 show you here is how this project came to be and how it is highly relevant, at least we think so, to the reconstruction of past and also present land use in dry lands. So we've moved quite a lot with which type of environment from the previous talk and I'm going to talk a bit globally about dry lands although the presentation will be mainly focused on one of the case study of the project which is in Africa so we'll switch to the more local later. So why are dry lands important? Well as you can see from the map on the screen dry land cover over 40% of earth surface and at home to about 2.3 billion people and with the current climate change trends they are bound to increase in surface and this which proves like a very demanding task in terms of feeding the population who's living in these areas and when you think about dry lands I bet that agriculture is not the first thing that comes to your mind and that's because most part of dry lands is below the 400 millimeter of rain per year which is considered the limit for viable agriculture. So when we think about dry land and agriculture we normally associate that with a source of water as an extra source of water rather than just the rain and normally we think of the crew agriculture or floodplain agriculture and that's the cultivation that's done on the bank of major or minor water courses. Let's take about nine for example which we'll see later in the example where people exploit the rich organic fertile soil that lies along the boundaries of the river to cultivate. Other types of agriculture that are carried on are obviously irrigated agriculture which can be done through the use of you know exploiting the water table so wells or through the use of water harvesting metals that can be sisters or they can be even more ephemeral ways like little low bound stone walls that help contain the water that falls with the rain. And then there is rain-fed agriculture which is kind of a practice which is practiced quite widely in regions that have a bit more of rainfall but with our great surprise from fieldwork it's practiced very intensively in hyperarid areas far from any water sources so far from rivers and far from wells and this type of agriculture is done exclusively using the rainfall in places where rainfall is an average of 100 120 millimeters per year so well below the considered limit for viable agriculture. So we know very little of this type of cultivation and this practice in the present and we know even less of that in the past and obviously if we avoid thinking about that and we don't put it on our maps of present and past land use reconstruction we are again creating a bias as Marco and many other were talking about of land use reconstructions. This is a map that most of you well known from Vidgren which is a reconstruction of land use in Africa in about 1800 AD. I'm going to focus on basically this area which is central Sudan and which is here considered just pastoralism which obviously is a very important land use strategy in this area but it's not the only one and you know you might think okay we know a little about the past but today we must know very well what's going on well this is a map that shows the spatial data agreement amongst nine different datasets on land cover but related especially to crops and the red colors means no agreement the green color means good agreement and the white means no crop at all so as you can see again for the area in which I'm gonna concentrate for this talk which is about here there is some agreement but not very you know high agreement on what's going on along the nine and the rest is just blank no crops at all actually when you go and look a little bit more at the ethnographic record for this practice in in arid and hyper arid areas you find quite a lot of quite a lot of data on it and as you can see from this map which is actually a product of stefanos research this practice is not that uncommon even in the sahara which is the most arid probably part of the world that we can think about and in here travelers have recorded the cultivation with just exclusively rainfall of wheat of well they call it wheat okay from the photographs it's really difficult to see whether it's wheat I mean it looks more like sorghum or some sort of millet which makes more sense but they call it wheat and they've they've recorded cultivation of palms for dates in all this area so it's kind of you know a practice that's not that restricted it's quite widespread so the project which started in january is actually going to try and figure out a little bit what can we say about this practice in the present and in the past and obviously as you might imagine this is quite an ephemeral practices it doesn't leave much traces on the ground so how can we reconstruct whether it was carried on in the past or not well the idea is let's go and look at the arco botanica remains of the archaeological sites that are located in this area and try to figure out directly from the arco botanica remain whether these crops were cultivated using irrigation or were just getting just the rainfall uh water just from the rainfall and here is like a case study that it's part of the project but it's also the idea behind the project because this is where it all started and so we're looking at central sudan the area of cartoon or well um durman and in here there's a the archaeological site of al-kidae i'm sorry probably the points are really small uh this site has been excavated for quite a few years from donatello's eye from the sudanese institute archaeological institute of italy and she's got a very good record on what was going on in terms of subsistence practices and it's a site that spans quite a long time from the so-called mesolithic to meriotic period so it will give us quite a nice view of long-term practices at the site and as you can see nowadays it's located just outside the boundary of the flooding area of the night and what actually um you know prompted the thinking of or the idea for this project is that when we were doing um the main idea is that there are almost no site in the interior and especially no archaeological no neolithic period site in the interior and um because obviously the conditions are very harsh so when we were doing survey for actually something completely different we came across the fields that i was showing in the first slide in this area which is about 15 to 20 kilometers inland well inland from the night river and here you can see more or less how the landscape changes with the you know changing or well with with getting farther and farther from the night so along the night you have these nice brown rich soils where they actually where today they cultivate sorghum and then as you move out so just outside the boundary of of the flooding plain you get a cultivation of Panicum which is more adapted to arid land and then when you move even further inland you get these fields again of Panicum and i know it's kind of difficult to see from from this this picture but this is a field obviously with the rest of the plant that just been harvested and all the area where you see a bit reddish these are all fields so these are huge field system it's not a little field for subsystem practices actually talking with local farmers they talk about owning fields of several hectares and actually being able to produce double of what they need for for their subsistence in good years so in years with 100 millimeter of rain and being able to sell the other half and actually this is something you can see very clearly also just from google earth this is the same point 2011 almost no rain nothing 2012 130 130 millimeters and you see the rows of fields appearing so it's actually a good tool to just pinpoint area where to go and look at as i said we talked about so we needed to understand how to investigate this archaeologically so we talked about people and they pointed us to two different field systems one they said we've used it a lot but it's not that good and the other one said you know we keep using it because it's very good and here are the two field system the one that it's not that good it's actually a huge field that was cultivated for about 10 years and then abandoned but heavily cultivated with plowing mechanical plowing etc because it's a nearer well although they say they didn't use the well to irrigate the field and the other one is something that we will never consider a good field it's in the middle of the desert there's no vegetation around very arid so we started to understand how to link this with the archaeology and what we came up is with the project is to look at various properties amongst which phytoliths which are biogenica silica which is inorganic so it preserves very well and there are a few studies that have linked the formation of phytoliths to the quantity of water that the plants received in the past so we thought we'll go in this way another type of study that has been done on plants in arid areas is how the morphology of the plant changes with more or less water and for example this study which is the only one I could find on the C4 plants which are the plants that are present in this area shows how with more water the plants tend to produce less hair which is actually one of the easiest phytoliths to find so I looked at the two fields that I showed that I showed before these one are the bed field that actually you know in theory had more water and these ones are the field the good field that for us was not suitable at all and actually phytoliths confirm that against what you can see on the ground where you would assume on the ground the site in the desert actually retains more moisture okay so what phytoliths are telling us you know these samples have less hair so you know the plants that were growing there had less hair and so this is actually a site that retains more moisture which actually speaks of the importance of talking to people and the importance of traditional ecological knowledge to understand these type of practices and you know I'm just at the conclusion the first one is obviously that there's a lot of work to do these are very very very preliminary results and the project has just started so I hope I hope I'll be able to give you more detail in the next future but also that this approach combining different proxies and especially concentrating on traditional ecological knowledge is very promising for this type of study and definitely archaeology, archaeological science, archaebotany can inform on past land use and be integrated in climate modeling thank you