YADVINDER MALHI
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Travels in ecosystem science

Some observations and musings from the field and the office.
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To get regular updates on the science-focussed postings on this blog you can follow me on Twitter (@ymalhi)

Eating up the world’s food web and the human trophic level

26/12/2013

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A new paper in Proceedings of the National Academy of Sciences has measured the "trophic level" of human beings for the first time. Falling between 1 and 5.5, trophic levels refer to where species fit on the food chain. Apex predators like tigers and sharks are given a 5.5 on trophic scale since they survive almost entirely on consuming meat, while plants and phytoplankton, which make their own food, are at the bottom of the scale. Humans, according to the new paper, currently fall in the middle: 2.21. However, rising meat-eating in countries like China, India, and Brazil is pushing our trophic level higher with massive environmental impacts. 
Read more at http://news.mongabay.com/2013/1205-hance-human-trophic-levels.html#1iFF3K2R1tKPZvBy.99

The paper can be downloaded here.
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OneZoom - a fantastic new exploration of the diversity and history of plant life

23/12/2013

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The OneZoom website has just released a wonderful exploration of the taxonomic linkages and evolutionary history of plant life. It is a unique tool for diving in and understanding the linkages between species, and simply understanding how the complexity of variation of plant families fits together into a single evolutionary jigsaw. The plants tool can be found here: http://www.onezoom.org/plants.htm
It is well worth a play play around with.

Previously they have produced similar analyses for vertebrates, which can be found here: http://www.onezoom.org
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Höhe Tauern National Park, Austria

22/12/2013

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The Höhe Tauern (High Tauern) range is the highest mountain range in the eastern Alps, and forms the backbone of Austria. It is a high wild zone, cut by inhabited low valleys and fringed by ski resorts (we stayed at Zell-am-See for a wonderful week of skiing and exploring). It is the silent, snow-glistening realm of golden eagles, ibexes and lynxes, of groves of fir and larch, of rushing glacial green rivers, a wild heart in the centre of Europe.
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New species of Amazonian tapir discovered

18/12/2013

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In what will likely be considered one of the biggest (literally) zoological discoveries of the Twenty-First Century, scientists today announced they have discovered a new species of tapir in Brazil and Colombia. The new mammal, hidden from science but known to local indigenous tribes, is actually one of the biggest animals on the continent, although it's still the smallest living tapir. Described in the Journal of Mammology, the scientists have named the new tapir Tapirus kabomani after the name for "tapir" in the local Paumari language: "Arabo kabomani." 

See a Mongabay article here.

Tapirus kabomani, or the Kobomani tapir, is the fifth tapir found in the world and the first to be discovered since 1865. It is also the first mammal in the order Perissodactyla (which includes tapirs, rhinos, and horses) found in over a hundred years. Moreover, this is the largest land mammal to be uncovered in decades: in 1992 scientists discovered the saola in Vietnam and Cambodia, a rainforest bovine that is about the same size as the new tapir. 

Found inhabiting open grasslands and forests in the southwest Amazon (the Brazilian states of Rondônia and Amazonas, as well as the Colombian department of Amazonas), the new species is regularly hunted by the Karitiana tribe who call it the "little black tapir."  "[Indigenous people] traditionally reported seeing what they called 'a different kind of anta [tapir in Portuguese].' However, the scientific community has never paid much attention to the fact, stating that it was always the same Tapirus terrestris," explains lead author Mario Cozzuol, the paleontologist who first started investigating the new species ten years ago. "They did not give value to local knowledge and thought the locals were wrong. Knowledge of the local community needs to be taken into account and that's what we did in our study, which culminated in the discovery of a new species to science." 

Read more at http://news.mongabay.com/2013/1216-hance-new-tapir-kabomani.html?fbfnpg#hCVTHKJTTZDXTGfK.99
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A pair of Kobomani tapirs caught on camera trap. The individual on the left is a female and on the right a male. Females of the new species are characterized by a light patch on lower head and neck. Photo courtesy of Fabrício R. Santos.
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Christmas party for the Ecosystems Lab!

15/12/2013

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Global food supply and demand

11/12/2013

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This short essay, by Jon Foley, is the clearest and most rational exposition of the challenge of feeding the world population this century while maintaining a vibrant biosphere that I have come across.

The global food supply has a demand problem
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Predicting Amazonian deforestation and its biodiversity consequences

10/12/2013

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We had a great talk by Rob Ewers of Imperial College a few weeks back. Lots of interesting new analyses. In particular he introduced the concept of "terrqgeny" to describe the history of forest fragments in a landscape. The slides and podcast of the seminar can be viewed here.
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The sensitivity of wood production to seasonal and interannual variations in climate in a lowland Amazonian rainforest

8/12/2013

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This new paper, led by Lucy Rowland for her PhD work, looks at seasonal patterns of tree growth using an amazing dataset (now 8 years long and still continuing) of seasonal tree growth in two of our forest plots in Tambopata, Peru. Javier-Silva Espejo played a key role in the early years of these measurements, followed by Filio Farfan-Amezquita. 
The paper finds trees grow more in the wet season (not that surprising perhaps) but also breaks the analysis down by tree functional group. Fast-growing, low wood density trees and tall trees show much more seasonality than short trees with high wood density, giving evidence for a trade-off between rapid growth and hydraulic vulnerability.

Rowland L., Y. Malhi, J. E. Silva-Espejo, F. Farfán-Amézquita, K. Halladay, C. E. Doughty, P. Meir, O. L. Phillips. (2013) The sensitivity of wood production to seasonal and interannual variations in climate in a lowland Amazonian rainforest. Oecologia, Advanced Publication Online
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Research networks on Amazon conservation, by country.

4/12/2013

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Here is another network analysis from Richard Ladle, looking at the research network for "Amazon" and "conservation" grouped by affiliation country of the researchers. In this network the most prolific countries are Brazil, the USA and the UK. Otherwise everything seems connected to everything - I see little structure in the network.
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Research networks in the Amazon, climate change and conservation

3/12/2013

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Below are a couple of interesting network structure analyses on the topics "Amazon and climate change" and "Amazon and conservation". They were conducted by Richard Ladle of the Federal University of Alagoas and Oxford University. Research was based on 1063 papers from Web of Science with "Amazon/climate change" or "Amazon/conservation" in title, abstract or keywords. Richards only mapped "the most productive scientists ("the silverbacks") as these are the guys that drive the networks".

Lines represent co-authorship connections (thicker lines=more joint  papers) and balls represent number of papers. The proximity of the balls is an indication (somehow) of how closely people work together. Centrality in the diagram indicates to what extent the person is a key node linking different regions of the network.

The analysis needs three programs: web of science/scopus (to get the data), bibexcel (which converts the bibliographic file and does the network statistics) and Pajek (used for the visualization). The software is freely available, and there is a powerpoint that shows you how to use bibexcel.

Beyond the obvious chance for self-aggrandisement ("how big is your ball?") there are a number of  features of interest.

The first diagram is for "Amazon" and "climate change". It shows a number of interesting features. There are three countries (or four if Laurance is taken as Australian): the UK, the USA and Brazil. In the centre is a closely collaborating UK cluster (Malhi, Meir, Philips and formerly Aragao) which has links across the network, and which focusses on field monitoring and experiments. Also close to the centre are two key Brazilian meteorologists (Nobre/Marengo); Nobre is particular was a central figure in the influential LBA programme in Brazil.. On bottom right is a cluster of climate and biosphere modellers (Betts, Sitch, Jones, Cox, Huntingford) with tight links to each other and fairly strong interactions with the field-focused centre. To the left is a US/Brazil cluster (Nepstad/Costa/Coe/Soares/
Moutinho) with strong links within the cluster and multiple but weaker links to rest of the network . Top left is another prolific figure (Laurance) with links to multiple strands of the network, and Barlow, with some links to other parts of the network. Above centre are two strongly collaborating figures (Bush/Silman) with a strong focus on the Andes and western Amazonia, and on paleoecology. A number of other researchers (Fearnside, Clark, Cerri) are prolific but with only weaker links to the rest of the network. It should be emphasised that the network only shows connectivity under this specific search - two researchers may be collaborating on various topics but if they have not published on Amazon and climate change they would not show up as linked in this diagram.
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The second is for "Amazon" and "conservation". Some familiar names from the previous diagram, but also some key new ones, notably Peres and associates, and some changes in relative size of publication volume. The most striking feature is that two discrete networks exist, at least for this search. Why is this? I can safely vouch that it is not competition or animosity, simply happenstance that key connections have not been made in under this research question (incidently, there is a new project on human-modified tropical forests in Brazil, ECOFOR, that involves Barlow, Gardner, Malhi and Phillips, so we can expect these two networks to connect in a few years).
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All fascinating, but what do we learn that is new? To an outsider it is certainly a useful overview of key actors and their collaborative relationships, and can also reveal some interesting bulk national features such as the surprisingly strong role of UK scientists, or the lack of visible high publication scientists in South America  outside of Brazil, or in Europe outside of the UK (in the English language, admittedly, which is a significant filter). And how does visibility as a scientist map on to influence in key debates?
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    Yadvinder Malhi is an ecosytem ecologist and Professor of Ecosystem Science at Oxford University

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