PRO SILVA CONFERENCE AND VISIT TO CROATIA
1-4 June 2005
Mike Seville and Rik Pakenham
Mike Seville is the Chairman and Rik Pakenham
a committee member of the Continuous Cover
Forestry Group, which is affiliated to Pro Silva
in Europe. This is a federation of foresters who
advocate forest management based on natural
Woodland Heritage kindly sponsored them to attend
this annual conference and study tour, which is held
in a different member country each year.
Croatia used to be part of Yugoslavia but is now a
Republic with a population of approximately 4.5
million people and an area of 5,654,200 hectares.
Forestry has a long history, within the statutes of
many Dalmatian towns are regulations on the
preservation and conservation of forests as early as
the 13th century. The first forestry offices were
established in 1765 with the first manual on forest
management, the Forest Order issued by Maria
Theresa in 1769.
Forests comprise 44% of the total area, of which
82% are state owned and 18% privately. Composition
by tree species is 84% deciduous and 16% coniferous.
The main species are Beech 35%, Pedunculate Oak
14%, Silver Fir 10%, Sessile Oak 10%, Hornbeam 8%,
Ash 4%, Norway Spruce 2%, other broadleaves 13%,
other conifers 6%.
Forest communities are divided into two vegetation
regions, the Mediterranean and the Euro-Siberian-
North American, within which there are respectively
two and five vertical vegetation belts. The country is
very rich in species diversity having 4,500 plant
species, half of which live in the forests. 260 are
woody species, 60 of which have commercial value.
Annual increment is 9.6 million m³ and the annual cut
is 5.3 million m³, 46% of which is sawmill timber, 37%
fuelwood and 17% waste.
Forest education began in 1860 and is now based in
the Faculty of Forestry and the Academy of Forest
Sciences at the University of Zagreb, and the Forestry
Institute at Jastrebarsko. The Faculty owns five
teaching-experimental centres and 3.5 million hectares
of forests. Approximately 100 students graduate each
It was one of these teaching centres we visited on
our first day.
Excursion 1: Natural regeneration of Silver Fir stands
using group selection system at the Forest research
and educational centre of Zalesina.
The forest is situated 130 km west of Zagreb and 50
km east of the Adriatic sea in a mountainous area
between the south eastern Alps and the Dinaric
We visited the Belevine management unit which
covers 294 ha between 720-870 m elevation. The soils
are podzols over lying schists and sandstones. Air
temperatures range from -3° to + 16° C, precipitation
averages 2500 mm and snow lies for approximately
Historically this was a virgin Beech forest with very
few conifers. Exploitation began at the end of the
16th century, but increased towards the end of the
18th century when roads and railways were built.
From 1871 the forest was owned by German families
and from this time the concept of creating pure
conifer stands was put into practice.
Records show that the Beech content in 1867 was
67%. By 1950 it was only 3%. Much of the Beech was
exported to Venice for the Murano glass works.
The current structure originated from natural
regeneration under a selection system, the main
species being Beech, Silver Fir, Norway Spruce (not
native), Rowan, Sycamore, Lime and Elm.
For the last 50 years the forest has been managed
by the Faculty of Forestry under set management
guidelines which aim to have an optimal volume of
440m³/ha, a basal area of between 34-37 m², selection
cutting interventions every 10 years removing 25% of
the volume – aiming to form mixed stands of 80% Fir
Target diameters for cutting are Fir 70cm dbh and
Beech 50cm dbh. Single tree and Group selection
systems are used.
All species regenerate freely except Norway Spruce
which has been used as a pioneer on fire, wind
blow, or on die-back areas caused by pollution.
The maximum gaps created by felling are 1.5 times
the height of the neighbouring trees, generally 30-50
The students study for a four year degree and are
tutored in all aspects of forest management including
six months practical work in the forests. At the time
of our visit they had felled Silver Fir, delimbed,
measured over bark, peeled the tree, measured under
bark, cross cut and were waiting to extract the timber.
Excursion 2: Natural regeneration of Fir-Beech stands
using the Single Tree Selection system.
This forest was situated in the Dinaric mountains
growing on steep slopes with many limestone
outcrops. Similar to the lunch-time stop, the best trees
were growing in the deeper soils between the rocks,
but trees were also on the shallower soils over the
Limestone and this created a large range of heights.
These features led to the choice of using a Single
Tree Selection system to enhance stability and retain
The main species were Silver Fir, Norway Spruce
and Beech with Sycamore and Elm.
Experimental plots showed 931 trees/ha with
diameter range of 1-110cm dbh, basal area of 41m²,
standing volume of 601 m³/ha and annual increment
The diameter distribution was <30cm 15%, 31-50cm
15%, >51cm 70%.
Cutting interventions were every ten years removing
20–25 % of the volume, which approximated the
increment over that period.
Although the terrain made felling and extraction
difficult the following average expenditure and
income was achievable:
Price roadside €48/m³, fell and extract €7, tending
€9, administration €10, return €22/m³.
This was a beautiful forest exhibiting the best
that Selection systems can offer.
Having spent the night in Delnice in the west near
the Slovenian border we travelled east, almost to the
Hungarian border to the Bjelovar forest district.
On this side of the country the climate was very
different, with hot summers and cold winters. The
average temperatures were 10-12º C, with
precipitation being 850mm per annum. The landscape
was flat, or rolling hills with wide flood plain valleys
Excursion 3: Natural regeneration of Beech-Sessile Oak
forests by Shelterwood cutting.
This forest was situated in the Bilogora Hills at 150
metres altitude. It was predominantly Beech with
Oak, both Robur and Petrea and a small percentage
of Cherry, Lime and Hornbeam.
The system regenerated the forest over 10-12 years
with three thinnings and a final clear cut over this
period. The aim was to establish a predominantly
Beech/Oak forest with other minor species.
Beech produced viable seed every year and Oak
every 3-4 years. The regeneration area was 34 ha
which had been fenced to exclude Wild Boar. Boar
numbers are increasing since the end of the recent
war as people no longer need to kill them to survive.
Local hunting clubs now carry out the control.
The standing volume at the beginning of the
regeneration period was 520m³/ha, Beech are
managed on 100-110 year rotations before Red Heart
attacks the tree.
The average prices received roadside were Beech
€50 and Oak €100 per m³, Oak veneer could fetch up
three times this price. The timber is sold to a
traditional set of complicated rules, but was of high
The outcome of this management system could be
seen in the adjoining compartment where 60 ha of
20 year-old, even-aged forest stood at up to 10,000
This view came as rather a shock compared with
what we had seen the day before, and no
explanation, apart from tradition, was offered for not
considering adopting selection systems to develop an
Excursion 4:The management of Beech-Lime stands.
A 51 year old stand that totalled 50 ha, with 50%
Lime (argentea), 18% Beech, 18% Hornbeam 14%
other species including Wild Cherry. The standing
volume was 295 m³/ha with an average top height
28 metres and yield of 11m³/ha per annum. Lime only
grows in this part of Croatia between 200-400 metre
The Lime is worth more than the Beech in
monetary terms and is used for internal
panelling, veneer and plank. However it is a
pioneer species, does not grow under other Lime and
is very aggressive both from suckers and seed. The
site type is Beech/Oak and it is envisaged that this
will dominate in the next generation.
Excursion 5: Flood plain forest stand of Black Alder.
The next stop was within the river Drava flood plain
almost adjacent to the Hungarian border. Here we
were in the Black Alder/Oak forest area that totalled
5,000 ha, of which 2,000 ha were Black Alder. We
visited a stand of Black Alder that was 96 years old,
an average height of 37 metres, a mean dbh of 37 cm
and a standing volume of 750m³/ha, other minor
species were Field Maple, Hornbeam and Bird Cherry.
It formed part of a forest reserve and had been
protected since 1975. It survived in an almost natural
state because of the water regime, where the constant
water table level was 1 metre below the surface, but
spring and autumn floods were essential to retain this
regime. This was one of the few areas within in the
Danube water-shed that had not been affected by the
damming of the water courses, and this gave rise to a
Gley type soil with sand.
To see 750 m³/ha of this species was almost
unique and well worth the visit despite the Black
Fly and Midges !
The last day was spent in the Lowland and
Floodplain forests of Croatia between the rivers Sava
and Drava. These forests cover 290,000 hectares of
which 205,000 hectares are pedunculate oak, 27,000
hectares of narrow leaved ash, 17,000 hectares of
black alder as well as white willow, poplars and
other mixed softwoods and hardwoods. The total
growing stock is 72,900,000m³, the annual increment
2,076,000m³ and the annual cut 1,280,000m³ or 61% of
The forests fall in to four main stand types:
Oak and hornbeam
Oak and narrow-leaved ash
Oak and alder
Excursion 6: Climax Oak and Hornbeam forest
The first stand we visited was an area of
magnificent 175 year old oak and hornbeam with
450m³/ha of oak and 178m³/ha of hornbeam. This
was climax forest on an area which did not flood and
where the water table was typically between -1m and
-7m below ground level with the oak having an
annual increment of 6.37m³/ha and the hornbeam
Again this woodland was being regenerated
naturally by a shelterwood system though, where
previously the method would have been to clear all
the undergrowth and wait either 5 or 15 years and
then fell all the oak, now the crop was removed in 3
cuts over a 6-8 year period, as they were finding
that the young oaks could only live under the
canopy for a maximum of four years due to
problems with mildew, mice and wild boar.
Excursion 7: Floodplain Oak and Ash, Oak and Alder
Although at the same altitude, 93m, the ground
conditions at this site were very different from the
previous one and the area was characterised by small
scale, but distinct changes in vegetation type caused
by very small differences in height relative to the
water table. At the first stop the soil was heavy clay
and the area flooded twice a year. It had been an oak
elm mixture, but the elm had been lost and was now
being replaced by ash. Although slightly younger
than at the previous site, the oak was of a
significantly smaller diameter being slower
grown. This made it at least 20% more valuable
at €360/m³ as opposed to €260/m³ for the wider
ring width oak.
Possibly because of the soil conditions the oak here
does not fruit, so regeneration was by seeding of oak
at a rate of 800kg – 1 ton of acorns per hectare.
Within feet of this site, the land was constantly
flooded and the crop changed to alder swamp.
We then walked on to a recently regenerated area.
This 9 hectare site had received a sanitation felling in
1998 which had opened up the canopy sufficiently to
allow seeding and regeneration. In 2001 40% of the
overstorey, 500m³/ha, had been removed and in 2004
the remaining trees had also been felled. Although
the crop was now well established there had been
significant tending costs: 31 man days for fencing, 137
man days for weeding and unspecified costs for two
Whilst there was no doubt that the shelterwood
systems used by the Croatians were working and
producing good quality timber, there was much
discussion within the group as to why a more
intimate selection system which had the
potential to save on costs and prevent the felling
of trees before their optimum size and value,
had not been adopted. Again this appeared to be
a combination of tradition and a lack of will to
experiment and change perhaps as a legacy of
the communist era.
In the afternoon of the last day we left the forest
behind for a surprise visit to the Lonjsko polje nature
park. This fascinating village of sawn oak houses and
adjacent wetland was a step back in time and it was
heartening to see that the Croatians had recognised
its importance and were taking steps to safeguard it.
The reserve is an important breeding ground for
storks, spoonbills and other wetland birds and is
notable for the semi-feral wild pigs historically kept
by the villagers and currently being re-introduced.
More information is available at the reserve website
Whether or not you agree with the management
systems adopted by the Croatians, there is no doubt
that they value their forests and manage them to a
Their forests and foresters are held in high
regard and contrary to some opinion, they are
not cutting more than their increment for quick
Western currency. Indeed, if they have a problem
it is that they are not cutting enough timber to
sustain the regeneration of their forests.
The more one travels in Europe the more one
realises we have a great deal to learn from European
foresters with their long history of forest management
and how the love of trees and forests can bring
people together to share their knowledge.
Mike Seville and Rik Pakenham