Sustainable land use: What’s archaeology got to do with it?

This might come as a shock, but archaeology is actually relevant to the modern world! And it is particularly useful for looking at how to address environmental problems! How?
With increasing strains on land and resources to feed growing populations in decreasing space, maximising land usability through maintenance of soil fertility and stability, to increase productivity is a priority. In ever decreasing space, the decay of waste in populated areas is made all the more important for land use planning if we hope to maintain viable areas, and not create large ‘no go’ zones for cultivation and other activities. What’s more, if we can actually use the decay of waste and urban processes to positively affect land, then strains on land may be reduced. Archaeology is an expert at examining waste and decay.

In addressing complex modern problems, it makes sense to use as large a knowledge base as possible, from a wide variety of scenarios, to provide guidance on solutions. I believe that archaeology is a valuable tool as ancient remains contain an overwhelming archive of information on human-environment relationships and responses to environmental change over long expanses of time. Archaeology can be used to address modern-relevant problems such as changing landscapes and populations’ response to climate change. Although there are some obvious differences between ancient and modern eras, enough similarities remain (e.g. human behaviour and ecological responses) that results from archaeology are highly relevant.

To be truly sustainable we need to think on long timescales rather than use quick solutions. Too often policy and planning is constrained by factors such as electoral cycles which shorten the vision for the future. Occasionally a century may get mentioned, but to archaeologists even this amounts to very little, and thinking on this scale appears almost irresponsibly blind to the future. Archaeological research maps human activity over very long periods of time and shows that human actions from thousands of years ago can still be seen in impressions on landscapes and ecological characterisation today. Archaeology is very adept at emphasising the importance of long timescales.

Human-environment interaction and impact works on both short and long timescales, often through different mechanisms. In the short term (meaning time of settlement at a site), humans will take part in activities which affect the environment in that period such as farming, hunting, mining and collection of fuelwood. In the long term (the period of decay following abandonment of a site), the environment is influenced by some of the short term impacts e.g. absence of certain species, but is also affected by the breakdown of cultural materials which change the chemical and physical properties of soils and landscapes. The different scales are important when thinking about processes of change and the tipping points for an environment (the point of no return), be that on the micro-scale of a site or an island, or the much larger global scale.

So, human activity chemically and physically affects soils often through very unintentional activities; this may be something as obvious as industry, or it may be simple ‘daily life’. Archaeologists often use chemical signatures in soils to identify the location of sites and activity areas. Examples of these are: phosphorous from organic deposits; Rare Earth Elements from human hair, skin and teeth or marine resources; calcium carbonate from lime processing; mercury from cinnabar used as a red dye, paint and ceremonial substance; manganese, copper and iron from pigments for painting ceramics. The absence or presence of many of these substances can have effects such as on the bioactivity of soils, plant productivity, and plant species make-up according to habitat preferences. Therefore the character of vegetation growing over ancient deposits, and as a consequence also fauna, may in part be directed by ancient human activities. Recognising the ecological effects of production processes and disposal of industrial waste is of course not new, but the long-term perspective from archaeology is an interesting addition to the mix.

My research is using the ancient Maya site of Marco Gonzalez as an example to demonstrate the different timescales for human impact on the immediate environment of an area; biodiversity, vegetation characterisation and soil characteristics among these. Marco Gonzalez is situated at the southern end of the island of Ambergris Caye in Belize, Central America. The site covers an elevated area of at least 355 by 185 metres. It has a long occupation history, from the Preclassic (around 100 BC) to the Postclassic (up to about AD 1300) era, with evidence of heavy involvement in trading, ‘industrial’ processes such as salt making and exploitation of marine resources.

The vegetation and soils at the site are distinctive from the surrounding area, which suggests that the cultural history has left a long-term signature on the environment as it is seen today. A distinctive feature of the site is its black soils, which have high carbon and artefact content. Although natural processes have played their part, the vegetation at the site grows on top of anthropogenic soils that could not have formed at this location under purely natural formation processes. It is the understanding of this transformation that is particularly important for modern issues, principally materials usage and waste disposal. Modern populations on the Caye extract the black soils from archaeological sites for their gardens, as they are excellent for cultivation, being stable with high nutrient content. This demonstrates their value and the importance of understanding how they develop in order that similar conditions might be produced elsewhere to create highly-cultivable land.

The understanding of short and long term human-environment relationships relies on reconstructing the character of the environment through time and detailing the activities that occurred at the site. In my first year of study, I have been mainly researching salt production, which occurred at the site from around AD 600 to 800. Salt would have been produced by heating seawater over a fire and appears to have been an activity that used large amounts of fuelwood, but also sequestered large amounts of carbon in the soils through charcoal waste.

In April 2013 I made my first trip to the site to familiarise myself with the environment and plan for summer fieldwork. Although I had seen images of the site, it was particularly striking in person just how much the site area contrasts with its surroundings. The surrounding area is waterlogged with black mangroves, but the site area is littoral forest with black soils and species such as gumbo limbo and black poisonwood. Human activity is very obvious, with pottery sherds littering the forest floor and piles of conch shells with ‘kill holes’, unlike anything I’d seen before in terms of surface artefact density (brought up by ‘helpful’ crabs that dig holes through the site!).

The trip also allowed re-examination of previously excavated material, to understand past activities at the site, and in particular study salt production artefacts to begin to create a picture of this industrial process so that environmental impact can be more accurately assessed. It also allowed for visits to other sites on the island with similar soils, to understand more of the context of the site and soil formation.

                                                                                                                                                                 

Lindsay Duncan is a PhD student with the ISR and the UCL Institute of Archaeology