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Imaggeo on Mondays: One of the oldest evergreen rainforests in the world

Imaggeo on Mondays: One of the oldest evergreen rainforests in the world

A blazing sky and shimmers cast by water ripples frame the spectacular beauty of one of the world’s oldest treasures: an evergreen rainforest in Thailand. Today’s featured image was captured by Frederik Tack, of the Institute for Space Aeronomy in Brussels.

This picture was taken during sunset between the limestone mountains with the sunlight reflecting on beautiful Ratchaprapha lake in Khao Sok National Park.

Khao Sok National Park is one of the oldest evergreen rainforests in the world since Thailand has remained in a similar equatorial position throughout the last 160 million years. The climate in the area has been relatively unaffected by ice ages, as the landmass is relatively small and has seas on both sides. Even whilst other places on the planet were suffering droughts, the Khao Sok region still received enough rainfall to sustain the forest.

Khao Sok is also famous for its vertiginous limestone cliffs or ‘karst’ mountains. In most of the region, ground level is about 200m above sea level with the average mountain heights around 400m. The tallest peak in the National Park is 960m high. The national park area is inhabited by a large range of mammals such as tigers, elephants, tapirs and many monkey species. Birds such as hornbills, banded pittas and great argus are as well forest residents. Less commonly seen reptiles include the king cobra, reticulated python, and flying lizards.

One of the most interesting areas is stunningly beautiful Cheow Lan or Ratchaprapha Lake in the heart of the National Park. It is an 165-square-kilometre artificial lake, created in 1982, by the construction of Ratchaprapha Dam as a source of electricity.

By Frederik Tack, of the Institute for Space Aeronomy in Brussels

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

How certain plants survive mass extinction events: study

How certain plants survive mass extinction events: study

We often read about Earth’s mass extinction events and how they wiped out vast numbers of animal species, leaving survivors to evolve and repopulate the planet. But it’s rarer to hear about how plants managed these catastrophes.

A new study published last month by a team at University College Dublin, Ireland, in the journal Nature Plants shows how plants with thicker, heavier leaves were more likely to survive the Triassic-Jurassic mass extinction caused by an episode of global warming 200 million years ago – around the time when dinosaurs came to dominate the planet. The extinction event is known to have had a massive impact on life, both on land and in the oceans, with an estimated half of species on Earth going extinct at the time.

“Previously we knew a bit about plant survival in terms of their abundance – whether they are present or absent in fossil record,” says the study’s lead author Wuu Kuang Soh, of University College Dublin, “but we didn’t know how they survived or the intrinsic factors of plants that contributed to their survival.”

By looking at fossilized leaves of two plant groups uncovered in Greenland, the authors suggest that the reason for some plants’ survival is that those with heavier leaves were more resilient to environmental stressors such as high air temperature and rising carbon dioxide.

According to Barry Lomax, a lecturer in Environmental Science at the University of Nottingham, UK, who was not involved in the research, “being able to establish that different plant groups respond differently to stress, and that their capacity to adapt to this stress is reflected in their propensity for survival, is a great piece of detective work.”

New proxy development

The work presented in this study – a joint research effort by University College Dublin and Macquarie University, Australia – relied heavily on the development of a new proxy i.e. a physical characteristic which is used to infer details about some related, but immeasurable, trait. By showing how the thickness of a plant’s leaf cuticle (the protective layer covering a leaf) is related to the leaf mass per unit area (LMA) in modern leaves, the team were able to use their fossils to identify how heavy the paleo leaves were for their size.

Macrofossil of 200 million years old Triassic ginkgo, Sphenobaiera spectabilis. Used with permission of the study authors (Credit: Mark Wildham).

For some scientists, this development itself is the study’s highlight. “I think the key finding of the work is that it gives us another set of tools to unpick how plants have responded to large scale perturbations in the carbon cycle which have influenced climate,” says Lomax.

By using the new proxy for LMA the authors were able to look at changes in two plant groups – Ginkoales (an gymnosperm order – see image) and Bennettitales (a now extinct order of seed plant)– across the Triassic-Jurassic mass extinction, and discover their opposing fates; the former flourishing and the latter experiencing sharp ecological decline.

“We found that plants with higher LMA had a higher chance of survival than plants with lower LMA during this global warming induced mass extinction event” says lead author Soh.

Commenting on the study, Charilaos Yiotis, a plant physiologist at University College Dublin who did not participate in the research, says that “under the greenhouse conditions of the Triassic-Jurassic Boundary – or, may I add, under near-future greenhouse conditions – plants with fast leaf turnover rates (low LMA) are outcompeted by those adopting more “conservative” strategies like robust, low turnover leaves (high LMA).” The turnover rate Yiotis refers to is the time taken for leaves to be produced and then fall.

“The spectrum describes how “fast” or “slow” the plant is turning over its nutrient resources,” adds Dana Royer, a paleobotanist at Weslayan University, Connecticut, who peer-reviewed the paper for Nature. “At the fast-return end (low LMA), plants have high photosynthetic rates, high nutrient contents, short-lived (deciduous, for example) and cheaply built leaves. This is the live-fast-die-young strategy. At the slow-return end (high LMA), plants show the reverse.”

The current mass extinction

The study’s findings are important in relation to the sixth mass extinction event which is currently underway. Scientists believe that a similar extinction process to those in the past is now taking place, as the variety of life on land gives way to the seemingly unstoppable human developments of agriculture, industry, and urbanisation. By looking at the paleo-evidence the authors tentatively suggest that today’s plant communities which host thicker, heavier leaves (high LMA) may be better adapted to deal with the current episode of anthropogenic warming, and therefore have a better chance of future ecological success than plants with lighter leaves (low LMA).

“More specifically, plants that can have leaves with both low and high LMA appear to do well after surviving a catastrophic mass extinction episode,” says Soh. “Our finding is important because it means that plants with flexibility in LMA will be the favourite to flourish during future global warming.”

“A shift to higher LMA is common for plants when they are exposed to high CO2” says Royer, “so the fact that the authors are finding the same response in a “natural” experiment – albeit 200 million years ago – lends support to the idea that we should expect a similar response in our own future.”

Further looking to the future, University College Dublin’s Charilaos Yiotis finds it alarming that most plants of economic importance today would probably never have made it through the Triassic-Jurassic Boundary.

“At a time where humanity’s biggest challenge is to feed an ever-growing human population,” he says, “this study should make us think again about how big a threat climate change is to future food security.”

By Conor Purcell, a Science & Nature Writer with a PhD in Earth Science.

Conor has previously worked with the authors of this paper, but not on the project itself. He can be found on twitter @ConorPPurcell and some of his other articles at cppurcell.tumblr.com.

References

Soh, W.K., Wright, K.L, Bacon, T.I., et al., Palaeo leaf economics reveal a shift in ecosystem function associated with the end-Triassic mass extinction event, Nature Plants, 3, doi:10.1038/nplants.2017.104, 2017.

Editor’s note: This blog post provides a summary to a research paper that is paywalled, unlike other scientific articles featured on GeoLog. The EGU supports and promotes open access, publishing 17 open access journals and having endorsed Open Access 2020, an initiative to promote the large-scale transition to open access publishing. Since research in the realm of palaeontology and evolutionary biology is rarely featured on GeoLog, an exception was made on this occasion to publish a story on a scientific paper not accessible to all. The lead author of the study is happy to be contacted with questions about the research; if you’d like to find out more please email Wuu Kuang Soh (wuukuang@gmail.com).

 

 

Imaggeo on Mondays: The unique bogs of Patagonia

Imaggeo on Mondays: The unique bogs of Patagonia

Patagonia, the region in southernmost tip of South America, is as diverse as it is vast. Divided by the Andes, the arid steppes, grasslands and deserts of Argentina give way to the temperate rainforests, fjords and glaciers of Chile. Also on the Chilean side are rolling hills and valleys of marshy topography: Patagonia’s bogs. Today, Klaus-Holger Knorr, a researcher at the University of Münster’s Institute for Landscape Ecology, tells us about what makes these peatlands so unique.

This picture shows an ombrotrophic, oceanic bog at the Seno Skyring Fjord, Patagonia, Chile. It is a view from the inner part of the peatland south toward the shore of the Fjord, in the background Isla Escapada and the Gran Campo ice field. Ombrotrophic bogs are peatlands (accumulations of more or less decomposed plant material which collect in a water-saturated environment) receiving their water and nutrients solely from the atmosphere, i.e. by rain, wet and dry deposition.

Similar to their Northern counterparts in Canada, Northern US, Fennoscandia or Siberia, these southern Patagonian peatlands  formed after the last deglaciation and accumulated huge amounts of carbon as peat.

Peatlands cover only about 3 % of the global land surface but store about a third of the soil carbon pool. Peat is formed primarily as there is excess rainfall, peat soils are water logged, oxygen gets depleted, and decomposition is limited. Pristine, undisturbed peatlands can store as much as 10-50 g carbon per square meter and year.

What makes the peatlands in Patagonia  particularly interesting  is their pristine, undisturbed conditions and extremely low input of nutrients from the atmosphere, compared to the high input into sites in densely settled or industrial regions. This allows studies of peatland functioning under natural conditions and absence of anthropogenic impacts.

Moreover, peatlands in Patagonia harbor a specific kind of vegetation, including cushion forming plants such as Astelia pumila and Donatia fascicularis. These cushion forming plants have a very low above ground biomass but an extremely large rooting system, reaching down to a depth of >2 m in case of A. pumila. As these roots act as conduits for oxygen to sustain viability of the roots in the water logged peat, they have been shown to aerate large parts even of the saturated zone, thereby impeding high methane production and emission. Oxygen supply by these roots is even hypothesized to stimulate peat decomposition and thereby lead to particularly decomposed peat under cushion plant cover.

Another plant species only occurring in peatlands of Southern Patagonia, a small conifer named Lepidothamnus fonkii, has developed a particular strategy to overcome nutrient deficiency: it has formed a close association with bacteria being able fix atmospheric nitrogen to fulfill the demand of nitrogen for growth. While such nitrogen fixation is well known for legumes and some tree species, it has rarely been found for conifers.

A further important factor for peatlands in Patagonia, leading to the term “oceanic bogs”, is the fact that these peatlands in close vicinity to the seashore receive high inputs of sea salts from sea spray, modifying availability of associated elements such as Sodium, Calcium, Magnesium, Sulphur and others.

By Klaus-Holger Knorr, researcher at the University of Münster’s Institute for Landscape Ecology

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

 

Imaggeo on Mondays: Measuring the wind direction

Imaggeo on Mondays: Measuring the wind direction

Remote, rugged, raw and beautiful beyond measure, the island of South Georgia rises from the wild waters of the South Atlantic, 1300 km south east of the Falkland Islands.

The Allardyce Range rises imposingly, south of Cumberland Bay, dominating the central part of the island. At its highest, it towers 2935 m (Mount Paget) above the surrounding landscape. In the region of 150 glaciers carve their way down the rocky peaks, toward craggy clifftops and the emerald green waters of the ocean.

Geologically speaking, the territory is unique. South Georgia sits atop the place where the South American Plate and the Scotia Plate slide past one another; exactly which can claim ownership of the mountainous outpost is highly debated.

As East and West Gondwana split, about 185 million years ago, South Georgia was pulled away from Tierra del Fuego, an archipelago off the southernmost tip of mainland South American, and experienced severe volcanism.

The island is so remote and exposed, it creates its own weather system. It sits in the path of very strong winds, the westerlies, which flow through the subtropical highs in the Southern Hemisphere.  As air flows over the high mountains of South Georgia, they generate atmospheric gravity waves (which transfer energy from the troposphere – the layer closest to the Earth’s surface – to the upper layers of the atmosphere, including the stratosphere, where the ozone layer is found). Atmospheric gravity waves are responsible for the transfer of considerable amounts of energy over large distances, and thus have a substantial impact on weather and climate.

It is precisely to study South Georgia’s atmospheric gravity waves that Andrew Moss, the author of today’s photograph, journeyed to the remote island back in January 2015 as part of the South Georgia Wave Experiment (SG-WEX). The project was led by the University of Bath, in collaboration with the British Antarctic Survey, the University of Leeds, and the UK Met Office. As part of this project Andrew worked with a colleague at the University of Bath (UK) to release radiosondes – a small, expendable instrument package that is suspended below balloon which measures pressure, temperature and humidity – to better understand the atmospheric conditions and measure atmospheric gravity-wave activity above the island.

The chilly, often cloudy and wet landscape is a wildlife haven. It is home to a staggering five million seals and 65 million seabirds.  The wildlife is so rich, on and off the island, that large swathes of South Atlantic waters surrounding South Georgia are protected and onshore activities which might disturb wildlife require permits.

“Over the course of the two-week field campaign, King Penguins, fur seals and elephant seals often surrounded us while we worked,” describes Andrew.  “During the trip, I captured a group of penguins, with their backs to the wind, clustered together on a windy day.”

References and further reading:

Imaggeo on Mondays: Atmospheric gravity waves (GeoLog, EGU Blogs, April 2017)

Hoffmann, L., Grimsdell, A. W., and Alexander, M. J.: Stratospheric gravity waves at Southern Hemisphere orographic hotspots: 2003–2014 AIRS/Aqua observations, Atmos. Chem. Phys., 16, 9381-9397, https://doi.org/10.5194/acp-16-9381-2016, 2016.

South Georgia & the South Sandwich Islands Government website

Radiosondes – a guide by the National Weather Service (NOAA)

Find out more about Andrew, here: https://www.researchgate.net/profile/Andrew_Moss8