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ŠUMARSKI LIST 11-12/2010 str. 33     <-- 33 -->        PDF

M. Cojzer, R. Brus: SPECIES COMPOSITION AND SUCCESSIONAL PATHWAYS ON ABANDONED ... Šumarski list br. 11–12, CXXXIV (2010), 581-591
sing plots were the size, the shape and the developmental
stage of the abandoned land. All plots were square
shaped and north-east oriented.


Vegetation records were carried out on 52 plots in
total. 37 plots (20x20 m) were set on abandoned agricultural
land, of which 5 were in young growth developmental
stages, 15 in a thicket phase, and 17 in a pole
stand phase. 15 plots (20x10 m), 5 for each developmental
phase, were analysed in forest areas. The survey was
carried out from the beginning of August until the end of
October 2006, and in September 2007. Each plot was set
according to its developmental phase (one plot – one developmental
phase), and its floristic composition was recorded
by counting the individuals of tree and shrub


species. The source of the plant nomenclature was the
Mala flora Slovenije (Martinčič et al., 2007).


To analyse the vegetation composition for every
single developmental phase, an appropriate treatment
was assigned to each study plot. Six equivalent treatments
were: A – abandoned land in young growth
phase, B – abandoned land in thicket phase, C – abandoned
land in pole stand phase, D – forest in young
growth phase, E – forest in thicket phase, F – forest in
pole stand phase. All vegetation samples which were
carried out on abandoned land, together created Z treatment,
and all vegetation samples which were carried
out on forest plots, formed G treatment.


2. 3 Statistical analyses – Statističke analize
MapInfo v. 8.5 software was used for spatial data
processing, and Excel for data analysis. Statgraphics
Plus for Windows software was used for statistical data
processing. Data were analysed by analysis of variance
(One-way ANOVA), where parametric (t-test) and nonparametric
tests (LSD test, Duncan variance homogeneity
test) were used. Since the number of subjects per
ha is not a normally distributed variable, a preliminary
»square root« transformation was performed for the
ANOVA. Species diversity was calculated by the Shannon’s
diversity index (H´; H´= -.(pi ln pi)) (Shannon,
1948). CANOCO 4.5 for Windows (ter Braak and


Šmilauer, 2002) was used for calculation. The number
of species per plot (species composition), their stability,
and species density (the number of species
individuals per ha) were calculated for each plot separately.
Species stability was calculated according to the
share of individual species occurrence in the previous
samples. We analysed the plot similarity vegetation
composition by using the detrended correspondence
analysis (DCA), considering the number of individuals
per ha. DCA analysis was carried out with the help of
CANOCO 4.5 for Windows (ter Braak and Šmilauer,
2002).


3 RESULTS – Rezultati


3. 1 The share of forest area and abandoned land –
Udio šumskih površina i zemljišta u zarastanju


In twenty years (1985-2005) the forest area of Haloze
increased by 6.9 % (Tab. 1). The share of forest
cover in the Haloze region is thereby 42.2 %, but
twenty years ago it used to be 39.4 %. And, if (by the
next forest management plan renewal) all presently recorded
areas of abandoned land are classified as forest,
in 2015 (comparably to the year 1985) the forest area
will have increased by 13.0 %, and the total forest area
of Haloze will total 44.5 %.


Table 1
Changes in the forest area in Haloze in the period
from 1985 to 2005 (ZGS, 2005)


Tablica 1. Promjena šumskih površina u Halozama od 1985
do 2005 godine


Year
Godina
Forest area
Površina šuma
(ha)
Index
Indeks
(%)
1985 6916.70 100.0
2005 7396.70 106.9
2015 7803.49 112.8


3. 2 Species composition and density of individuals (on abandoned land and forest) –
Vrste drveća i grmlja te gustoća jedinki (na napuštenom zemljištu te u šumi)


Abandoned land was more species diverse than forest;
47 species were identified on abandoned land (33
tree and 14 shrub species), and 36 species in forest (25
tree and 11 shrub species) (Tab. 4).


With regard to the treatment, the ordination shows
(Fig. 2), that by the first axis, which explains most of
the variability, we can distinguish between two groups
of samples: abandoned land (Z – treatment) and forest
(G - treatment). The total inertion of DCA is 6.281; the
eigenvalues of the first four axes were 0.728, 0.470,


0.322, 0.201, which cumulatively explained 11.6 %,


19.1 %, 24.2 %, 27.4 % of variability in species data.
Gradient length of the first axis is 4.663, which justifies
the use of uni-modal ordination methods (ter Braak and
Šmilauer, 2002). The second axis shows a relatively
high variability in vegetation composition per plot on
abandoned land and a little lower variability in forest.
Table 2 shows the average number of species per
plot. There was no difference in average number of all
species per plot, and in the average number of tree spe