Silviculture and Cinegetics Review - Societatea Progresul Silvic

FORESTRY BELTS SILVICULTURE AND CINEGETICS REVIEW XVII/30/2012
Making watercourses protection forest belts should be
a priority in our country due to systematic removal of
existing forest vegetation along watercourses, around
lakes or ponds and land use for agricultural land
expansion or for community development. Along the
main rivers, the area occupied by forest, on a corridor
of 1.5 km on either side, range from 10.21% for the
Siret River to 26.77% for Jiu River (Mihăilă et al.
2010). Lack of vegetation adjacent to such waters
increased risk of flooding and favored discharge of
many residues in the water, erosion of banks,
degradation of aquatic habitats and acceleration of
sediment deposition in streams, lakes and ponds.
Watercourses protection forest belts perform multiple
functions, mainly of protection: (i) drought and
erosion protection; (ii) reduction in wind erosion; (iii)
fixing of banks; (iv) reduction in evaporation of water
from rivers; (v) ensuring as steady flow rates as
possible; (vi) curb the strong air currents (extremely
harmful), such as those that cause dust storms; (vii)
moistening slopes, by accumulating large amounts of
water and snow precipitation, by promoting
infiltration and supplying underground leakage; (viii)
reduce flood damage; (ix) protecting dams during
large floods.
The importance assigned to them, their spread on
large tracts and the high expenditure they require,
make that these forest belts can only be achieved in
projects at national level and with funding provided
by the state. Setting priorities in designing such
protection forest belts is required as a first step to
achieve these types of forest belts. Before determining
what kind of forest belt shall be installed in an area it
should be considered each watercourse, in terms of
climate and stationary conditions, of presence or
absence of forest vegetation and of the main features
that must be met by these forest belts (stabilization of
banks, filter pollutants from agriculture or industry,
etc.). Because it is impossible to install protection
forest belts along the length of a river's water network
there must be chosen those places, which assure their
maximum effectiveness.
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Choosing the best forest belts installation solutions
involves choosing species, in accordance with
stationary conditions and location, taking into account
the main disruptive factors.
Making watercourse protection forest belts requires
the existence on both sides of the watercourse, of
three areas differently made and with different
functions, presented below (Anonymous 1997) (Fig.
6).
- Zone I is located immediately beside the water and
corresponds to water banks. Recommended species
for this area are fast growing trees and shrubs, which
support long-term flooding.
This band of trees: i) consolidates the banks, ii)
provides a moderating water temperature, iii)
enhances aquatic activity, through contribution of
organic matter, provided by forest vegetation, iv) is
the last filter for pollutants that come from agriculture;
v) reduces fluctuations in water flow.
- Zone II, wider than the first, is located in the vicinity
of zone I and is composed of fast growing species of
trees and shrubs, tolerant of short-term stagnation of
water.
Forest vegetation performs the following functions: i)
retains nutrients and absorbs them, ii) provides rain
water infiltration, iii) enhances biodiversity; iv)
provides multipurpose wood and non-wood products.
It is important that in choice of species be considered
the root system and crown shape. Roots of species are
designed to transform pollutants that come adjacent
from land preventing them from reaching into the
water.
Shade which trees provide leads to lower water
temperatures, conditions which reduce algae growth
and improves the oxygen content of water.
Installation of a forest belt, with impenetrable
structure (trees and shrubs) is to slow the water flow
on the surface and promote its infiltration.
Forest belt density will be established according to its
primary role and the size of the watercourse.
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