FLORISTIC INVESTIGATION OF QUERCUS CERRIS AND QUERCUS
FRAINETTO COMMUNITIES IN BULGARIA
M. Lyubenova, R. Tzonev, K. Pachedjieva
Sofia University “St. Kliment Ohridski”, Faculty of Biology,
Department of Ecology, blvd. Dragan Tzankov 8, Sofia–1164, Bulgaria
Correspondence to: Mariyana Lyubenova
E-mail: [email protected]
ABSTRACT
The present research is a part of the investigations over the structure of mixed forest communities of Quercus cerris and
Quercus frainetto in Bulgaria. The investigated communities are typical for Habitat 91I0 – Euro-Siberian steppic woods with
Quercus spp., and Habitat 91MO – Pannonian-Balkanic turkey oak–sessile oak forests. The floristic composition of about 100
described plant communities is defined. According to the geobotanical zoning they refer mainly to the European broad-leaved
forest district and the Lower Danube province of Eurasian steppic and woodsteppic district. About 598 species of vascular
plants and about 24 species of bryophytes have been established during the investigation. The life forms (according to
Raunkier) and the floral elements (according to Assyov et al.) for the vascular plants have been determined. Over 60% of the
species refer to the families Asteraceae, Fabaceae, Poaceae, Rosaceae, Lamiaceae, Caryophyllaceae, Scrophullariaceae and
Liliaceae. In the species composition the participation of the Eur-Asian, Eur-Mediterranean, subMediterranean, Eur-Siberian
and the European floral elements is bigger. The life form Hemicryptophyte clearly predominates. A comparative floristic
analysis with published data for the investigated communities has been made.
Keywords: Bulgaria, floristic composition, oak community
(Quercus frainetto Ten., Quercus cerris L.)
Introduction
About 35% of the area of the broad-leaved forests in
Bulgaria is taken by oak forests in our days. In the past these
communities have taken much larger areas and the species
diversity of genus Quercus L. that formed them was greater.
Their intensive usage and direct destroying gradually have
lead to decreasing the areas and degradation of the
communities. A greater part of the forests are offshoot with
worsened wood properties, low productivity and decreased
forming and resource significance. In the present-day 7
species of genus Quercus L. take part in oak communities as
2 of them are Bulgarian endemic species (Q. thracica Stef.et
Ned. и Q. mestensis Bond et Ganc.). Q. frainetto Ten., Q.
cerris L., Q. dalechampii Ten. и Q. pubescens Willd. are the
main species which form the Bulgarian oak woods. They are
original for the country and create the appearance of the
indigenous broad-leaved vegetation (related to the
Southeastern province of Middle-European floristic district)
up to the middle mountain forest belt.
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The oak forests have important ecological significance
(protecting water resources, microclimatic, anti-erosion,
sanitary-hygienic, recreation and conservation function).
They are source of many other bioresources – mushrooms,
herbs, durable and workable wood, game etc. The
communities are used for pasture because of the welldeveloped grass layer. The oak is well-known also in the folk
medicine as an ingredient of many recipes.
A part of the investigations (1991 – 1995) devoted to
structure and functional parameters of xeroterm oak
communities in Bulgaria are quoted by Apostolova et
Slavova (1). Information for these communities is published
also by many other authors: Bondev et al. (3), Bondev at
Lyubenov (4), Velchev et Bondev (19), Velchev et Bondev
(20), Kachaunova et Bondev (14), Ninov et al. (16), Asenova
(2), Georgiev et al. (13), Rousakova et Tzonev (18) and
others.
A single IAVS workshop was devoted to the European
oak forests – past, present and future. There scientific reports
concerning the status, functional and structural parameters,
management and the economic usage of different types of
oak forests in Europe were presented (7).
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In climate changing conditions the significance of the oak
forests, especially this of the xeroterm oak forests for
preserving the species diversity, softening the ecological
regimes, protecting the social and economic climate of the
Balkan Peninsula becomes bigger and bigger.
The aim of the present investigation is generalization of
the published and original own investigations of the authors
for the flora of the turkey oak–Hungarian oak forests. This
will enable some comparative estimates of its ecological
character, economic significance and future changes.
Materials and methods
The investigated communities refer to the indigenous
xerotermic forest vegetation in Bulgaria. The Hungarian oak
and the turkey oak differ from each other clearly by its
ecological demands but their ecological areas overlap in a
considerable degree. Because of this reason on large areas the
form mixed communities.
The Hungarian oak (Quesrcus frainetto Ten.)
communities take about ½ of the total area of the oak forests
from sea level to 500 – 600 m, rarely 800 m a.s.l. The turkey
oak (Quercus cerris L.) communities take about 234 000 ha
area. The upper border of their distribution is close to that of
the Hungarian oak and is lower with 100 to above 200 m of
that of the sessile oak (Quercus dalechampii Ten.)
communities. The sessile oak forests are more mesophyte than
these of the Hungarian oak and turkey oak. At some places
(800 – 1000 m a.s.l.), the occurrence of Quercus petraea Liebl.
is observed. Certain resource and forming significance have
also the communities of Quercus pubescens Willd. which are
distributed up to 500 – 600 m a.s.l. The last (downy oak
communities) are more xerophyte and more thermophilic than
these of the Hungarian oak and turkey oak. Somewhere (100 –
300 m a.s.l.) in the forest composition may take part the
following species: Q. pedunculiflora C. Koch, Q. polycarpa
Schur., Q. virgiliana (Ten.)Ten. и Q. hartwissiana Stev. They
may also form mono-dominant communities.
An analyses of 98 forest communities with the dominance
of Quesrcus frainetto Ten. and Quercus cerris L. from
different regions of the country was made. The communities
were investigated phytocoenologically during a period of
about 28 years.
The analyzed communities refer to 16 Phytogeografical
regions of the country: Strandja mountain, Lower Kamchia
Valley, Black sea coast, Rhodopes, Western-Bulgarian
frontier mountain, Sofia-Kraishte, Sredna gora, Western
Balkan, Central Balkan, Fore Balkan, Ludogorski, Danube
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plain, Eastern Rhodopes, Upper Tracian, Sacaro-Dervenski
and Straldza-Burgaski.
The average annual temperatures in the biotopes vary
between 8.1 and 12.9 degrees Celsius and the average annual
precipitation – between 554 and 713 mm. The established
types of soils are the following: Hromic luvisols (40 % of the
communites), Leptosols (16%), Luvisols (16%), Planosols
(16%), Grey luvisols (8%) and Umbric cambisols (4%).
According to its origin the investigated forest communities
are offshoot ones, except 6 of them – 3 are of mixed and 3 are
of seminal origin. The average age vary from 28 to 125 years.
The tree layers have also varying between 0.4 and 0.9 average
canopy, average diameter of the stems between 7 cm and 46
cm and average height of the trees from 4 to 25 m.
The investigated communities were analyzed by plots of
2.5x103 m2 except 5 regions where the description of the
vegetation was made on plots of 300, 600, 980, 2.7x103 and
5x103 m2. The species were determined by Dimitrov et al.
(8), Kozuharov et al. (15), Flora NR Bulgaria (12). For
defining the life forms the Raunkiaer classifications was
used. The floral elements are after Dimitrov et al. (9) and the
antropophytes and ruderals in the species composition of the
investigated oak communities – after Petrova et Vladimirov
(17). The Bulgarian Medical plants Act was used for
determining the participation of medicinal plants and the
Bulgarian Law on biological diversity (6) and CITES (8) –
for identifying the species with conservation significance.
Comparisons with the average biological specter of the
Earth and the average biological specter for Bulgarian
vegetation are made. References with published
investigations for other forest communities were also
accomplished (10, 11).
Results and Discussion
The investigation of the species diversity for the xerothem
oak vegetation shows the availability of 595 species of higher
plants. That is 15.43% of the Bulgarian flora. They refer to
67 families and 271 genera. The following 9 families are
presented with a greatest number of species: Asteraceae –
10.4 %, Fabaceae – 10.38%, Poaceae – 9.38%, Rosaceae –
6.7%, Lamiaceae – 5.7%, Caryophyllaceae – 5.4%, Apiaceae
– 4.9%, Scrophulariaceae – 4.7% и Liliaceae - 4%.
There is a great variety of floral elements that is
characteristic for the country because of its geographical
location and the multiform relief. The described species refer
to 32 floral elements. With a biggest participation are the
Euroasian
(15.43%),
Euromediterranean
(15.06%),
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subMediterranean (14.50%), Eurosibiric (10.22%), European
(9.67%), Mediterranean (5.76%), Boreal (5.20%), subBoreal
(4.83%), Pontmediterranean (3.16%), Balkan (2.97%) and
Eurosubmediterranean (2.97%) floral elements (Fig. 1). To
the counted 11 groups refer 89.78% of the species
composition and to the remaining 21 groups – only 10.22%.
The
predominant
elements
are
the
Euroasian,
Euromediterranean, subMediterranean and Eurosiberian
which is normal for the temperate continental climate. The
comparison between the interrelations received and the
published data for the chestnut-tree communities shows a
decreased
participation
of
the
Mediterranean,
Eurosubmediterranean and subBoreal floral elements. In the
investigated beech forests the Euroasian floral elements are
presented with a greatest percent share but because of the
more mesophyte character of the vegetation the following
positions are taken by species with European, subBoreal and
Boreal distribution. Comparing to the data for the whole
vegetation of the country in the investigated vegetation it is
observed reduced participation of the Euroasian and the
European floral elements.
The distribution of the Raunkaer life forms is as follows:
Hemicryptophytes – 55.8%, Terophytes – 15.98%,
Phanerophytes and Cryptophytes – 11.51% each group,
Chamaephytes – 3.1% and Terophytes-Hemicryptophytes –
2.1% (Fig. 2; Fig. 3). In the biological specter the group of
the Hemicryptophytes predominates.
10%
16%
3%
3%
3%
5%
15%
5%
6%
14%
10%
10%
Eur-As
Eur-Med
subMed
Euro-Sib
Eur
subBoreal
Pont-Med
Euro-sMed
Bal
Others
Med
Boreal
Fig. 1. Proportion between floral elements in investigated oak vegetation in Bulgaria
2% 3%
12%
16%
12%
55%
Ch
Cr
H
Ph
Th
Th-H
Fig. 2. Proportion between life forms in investigated oak vegetation in Bulgaria
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60,00
50,00
%
40,00
30,00
20,00
10,00
0,00
Ch
Cr
H
Ph
Th
Th-H
Life form
Oak forests
Bulgarian vegetation
Normal for the earth
Fig. 3. Biological spectrums in oak forests, in Bulgarian vegetation and characteristic for the normal biological specter of the Earth
According to the vegetation of the country (5) a tendency
of increasing participation of the Cryptophytes and
Hemicryptophytes is observed and in comparison with the
normal biological specter of the Earth – that of the
Terophytes. When comparing of the data received with the
published investigations for the chestnut-tree forests in
Bulgaria an increasing percent share of the Cryptophytes and
Terophytes is noticed while the Phanerophytes and
Hemicryptophytes decreases. The tendencies observed are
connected with the xeroterm character of these forests.
The following species are protected according to the
Bulgarian Law on biological diversity and the quoted
convention: Onosma heterophylla Griseb., Himantoglossum
caprinum (Bieb.) Sprengel, Vicia pisiformis L., Allium
cupani Rafin. The number of the rare and protected species in
the vegetation for the investigated localities is low – 4.The
ruderal vegetation is presented by 154 species or 26.42% of
the established species. That is 27.35% of the antropophyte
flora of Bulgaria. The penetrating of many ruderal species is
caused by the anthropogenic pressure expressed in pasture,
fellings, collecting of herbs, mushrooms and others, logging
and closure to built-up and populated areas.
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Apostolova I., Slavova L.(1997) Conspectus of plant
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Convention on International Trade in Endangered
Species of Wild Fauna and Flora /CITES-1991/.
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