Journey to the edge of Amazonia
A long day's drive from Brasilia, through the vast landscapes of northern Goais in central Brazil, a landscape of fragments of cerrado savanna and forest in a matrix of cattle ranches and soya bean fields. Big skies, big rains and big cowboy hats. Then over the might River Araguaia into Mato Grosso, past extraordinary hills and cliffs lining a broad valley cleared for soya and cattle, but still carrying a vast scale of beauty. And finishing off in the small university town of Nova Xavantina, right on the transition between the Amazon rainforest and the cerrado savanna. It is this transition that we will be focusing our work on for the next six weeks (led by Imma Oliveras), hosted by Bia and Ben Hur Marimon of the State University of Mato Grosso.
At São Luis do Paraitinga, Brazil, on the edge of the Serra do Mar State Park, a girdle of lush Atlantic rainforest on mountains overlooking the coast. We are here for the launch of the ECOFOR project, a NERC and FAPESP-funded project that looks at ecosystem function and biodiversity along disturbance gradients ranging from old-growth forest through logged, burned and recovering forests. The forests here are shorted and more open than many Amazonian forests, but lush and full of bamboos and epiphytes. A great team of Brazilian and UK scientists.
Megafauna extinctions and what they mean for understanding our relationship with nature #oxmegafauna
Here is some media coverage about our Oxford megafauna conference
George Monbiot has a piece in the Guardian pondering the meaning of the Pleistocene megafaunal extinctions on what it means to be human and how we understand our relationship to nature.
Is this all humans are? Diminutive monsters of death and destruction?
New research suggests that there was never a state of grace. We have always been the nemesis of the planet's wildlife
And a piece on BBC news reviews some of the discussions we had on the evidence of human cause of the extinctions, and what the consequences were for ecosystem function.
Ecologists learn lessons from the 'ghosts of megafauna'
As I say in the BBC piece, I find the evidence that humans had the primary role in causing the Pleistocene extinctions pretty convincing (with the possible exception of Eurasia, where climate change drove down populations in refugia and humans played a role in preventing these species from bouncing back as they had done in previous periods of climate change).
As for what it means for our sense of our place in nature, I think Monbiot is right in identifying that there never was a golden age in our relationship with the rest of nature. Probably for millions of years and certainly for tens of thousands of years we have been a new kind of superpredator, and thereby been disrupting ecosystems around us and driving species to extinction, either directly through hunting or indirectly through habitat change and trophic cascades. This does not negate our need to reverse the tide of destruction, but it is perhaps better to do so with the wide-eyed clarity of understanding the deep history of our impact on the environment than has accompanied our rise as a species, rather than harking back to a prehistoric golden age that never was.
Photos from the megafauna and ecosystem function conference at St John's College
The conference blog is available here.
And most talk and audio files are available here.
It was an utterly stimulating meeting and I am still digesting the amazing insights and perspectives.
Here's a really nice link with lots of wonderful educational animations about biodiversity, where it is found, and why it matters. From the California Academy of Sciences and the Khan Academy. One example is shown below but there are many more.
The World of Biodiversity
We have a new paper in Nature Communications, led by Fernando Espirito-Santo, that describes the full spectrum of natural disturbance regimes in the Amazon for the first time. How often does a sing large tree fall over, or a bunch of trees, compared to when a storm blow down knocks over a larger area of trees. Such questions are important if we are to understand what drives tree death in the tropical rainforest, and also affect how we interpret the apparent increase of biomass we see in the RAINFOR plot network. The paper combined analyses at multiple scales: Landsat satellite data over the whole region, airborne lidar data and intermediate scales, and fine-scale tree mortality data from forest plot networks. The end result is the first complete description of the disturbance regime at multiple scales in a tropical forest region (Figure 3). This is truly a thing of beauty.
In terms of carbon sinks, the analysis shows that large stochastic disturbances are too infrequent to have a significant influence on the carbon sink observed. The big disturbances appear too rare to cause most of the forest plots to be recovering from stochastic disturbances.
The paper is available for download here.
Espírito-Santo, F. D. B. et al. Size and frequency of natural forest disturbances and the Amazon forest carbon balance. Nat. Commun. 5:3434 doi: 10.1038/ncomms4434 (2014). Supplementary material.
Exciting first day at the megafauna conference.
We are blogging the conference here
Also there is an active Twitter feed at #oxmegafauna.
There is an article in the Observer today that sets up this week's conference: Megafauna and Ecosystem Function from the Pleistocene to the Anthropocene.
What killed off the giant beasts – climate change or man?
It introduces the topic quite nicely. The article does focus heavily on "what is the cause of the Pleistocene extinctions?" which we have deliberately made only a small component of the conference. This debate has been going on for decades, with interesting new data emerging all the time. It seems to be that a reasonably consistent view is emerging that humans had some role in all continents, with a possible strong interaction with climate change in North America and Europe.
We will get an update on this debate, but really want to focus on a different question which has been asked much less: what are the consequences of these past and ongoing extinctions, and can anything be done about them?
There are a few errors and misquotes in the article. Most notably, a confused paragraph about elephants eating avocados and fertilising the rainforest. This can be broken down more accurately into three parts:
1. Many fruit with large fleshy bodies and large seeds are likely to have been designed to be dispersed in the guts of megafauna. An avocado is an example of such a fruit.
2. Megafauna would have played a large role in dispersing these seeds through the forest, as forest elephants do in Central Africa today.
3. Separately, we have developed a model which suggests that megafauna play a large role in dispersing and diffusing nutrients through their dung.
All in all, an incredibly exciting few days are ahead. Podcasts and slides of most talks will be made available soon after the talks. And we will try out an experiment (for me anyway) in tweeting with the hashtag #oxmegafauna.
A novel new RAINFOR paper led by Tim Baker explores the links between tree lifetimes and species diversity. It shows that many clades of short-lived trees show particularly fast diversification rates, suggesting that short lifetimes is a strategy that favours rapid diversification.
There is a nice BBC piece on it here.
Baker, T. R., Pennington, R. T., Magallon, S., Gloor, E., Laurance, W. F., Alexiades, M., Alvarez, E., Araujo, A., Arets, E. J. M. M., Aymard, G., de Oliveira, A. A., Amaral, I., Arroyo, L., Bonal, D., Brienen, R. J. W., Chave, J., Dexter, K. G., Di Fiore, A., Eler, E., Feldpausch, T. R., Ferreira, L., Lopez-Gonzalez, G., van der Heijden, G., Higuchi, N., Honorio, E., Huamantupa, I., Killeen, T. J., Laurance, S., Leaño, C., Lewis, S. L., Malhi, Y., Marimon, B. S., Marimon Junior, B. H., Monteagudo Mendoza, A., Neill, D., Peñuela-Mora, M. C., Pitman, N., Prieto, A., Quesada, C. A., Ramírez, F., Ramírez Angulo, H., Rudas, A., Ruschel, A. R., Salomão, R. P., de Andrade, A. S., Silva, J. N. M., Silveira, M., Simon, M. F., Spironello, W., Steege, H. t., Terborgh, J., Toledo, M., Torres-Lezama, A., Vasquez, R., Vieira, I. C. G., Vilanova, E., Vos, V. A., Phillips, O. L. (2014), Fast demographic traits promote high diversification rates of Amazonian trees. Ecology Letters. doi: 10.1111/ele.12252
Yadvinder Malhi is an ecosytem ecologist and Professor of Ecosystem Science at Oxford University