variety 
circle. 
circle. 
rectangle 
rectangle 
rectangle 
rectangle 
rectangle 
rectangle 10 
vegetation 
radius 5 
radius 6 
5 by 5 
6 by 6 
7 by 7 
8 by 8 
9 by 9 
by 10 
1 
374,0 
337,3 
502,9 
462,9 
428 
396,9 
369,2 
344,4 
2 
282.5 
295,7 
200,9 
223,7 
256,5 
274,5 
288,0 
297,6 
3 
81.1 
103,6 
22,7 
36,2 
51,6 
67,5 
83,2 
98,7 
4 
13.6 
22.2 
1,22 
2,9 
5,7 
9,4 
14,1 
19,7 
5 
1.6 
3,5 
0,09 
0,32 
0,84 
1,7 
2,9 
6 
0,07 
0,27 
0,03 
0,08 
0,2 
variety 
circle. 
circle, 
rectangle 
rectangle 
rectangle 
rectangle 
rectangle 
rectangle 10 
structure 
radius 5 
radius 6 
5 by 5 
6 by 6 
7 by 7 
8 by 8 
9 by 9 
by 10 
1 
363,2 
327,4 
487,8 
449,4 
415,4 
385,1 
357,7 
333,2 
2 
263,4 
272.9 
197,0 
223,4 
243,5 
258,4 
269,5 
276,8 
3 
96,4 
117,0 
37,2 
52,6 
68,0 
83,2 
97,9 
111,9 
4 
26,6 
38.5 
4,2 
8,5 
14,0 
20,5 
27,8 
35,8 
5 
5,3 
9,2 
0,28 
0,82 
1,87 
3,5 
5,5 
8,0 
6 
0,71 
1,66 
0,05 
0,15 
0,34 
0,7 
1,24 
7 
0,11 
0,26 
0,02 
0,05 
0,1 
0,17 
8 
0,05 
0,03 
Table 1: focaldiversitv (in some software "focalvariety ") of vegetation and structure of vegetation depending 
on the moving window (4 m resolution) in hectares. The table shows, that the critical question for calling an 
area "highly structured" is the determination of a filter size and the absolute values of a variety for each filter 
size. For example, a rectangle moving window of 7 by 7 pixels results in 428 ha (out of 726 ha of this small 
sample) with a variety of l, which means spatial homogeneity. This is clearly to define. But what is "highly 
structured"? Is it values of 2 and more or values of 4 and more? 
Table 1 shows how the results are depending on form and size of the moving window. This 
simple fact is not always considered. Focaldiversity algorithms are implemented in most of the 
relevant GIS-packages and increasingly (and sometimes unreflectingly) used in landscape 
ecology. Dillworth et al. (1994) observed that geometric windows may have some 
shortcomings when used to access spatial characteristics of nominally scaled data and suggest 
the use of more complex 'geographic' windows. Meanwhile, sophisticated software packages 
for landscape analysis such as FRAGSTATS (McGarigal and Marks 1994) exist for both 
vector and raster data to analyse landscape and to quantify landscape structure. Nevertheless, it 
is necessary to point at the importance of understanding the influence of the designation of 
matrix elements, cell size, or size of the moving window. 
Adding a qualitative aspect 
The results of the focalvariety calculation of the layer structure are corrected in order to the 
structural value of the classes. On the contrary to the vegetation layer, the survey consists of 
qualitative terms such as "rich structured" or "low structured". This qualitative aspect has to be 
added. The adding values are determined by experts. Values are recoded to an ordinal level. As 
shown above, the absolute values of the resulting diversity depend on the size of the moving 
window. Taking the original values would not only be pseudo-accurate but would lead to 
wrong results. Nevertheless, recoding is one of the critical points in this method. This step can 
influence or manipulate the spatial distribution of the resulting values more than anything else. 
Therefore we need experts to establish rules for the reclassification of the resulting values due 
to reality. We have to remember the size of the moving window (e.g. 7x7 rectangle at 4m pixel 
size means 784 m 2 ). In this context, what means "high" and what means "low"? In this case 
study it was tried to let some experts independently search for the answer and the mean value 
was taken. 
Correlation with the distribution of indicator species: Structural diversity as a measure 
for habitat quality?