DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu



ŠUMARSKI LIST 13/2005 str. 28     <-- 28 -->        PDF

S. Matić. I. Anić, M. Oršanić: SILVICULTURAL TREATMENTS AIMED AT IMPROVING THE ANTI-EROSION Šumarski list SUPLEMENT (2005). 17-30
fulfilment, at present and in the future, of fundamental
commercial, ecological and social functions
at the local and global level without causing harm to
other ecosystems.


This order is not random. As seen from the list, priority
is given to the stability of forest ecosystems and
the fulfilment of non-commercial forest functions.


Non-commercial forest functions are divided into a)
social and b) ecological or protective functions (Prpić
1992). Anti-erosion and water-protective forest functions
belong to the latter group. There is extensive scientific
literature dealing with this topic in Croatia, especially
with relation to biological erosion control and the anti-
erosion function of the plant cover: Topic et al
(2005), Topic (2001, 1996, 1995), Komlenović et
a/(1992), Vidaković et al (1984). According to Prpić
(1992), the fulfilment of the anti-erosion function
depends on the relief, exposure, soil and precipitation.
This author points out that the impact of forests on water
protection is determined by site and forest stand. Important
factors in this respect include the relief, geological
substrate, soil, the type of tree species making up a
stand, stand´s age and crown canopy. Hence, the structure
of a forest stand is one of the distinctive factors that
contribute to the anti-erosion and water-protective forest
function.


The structure of a forest stand is the result of silvicultural
treatments. Silvicultural treatments are aimed
at regulating and sustaining the structure of a forest
stand in accordance with the silvicultural properties of
a tree species forming the stand, site characteristics and
management objectives. If the structure of a forest
stand is regulated and maintained with silvicultural treatments,
then these treatments can also be used to regulate
the anti-erosion and water-protective function of a
forest stand.


There are two main groups of silvicultural treatments:
forest tending and forest regeneration. Forest
tending influences the forest stand and its site in such a
way that it sustains the optimal structural condition
that ensures its stability, diversity, productivity and capacity
for natural regeneration. This condition should
be maintained permanently regardless of whether the
stand in question is an even-aged or an uneven-aged


forest. The next logical silvicultural step involves the
ability of the tended stand to regenerate naturally,
which will guarantee sustainability provided the regeneration
treatments are applied professionally. No forest
management objective is a gift of nature and none
can be achieved if a stand is left to natural processes
and spontaneous growth. The objectives can only be
achieved is a stand is properly tended. Tending regulates
the development of a stand in accordance with natural
laws and makes optimal use of the site conditions,
biological properties and ecological requirements of a
species being tended.


Forest regeneration is the replacement of one generation
of a forest stand with another or the replacement
of a mature tree with a young tree. This is the most sensitive
and the most complex process in the life of a forest.
It is accomplished with the shelterwood method.
Care should be taken not to inflict any stresses on forest
site. The shelterwood method ensures the replacement
of one generation with another at a minimal
shock for the forest site and the forest soil in particular.
The task of creating a new generation is complemented
with that of preserving the forest soil from adverse effects
which may cause degradation processes. According
to Varal ly ay (1998), these effects include water-
and wind-induced soil erosion, acidification, salinization,
alkalization, physical degradation (compacting,
breaking up the structure and similar), changes in
the moisture regime (a drop in the groundwater table,
water logging, drying), biological degradation (reduced
range of species and their biological activity), unwanted
changes in the bio-geo-chemical and nutritive
cycle, contamination of soil with toxic substances, lessened
adsorption capacity, and soil coverage with ground
weed vegetation, invasive tree species (false acacia)
and shrubs (false indigo).


This article explores some specific features of silvicultural
tending and regeneration which are used to improve
the anti-erosion and water-protection forest
function. We will particularly focus on several historical
silvicultural methods in Croatia. Some examples of
pedunculate oak forests, selection forests and forests in
the Mediterranean region of Croatia will be analysed.


FORESTS OF PEDUNCULATE OAK


Tending forest stands was introduced in the Croatian
forestry practice at a very early date. Tending treatments
performed according to particular developmental
stages were done simultaneously with the regeneration
of virgin stands and the growth of the first generation
of commercial forest stands.


In Croatia, the first written sources on forest tending,
and in particular on the tending of pedunculate oak, date


from the end of the 19th century, shortly after the first articles
in the field of forest regeneration were published.
As early as 1878, Pauz i n published an article on thinning
in young stands. H an k o n y i (1890) discusses the
tending of oak forests with cleaning, i.e. the removal of
shrubs, poplars, willows and other species. Kozarac
(1897) describes the tending of young oak stands in the
seedling and young growth developmental stages. He