Fire and Late Oligocene to Mid-Miocene peat mega-swamps of south-eastern Australia: a floristic and palaeoclimatic interpretation

2016 ◽  
Vol 64 (8) ◽  
pp. 609 ◽  
Author(s):  
Ian R. K. Sluiter ◽  
David T. Blackburn ◽  
Guy R. Holdgate
Keyword(s):  
New Caledonia ◽  
Regional Scale ◽  
Climatic Conditions ◽  
Mean Annual Precipitation ◽  
Late Oligocene ◽  
Structural Context ◽  
Open Canopy ◽  
Eastern Australia ◽  
Brown Coals ◽  
Gippsland Basin

The Late Oligocene to Mid-Miocene (25–13 million years ago) brown coals of the Gippsland Basin in southern Victoria, Australia, were deposited in peat mega-swamps, unlike any in the world at the present day. The swamps preserve a rich botanical suite of macro- and microfossils, many of which can be identified with plant genera and families present today in Australia, New Caledonia, New Zealand and New Guinea. The peat-forming environments also preserve evidence of past burning in the form of micro-charcoal as well as macro-charcoal, the latter being evident as regional lenses or layers of fusinite, generally in coals of the darkest colour termed dark lithotypes. The presence of micro-charcoal in dark and some other lighter lithotypes indicated that fires also burnt locally, although they may have been extinguished before regional-scale burning occurred. It is also feasible that some peat mega-swamp plant communities dominated by rainforest angiosperm plants may have been fire excluders and prevented widespread fires from developing. Pollen and macrofossil evidence is presented of a distinctive southern conifer and angiosperm flora with an open canopy, primarily associated with the darkest coals that formed in the wettest parts of the peat-forming environment. Elsewhere, swamp forests with a large rainforest component grew on swamps raised appreciably above the regional groundwater table in a structural context akin to the ombrogenous peats of tropical coastal Sumatra and Sarawak. These vegetation types were not fire prone, but may have occasionally burnt at a local scale or at forest margins. Evidence is presented for the existence of seasonal climatic conditions that would appear to have facilitated a drying-out of the peat swamps in the warmest months of the year. A mesothermal climate was invoked where mean annual precipitation was at least 1500 mm, and possibly as much as 2000 mm, and mean annual temperatures were ~19°C.

scholarly journals Remote sensing of <i>Trichodesmium</i> spp. mats in the western tropical South Pacific

2018 ◽  
Vol 15 (16) ◽  
pp. 5203-5219 ◽  
Author(s):  
Guillaume Rousset ◽  
Florian De Boissieu ◽  
Christophe E. Menkes ◽  
Jérôme Lefèvre ◽  
Robert Frouin ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Large Scale ◽  
New Caledonia ◽  
Hot Spot ◽  
Regional Scale ◽  
Atmospheric Correction ◽  
South Pacific ◽  
Aggregation Processes ◽  
Modis Imagery ◽  
Generate Surface

Abstract. Trichodesmium is the major nitrogen-fixing species in the western tropical South Pacific (WTSP) region, a hot spot of diazotrophy. Due to the paucity of in situ observations, remote-sensing methods for detecting Trichodesmium presence on a large scale have been investigated to assess the regional-to-global impact of this organism on primary production and carbon cycling. A number of algorithms have been developed to identify Trichodesmium surface blooms from space, but determining with confidence their accuracy has been difficult, chiefly because of the scarcity of sea-truth information at the time of satellite overpass. Here, we use a series of new cruises as well as airborne surveys over the WTSP to evaluate their ability to detect Trichodesmium surface blooms in the satellite imagery. The evaluation, performed on MODIS data at 250 m and 1 km resolution acquired over the region, shows limitations due to spatial resolution, clouds, and atmospheric correction. A new satellite-based algorithm is designed to alleviate some of these limitations, by exploiting optimally spectral features in the atmospherically corrected reflectance at 531, 645, 678, 748, and 869 nm. This algorithm outperforms former ones near clouds, limiting false positive detection and allowing regional-scale automation. Compared with observations, 80 % of the detected mats are within a 2 km range, demonstrating the good statistical skill of the new algorithm. Application to MODIS imagery acquired during the February-March 2015 OUTPACE campaign reveals the presence of surface blooms northwest and east of New Caledonia and near 20∘ S–172∘ W in qualitative agreement with measured nitrogen fixation rates. Improving Trichodesmium detection requires measuring ocean color at higher spectral and spatial (<250 m) resolution than MODIS, taking into account environment properties (e.g., wind, sea surface temperature), fluorescence, and spatial structure of filaments, and a better understanding of Trichodesmium dynamics, including aggregation processes to generate surface mats. Such sub-mesoscale aggregation processes for Trichodesmium are yet to be understood.

scholarly journals Fire and Its Interactions With Other Drivers Shape a Distinctive, Semi-Arid ‘Mallee’ Ecosystem

2021 ◽  
Vol 9 ◽  
Author(s):  
Michael F. Clarke ◽  
Luke T. Kelly ◽  
Sarah C. Avitabile ◽  
Joe Benshemesh ◽  
Kate E. Callister ◽  
...  
Keyword(s):  
Regional Scale ◽  
Fire Regimes ◽  
Field Studies ◽  
Arid Ecosystems ◽  
Coarse Grained ◽  
Pest Species ◽  
Age Classes ◽  
Eastern Australia ◽  
Animal Communities ◽  
Semi Arid

Fire shapes ecosystems globally, including semi-arid ecosystems. In Australia, semi-arid ‘mallee’ ecosystems occur primarily across the southern part of the continent, forming an interface between the arid interior and temperate south. Mallee vegetation is characterized by short, multi-stemmed eucalypts that grow from a basal lignotuber. Fire shapes the structure and functioning of mallee ecosystems. Using the Murray Mallee region in south-eastern Australia as a case study, we examine the characteristics and role of fire, the consequences for biota, and the interaction of fire with other drivers. Wildfires in mallee ecosystems typically are large (1000s ha), burn with high severity, commonly cause top-kill of eucalypts, and create coarse-grained mosaics at a regional scale. Wildfires can occur in late spring and summer in both dry and wet years. Recovery of plant and animal communities is predictable and slow, with regeneration of eucalypts and many habitat components extending over decades. Time since the last fire strongly influences the distribution and abundance of many species and the structure of plant and animal communities. Animal species display a discrete set of generalized responses to time since fire. Systematic field studies and modeling are beginning to reveal how spatial variation in fire regimes (‘pyrodiversity’) at different scales shapes biodiversity. Pyrodiversity includes variation in the extent of post-fire habitats, the diversity of post-fire age-classes and their configuration. At regional scales, a desirable mix of fire histories for biodiversity conservation includes a combination of early, mid and late post-fire age-classes, weighted toward later seral stages that provide critical habitat for threatened species. Biodiversity is also influenced by interactions between fire and other drivers, including land clearing, rainfall, herbivory and predation. Extensive clearing for agriculture has altered the nature and impact of fire, and facilitated invasion by pest species that modify fuels, fire regimes and post-fire recovery. Given the natural and anthropogenic drivers of fire and the consequences of their interactions, we highlight opportunities for conserving mallee ecosystems. These include learning from and fostering Indigenous knowledge of fire, implementing actions that consider synergies between fire and other processes, and strategic monitoring of fire, biodiversity and other drivers to guide place-based, adaptive management under climate change.

scholarly journals The Indo-Pacific Amalda (Neogastropoda, Olivoidea, Ancillariidae) revisited with molecular data, with special emphasis on New Caledonia

2020 ◽  
Author(s):  
Yuri I. Kantor ◽  
Magalie Castelin ◽  
Alexander Fedosov ◽  
Philippe Bouchet
Keyword(s):  
Gene Flow ◽  
Molecular Analysis ◽  
New Caledonia ◽  
Narrow Range ◽  
Regional Scale ◽  
Molecular Data ◽  
Shell Morphology ◽  
Species Limits ◽  
South West ◽  
Strait Of Malacca

In the ancillariid genus Amalda, the shell is character rich and 96 described species are currently treated as valid. Based on shell morphology, several subspecies have been recognized within Amalda hilgendorfi, with a combined range extending at depths of 150–750 m from Japan to the South-West Pacific. A molecular analysis of 78 specimens from throughout this range shows both a weak geographical structuring and evidence of gene flow at the regional scale. We conclude that recognition of subspecies (richeri Kilburn & Bouchet, 1988, herlaari van Pel, 1989, and vezzaroi Cossignani, 2015) within A. hilgendorfi is not justified. By contrast, hilgendorfi-like specimens from the Mozambique Channel and New Caledonia are molecularly segregated, and so are here described as new, as Amalda miriky sp. nov. and A. cacao sp. nov., respectively. The New Caledonia Amalda montrouzieri complex is shown to include at least three molecularly separable species, including A. allaryi and A. alabaster sp. nov. Molecular data also confirm the validity of the New Caledonia endemics Amalda aureomarginata, A. fuscolingua, A. bellonarum, and A. coriolis. The existence of narrow range endemics suggests that the species limits of Amalda with broad distributions, extending, e.g., from Japan to Taiwan (A. hinomotoensis) or even Indonesia, the Strait of Malacca, Vietnam and the China Sea (A. mamillata) should be taken with caution.

Stand dynamics and species composition control long-term post-fire trends in evapotranspiration and streamflow from South-eastern Australia’s Temperate Eucalyptus forests

2021 ◽  
Author(s):  
Assaf Inbar ◽  
Richard Benyon ◽  
Patrick Lane ◽  
Shyanika Lakmali ◽  
Shane Haydon ◽  
...  
Keyword(s):  
Species Composition ◽  
Forest Dynamics ◽  
Simulation Analysis ◽  
Stocking Density ◽  
Climatic Conditions ◽  
Water Yield ◽  
Multiple Sources ◽  
Acacia Dealbata ◽  
Eastern Australia

&lt;p&gt;Most of the water that ends up in Melbourne&amp;#8217;s water supply catchments originates from wet Eucalyptus forests that are dominated by Eucalyptus regnans, the tallest known angiosperm on earth. Studies had shown that catchments that are dominated by these forests can experience a significant long-term (&gt;100 years) reduction in streamflow after a stand-replacing fire, which was attributed to higher water-use of the dense overstory regrowth. However, despite several lines of evidence, the direction, extent and duration of post-fire hydrological behaviour vary significantly between catchments and between fire events. Here we propose that this variability is caused by initial stocking density and species composition after the fire, and the climatic conditions that prevail during forest regeneration that affect tree growth and mortality rates. In order to test the hypothesis, we formulated an ecohydrological model that simulates hydrology, growth and forest dynamics of E. regnans and Acacia dealbata, which are known to compete for resources during the initial stages of vegetation recovery. The new model shows high skill in predicting long-term streamflow when compared to observations using multiple sources of data. Simulation analysis shows that the direction, extent and duration of post-fire hydrological behaviour are sensitive to initial stocking density and to the relative abundance of species that regenerate after the fire, which influence the rate of self-thinning during stand development. Furthermore, simulation results show that the observed long-term reduction in streamflow is less likely to occur when the forest would have been less dense before the fire, which theoretically could only occur when a high proportion of the short-lived A. Dealbata regenerated after the previous fire. This highlights the importance of including mechanisms that control the effect of species composition on forest dynamics when modelling the effect of possible future climatic scenarios on water yield.&lt;/p&gt;

Net Primary Production in the Shortgrass Steppe

2008 ◽  
Author(s):  
William K. Lauenroth ◽  
Daniel G. Milchunas
Keyword(s):  
Global Change ◽  
Primary Production ◽  
Net Primary Production ◽  
Regional Scale ◽  
Ecosystem Dynamics ◽  
Shortgrass Steppe ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
Spatial And Temporal Patterns ◽  
Temporal And Spatial

Net primary production (NPP), the amount of carbon or energy fixed by green plants in excess of their respiratory needs, is the fundamental quantity upon which all heterotrophs and the ecosystem processes they are associated with depend. Understanding NPP is therefore a prerequisite to understanding ecosystem dynamics. Our objectives for this chapter are to describe the current state of our knowledge about the temporal and spatial patterns of NPP in the shortgrass steppe, to evaluate the important variables that control NPP, and to discuss the future of NPP in the shortgrass steppe given current hypotheses about global change. Most of the data available for NPP in the shortgrass steppe are for aboveground net primary production (ANPP), so most of our presentation will focus on ANPP and we will deal with belowground net primary production (BNPP) as a separate topic. Furthermore, our treatment of NPP in this chapter will ignore the effects of herbivory, which will be covered in detail in chapter 16. Our approach will be to start with a regional-scale view of ANPP in shortgrass ecosystems and work toward a site-scale view. We will begin by briefly placing ANPP in the shortgrass steppe in its larger context of the central North American grassland region. We will then describe the regional-scale patterns and controls on ANPP, and then move to the site-scale patterns and controls on ANPP. At the site scale, we will describe both temporal and spatial dynamics, and controls on ANPP as well as BNPP. We will then discuss relationships between spatial and temporal patterns in ANPP and end the chapter with a short, speculative section on how future global change may influence NPP in the shortgrass steppe. Temperate grasslands in central North America are found over a range of mean annual precipitation from 200 to 1200 mm.y–1 and mean annual temperatures from 0 to 20 oC (Lauenroth et al., 1999). The widely cited relationship between mean annual precipitation and average annual ANPP allows us to convert the precipitation gradient into a production gradient (Lauenroth, 1979; Lauenroth et al., 1999; Noy-Meir, 1973; Rutherford, 1980; Sala et al., 1988b).

scholarly journals Deepwater Indo-Pacific species of the snake-eel genus Ophichthus (Anguilliformes: Ophichthidae), with the description of nine new species

Zootaxa ◽  
2010 ◽  
Vol 2505 (1) ◽  
pp. 1 ◽  
Author(s):  
JOHN E. McCOSKER
Keyword(s):  
New Species ◽  
Western Australia ◽  
New Caledonia ◽  
The Philippines ◽  
Junior Synonym ◽  
Identification Key ◽  
Gulf Of Aden ◽  
Eastern Australia ◽  
Pacific Species ◽  
Depth Distributions

The 19 Indo-Pacific species of the snake-eel genus Ophichthus (family Ophichthidae, subfamily Ophichthinae) that live at or below 200 m are reviewed. Included are: Ophichthus aphotistos, O. brachynotopterus, O. echeloides, O. exourus, O. genie, O. kunaloa, O. megalops, O. mystacinus, O. serpentinus, O. urolophus, and nine new species which are described: O. alleni from 115–200 m off eastern Australia; O. aniptocheilos from 391–421 m off Tonga; O. congroides from 300 m off the Tuamotu Islands; O. hirritus from 600 m off the Seychelle Islands; O. humanni from 254–300 m off Vanuatu; O. ishiyamorum from 258–400 m off the Gulf of Aden, Somalia; O. lentiginosus from 400 m off Vanuatu and New Caledonia; O. microstictus from 362–450 m off Tonga, Fiji, and possibly New Caledonia; and O. tomioi from 300– 423 m off the Philippines, Marquesas, Fiji, and the Seychelle Islands. The range and depth distributions of the following are expanded to include: O. brachynotopterus to New Caledonia and Vanuatu between 541–580 m; O. mystacinus to Tonga, Fiji, and the Philippines between 371–824 m; and O. urolophus to Western Australia and Indonesia between 40– 420 m. An identification key is provided. Characteristics and the behavior of species of the subgenus Coecilophis, to which all treated species except O. aphotistos belong, is discussed. Ophichthys madagascariensis Fourmanoir (1961) is proposed to be a junior synonym of Pisodonophis cancrivorus (Richardson 1848).

scholarly journals Grania (Annelida: Clitellata: Enchytraeidae) of the Great Barrier Reef, Australia, including four new species and a re-description of Grania trichaeta Jamieson, 1977

Zootaxa ◽  
2009 ◽  
Vol 2165 (1) ◽  
pp. 16-38 ◽  
Author(s):  
PIERRE DE WIT ◽  
EMILIA ROTA ◽  
CHRISTER ERSÉUS
Keyword(s):  
New Species ◽  
Great Barrier Reef ◽  
New Caledonia ◽  
Barrier Reef ◽  
Interspecific Divergence ◽  
Eastern Australia ◽  
New Material ◽  
Voucher Specimens ◽  
The Mean ◽  
Phylogenetic Affinities

This study describes the fauna of the marine enchytraeid genus Grania at two locations on the Australian Great Barrier Reef: Lizard and Heron Islands. Collections were made from 1979 to 2006, yielding four new species: Grania breviductus sp. n., Grania regina sp. n., Grania homochaeta sp. n. and Grania colorata sp. n.. A re-description of Grania trichaeta Jamieson, 1977 based on new material is also included, along with notes and amendments on G. hyperoadenia Coates, 1990 and G. integra Coates & Stacey, 1997, the two latter being recorded for the first time from eastern Australia. COI barcode sequences were obtained from G. trichaeta and G. colorata and deposited with information on voucher specimens in the Barcode of Life database and GenBank; the mean intraspecific variation is 1.66 % in both species, while the mean interspecific divergence is 25.54 %. There seem to be two phylogeographic elements represented in the Great Barrier Grania fauna; one tropical with phylogenetic affinities to species found in New Caledonia and Hong Kong, and one southern (manifested at the more southerly located Heron Island) with affinities to species found in Southern Australia, Tasmania and Antarctica.

Triassic mudstones of the Central North Sea: cross-border characterization, correlation and their palaeoclimatic significance

2020 ◽  
pp. SP494-2019-61
Author(s):  
Stuart G. Archer ◽  
Tom McKie ◽  
Steven D. Andrews ◽  
Anne D. Wilkins ◽  
Matt Hutchison ◽  
...  
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Regional Scale ◽  
Climatic Conditions ◽  
Fluvial Systems ◽  
Correlation Lengths ◽  
Cross Border ◽  
The Uk ◽  
Stratigraphic Nomenclature ◽  
Central North Sea

AbstractThe Triassic of the Central North Sea is a continental succession that contains prolific hydrocarbon-bearing fluvial sandstone reservoirs stratigraphically partitioned by mudstones. Within the Skagerrak Formation of the UK sector, hydrocarbon accumulations in the Judy, Joanne and Josephine Sandstone members are top sealed by the Julius, Jonathan and Joshua Mudstone members, respectively. However, UK and Norwegian stratigraphic correlations have been problematical for decades, largely due to biostratigraphic challenges but also due to the non-uniqueness of the lithotypes and because the cross-border stratigraphic nomenclature differs and has yet to be rationalized. This study focuses on mudstones rather than sandstones to unify cross-border correlation efforts at a regional scale. The mudstone members have been characterized by integrating sedimentological, petrophysical and geophysical data. The facies are indicative of playa lakes that frequently desiccated and preserved minor anhydrite. These conditions alternated with periods of marshy, palustrine conditions favourable for the formation of dolostones. Regional correlations have detected lateral facies changes in the mudstones which are important for their seismically mappable extents, resulting palaeogeographies and, ultimately, their competency as intraformational top seals. Significant diachroneity is associated with the lithological transitions at sandstone–mudstone member boundaries and although lithostratigraphic surfaces can be used as timelines over short distances (e.g. within a field), they should not be assumed to represent timelines over longer correlation lengths. Palaeoclimatic trends are interpreted and compared to those of adjacent regions to test the extent and impact of climate change as a predictive allogenic forcing factor on sedimentation. Mudstone member deposition occurred as a result of the retreat of large-scale terminal fluvial systems during a return to more arid ‘background’ climatic conditions. The cause of the member-scale climatic cyclicity observed within the Skagerrak Formation may be related to volcanic activity in large igneous provinces which triggered the episodic progradation of fluvial systems.

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