Wednesday, 27 April 2011

Pre-Columbian raised field agriculture: a review

ResearchBlogging.org

A new paper on raised field agriculture was published on line last week in the journal Ecological Engineering. The title, “Ecological engineers ahead of their time: The functioning of pre-Columbian raised-field agriculture and its potential contributions to sustainability today”, is a bit misleading. You would think it is just another paper claiming that the re-habilitation of raised field agriculture will provide means for sustainable, highly productive, flood/drought proof, politically correct and environment friendly tropical agriculture… but it is not. Instead, it is a good review of all the relevant literature about pre-Columbian raised field agriculture.
The paper, by Renard D., also includes valuable references to raised fields in Asia and is co-authored by a diverse and interdisciplinary group of researchers, including Bruno Glaser, a soil scientist who is among the most prominent world experts of terra preta, archaeologists that have long worked on pre-Columbian raised fields and ecologists. However, in my opinion, its conclusions fall short.
The main point of the paper, with which I fully agree, is that raised fields are found in a variety of environments that differ with respect to almost everything: you find raised fields in all kind of soils; you find them in the Amazon basin and in the Andes; you find them in permanent swamps/lakes and in seasonally flooded/dry savannahs. Therefore, it is very likely that, in different places/conditions, fields were managed in different ways. The paper examines almost all the theories and hypothesis that have been put forward about raised fields. However, while it becomes clear that some of these hypothesis are contradictory, such as the need (or no need) of fallow periods, Renard et al., regrettably, do not take positions. Having noticed all the differences between the fields, I would have concluded that their only common trait is that they improved the drainage and I would have therefore stressed that drainage is the defining aspect of raised field agriculture (see this)…but they do not conclude that, and I would be interested to know why.
They do conclude, and again, I fully agree with them, that before we start to rehabilitate raised field agriculture in real-life situations today, we should fill the huge gaps we still have in our understanding of how pre-Columbian raised field agriculture may have worked. I do hope Oxfam and the other NGOs promoting raised field agriculture in lowland Bolivia today read the paper and take on board its main recommendations.
 - Thanks to Anna for telling me about the paper.



Una nueva revisión de los estudios sobre agricultura en camellones


Un nuevo artículo sobre agricultura en camellones acaba de ser publicado en la revista Ecological Engineering. El titulo del artículo hace referencia al papel que los camellones pueden tener como herramienta productiva y sostenible. Sin embrago, no es el típico articulo que nos cuenta como, gracias a la rehabilitación de camellones, se puede revolucionar la agricultura tropical. Más bien, se trata de un artículo que hace un buen resumen de todo lo más importante que ha sido producido por la comunidad científica sobre el tema. Este trabajo incluye también referencias a los camellones de Asia. En la interdisciplinaria lista de autores, encabezada por Renard D., también encontramos a Bruno Glaser, un pedólogo experto mundial de terra preta, arqueólogos con años de experiencia trabajando en camellones y ecólogos.  Sin embargo, en mi opinión, en sus conclusiones se quedan cortos.
El punto principal del artículo, con el cual estoy totalmente de acuerdo, es que los camellones aparecen en una grande variabilidad de sitios y condiciones medioambientales: los encontramos en los más diferentes tipos de suelos; en la cuenca del Amazonas igual que en las regiones Andinas; en lagos igual que en pampas sujetas a ciclos de inundación y sequía. Entonces es muy probable que en diferentes sitios y condiciones los campos fueran manejados de manera distinta. El artículo hace el elenco de todas las teorías e hipótesis que se han hecho sobre la agricultura de camellones. Pero, en todos esos casos donde las hipótesis se contradicen (como por ejemplo sobre la posibilidad que los camellones se puedan cultivar de manera continuativa, sin dejarlos descansar) los autores no toman nunca posición. Una vez que queda claro que hay una gran diversidad de contextos geográficos donde se encuentra los camellones y que seguramente hubo distintos manejos,  yo diría que la única característica común a todo tipo de camellones y en todo sitio es que mejoran en drenaje. Pero Renard D. et al., no llegan a esta misma conclusión, y me interesaría saber el porqué.
Ellos concluyen su artículo afirmando que antes de montar proyectos de rehabilitación de camellones que involucren las comunidades locales, se deben llenar todos los grandes vacíos que todavía existen en nuestro conocimiento de cómo los camellones estuvieron funcionando. Y yo no podría estar más de acuerdo con esta conclusión. Espero que Oxfam y las otras ONGs que están involucradas en proyectos de rehabilitación con comunidades indígenas y campesinas, lean este artículo y lo tomen en cuenta.



D. Renard, J. Iriarte, J.J. Birk, S. Rostain, B. Glaser, & D. McKey (2011). Ecological engineers ahead of their time: The functioning of pre-Columbian raised-field agriculture and its potential contributions to sustainability today Ecological Engineering

Sunday, 17 April 2011

The Science and the rhetoric of climate change in the Bolivian Amazon


Comunicación.
Este Blog está en Ingles porque mi esperanza es que sea un espacio de discusión entre investigadores que pertenecen a varias disciplinas y de varios países. Y, aunque a mi también me cueste mucho, el idioma de la ciencia es el Ingles. Pero me doy cuenta que los Bolivianos (y quizás no solo ellos) podrían estar interesados en muchos de los temas que se encaran aquí y que el ingles puede ser una barrera a su participación. Por lo tanto me comprometo, desde el próximo post, a escribir en ambos idiomas. Mientras tanto, los Castellano hablante que tengan ganas de traducir los viejos posts al Español son muy bien venidos. Podéis poner la traducción en la sección de los comentarios y yo luego me encargaré de ponerla a continuación del texto principal. Espero que haya muchos voluntarios/as.

Development organizations are calling for funds to finance projects aimed at the mitigation of climate change risk in the Llanos de Moxos. 
Oxfam International in its web writes: “Climate change will increase both the intensity and frequency of extreme weather events, such as flooding or droughts. Beni, a district of Bolivia prone to alternate flooding and drought, is an example of a region where people are being forced to adapt to the changing climate.” A few weeks ago, AlertNet pointed out that climate change represents a threat to people in lowland Bolivia: “Widespread flooding in Bolivia, which prompted the government to declare a national emergency last week, shows the vulnerability of one of South America's poorest countries to changing weather patterns linked to climate change.” In the same article: "Roger Quiroga, emergency coordinator for Oxfam GB in Bolivia, described Beni as one of the "largest lakes in the world" during the annual rainy season, when 150,000 sq kms is covered, an area equivalent to the size of Ecuador or Nicaragua."
These projects often receive important press coverage, like that of the most important News media of the world: 
James Painter -  BBC News wrote: “If, as predicted by many experts, the cycles of El Nino/La Nina are going to increase in intensity and frequency, then the [Oxfam’s] project has the capacity to help poor families cope better with the extreme weather events and unpredictable rainfall that are to come.”

So, I decided to dig a bit deeper on what these many experts are actually predicting. 
The first step is to see how big the floods actually are. Hamilton et al. in the Journal of Geophysical Research  measured, for the Llanos de Moxos, a maximum flood extension of 92,094 Km2
and an average flood extension of 29,460 Km2, 5 times smaller than that asserted by Oxfam!!
The second paper I want to draw your attention to is Aalto et al. Nature  425, 493-497 (2003). Here he states that “transient processes driven by the El Niño/Southern Oscillation cycle control the formation of the Bolivian flood plains and modulate downstream delivery of sediments.” This basically means that the extreme flood events are related to El Niño. Thus, the frequency and intensity of future floods depend on how global warming will affect El Niño. 
I looked then for studies that assess this issue and I found a paper by Collins et al. published in 2010 in Nature Geoscience (3, 391-397). Title: The impact of global warming on the tropical Pacific Ocean and El Niño. Quote: “despite considerable progress in our understanding of the impact of climate change on many of the processes that contribute to El Niño variability, it is not yet possible to say whether ENSO [El  Niño  Southern Oscillation] activity will be enhanced or damped, or if the frequency of events will change.” Well, it seems that there is no scientific basis for claiming that climate change will cause more severe floods in the Llanos de Moxos.
 Ok, but what will happen on average? Maybe there will be more floods because there will be more total rainfall regardless of El Niño effect. So I looked for climate models at the IPCC website site but I didn’t know how to deal with them…too many models and scenarios to choose from…and I am not a climatologist. So I looked at papers of people who have already done this work like Mayle et al. and Malhiet al.…and what have they found out? That the increase of temperature will be coupled with a decrease in precipitations! It seems that the big problem might be coping with prolonged drought rather than severe floods.
If there is a climatologist out there, I would like to know his/her opinion!
Meanwhile…I wonder if overstating the effects of climate change  might be contributing to the growth in the number of climate skeptics, like my virtual friend Guidorzi :-)

La Ciencia y los cuentos sobre el cambio climático en la Amazonia Boliviana.
En este post tomo el proyecto de Oxfam en lo Llanos de Moxos como un ejemplo del mal uso que a menudo se hace de los datos científicos. Oxfam está construyendo campos de cultivo elevados (camellones) en los alrededores de Trinidad –Beni -Bolivia con un doble objetivo: proveer las poblaciones locales con una antigua herramienta productiva usada por los pre-Colombinos, supuestamente más efectiva del chaco (agricultura del “quema y roza”) y mitigar el riesgo de las graves inundaciones que supuestamente en el futuro golpearan los llanos de Moxos a causa del cambio climático. Bueno, ambos objetivos carecen de base científica. He discutido el porqué lo camellones pre-Colombinos de los Llanos de Moxos nunca fueron más productivos del chaco en un articulo que acaba de ser publicado en el Journal of Archaeological Science (y que he mandado a Oxfam hace meses sin recibir respuesta), y no voy a discutir ese aspecto ahora. Lo que quiero evidenciar aquí es que el ciclo de las inundaciones/sequías catastróficas del Beni está relacionado (aunque menos estrechamente de lo que parece) con el ciclo del El Niño/La Niña. Por lo tanto, la manera de cómo el cambio climático afectará las inundaciones de los llanos depende (en parte) de cómo cambiará la frecuencia y/o la intensidad del Niño. Bueno, los estudios científico actualmente disponibles nos dicen que NADIE tiene la menor idea de lo que pasará al Niño en el futuro. Otro factor que afectará el régimen de lluvias en los Llanos es la cantidad de vapor que se forma en la Amazonia,  y este valor es muy sensible a la deforestación. Pero de esto hablaremos mas adelante. Bueno, si no estáis de acuerdo o queréis añadir o preguntar algo, podéis hacer clic en “comments” aquí abajo :-)

 

Saturday, 16 April 2011

Why do people think archaeologists dig out dinosaurs??

We talked about the extinction of the Megafauna in the Americas a few weeks ago, meanwhile.... 
This appeared in the most important Italian news paper “La Repubblica”. For those who have problems with the Italian language, the title of the video is “Chile: the dinosaur incisors is 16 cm long”. Then it goes on with “At Padre Hurtado, a little Chilean village close to Santiago, a group of archaeologists directed by Pablo Masilla have found a well preserved cranium of a Mastodon “. In the video the Mastodon is defined as a “primitive proboscidate that populated America some millions of years ago”. 

Watch the video:

video

 
If you want to know more: Dinosaurs and Mastodons

Thanks to David Bowman for pointing it out in the Le Scienze’s blog
And to Machi for inspiring the post's title :-)

P.S.
The Mastodon is not a Dinosaur but a kind of Mammut. The "incisors" of the Mammut were actually the more then a meter long tusks, while the 16 cm long tooth is a molar. Mastodons disappeared about 10.000 years ago, not millions of years ago...those were, again, the dinosaurs (65) :-)

Wednesday, 13 April 2011

Human-environment interactions in pre-Columbian Amazonia: what do we really know about the environment?

Pitman et al. have just published a very interesting paper: “Volume and Geographical Distribution of Ecological Research in the Andes and the Amazon, 1995-2008” on the Open Access Journal - Tropical Conservation Science Vol. 4 (1):64-81, 2011. They have compiled a dataset of all articles based on the Andes and Amazon regions published between 1995 and 2008 in the two most prominent scientific journals of tropical ecology: Biotropica and Journal of Tropical Ecology.


Map of the tropical ecology field work sites (yellow circles) in the Andes and Amazon regions of South America. Pink circles show those areas in the Amazon basin where evidence of pre-Columbian complex societies has been reported: 1) Llanos de Moxos; 2) Upper Xingu River; 3) Marajó island – modified from Pitman et al.

The map shows a desolating reality: almost no field work has been done in the areas where evidence of pre-Columbian cultural complexity has been found! Can you believe that “historical ecologists” and “environmental determinists” have been quarreling for 30 years about the role the environment plays in allowing the formation of complex societies and we still hardly know anything about the environment? Don’t you think it is time archaeologists and anthropologist take geographers and ecologists to the field with them? Till now, the “multidisciplinary” approach has meant the archaeologist gave a sample to a soil scientist to analyze because he/she wanted an answer to a specific question, then the “answer provider” became a co-author. I think we need something different. From my point of view all archaeological excavations should be carried out with a soil scientist and an ecologist. Scientific research needs to be multidisciplinary in all its phases, especially during the fieldwork.

Sunday, 10 April 2011

Nevada

Hi, I am in Lake Tahoe, at the border between California and Nevada.

 Lake Tahoe

Lake Tahoe is 1900 m.s.l. and it is the third deepest lake in North America: 500 meters at its deepest point. Its basin formed by faulting in old metamorphic and granitic rocks and was then shaped by glaciers. The water is remarkably clear because 40% of it comes from rain that falls directly on the lake and the rest is filtered by granitic rocks and wetlands before it gets to the lake. 

 Wetlands on the southern side of the Lake, close to Zephyr Cove

During the last post glacial, a delta formed in the southern part of the lake. On this old delta is now South Lake Tahoe, a little city with many Casinos.

 Me and Maria after loosing 40$ playing Video Poker :-(

The area was completely deforested about 100 years ago to supply wood for mining. Just 20 miles away from South Lake Tahoe there is Virginia City: the American version of the Bolivian Cerro Potosì. 

Virginia City

Virginia City is the place where Mark Twain spent an important part of his life. He was a miner first and then worked for the Virginia City newspaper. Here he wrote his first novel.

 Mark Twain's desk