Three days, around 20 sampling locations and more than 50 plant samples collected across the Wrocław Plain.
Weather conditions in the Wrocław area between 28 and 30 May were ideal for fieldwork. During those three days, the DoHa Project team—Anna Józefowska-Domańska, Bogumiła Wolska, and Adam Budziszewski—travelled nearly 400 km across the Wrocław Plain to collect grasses, shrubs, and tree leaves from locations unaffected by contemporary or historical pollution. However, we were not alone. We received invaluable logistical and substantive support from Jan Majrak, a doctoral student at Antropos IPAN Doctoral School, and Mateusz Krupski from Wrocław University of Environmental and Life Sciences.
The purpose of all this is to deliver these plants to the isotope laboratory at Masaryk University in Brno. Why do archaeologists need modern plants from forested areas untouched by human hands? After complex preparation and laboratory analysis of the collected plants, we will obtain information about local values of strontium isotopes. This data will, in turn, allow us to understand the variation in strontium isotope ratios in the local environment of the Wrocław Plain region within the broader context of the Domasław cemetery study. Determining the characteristic values for the area within a radius of approximately 20 km from the studied burial ground (and in some places even up to 30 km) will enable us, in a later stage of the project, to determine which of the deceased buried in Domasław exhibit local strontium values and which, based on isotopic data, should be considered non-local individuals.
However, we’ll save the details about the lab work involved in analysing environmental samples for another time. Today, we want to focus on the route and the places we visited.
We’re sharing the route we took with you. We visited the area around Wrocław, but covering this route in a single day, even without carefully selecting the right locations and collecting samples and documentation, can be quite a challenge. Additionally, not every location is easily accessible by car. However, the route could serve as an interesting bicycle trail.
We based our selection of sites for environmental sampling on geological maps. Variations in local strontium values are largely related to the type and age of the parent rock, as well as to younger glacial deposits. We therefore sought to cover as broadly and accurately as possible, collecting plant samples from all geological types present in our region.
The next cartographic step we took was a thorough analysis of historical maps. In our analysis of this source, we focused on the location of larger forest complexes on successive maps, ranging from Prussian military maps from the era of the Silesian Wars through the German Messtischblatt to post-war Polish topographic and military maps. We considered the continuous presence of forest since the mid-18th century to be an indicator of low pollution levels, which could have affected the original strontium values that are so important to us. So much for the methods. Let’s now focus on the route itself.
We began our fieldwork by visiting Wojnowski Forest. At each location, we looked for grasses, shrubs, and tree leaves. These types of plants have different root systems that absorb nutrients from different levels of local sediments. Thus, plants growing in a single location penetrate the soil at various depths, and observing and understanding the differences in strontium levels will allow us to better understand local strontium values.
The next stop on our expedition took us to the Wilczyńskie Forests near Wisznia Mała. Collecting environmental samples is not just a stroll through wooded areas. It requires detailed knowledge of the location and careful observation of the local environment in order to eliminate any potential sources of contamination and collect the appropriate plant species. During our field research, we decided to collect specific plants. We therefore focused mainly on raspberry, blackberry, and currant bushes, as well as linden and oak leaves. Our colleague Jan’s help was invaluable in this task; by sharing his knowledge with us, he enabled us to collectively make the best botanical selection available at the locations we had marked on the map.
We also visited the beech forests near Skarszyn, and then, after exploring the forests around Chrząstawa, we headed south; once we crossed the Oder River, we focused on surveying the areas southward toward Wrocław. The precise procedure for collecting environmental samples for isotopic analysis also requires a thorough inventory and accurate recording of geographic coordinates. Therefore, each plant sample was placed in a paper envelope labelled with an inventory number and coordinates.
The next site on our map was located in a small forest between Zabardowice and Miłonów. After the first sites, which were located in larger forest complexes, it was time to collect samples from a part of the Wrocław Plain that had undergone a much higher degree of human-induced transformation. The area of our study had been deforested for centuries. The fertile soils mean that a large part of the area is still used for agriculture. In such places, it is most difficult to find sites with long-term forest cover.
In places like these, we were particularly delighted to see centuries-old oak and ash trees, even in the modest groves surrounded by the fields. Next, we visited the forest near Tyniec on the Ślęza, the grove surrounding the Early Mediaeval fortified settlement in Szczepankowice, the manor park in Kobierzyce, and the grove on the outskirts of Bielany Wrocławskie. That concluded our first, intense day.
On the second day of our expedition, we headed toward Pracze Odrzańskie, Mokrzański Forest, and Ratyński Forest. Fortunately, deciduous trees clearly dominated the forests we were interested in. However, we didn’t always manage to immediately find a satisfactory cluster of grasses, shrubs, and older trees with young leaves within arm’s reach… This seemingly simple task sometimes required longer walks and careful observation of the surroundings.
After collecting samples from a small grove near Sobkowice, we completed the intensive sampling phase in the wider area of the Bysztrzyca Valley and set off toward Szczytna Summit. We passed the Ślęża Massif, but we had planned to explore this unique strontium site on the final day of the sampling campaign.
We then headed toward Wrocław, stopping once more in the Bystrzyca Valley near Stradów, as well as in the small wooded areas of Gniechowice and Smolec. Finally, on the last day of the expedition, we travelled to Sobótka to visit two locations within the Ślęża Massif on foot. The planned route indicated that the easiest way for us to reach the summit of Ślęża would be along the way. An opportunity not to be missed.
In total, on the last day, we walked over 15 km to collect samples from two locations. Over the course of three days of fieldwork, we visited a total of 19 sites and collected over 50 plant samples. The next step will be laboratory analysis again. But we’ll write about that in our next post.
