Tuesday, January 19, 2016

Slash and Burn (Costa, Lopez, Kaal, Martinez, 2015)

"Environmental Changes in North-Western Iberia Around the Bell Beaker Period" is a chapter looking at evidence of changes in the landscape, soil and climate during the time of the Beakers, keeping in mind that they are one group among many.  (The hyperlink should be visible above)

This is a continuation of the previewable portion of "The Bell Beaker Transition in Europe" by Prieto-Martinez and Salanova.

Burning the Brushwood (Eero Järnefelt, 1893)
It may be easy to oversell the environmental impact of the Beaker period since it is really a continuation of Neolithic clearing practices and exasperated by climate change at the end of the third millenium.

Nevertheless, these authors see a fairly dramatic acceleration of soil erosion and clear evidence of slash and burn indicators in the soil.  The Beaker Period marks an intense increase in land use (in this area) for agricultural activities.*   It's during this time that many rock surfaces at high elevations became exposed, creating the canvass of Bronze Age rock art.

We already know from multiple isotopic studies that Beakerfolk had a diet rich in meats and dairy.  Aside from diet, loom weights suggest that much of their clothing was made of wool, so it follows that more pasture would have been required.

In addition to needing more room for animals, some crops like barley might have needed sandier soil at a higher and cooler elevation.  During the Beaker period many places experienced a cooler and wetter trend and this may have partly caused the shifting of preference between the varieties of barley and wheat grown, or maybe even where they were grown.

One thing that has been common in the United States is to use goats to clear lush underbrush in a deciduous landscape.  It'd be interesting to know if there was a relationship between the goat population and deforestation/defoliation during the Beaker period.

* I seem to recall in other areas of Europe, older fields are no longer maintained.  I'm not sure how the population size is estimated (concerning the population crash of the Late Neolithic), however erosion and drainage may have required seeking out previously unused land.


  1. FWIW, a recent study suggests that human activity like this helped to avert a serious Holocene era ice age (far worse than the "Little Ice Age").

    1. Interesting hypothesis. I've always wondered what impact concrete has on modern weather. It'd seem sensible to think deforestation would alter wind patterns or effects.

  2. Interesting, although not much info is provided in the referenced online version of the book. I'd like to warn once again against the assumption of equalizing "Bell Beaker period" with "Bell Beaker folk". In this case at least it is very clear that most of Galicia was not affected by Bell Beaker presence (see map here), which is limited to a few findings concentrated in three districts (south and north, but not the center, of sector IV and also sector II in the above map). So maybe it'd be more convenient to speak of late Chalcolithic, which only in a few cases includes beakers.

    As for your question about goats, I'd think that they do a good job keeping terrains free from bushes and new forest growth but to destroy a consolidated forest only with them seems a bit near-impossible, it'd take a very long time. Fire is definitely much faster.

    1. Agree with the folk/period, I put that clause in first.

      Slash and burn would have been preferable since it adds Potash and Nitrogen to sandy soils and reduces the acidity which would theoretically make a good base for barley and rye, assuming it was for that use. I don't believe they rotated crops, so they might have just burned brush every so often.

      A forest pasture can be made by goats taking out everything below the browse line as long as the canopy isn't too thick. But admittedly, using them for this purpose might have been implausible if wolves or lions were common at this time. They'd also have to be sufficiently fenced to force them to strip an area.

      On the third hand, I'll assume that these forests had considerable oak species and at least they would have been fire tolerant. So it's possible they could have slashed the understory and left the large trees standing if only for a pasture.

      I read this article last year, kind of gives an idea of what they'll do when fenced: http://www.noble.org/ag/livestock/goatvegetation/

    2. Of course! You're absolutely right: the fertilizing function is fundamental in slash and burn techniques, and that's also why they have to abandon the parcel for some other just a few years afterwards: they usually failed, without the use of manure and crop rotation, to keep the fertility of the land for long.

      However in the book they mention some "brañas" which are sort of terraces, with deeper soil and that may somehow have been used continuously. I wonder: did these peoples already know some sort of rotation techniques? If so, then the burning was probably for other reasons: to open new fields for a growing population.

    3. As for setting fires to oaks (what about beeches?: they are quite similar and at least nowadays more common, what about nut-giving trees like walnut and chesnut trees, which you probably want to keep alive?), I don't know but wouldn't late summer or early autumn, with all the leaves dry, cause widespread damage anyhow? Obviously you don't set an intentional fire if it's raining and I'd say that, if the climate was anything like today's, September or early October would have been the best time (August is typically too stormy, July too green). On the other hand you may want some rain before you burn half the country.

      In any case you still have to dispose the burnt trees and that is hard manual work. I wonder which tools they used, as copper is too soft.

    4. I'm not too familiar with beeches, but in North America they grow with maple. I'm kind of extrapolating my experience with North American trees (specifically oaks) and I did a little reading on Galician forests out of interest.

      My local Oaks grow about a half dozen or more species together and form the cornerstone of a woodland with well drained soil along with nut trees like walnut (and Spanish chestnut in Galicia) (hickory or pecan in America), etc.
      I think a lot of these trees would typically survive (and thrive) from a forest fire, so burning just kind of burns off the understory and foliage at the bottom, holly, vines, briar, poison ivy, ferns, etc.

      I've always wondered about cutting oaks and the harder conifers like cedar or yew in prehistoric times since oak and walnut will dull out a well oiled chainsaw quickly (been there). A copper axe would flatten after several strikes and I don't see how the axe could be hafted strong enough to be useful.

      I'm curious if they used some long forgotten method to fell trees using ox gangs or drilling holes in the trunk. Or they could have done it the ultra hard way too.

    5. @Maju,
      That map is very outdated for Galicia:

      In the late 25 years or so, partly due to the construction of new infrastructures, partly because archeologist now know where to search, a large number -let's say tens- of new stations have been found, both habitats and funerary contexts. Here you have rather recent data about both Maritime and Corded Beaker (AOC and CZ/M) in Galicia (note the maps in p. 33 and 40:

      And its characterization:

      In fact, in 2005 a local scholar wrote a paper titled “A new Beaker region...”:

      Here a regional study by the same author (2011) in the Morrazo peninsula:

      And here, a collective work where Galicia have a specific presence:

      Now, compare those papers with this 20 years old paper dated in 1992, where the author use adjectives as 'scarcity', 'dispersion', 'embryonary state of the question', or 'lack of stratigraphic sequences':

      As a side note for readers: whenever you read “NW Iberia”, you can translate it as “Galicia (and probably also northern Portugal)”. We Galicians are notably bad at marketing; except for the owner of Zara ;-P of Zara ;-P

    6. Today, most forest fires in Galicia -which are produced by arsonist- occur in late August and in september, in lands occupied by a mixture of local young oaks and shrubs and imported pine trees and eucalyptus. October is just usually too rainy.

      Beeches are rare today in Galicia, and are even scarce in the local toponymy -Faeiras, Porta Faxeira, Faedo- which usually tells a 1000-2000-3000... years old story.

    7. Thank you, Cossue, I stand corrected: it would seem as if Galicia was relatively important in the Atlantic arch of BB. It makes sense so I'm not really surprised after all.

      What I'm a bit surprised is about what you say on the relative absence of beeches. Here they are absolutely dominant where forests have not been altered, for example Irati, and the climate is similar, so I would have expected them to have also a presence in Galicia. Although I know that what prevails today is mostly pine and eucalyptus plantations, much as it happens here too in many areas (pine plantations feed the provincial treasuries... and also some private pockets).

      As for the fire season, I see I was not too much off the mark. You are probably right because one thing is my subjective impression about August being the month of storms and another what the official precipitation data says (not much rainier than September). Anyhow the data for A Coruña shows a much drier average August than in Bilbao, in spite of the topic about Galicia and the rain (in fact it rains more in Bilbao than in A Coruña through the year, curious).

    8. @BBB: the forestal diversity in North America is probably larger than in Europe. Here in the Ice Age, the tree line was pushed against the Mediterranean and that's why European trees lack the red pigment found in many North American and East Asian species (they use it against some plagues and in Ice Age Europe it was unnecessary). I'm not expert enough (I used to work as gardener but that's about my whole experience on the matter) but I think that's also a reason why European tree diversity is relatively smaller (and greater in general towards the south).

      In any case the species, even if related, are not the same ones, so there will be differences in habitat specialization. Compared to North America and East Asia, I have the feeling that maples are not that common, for instance, and there are less species quite clearly.

      I'm pretty sure that in the Chalcolithic, the tools used would be stone ones. Copper could not compete with flintstone, the Chalcolithic may be at the gates of Metal Ages but it is still in the Stone Age for all practical purposes. In pre-Columbian Mexico too, while they knew of copper and gold metallurgy, their weapons were all made of stone, largely obsidian. In terms of metallurgy, I think the most important development of Chalcolithic was the use of gold (and silver) for jewels and trade. Copper was used for what? Daggers mostly. There is an intent of using copper but it's not really successful not revolutionary, really. The real breakthrough came only with bronze.

    9. Yep. In Galicia we have a more marked summer drought than you there in the Basque Country, although raining days are very much the same (124 per year in Bilbo, 130 in Coruña... Although Santiago, my hometown, is rainier than both: 140 days and more than 1700 mm :-).

      Maybe beeches are less tolerant to that hydric stress than oaks? We have literally thousands of places named Carballo/Carballeira/Carballido/Carballosa (Galician carballo = oak, quercus robur) But just a few tens of Faedo/Faído/Faeiras/Faxeiras... ( < latin faga: beech).

    10. You may be onto something. From Wikipedia (Fagus sylvatica):

      Though not demanding of its soil type, the European beech has several significant requirements: a humid atmosphere (precipitation well distributed throughout the year and frequent fogs) and well-drained soil (it cannot handle excessive stagnant water). It prefers moderately fertile ground, calcified or lightly acidic, therefore it is found more often on the side of a hill than at the bottom of a clayey basin. It tolerates rigorous winter cold, but is sensitive to spring frost.

      I also notice a differential preference between oak (Q. robur) and beech in regards to soils: the beech likes them calcified, the oak rather not, the beech likes them "moderately" fertile, the oak deep. From the Spanish Wikipedia on Q. robur (the English one had no habitat info):

      Desde el nivel del mar hasta unos 1000 m de altitud, en los suelos profundos y frescos, principalmente en los desprovistos de cal y algo húmedos. Requiere un clima húmedo, oceánico, donde se acuse poco la sequía estival y es algo resistente al frío. Se asocia o pone en contacto con hayedos o con robledales de Quercus petraea y Quercus pyrenaica, con los que forma híbridos con facilidad.

      It may be rather a matter of soil types. Also maybe of symbolism but oak symbolism is strong in the Basque country yet I cannot find that preference in toponymy.

    11. @Cossue

      Thanks for the resources! I will add those to my running bibliography and eventually add those as a resource page somewhere on the blog.

      Agree that flint would be used until the Bronze Age. The problem we have with oaks in the U.S. is that they can't be farmed because they grow too slow, yet there is still great demand for oak.
      Also another major problem is the artificial suppression of natural fires which allows resinous trees like cedar to take over that sap the ground of water and choke out young oaks.

    12. @BBB,
      You're welcome! I'm learning, well, almost everything I know about Beakers here in your blog, so, thanks to you :-)

    13. @Cossue
      Well I bookreport mostly, hope I don't lead anyone astray! I appreciate it though.

  3. Related/Unrelated:

    "Oldest mines in Spain" (http://www.lavozdegalicia.es/sociedad/2016/01/19/00161453239156832794745.htm) Apparently the oldest known mine is not in the south, but in the north, in Asturias, dated to 4980 BP (cal): http://aura.abdn.ac.uk/bitstream/2164/5362/1/Early_atmospheric_metal_pollution.pdf

    1. Curious, thanks. What did they mine? Asturias is famous for coal mining but I'm quite sure they did not pay any attention to mineral coal back then. So what was it: copper, gold maybe? There's some gold in Asturian rivers, I know from TV, so I'm going to guess that it was gold.

    2. I think that the authors suggest copper, but apparently (also?) other minerals (tin?) during the late Atlantic Bronze Age, which represents also the most active phase. And then there is a halt in the transition from the first to the second Iron Age, 2470 cal. yr. BP.

    3. It may be copper, it's relatively common. Tin on the other hand is not and Galicia was, along with a few other Atlantic areas, the great source of tin in European Bronze Age (and that was what drove the Mycenaeans, Phoenicians and others over here more than anything else). However I'm not familiar with any tin mine in Asturias, it's rather a Minho area concentration of ancient mines. Also tin would have no or lesser interest before bronze went mainstream.