with the fossil leaves and pollen from each stratigraphic level and most of the taxa are shared with coeval Antarctic fossil wood floras.

Dominance determines fish community biomass in a temperate seagrass ecosystem

2019 ◽  
Author(s):  
Aaron Matthius Eger ◽  
Rebecca J. Best ◽  
Julia Kathleen Baum
Keyword(s):  
Species Richness ◽  
Ecosystem Function ◽  
Fish Community ◽  
Prey Capture ◽  
Fish Communities ◽  
Functional Trait ◽  
Ecosystem Functions ◽  
Community Biomass ◽  
Ecosystem Valuation ◽  
Species Abundances

Biodiversity and ecosystem function are often correlated, but there are multiple hypotheses about the mechanisms underlying this relationship. Ecosystem functions such as primary or secondary production may be maximized by species richness, evenness in species abundances, or the presence or dominance of species with certain traits. Here, we combined surveys of natural fish communities (conducted in July and August, 2016) with morphological trait data to examine relationships between diversity and ecosystem function (quantified as fish community biomass) across 14 subtidal eelgrass meadows in the Northeast Pacific (54° N 130° W). We employed both taxonomic and functional trait measures of diversity to investigate if ecosystem function is driven by species diversity (complementarity hypothesis) or by the presence or dominance of species with particular trait values (selection or dominance hypotheses). After controlling for environmental variation, we found that fish community biomass is maximized when taxonomic richness and functional evenness is low, and in communities dominated by species with particular trait values – those associated with benthic habitats and prey capture. While previous work on fish communities has found that species richness is positively correlated with ecosystem function, our results instead highlight the capacity for regionally prevalent and locally dominant species to drive ecosystem function in moderately diverse communities. We discuss these alternate links between community composition and ecosystem function and consider their divergent implications for ecosystem valuation and conservation prioritization.

Functional evenness of bird communities varies along the elevational gradient in Europe: Conservation implications

2019 ◽  
Author(s):  
Federico Morelli ◽  
Yanina
Keyword(s):  
Species Richness ◽  
Elevation Gradient ◽  
Bird Species ◽  
Elevational Gradient ◽  
Negative Association ◽  
Bird Communities ◽  
Breeding Bird ◽  
Bird Species Richness ◽  
Large Spatial Scale ◽  
Functional Evenness

ContextThe negative association between elevation and species richness is a well-recognized pattern in macro-ecology. ObjectivesThe aim of this study was to investigate changes in functional evenness of breeding bird communities along an elevation gradient in Europe. MethodsUsing the bird data from the EBCC Atlas of European Breeding Birds we estimated an index of functional evenness which can be assumed as a measure of the potential resilience of communities.ResultsOur findings confirm the existence of a negative association between elevation and bird species richness in all European eco regions. However, we also explored a novel aspect of this relationship, important for conservation: Our findings provide evidence at large spatial scale of a negative association between the functional evenness (potential community resilience) and elevation, independent of the eco region. We also found that the Natura2000 protected areas covers the territory most in need of protection, those characterized by bird communities with low potential resilience, in hilly and mountainous areas.ConclusionsThese results draw attention to European areas occupied by bird communities characterized by a potential lower capacity to respond to strong ecological changes, and, therefore, potentially more exposed to risks for conservation.

Plant diversity and species richness of Ljubljana marsh grasslands under the influence of different cutting and fertilizing regimes

2009 ◽  
Vol 57 (2) ◽  
pp. 197-203 ◽  
Author(s):  
T. Sinkovč
Keyword(s):  
Species Richness ◽  
Plant Diversity ◽  
Grassland Management ◽  
Botanical Composition ◽  
Significant Negative Effect ◽  
Negative Effect ◽  
Cutting Regimes ◽  
N Rates ◽  
Exploitation Intensity ◽  
Plot Design

The botanical composition of grasslands determines the agronomic and natural values of swards. Good grassland management usually improves herbage value, but on the other hand it frequently decreases the plant diversity and species richness in the swards. In 1999 a field trial in a split-plot design with four replicates was therefore established on the Arrhenatherion type of vegetation in Ljubljana marsh meadows in order to investigate this relationship. Cutting regimes (2 cuts — with normal and delayed first cut, 3 cuts and 4 cuts per year) were allocated to the main plots and fertiliser treatments (zero fertiliser — control, PK and NPK with 2 or 3 N rates) were allocated to the sub-plots. The results at the 1 st cutting in the 5 th trial year were as follows: Fertilising either with PK or NPK had no significant negative effect on plant diversity in any of the cutting regimes. In most treatments the plant number even increased slightly compared to the control. On average, 20 species were listed on both unfertilised and fertilised swards. At this low to moderate level of exploitation intensity, the increased number of cuts had no significant negative effect on plant diversity either (19 species at 2 cuts vs. 20 species at 3 or 4 cuts). PK fertilisation increased the proportion of legumes in the herbage in the case of 2 or 3 cuts. The proportion of grasses in the herbage increased in all the fertilisation treatments with an increased numbers of cuts. Fertiliser treatment considerably reduced the proportion of marsh horsetail ( Equisetum palustre ) in the herbage of the meadows. This effect was even more pronounced at higher cut numbers. The proportion of Equisetum palustre in the herbage was the highest in the unfertilised sward with 2 cuts (26.4 %) and the lowest in the NPK-fertilised sward with 4 cuts (1.4%).

Linking fish and crustacean taxonomic composition with seasonal contrasts in the soft-bottom intertidal zone

2020 ◽  
Author(s):  
M. A. Gondal ◽  
S. Iqbal ◽  
U. Atique ◽  
N. U. Saher ◽  
N. A. Qureshi ◽  
...  
Keyword(s):  
Species Richness ◽  
Water Temperature ◽  
Fish Species ◽  
Diversity Index ◽  
Taxonomic Composition ◽  
Primary Objective ◽  
Negative Effect ◽  
Fish Species Composition ◽  
One Year ◽  
Sw Monsoon

Abstract The primary objective of this study was to investigate the seasonal fish and crustacean variations concerning taxonomic composition, species richness, and diversity in sandy beach habitat. For this purpose, we investigated the Sonmiani Hor lagoon area during four distinct seasons, i.e., northeast (NE) monsoon, pre-monsoon, south-west (SW) monsoon, and post-monsoon for one year. During each haul, the net was pulled about 100m along the beach in 0.5m depth. The results showed a strong linear correlation between the diversity index and equitability in fishes (r = 0.978). The diversity index was strong negatively correlated with the abundance and biomass (r = -0.978, -0.972, respectively). The physical attributes like sea surface water temperature and salinity showed a strong negative effect on species assemblages (r = -0.981 and -0.943, respectively). The mean air and water temperature illustrated approximately 3°C difference during NE and pre-monsoon seasons. However, salinity, pH, and electrical conductivity did not show any significant seasonal variabilities. Under the ecological indices, the fish species displayed higher diversity (H’ = 3.19) during SW monsoon, whereas the lowest diversity was observed during pre-monsoon (H’ = 1.58). The equitability and species richness, however, remained more noticeable during SW monsoon (J’ = 0.81). The total number of individuals of fish and crustaceans reached 4799 with 3813 fish individuals and 986 individuals of crustaceans. A total of 27 families of fish while five crustacean families comprising of 30 genera and 38 fish species while ten genera and 17 species of crustaceans were recorded. Liza subviridis displayed the highest abundance among the sampled fish species. In conclusion, fish species constituted a significant part of the coastal fauna in the study area. The seasonal variations displayed distinct variations in fish species composition and diversity.

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