DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu



ŠUMARSKI LIST 1-2/2009 str. 63     <-- 63 -->        PDF

I. Dakskobler: FITOCENOLOŠKAISTRAŽIVANJA ŠUMSKIH EKOSUSTAVANA POČETKU 21. STOLJEĆAŠumarski list br. 1–2, CXXXIII (2009), 53-62
Society for Vegetation Ecology in the 1970s and 1980s, was also a map of natural
potential vegetation of Yugoslavia in the scale of 1:1.000.000 (B.
Jovanović et al. 1986) and Prodromus phytocoenosum Jugoslaviae (Zupančič
et al. 1986). The work of the time was incorporated also into the Map of
Natural Vegetation of Europe in the scale of 1:2500000 (Bohn et al. 2000).


Development of fast and more advanced personal computers in the 1980 s,
which paved a way for relatively simple massive utilisation of mathematical
methods (above all multivariate statistics) in comparisons of phytocoenological
relevés and their grouping by environmental factors, brought about a significant
turnaround in vegetation research conducted according to the
Central-European and other methods. One of the first widely used software of
this kind was TWINSPAN (Hill 1979). Later on other program packages, such
as MULVA (Wildi & Orloci 1996), SYN-TAX (Podani 2001), JUICE (Tichy2002), CANOCO (Ter Braak & Šmilaure 2002), PC-ORD (McCune &
Mefford 2006), etc. were applied as well. In this respect, a problematic issue
in the Central-European method is the subjective selection of relevés and subjective
evaluation of cover or abundance of species with ordinal values (e.g. r,
+, 1, 2, 3, 4, 5). There have been discussions among experts on the correct
procedures for numeric processing of ordinal input data. Some, e.g. Podani
(2005), believe that only ordinal classification and non-metric ordination
methods are suitable for such data. Others disagree. A similar problem exists
with the statistical analysis of data acquired using non-random (subjective)
sampling, such as are also our relevés. Experts published their pro et contra
views on when and to what extent such analysis is appropriate in the journal
Folia geobotanica (Herben & Chytrý 2007). Despite the above concerns it is
still true that the Central-European method allows a relatively fast, simple
and inexpensive way of acquiring useful data on vegetation and its connections
with the environment. Databases of vegetation relevés (e.g. TURBOVEG
– Hennekens & Schaminée 2001) already keep large amounts of
historic, several decades and even half a century old relevés that were made
with subjective plot selection. Disregarding these relevés on account of their
statistically problematic (subjective and non-random) origin would mean discarding
very valuable ecological data. Ecologists therefore use these data to
their advantage, but with regard to their limitations. These data are used also
in contemporary overviews of vegetation of large regions (e.g. in Willner &
Grabherr 2007). Using and processing large quantities of relevés has
changed the views of the basic unit of the syntaxonomic system – association


–in many ways, and has affected the way we see the concept of character and
differential species (comp. Willner 2006). When selecting diagnostic species
authors apply different computing procedures. A large number of relevés
enable a relatively objective calculation of fidelity of species to certain syntaxa
and their diagnostic value (e.g. with phi-coefficient – Tichý & Chytrý
2006). As a rule, in formalized classification the number of syntaxonomic
units of a vegetation formation (e.g. forest communities) within a certain
region is reduced. The question remains, however, whether such reduction is
founded on the actual site conditions and on the actual phytocoenoses.
Before the turn of the century there was a shift from the knowledge (study)
of plant communities to the knowledge (study) of habitats. It is an acknowledgement
of the Braun-Blanquet method that the most widely used habitat
type classification in Europe (Devillers & J. Devillers-Teschuren 1996) is in
many ways based on this method itself, as well as on its findings and its
review of plant communities, arranged in a hierarchical system.


If we compare Braun-Blanquet’s Phytocoenology from 1964 and van der
Maarel’s Vegetation ecology, which was published in 2005, we can observe a
significant development and a broad array of different approaches to the