Category Archives: Science

More on Wood Wide Web

Plant communications is one of the coolest things in contemporary biology.   All  animal life depends on plants, of course, but plants also turn out to have complex social systems and even intelligence of a non-human sort.  It’s hard for us to understand because, compared to plants, we are “hasty” (as Tolkien so memorably put it.)

In the last twenty years, it has become clear that a forest is not a bunch of trees, but complex network more like a city.  Furthermore, not only the trees, but also the microbes and fungi are part of this amazing communication and transport system.

Researchers from British Colombia have tagged this the “Wood wide web”, which is certainly catchy if not entirely apt.

This summer, an international team report on a global map of forest symbiotes, i.e., the fungal ecology under the ground of forests around the planet [2].  Different trees need different fungi, so a map of the fungi is also a map of the kinds of trees there.

The study finds that there are two major types of microbial symbionts (and therefore, trees), ectomycorrhizal and arbuscular mycorrhizal.  The two different types appear adapted to different climactic conditions. (Actually they found five important classes, but the top two predominate.)

[Caveat:  my grasp of these microbial species is limited, so some of my coments may be confused or confusing.  Please refer to the paper for a full and correct explanation of the findings.]

Ectomycorrhizal trees live in dry high latitudes (places with winter), where decomposition is inhibited in some seasons. arbuscular mycorrhizal trees live in warm wet a seasonal areas (tropics), where decomposition is continuous.  This is visible in the rather clear geographic delineation of areas on the map:  the climate drives the microbes, which determine which trees will thrive where.

Underlying this all is the relationship between the microbial world and trees.  The underground microbes deliver nutrients to the forest, and in exchange, trees deliver sugar (a lot of Carbon!) and other products of photosynthesis to the microbes.  Ectomycorrhizal fungi decompose leaf litter and other materisal deliver Phosphorous and Nitrogen from soils to trees.  Arbuscular mycorrhizal transport Phosphorous from minerals (not depending on decomposition).

Using data from the Global Forest Biodiversity Initiative database, to assemble a map of the types of trees from 1 million recorded locations. The research mapped these species to their known microbial symbiotes, to infer a map of the symbiotes.  The symbiotes were classified into five main groups, which they term “tree symbiotic guilds”.

This dataset was used to investigate correlations of climate soil, topography, estimated decomposition rates, and other variables with these guilds. The data suggest that there is a positive feedback between climate and decomposition, which cause sharp transitions in the cost benefits and efficiency of the different symbiotes.

“The abrupt transitions that we detected between forest symbiotic states along environmental gradients suggest that positive feedback effects may exist between climatic and biological controls of decomposition” ([2], p. 408)

One implication of this hypothesis is that relatively small, gradual changes in climate will lead to rapid changes in the symbiotes and the trees above.  They report simulations of future climate (circa 2070) which predict that the relatively small climate change could result in a 10% decline of ectomycorrhizal trees, which will be replaced with others.

However, the study suggests the close links between the atmosphere, soil, and plant life.

“our finding that climatic controls of decom- position are the best predictors of dominant mycorrhizal associations provides a mechanistic link between symbiont physiology and climatic controls on the release of soil nutrients from leaf litter.” ([2], p. 407)

This hypothesized turnover is potentially important because the ectomycorrhizal fungi are prodigious collectors of Carbon, while arbuscular mycorrhizal release Carbon into the atmosphere.  A large change over from the former to the latter would mean that less CO2 would be equestered by the forests, further accelerating changes to the atmosphere through a positive feedback.

  1. Claire Marshall, Wood wide web: Trees’ social networks are mapped, in BBC News – Science & Environment. 2019.
  2. B. S. Steidinger, T. W. Crowther, J. Liang, M. E. Van Nuland, G. D. A. Werner, P. B. Reich, G. Nabuurs, S. de-Miguel, M. Zhou, N. Picard, B. Herault, X. Zhao, C. Zhang, D. Routh, K. G. Peay, Meinrad Abegg, C.  Yves Adou Yao, Giorgio Alberti, Angelica Almeyda Zambrano, Esteban Alvarez-Davila, Patricia Alvarez-Loayza, Luciana F. Alves, Christian Ammer, Clara Antón-Fernández, Alejandro Araujo-Murakami, Luzmila Arroyo, Valerio Avitabile, Gerardo Aymard, Timothy Baker, Radomir Bałazy, Olaf Banki, Jorcely Barroso, Meredith Bastian, Jean-Francois Bastin, Luca Birigazzi, Philippe Birnbaum, Robert Bitariho, Pascal Boeckx, Frans Bongers, Olivier Bouriaud, Pedro H  S Brancalion, Susanne Brandl, Francis Q. Brearley, Roel Brienen, Eben Broadbent, Helge Bruelheide, Filippo Bussotti, Roberto Cazzolla Gatti, Ricardo Cesar, Goran Cesljar, Robin Chazdon, Han Y. H. Chen, Chelsea Chisholm, Emil Cienciala, Connie J. Clark, David Clark, Gabriel Colletta, Richard Condit, David Coomes, Fernando Cornejo Valverde, Jose J. Corral-Rivas, Philip Crim, Jonathan Cumming, Selvadurai Dayanandan, André L. de Gasper, Mathieu Decuyper, Géraldine Derroire, Ben DeVries, Ilija Djordjevic, Amaral Iêda, Aurélie Dourdain, Nestor Laurier Engone Obiang, Brian Enquist, Teresa Eyre, Adandé Belarmain Fandohan, Tom M. Fayle, Ted R. Feldpausch, Leena Finér, Markus Fischer, Christine Fletcher, Jonas Fridman, Lorenzo Frizzera, Javier G. P. Gamarra, Damiano Gianelle, Henry B. Glick, David Harris, Andrew Hector, Andreas Hemp, Geerten Hengeveld, John Herbohn, Martin Herold, Annika Hillers, Eurídice N. Honorio Coronado, Markus Huber, Cang Hui, Hyunkook Cho, Thomas Ibanez, Ilbin Jung, Nobuo Imai, Andrzej M. Jagodzinski, Bogdan Jaroszewicz, Vivian Johannsen, Carlos A. Joly, Tommaso Jucker, Viktor Karminov, Kuswata Kartawinata, Elizabeth Kearsley, David Kenfack, Deborah Kennard, Sebastian Kepfer-Rojas, Gunnar Keppel, Mohammed Latif Khan, Timothy Killeen, Hyun Seok Kim, Kanehiro Kitayama, Michael Köhl, Henn Korjus, Florian Kraxner, Diana Laarmann, Mait Lang, Simon Lewis, Huicui Lu, Natalia Lukina, Brian Maitner, Yadvinder Malhi, Eric Marcon, Beatriz Schwantes Marimon, Ben Hur Marimon-Junior, Andrew Robert Marshall, Emanuel Martin, Olga Martynenko, Jorge A. Meave, Omar Melo-Cruz, Casimiro Mendoza, Cory Merow, Abel Monteagudo Mendoza, Vanessa Moreno, Sharif A. Mukul, Philip Mundhenk, Maria G. Nava-Miranda, David Neill, Victor Neldner, Radovan Nevenic, Michael Ngugi, Pascal Niklaus, Jacek Oleksyn, Petr Ontikov, Edgar Ortiz-Malavasi, Yude Pan, Alain Paquette, Alexander Parada-Gutierrez, Elena Parfenova, Minjee Park, Marc Parren, Narayanaswamy Parthasarathy, Pablo L. Peri, Sebastian Pfautsch, Oliver Phillips, Maria Teresa Piedade, Daniel Piotto, Nigel C. A. Pitman, Irina Polo, Lourens Poorter, Axel Dalberg Poulsen, John R. Poulsen, Hans Pretzsch, Freddy Ramirez Arevalo, Zorayda Restrepo-Correa, Mirco Rodeghiero, Samir Rolim, Anand Roopsind, Francesco Rovero, Ervan Rutishauser, Purabi Saikia, Philippe Saner, Peter Schall, Mart-Jan Schelhaas, Dmitry Schepaschenko, Michael Scherer-Lorenzen, Bernhard Schmid, Jochen Schöngart, Eric Searle, Vladimír Seben, Josep M. Serra-Diaz, Christian Salas-Eljatib, Douglas Sheil, Anatoly Shvidenko, Javier Silva-Espejo, Marcos Silveira, James Singh, Plinio Sist, Ferry Slik, Bonaventure Sonké, Alexandre F. Souza, Krzysztof Stereńczak, Jens-Christian Svenning, Miroslav Svoboda, Natalia Targhetta, Nadja Tchebakova, Hans ter Steege, Raquel Thomas, Elena Tikhonova, Peter Umunay, Vladimir Usoltsev, Fernando Valladares, Fons van der Plas, Tran Van Do, Rodolfo Vasquez Martinez, Hans Verbeeck, Helder Viana, Simone Vieira, Klaus von Gadow, Hua-Feng Wang, James Watson, Bertil Westerlund, Susan Wiser, Florian Wittmann, Verginia Wortel, Roderick Zagt, Tomasz Zawila-Niedzwiecki, Zhi-Xin Zhu, Irie Casimir Zo-Bi and Gfbi consortium, Climatic controls of decomposition drive the global biogeography of forest-tree symbioses. Nature, 569 (7756):404-408, 2019/05/01 2019.

Batwing dinosaur

This summer a team of Chinese researchers report on a new flying dinosaur, tagged Ambopteryx ongibrachium, which has very batlike wings and probably flew like a flying squirrel [2].

This find means that there are multiple (at least four) different families of ancient animals that could fly (not counting insects, and not counting pterosaurs which also had membranous wings.).  Most of these families died out, only one family evolved into birds. (And bats evolved later.)

Flying is such a good idea, it has emerged multiple times!

The fossil comes from the rich beds of Northwest China, which are producing so many new discoveries.

This find confirms an earlier fossil that was controversial because no theropod was known to have a pterosaur like wing.  But obviously, this group does!

“Who knows what we might find.” Prof. Steve Brusatte quoted in the NYT [1])

  1. Lucas Joel (2019) Dinosaur With Bat Wings Was More Than Legend. New York Times,
  2. Min Wang, Jingmai K. O’Connor, Xing Xu, and Zhonghe Zhou, A new Jurassic scansoriopterygid and the loss of membranous wings in theropod dinosaurs. Nature, 569 (7755):256-259, 2019/05/01 2019.

Small Tyrannosaur Form New Mexico

Tyrannosaurus Rex – the name alone is the epitome of why we love dinosaurs.  Pompous and reactionary, a mucked up adaptation of Greek and Latin roots—how can an animal with this moniker not appeal to six year olds of all ages?

These days, we have found that T. rex is part of a large family of species, that flourished up until the Chicxulub impact.   We know relatively little about the ancestors of T. rex and their large contemporaries, because the period 100-80 Mya saw high sea levels which did not preserve as many fossils (at least for land animals).  During this poorly represented period, tyrannosaurs evolved from small, fairly ordinary hunters to the monstrously large top predators we all know and love.

Still, each year, we find more branches on this family tree.   This spring, a team of researchers report on yet another small ancestor of T. rex [2].  Found in mid-Cretaceous deposits in New Mexico, the new species is tagged Suskityrannus (Suski is the Zuni word for ‘coyote’ – Coyote Tyrant).

The animal was medium sized, maybe 3 meters long, As such, it is an intermediate size between tiny ancestors and the later megaspecies.  The fossils are interesting because they exhibit characteristics including the skull and feet that are similar to the later giants.  This indicates that many aspects of the T. rex body plan developed much earlier in smaller bodied animals.

Image caption An artist’s impression of what Suski might have looked like. Credit: VIRGINIA TECH/A.ATUCHIN. From [1] (Note: the artist imagines the animal was fuzzy, which is not evident one way or another from the remains.)
This fossil shows that T. rex is a scaled up version of smaller hunters, i.e., most of its body did not evolve contemporaneously with growing size, they just got bigger.

But why did these features evolve in the early and mid Cretaceous?  There isn’t really enough evidence to understand the overall ecology and life of the earlier species at this time.  However, the New Mexico deposits have a number of contemporary species, which all seem to be small ancestors of later species.

So, now we have two mysteries:  why did these species evolve in the first place, and why did them become so large later?

  1. BBC News, Small tyrannosaur ‘was cousin of T. rex’, in BBC News – Science & Environment 2019.
  2. Sterling J. Nesbitt, Robert K. Denton, Mark A. Loewen, Stephen L. Brusatte, Nathan D. Smith, Alan H. Turner, James I. Kirkland, Andrew T. McDonald, and Douglas G. Wolfe, A mid-Cretaceous tyrannosauroid and the origin of North American end-Cretaceous dinosaur assemblages. Nature Ecology & Evolution, 2019/05/06 2019.


Lithium Harvesting at Salar de Uyuni

Lithium is hot!  Our ubiquitous digital devices and solar energy systems need rechargeable batteries, and Lithium ion batteries are the best we have right now.  So there is a Lithium boom, and anywhere with Lithium mines can make a lot of money.  (Information about known and suspected sources of Lithium and other minerals can be found in the USGS Mineral Commodity Summaries [1].)

A lot of the world’s Lithium comes from mineral brines, where underground water has dissolved Lithium and other minerals from rocks.   In South America, there are areas where rich brine can be pumped into ponds, and evaporated by the sun, yielding mineral salts.  These operations can be seen from space.

The market is strong now, so everyone is looking for Lithium.  In Bolivia, 3600 meters above sea level, the interesting Salar de Uyuni area is the world’s largest salt pan (dried remains of an ancient lake bed).  Under the salt is a mineral rich blue green brine (ick!), that is estimated to have a lot of Lithium as well as other stuff.

“The Bolivian salt flat holds vast quantities of the element, but bringing it to market poses challenges.”

This area has not seen much Lithium harvest in the past.  It isn’t as sunny, so evaporation takes longer.  And there is a lot of stuff in the brine besides the Lithium, so you have to purify it.

But money calls, so there seems to be renewed activity.  NASA satellites show new evaporation pools and other facilities booted up in the last 5 years [2].  (See the NASA page for a neat before and after view of the area.)

From [2]. Evaporation ponds, Salar de Uyunim Bolivia, January 2, 2019.

  1. U.S. Geological Survey, Mineral Commodity Summaries. U.S. Department of the Interior, Washington, DC, 2019.
  2. Adam Voiland., Lithium Harvesting at Salar de Uyuni, in NASA Earth Observatory. 2019.

Experiments in evolution of Flight

It is still a great mystery how birds evolved flight.

In recent decades many new fossils have revealed a great variety of feathery dinosaurs, with a variety of wing like limbs.  In fact, these features seem to be very old, predating the branching of avian dinosaurs from the rest of the family.  But it still isn’t clear how you get from running-hopping-jumping to gliding-flying. (See here, here, here, here, here, here)

It would be so interesting to actually see some of these ancient animals in action, to see how they really moved and what they really could do.

This spring, researchers in Beijing have done the next best thing:  they are experimenting with contemporary descendants of the dinosaurs to see how nascent wings might work [1].

Specifically, the research examines one of the hypothetical paths from running to flying:  terrestrial animals with proto wings, ran on hind legs, and the running caused the wings to bounce up  and down—a precursor to flapping.

This hypothesis was developed in mathematical models, robotic simulations based on fossils, and, more interestingly, by equipping young ostriches with a mechanical backpack with 3D printed mechanical “wings”!  The backpack was tuned to reflect various designs of limbs and with different feathers.

The results show that the bouncing run of the ostriches can make the “wings” flap, and with plausible assumptions, develop lift.  They conclude that “the experiments on artificial wings placed on the back of a juvenile ostrich indicated that the forced vibrations of plumage forearms during walking and running taught the winged theropods to flap their wings.” (p. 12)


They conclude that powered flight might have developed “by bipedal motion in the presence of feathered forelimbs”.

This is certainly one possible path to flight, especially flapping flight.  However, there are different ways to fly, and other plausible paths to get there, including hopping and gliding from trees.  So I don’t think it is safe to conclude that this is the only path to flight.  In fact, with all the different feathered species, there may well have been multiple emergences of flight.

  1. Yaser Saffar Talori, Jing-Shan Zhao, Yun-Fei Liu, Wen-Xiu Lu, Zhi-Heng Li, and Jingmai Kathleen O’Connor, Identification of avian flapping motion from non-volant winged dinosaurs based on modal effective mass analysis. PLOS Computational Biology, 15 (5):e1006846, 2019.


Caffeine Perks Up Perovskite

I have long said that coffee is the fuel that powers grad school (though funding is the fuel that powers research), but this spring researchers at USC and several Chinese institutions report on a serendipitous discovery that really puts the “Perk” in Perovskite [2].

Perovskite is the up and coming next thing for photo voltaic (PV) power generation.  But first, we have to figure out how to create useful devices from this notoriously  touchy material.

Reportedly on a joke [1], the researchers added caffeine to the process (after all, the researchers work better with caffeine, so why not?)  Surprisingly, it had a major effect, and a positive one.

As far as I understand, the caffeine molecules interact strongly with lead in the Perovskite, “o slow down the PVSK crystal growth and induced a preferred orientation”  ([2], p. 2),  which created superior crystalline film.  In addition to improved performance (as much as 23% increase), the film is very stable.

Now, I’m no expert in materials, so I can’t critique the details of this study.  The implications are obvious, though.  This is a promising step towards a simple, cost effective manufacturing process to create larger, stable PV films using Perovskite.


A lot more work is needed to get PV cells that can last decades of actual use, but this is a good step.

  1. Peter Fairley, Caffeine Cranks Up Solar Cells, in IEEE Spectrum – Energywise. 2019.
  2. Rui Wang, Jingjing Xue, Lei Meng, Jin-Wook Lee, Zipeng Zhao, Pengyu Sun, Le Cai, Tianyi Huang, Zhengxu Wang, Zhao-Kui Wang, Yu Duan, Jonathan Lee Yang, Shaun Tan, Yonghai Yuan, Yu Huang, and Yang Yang, Caffeine Improves the Performance and Thermal Stability of Perovskite Solar Cells. Joule, 2019/04/25/ 2019.

Antarctica Melting Fast

The ice is melting.  Glaciers are retreating, Greenland and the Arctic are rapidly melting.

The picture in Antarctica is complex, some places are melting, others are not.  Many places are not very well-known, so we can’t be too sure.

This spring a new study reports that the Ross Ice Shelf (“the world’s largest ice shelf” [1]) is melting faster than previous estimates [2].  Uh oh.

Ice shelves float on the ocean, and generally melt when the ocean water warms, melting the ice from below.  Some of the ice shelves surrounding Antarctica have been rapidly thinning, leading to break ups, and their thinning allows faster flow of inland glaciers into the ocean.

The giant Ross Ice Shelf (RIS) has been stable to date, except for one region.  The new study took radar measures of the area repeated after one year (in 2013 and 2014).  The measurements show rapid melting near the leading edge of the ice, particularly in the summer.  There is an exponential melting rate in the first km of the ice.

Fig. 1: Basal melt rates of the north-western RIS. (From [2]
Other instruments under the ice indicate heating of the sea water in the summer, which infiltrates under the ice.  Basically, the summer sun is warming a region of the ocean, and this warm water is melting the ice in that area.

The warm water corresponds to the Ross Sea Polynya, an area that is usually relatively free of sea ice due to off shore winds.  In short, right offshore of the RIS there is an ice-free “bare spot” that absorbs heat from the summer sun.  A lot of heat, at least in the surface of the ocean.

It isn’t so clear how this buoyant warm water on the surface is pushed under the ice.  The researchers suggest that “circulation near and beneath the ice shelf is strongly influenced by density gradients caused by seasonal brine release in the polynya” ([2], p. 5)  This is a bit speculative, so more observations are certainly in order.

Whatever the process, these observations do show a strong effect from seasonal warming, apparently driven by local atmosphere and ocean conditions, which are influenced by the melting of the ice—potentially a positive feedback leading to accelerating ice loss.

In addition, this very strong local warming is at a sensitive location, near Ross Island.  Melting here could “unpin” the whole shelf, leading to rapid movement and further melting.  The destabilization of the RIS could release vast areas of the West Antarctic Ice Sheet, one of the largest reservoirs of ice.

“Although some frontal regions are unimportant to the stability of ice shelves, others contain critical pinning points that sustain the location of the front ” ([2], p.5)

In short, this is yet another indication that things are changing quickly in Antarctica, and may accelerate.  When this happens, vast amounts of ice will melt into the oceans, with rapid rises in sea level.  Glub!

  1. BBC News, Signs of faster melting in world’s largest ice shelf, in BBC News – Science & Environment. 2019.
  2. Craig L. Stewart, Poul Christoffersen, Keith W. Nicholls, Michael J. M. Williams, and Julian A. Dowdeswell, Basal melting of Ross Ice Shelf from solar heat absorption in an ice-front polynya. Nature Geoscience, 2019/04/29 2019.