Table 1
The different laboratories that provided their measurement series (oak) for the research.
| LABORATORY | COUNTRY | RESEARCHERS | SERIES | LOCATIONS | REMARKS |
|---|---|---|---|---|---|
| BAAC (Deventer) | Netherlands | S. van Daalen | 59 | 9 | |
| Centre Européen d’Archéométrie – University of Liège (Liège) | Belgium | J. Eeckhout, P. Hoffsummer, D. Houbrechts, P. Hoffsummer | 135 | 8 | |
| University of Freiburg, Chair of Forest Growth and Dendroecology | Germany and France | W. Tegel | 1035 | 54 | |
| Van Daalen Dendrochronologie (Deventer) | Netherlands | S. van Daalen | 64 | 1 | |
| Labor für Dendroarchäologie – University of Cologne (Cologne) | Germany | B. Schmidt | 439 | 8 | From four places: Cologne, Koblenz, Oberaden & Xanten. |
| RING foundation (Amersfoort) | Netherlands and Belgium | Julia Borquez, S. van Daalen, M. Domínguez-Delmás, D.M. Duijn, H. van Enkevort, A.E. Hanraets, N. van Helmond, E. Jansma, U. Sass-Klaassen, P. van Rijn, T. Vernimmen, R.M. Visser, Y.E. Vorst | 1933 | 172 | Data includes measurement series that were collected institutes before the RING existed (Rijksdienst voor het Oudheikundig Bodemonderzoek (ROB), supervision: J.A. Brongers (1986-1991) and University of Amsterdam (UvA/IPP), supervision E. Jansma (1985–1993)) |
| Vlaams Instituut voor Onroerend Erfgoed (VIOE, Brussels) | Belgium | A. de Groot, K. Haneca | 51 | 7 | |
| Totals | 3006 | 259 |
Figure 1
The find locations of the complete dataset (each data provider indicated with different colours). The published chronologies used are visualized as diamonds. The top-right histogram shows the number of available tree rings for the complete dataset (excluding published chronologies).
Figure 2
The research model of this study.
Figure 3
Network of the site chronologies from the ITRDB/Dendrobox (Zang 2015). On the left the nodes are coloured by continent on the right by species (for convention of species codes see Grissino-Mayer 1993).
Figure 4
Kernel density estimation of the geographic distances between nodes in the network (4) of site chronologies from the ITRDB (based on data from Zang 2015). On the left all species are shown, on the right only selected species. The selected species are Abies Alba (ABAL: 49 site chronologies), Pinus Sylvestris (PISY: 127 site chronologies), Picea abies (PCAB: 117 site chronologies) and Quercus sp. (QUSP: 67 site chronologies). The selection is made based on the frequency in the Dendrobox-dataset and the most often dendrochronologically analysed European tree species from archaeological contexts dating to the Roman period (see also Visser 2015).
Figure 5
Histogram with the number of measurements per tree.
Figure 6
Find locations of site chronologies (both published and my own) and material that was not grouped.
Table 2
The number of site-groups created.
| SITE-GROUPS | TREES | |
|---|---|---|
| Oak (Quercus spp.) | 178 | 2607 |
| Ash (Fraxinus excelsior) | 9 | 84 |
| Silver fir (Abies alba) | 7 | 32 |
| Elm (Ulmus spp.) | 2 | 28 |
| Spruce (Picea abies) | 1 | 4 |
Table 3
The network variables describing oak network types 1-4 for site chronologies, series and the combined networks of chronologies and series.
| CHRONOLOGIES | TREES | COMBINED | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NETWORK-TYPE | 1 | 2 | 3 | 4 | 1 | 2 | 3 | 4 | 1 | 2 | 3 | 4 |
| Components | 7 | 10 | 5 | 6 | 107 | 35 | 98 | 38 | 44 | 23 | 44 | 22 |
| N | 130 | 151 | 155 | 171 | 1255 | 1741 | 1331 | 1778 | 1551 | 1794 | 1680 | 1927 |
| E | 214 | 287 | 407 | 486 | 2175 | 5048 | 2664 | 5529 | 2150 | 3508 | 2634 | 4113 |
| C | 0,224 | 0,256 | 0,376 | 0,360 | 0,193 | 0,168 | 0,212 | 0,185 | 0,000 | 0,000 | 0,000 | 0,000 |
| K | 3,552 | 4,266 | 5,542 | 6,064 | 4,088 | 6,037 | 4,642 | 6,505 | 2,934 | 4,034 | 3,306 | 4,399 |
| δ | 14 | 12 | 12 | 11 | 29 | 20 | 27 | 19 | 22 | 16 | 16 | 16 |
Figure 7
The degree distribution of the networks of site chronologies on the left and the network of measurements series on the right. All exhibit a power-law distribution.
Figure 8
Histograms showing the count of distances between nodes, faceted per network degree for network type 1 (site chronologies).
Table 4
The number of communities and, between brackets, the total number of nodes in communities that were found in the networks of site chronologies using the Girvan-Newman algorithm (GN) and the Clique Percolation Method (CPM).
| NETWORK TYPE | GN | CPM | |||||
|---|---|---|---|---|---|---|---|
| k = 3 | k = 4 | k = 5 | k = 6 | k = 7 | k = 8 | ||
| 1 | 19)130) | 8(61) | 4(29) | 2(10) | |||
| 2 | 19(151) | 7(76) | 5(41) | 2(15) | |||
| 3 | 14(155) | 7(110) | 6(68) | 3(39) | 1(22) | 1(10) | 1(8) |
| 4 | 15(171) | 8(122) | 8(86) | 3(42) | 2(29) | 1(13) | 1(8) |
Figure 9
Communities as detected by applying the GN-algorithm in the network of means (network type 4).
Figure 10
Communities as detected with the CPM for network type 4 (upper left: k = 3, upper right: k = 4, lower left: k = 5, lower right: k = 6).
Figure 11
The community GN_3 in network type 1 with the analytical network on the right and the spatial network on the left.
Figure 12
Provenance groups projected on the different GN-communities, network type 4 (see also Figure 8).
Figure 13
Network (type 1) with nodes coloured using a typology of sites, with the categories military, civilian, religious, natural and unknown/unclear. Military clusters are marked in transparent green.
Figure 14
A model to describe the Roman timber economy in relation to provenance of wood.