Plant species diversity and structural characteristics of the old-growth spruce-fir-beech forests in Biogradska Gora

Abstract

Species richness is a fundamental parameter of the site biodiversity potential. Quantification and comparing the taxon richness of mixed forests of spruce, fir and beech (Piceo-Abieti-Fagetum Čol. 1965.) were conducted according to the phytosociological studies followed by the Braun-Blanquet method. We recorded 41 vascular plant species in four sample plots of the total area of 1 ha. Concerning the plant species composition, we found differences in species richness between mixed forests of spruce, fir and beech and fir-beech forests in Biogradska Gora. Number of species was lower than in the forest community of fir-beech in the same preserved area, but higher than in the managed forests of spruce-fir-beech. The overview of structural characteristics was developed on the basis of data from four clusters. The number of trees per unit area varied from 300 to 445 trees per ha. Estimated values of timber volume were from 558.9 m 3 /ha to 749.0 m 3 /ha. The results presented in this paper show that mixed forests of spruce, fir and beech on Biogradska Gora belong to forest ecosystems of high degree of preservation, with high values of growing stock and with a structure that is characteristic of the old-growth forests.

Full text

Green Room Sessions 2018 International GEA (Geo Eco-Eco Agro) Conference - Book of Proceedings
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Original Scientific paper
Plant species diversity and structural characteristics of the
old-growth spruce-fir-beech forests in Biogradska Gora
Milić ČUROVIĆ
1
*, Aleksandar STIJOVIĆ
2
and Slobodan STIJEPOVIĆ
3,
*
1
University of Montenegro, Biotechnical Faculty; Montenegro, curovic@t-com.me
2
Institute of Forestry, Podgorica, Montenegro; Montenegro, stijovicaleksandar@gmail.com
3
National Parks of Montenegro; Montenegro, slobodan.stijepovic@gmail.com
* Correspondence: curovic@t-com.me
Abstract
Species richness is a fundamental parameter of the site biodiversity potential. Quantification and comparing the
taxon richness of mixed forests of spruce, fir and beech (Piceo-Abieti-Fagetum Čol. 1965.) were conducted
according to the phytosociological studies followed by the Braun-Blanquet method. We recorded 41 vascular
plant species in four sample plots of the total area of 1 ha. Concerning the plant species composition, we found
differences in species richness between mixed forests of spruce, fir and beech and fir-beech forests in
Biogradska Gora. Number of species was lower than in the forest community of fir-beech in the same preserved
area, but higher than in the managed forests of spruce-fir-beech.
The overview of structural characteristics was developed on the basis of data from four clusters. The number of
trees per unit area varied from 300 to 445 trees per ha. Estimated values of timber volume were from 558.9
m
3
/ha to 749.0 m
3
/ha.
The results presented in this paper show that mixed forests of spruce, fir and beech on Biogradska Gora belong
to forest ecosystems of high degree of preservation, with high values of growing stock and with a structure that
is characteristic of the old-growth forests.
Keywords:
old growth forest, spruce, fir, beech, Biogradska Gora
Introduction
Biogradska Gora, on the mountain Bjelasica in Montenegro, is one of the largest long-term preserved
forests in the south-east Europe. The history of this forest protection dates back to 1878 when the local
people, after the liberation of Kolasin area from the Turks, had offered the Biogradska Gora forests to
the duke Nikola Petrovic and he protected it as the hunting preservation area. Since 1952 Biogradska
Gora has been the National Park with strong preservation forest area of 1600 ha.
The term old-growth forests include such forests developed during the long periods without
relevant human impact and natural catastrophic disturbances (Peterken 1996). Extensive forest
exploitation in Europe caused their structural and compositional homogenization and simplification,
leaving only remnants of old-growth temperate forest ecosystems. (Axelsson and Oestlund 2001). The
mountainous regions of the Bavarian Limestone Alps were primarily covered by the mixed Norway
spruce (Picea abies [L.] Karst.) - European Beech (Fagus sylvatica L.) - Silver fir (Abies alba Mill.) forests,
but currently, many initially mixed forests have been replaced by spruce dominated or pure spruce
stands (Baier et al 2005).
Forest ecosystems of Biogradska Gora are characterized by a high degree of preservation. The
Biogradska Gora mixed Abies-Picea-Fagus forest is one of the largest old-growth forest remaining
(1230 ha) in the central-southern Europe (Motta et al 2015).
According to the First National Forests Inventory of Montenegro (MARD, 2013),the forests of
fir, spruce and beech (Piceo-Abieti-Fagetum Čol. 1965.) constitute 4.7% of the surface area covered by
forest in Montenegro. For a long time it has been considered that mixed forests of spruce, fir and
beech (Piceo-Abieti-Fagetum Čol. 1965.) are just sub-associations of beech and fir forest association

Green Room Sessions 2018 International GEA (Geo Eco-Eco Agro) Conference - Book of Proceedings
234
(Abieti Fagetum moesiacae B. Jov. 1976.), but the prevailing opinion is that it is a separate association
(Mišić and Jovanović 1983).
Understanding the development process in intact forests is essential for learning the most
effective way to manage forests in a manner that would retain sufficiently high level of biodiversity
(Medarevic et al 2004). Structure and species composition of old-growth forests should be base for
management approaches according to the future climate changes (Millar et al 2007).
The ecological value of unevenly aged, old growth forests can be seen also through stability
in relation to erosion processes. So the basin of the Biogradska River, according to the erosion
processes is classified as the 4
th
category of destructiveness and, regarding the classification of erosion
intensity, belongs to the areas of weak mixed erosion (Spalevic et al 2004). In some other parts of
Bjelasica Mt. with not stabile forest ecosystems, erosion processes are classified as more dangerous
(Spalevic et al 2013; Spalevic et al 2015; Spalevic et al 2016; Vujacic et al 2017).
The significance of this research is also resembled in the fact that there is modest knowledge
about competitive and facilitative interactions between trees and species in the mixed fir–beech–
spruce forests (Bosela et al 2015).
Materials and Methods
The basic information for plant species richness was collected by the Braun-Blanquet method (1964) of
phytosociological study. In total, 4 phytosociological relevés were taken in tree dominant mixed
forests of spruce, fir and beech. The surface of each experimental plot was 0.25 ha.
Structural characteristics were researched on the basis of data from 4 clusters (Figure 1). Each
cluster consisted of four sample plots, placed on the top of a square whose leg length was 200 m. The
sample plot consisted of four concentric circles, with the radius of the first circle r1=5.64 m (p1=1 acre
on plain terrain), of the second circle r2=7.98 m (p2=2 acres), of the third circle r3=12.62 m (p3=5 acres)
and the radius of the fourth circle was r4=17.84 m (p4=10 acres). Diameter measurement was
performed on the first concentric circle, on all trees above 10 cm. On the other concentric circle,
diameters were measured on all trees above 15 cm, on the third circle diameters on all trees above 30
cm and on the fourth circle diameters of trees above 50 cm. Measurement was performed during 2017.
Growing stock – timber volume was calculated using timber volume tables for Montenegrin
forests. (Marković 2004).
Figure 1. Position of clusters

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235
Results and discussion
Vegetation
Total number of vascular plant species recorded in four sample plots of the total area of 1 ha was 41
(Table 1).
Table 1. Phytosociological releve´s performed in the studied sites
Association
Piceeto- Abieti- Fagetum
s. lat.
Sub-association
Typicum
Presence
degree
Locality Biogradska gora
N
o
of releve´ F1 F2 F3 F4
Altitude (m)
1200
1200
1200
1200
Exposition SSW SW N NE
Slope (°)
15
-
25
30
25
35
Flor I
Canopy
0,6
0,5
0,6
0
,6
Fagus moesiaca 2.1 1.2 2.2 3.2 V
Abies alba
3.2
3.2
3.2
1.2
V
Picea abies
1.2 1.2 1.2 V
Acer pseudoplatanus
+ II
Floor II
Canopy
0,2
0,2
0,1
0,2
Average height (m) 5 3 4 3
Abies alba
1.2
1.2
1.2
1.2
V
Fagus moesiaca
1.2 + 1.2 + IV
Picea abies
+
+
II
Sorbus aucuparia
+ I
Floor III
Canopy
0,9 0,7 0,7 0,8
Festuca drymeia
4.5 2.3 +.2 1.2 V
Athyrium filix
-
femina
+ + 2.2 1.2 V
Oxalis acetosella
1.2
1.2
1.2
1.2
V
Asperula odorata
1.2 +.2 +.2 V
Glechoma hirsute
+
+.2
1.2
V
Dryopteris dilatata
+ + + + V
Asarum europaeum
+
+.2
IV
Dryopteris filix- mas + + 2.2 2.2 IV
Rubus hirtus
+.2
1.2
1.2
IV
Euphorbia amygdaloides
+ IV
Cardamine bulbifera + IV
Viola sylvestris
+ IV
Lonicera nigra
+
IV
Polygonatum verticillatum
+
IV
Geranium robertianum
+ + IV
Mycelis muralis
+ + +.2 IV
Prenanthes purpurea
+
+
+
IV
Vaccinium myrtillus + III
Lonicera alpigena
+
III

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Saxifraga rotundifolia + III
Polystichum aculeatum
1.
2
+
III
Epilobium montanum
+
+
+
III
Actaea spicata
+
+
III
Symphytum tuberosum + II
Neottia nidus
-
avis
+
II
Abies alba
+.2
II
Luzula sylvatica
3.3 II
Sorbus aucuparia
+
II
Lilium martagon
+
II
Paris quadrifolia
+
+
II
Veronica montana
+
II
Circea luteciana
+
+
II
Allium ursinum
+
I
Galium rotundifolium + I
Lunaria rediviva
2.2
I
Salvia glutinosa
+
I
Polypodium vulgare
+.2 I
Euphorbia carniolica
+
I
In the studied stands, spruce, fir and beech are dominating species in tree and shrub layers.
Beside the basic floristic elements of those floors, we recorded also Acer pseudoplatanus and Sorbus
aucuparia, as the secondary tree species in the researched stands.
The floor of the ground flora (III Floor) is characterized by larger number of acidophilic
species. Among them, the highest abundance is of fescue (Festuca drymeia), followed by Oxalis
acetosella, Athyrium filix-femina and numerous bryophytes.
Concerning the plant species composition, we found differences in species richness between
mixed forests of spruce, fir and beech and fir-beech forests in Biogradska Gora. Species richness was a
bit lower than in the forest community of fir-beech (Abieti-Fagetum moesiacae B. Jov. 1976), where 58
species were found (Curovic et al. 2011).
Also the number of recorded species (41) proved to be higher compared to the managed
forests of the same mountain. In the managed forests of Bjelasica (Gazdic et al 2016), significantly
higher number of plant species(60 species) in the beech and fir association were found, if compared to
the association of beech, fir and spruce (30 species).
Structural characteristics
Basic insight into the structural characteristics of forests of spruce, fir and beech on Biogradska Gora
can be obtained by analyzing the two basic structural elements - number of trees and wood volume
per unit area (Table 2).
Present structure of Biogradska Gora forest is just the result of spontaneous development
processes over a long time period because those ecosystems are developed without human activities
influence. The average quantity of standing volume in forests of Biogradska gora indicates that these
are very valuable and productive forest ecosystems. Estimated number of trees per unit area on the
experimental plots is 300 to 445 trees per ha. Timber volume values varied,from 558.9 m
3
/ha to 749.0
m
3
/ha.
In the best spruce-fir-beech stands on the Mt. Ljubišnja in Montenegro at the Vukodol site,
501 trees/ha with 404.3 m
3
/hawere measured. The average number of trees per unit area at the Sula
site was 644 trees/ha and determined standing wood volume was 584.4 m
3
/ha (Curović et al 2011a).

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The average values of those two structure elements within the stands of mixed forests of
spruce, fir and beech type in the “Tara” National Park, in Serbia, according to Medarevic et al.(2007),
were 456 trees/ha with the average volume of 709 m
3
/ha. The mixture per volume for fir: spruce :
beech = 50% : 2% : 48%, was measured in the virgin Pecka forest in Kosevski rog (Slovenia), with an
average standing volume of 647 m
3
/ha (Boncina et al 2003).
Table 2. Basic structural elements
Species N/ha N% V/ha V% G/ha Ds Hs Hs/Ds
Cluster 1 Pcs/ha
m
3
/ha m
2
/ha cm m
Fir
51
.
7
76
.
8
54
.
6
26
.
6
0
.
5
Spruce
4
.
2
3
.
3
43
.
6
24
.
6
0
.
6
Beech
44
.
2
19
.
9
37
.
4
20
.
7
0
.
6
Total Cluster 1
300
100
.
0
692
.
0
100
.
0
44
.
7
50
.
1
25
.
1
0
.
5
Cluster 2
Fir
48.5
71.6
53.9
26.8
0.5
Spruce
13.1
14.8
59.4
32.7
0.6
Beech
38.5
13.6
34.9
19.4
0.6
Total Cluster 2
325
100.0
749.0
100.0
44.1
51.2
26.3
0.5
Cluster 3
Fir
16.9
55.9
60.1
32.2
0.5
Spruce
19.7
16.7
37.2
24.7
0.7
Beech
58.5
24.6
23.9
18.1
0.8
Sycamore maple
4.9
2.8
29.7
19.9
0.7
Total Cluster 3
355
100.0
558.9
100.0
31.6
44.0
26.2
0.6
Cluster 4
Fir
25.3
35
.7
44.4
19.9
0.4
Spruce
2.8
15.7
80.5
34.4
0.4
Beech
71.9
48.5
32.5
19.8
0.6
Total Cluster 4
445
100.0
613.8
100.0
44.9
42.7
21.8
0.5
Average values for all 4 Clusters
Fir
34.1
61.2
53.7
26.5
0.5
Spruce
9.6
12.4
57.3
30.0
0.6
Beech
55.
1
25.8
32.4
19.7
0.5
Sycamore maple
1.2
0.6
29.7
19.9
0.7
Average
356
100.0
653.4
100.0
41.3
47.2
24.7
0.5
Compared to the stands of the presented research, although there are smaller number of trees
per unit of area, the presence of remaining trees of extremely large dimensions in Biogradska Gora
resulted in a substantially higher standing volume.
Mixed forests of spruce, fir and beech on the studied sites, according to the structural data,
represent the forests of high site classes, in which all three main species reached high dimensions of
average diameter (Ds) and height (Hs). According to the achieved dimensions in the studied areas,
spruce and fir are dominant, while beech is rather in a subordinate position.
There are numerous studies showing that the share of fir in European blending forests is
decreasing (Jaworski et al 2002; Diaci et al 2010; Vacek et al 2014). In mixed forests in the Lom forest
reserve in Bosnia and Herzegovina Bottero et al. (2011) found a sharp decrease in the share of fir. A
decrease in fir representation in mixed forests was also observed in Slovakia (Štefančik 2006). In the
studied stands on Biogradska Gora, the share of fir is quite good. Primeval forest structure and full
canopy is especially suited for fir. Natural regeneration of fir in the fenced parts of the mixed forests
is much higher than in the unfenced parts (Klopčić et al 2010). Vrska et al (2006) concluded that
completely fencing virgin forests is currently the only way of ensuring relatively natural spontaneous
development of mixed spruce-fir beech forests.

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Conclusions
Presented data show that forest ecosystem of spruce, fir and beech (Piceo-Abieti-Fagetum Čol. 1965)
in the Biogradska Gora preservation area is predominantly characterized by structurally irregular
forests of primeval character. It shows the typical structural characteristics of old-growth forests:
presence of large and old trees with relevant growing stock.
Biodiversity is significant and larger than in managed forests of the same forest communities
in Montenegro.
All three main species reached high dimensions of average diameter (Ds) and height (Hs).
Spruce and fir are dominant according to the achieved dimensions in the studied areas, while beech is
rather in a subordinate position.
There are numerous studies showing that the share of fir in the European blending forests is
decreasing. Natural regeneration of fir in the fenced parts of the mixed forests is much higher than in
the unfenced parts. Completely fencing virgin forests is currently the only way of ensuring relatively
natural spontaneous development of mixed spruce-fir beech forests.
By comparing the determined wood volume with the presented results of studies from the
best quality forests in the South-East Europe, it can be concluded that mixed forests of spruce, fir and
beech on Biogradska Gora are forests of the high site class with large standing volume and with high
biodiversity level.
Conflicts of Interest: The authors declare no conflict of interest.
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