WOOD CHARCOAL : INTERPRETATION
As stated in introduction wood charcoals provide information about woody plant uses and wood supply strategies for past human societies. Wood charcoals can also inform us, in some extent, about past vegetation but this aspect of anthracology won't be addressed here as the aim of this tutorial is focused on wood economy. First is discussed identifiying and interpreting wood and tree uses. Then we are treating identifying and interpreting wood supply strategies. However never forget that both economical and environmental studies rely on current ecology. Thus because you are conducting a study on wood economy doesn't mean you have to neglect working on vegetation reconstruction.
Wood and tree uses
Wood charcoals can provide information about different uses of wood and more generally trees; by combining data analysis results with archaeological contexts information about the samples collected. The different uses in question are fuel (firewood), construction (timber, tools or objects) and animal diet (especially leaf fodder).
Concerning firewood (fuel wood) only archaeology can help determine what type of activity the wood was burnt for: domestic activity (cooking, heating, lighting…), craftsmanship (pottery, metallurgy, bakery…) or even ritual activity (incineration, religious ceremony, feasting…). Depending on the type of remains associated with the wood charcoal recovered, it is possible to assess what kind of fire they are the remnants, particularly when dealing with short-term deposits (ovens, hearths, kilns...). Wood charcoal from long-term deposits are more difficult to characterise, but a careful examination of all the structures and artefacts associated with should allow us to define the type of activity this wood was burnt for.
Domestic firewood study is usually a part of past environment studies. It is supposed that without others evidences wood charcoals are remnants of domestic fuel, so this type of fuel is never really studied per se. Domestic firewood is from local origin, and its collect is mostly related to availability in a certain range of the settlement (Chabal 1997, Dufraisse 2006). Collection of firewood depends also of different others factors, such as facility of access for collection, degree of humidity, size of wood, and cultural choices, difficult to prove archaeogically, but nonetheless existing (Asouti and Austin 2005,Théry-Parisot 2005).
More specific studies are dedicated to wood used as fuel for craftmanship, mainly metallurgy (e.g. Van Grunderbeek et al. 2002, Hunt et al. 2007) Others specific studies concern wood use for ritual practices, mainly in funerary context, since archaeological evidences are most of the time more obvious for these practices. These studies show a selection of certain species, such as the pine used by ancient Maya (Morehart et al. 2005), or certain parts of the tree, such as the bark (Beauclair et al. 2009).
Construction wood includes timber, and also tools and objects made partially or totally from wood. When a burnt building is excavated, it is possible to find charred timber wood either in situ or mixed through the sediment. Finding timber in situ is the only way to have reliable information about the species used (Willcox 1992, Asouti and Griffiths 2003, Pessin 2003, Sadori et al. 2008). However, some assumptions can be made from timber remains mixed through the sediment, but data from such contexts should be interpreted very carefully, since it is highly likely that timber remains are mixed with fuel remains (Pessin 2004). Concerning wood tools or objects, the finds need to be complete or, for the least, recognisable as tools or objects for an interpretation could be possible. No published example of identification of wood tools or objects are known from wood charcoal. However, such publications (books or articles) exist for uncarbonised wood (e.g. Brisbane and Hather 2007, Chabal 2007).
Concerning construction wood there is always some sort of selection, even if it is wood in a close range of the settlement that was used. For example, wood used in timber along the Syrian Euphrates was mainly collected in the riverine forest because it was the main vegetation formation near the sites concerned, and even when others formations (like oak park woodland) were located in a closer range than on others settlements (Aurenche 1981). Nevertheless importation of wood occured sometimes (Pessin 2004: 303, 305), either by tradition or if the building is prestigious of some sort (ceremonial building, palace, temple, high-ranked official...).
Anatomical stigmata could be observed on ring porous wood, especially Fraxinus (ash tree) and deciduous Quercus (oak). Those stigmata have been associated to the practice of pollarding trees (Haas and Schweingruber 1994). Small branches are used either for firewood or animal fodder (more precisely leaf fodder). Combined with certain 'anomalies' noticed in some anthracological diagram established for sheepfold caves in southern France, those stigmata could demonstrate pollarding of trees for leaf fodder supply (Thiébault 2005, 2006). Furthermore, leaves of ash and deciduous oak are known ethnographically for their nutritice value for animal (for reference about ash see Papachristou and Nastis 1996; for reference about deciduous oak see Kamalak et al. 2004).
Wood supply strategies
Interpretations in terms of wood supply strategies can be fulfilled by combining information on the identified taxa ecology, results of dendro-anthracology analysis and data provided by a wood use study. These interpretations can also provide information about woodland management and trade or exchange of wood.
The different techniques of wood cutting (used in woodland management) are well known by the mean of ethnography and forestry: coppicing, pollarding, trimming and pruning. It is somehow difficult to prove any of these techniques was used, but it is possible on certain types of wood (the ring-pourous Angiosperms) to detect stigmata of pollarding or trimming (Haas and Schweingruber 1994, Bernard et al. 2006).
Otherwise a careful examination of anthracological and archaeological data alllows us to know which were the main vegetation formations exploited and with which purpose (see Wood and tree uses above). Some interpretations can be made from the analysis of anthracological spectra (Asouti 2003, Pessin 2004), but such a study is truly improved with a dendro-anthracological analysis. Dendro-anthracology allows us to acquire information about the size or caliber of the wood, but also about its state before combustion (Marguerie and Hunot 2007, Dufraisse 2008; see also Dendro-anthracology analysis). It is then possible to assess more precisely wood supply strategies through time. Furthermore correlation with the archaeological data available (such as the density of occupation in the area studied or the tools used to cut wood) allows us to draw a more detailed picture of woodland management over a certain period of time (from a generation to hundreds of years) (Dufraisse 2006, 2008).
Trade and exchange
Among the taxa belonging to the anthracological assemblages, most of them are present in the region, either "naturally" or cultivated. However, some taxa may have been imported by the inhabitants of the settlements studied (as mean of trade or exchange for others goods). Determining the taxa potentially imported on the site is based on modern ecological data. Those taxa that can't be grouped in a coherent vegetation formation are likely to be imported, furthermore if they are present in a low frequency and quantity (but it is not always that simple). It is assumed that such taxa present in very few samples and by very few fragments are exogenous and not cultivated (Pessin 2004: 305, 324-25). Nonetheless it is really difficult to demonstrate importation of wood without the help of modern vegetation data and some of the species supposed to be present in a region could also be imported.
Concerning anthracological remains, species determined as imported are identified from timber (Asouti and Griffiths 2003, Pessin 2004: 305). No known methods of analysis allows us to determine with accuracy the region of origin of imported wood. However some information may be acquired by mean of historical texts, especially in regions characterised by an early apparition of writing. Thus in the Near East the different textual archives, found notably in Mari and Ebla, allow us to have an idea of the different roads existing for trade, all along with the different goods circulating between the different states during the periods documented.
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