Nicola Arndt und Matthias Pohl - Neobiota

Over this distance matrix several methods of non-overlapping hierarchical clustering were performed.
The Unweighted Arithmetic Average was selected because it had the highest cophenetic correlation
coefficient (Pearson = 0,92047).
The resulting dendrogram was then split in five parts according to the Euclidean distance: from 0,0
minimum aggregation, then 0,5; 0,6; 0,7; 0,8 and 0,9 the maximum aggregation level (Figure 5). This
classification was transformed into a table and added to the ArcInfo identity map table. Again in
ArcInfo the classification maps were created by dissolving the boundaries of neighbouring polygons
with the same cluster classification
A1
A4
B41
C11
B42
C9
C5f
0,0 0,5 0,6 0,7 0,8 0,9
Figure 4 (Left): The combination map in the scale of 1:7,500,000 for the southern United Kingdom. The straight
lines are from ITE map.
Figure 5 (Right): The first three clusters formed in hierarchical classification by Euclidean distance in the
dendrogram. The letters on the left represent the natural vegetation codes of BfN, and the numbers on top the
Euclidean distances on the cluster tree or dendrogram.
4 Results
The methodology described above led to six experimental DMEER maps, each containing between 46
and 189 DMEER classes and representing different aggregation levels, as summarised in Table 1.
Table 1: Basic features of the six maps.
Euclidian distance Number of classes
Number of classes that
cover 80 % of the area
Average area by
polygon/cluster of the
remaining 20 % of the area
0,9 46 11 652 km 2
0,8 79 17 663 km 2
0,7 106 26 533 km 2
0,6 133 29 521 km 2
0,5 156 36 410 km 2
0,0 189 43 394 km 2
The DMEER map with 46 classes is the map with the maximum aggregation level; it represents the
dendrogram split at 0,9 Euclidean distance. The 11 largest classes together cover 80 % of the total
DMEER area (Figure 6).
The largest 27 clusters cover 90 % of the total area. In the smaller clusters the mean polygon area is
31