Silviculture and Cinegetics Review - Societatea Progresul Silvic

FORESTRY BELTS SILVICULTURE AND CINEGETICS REVIEW XVII/30/2012
(Steppe)
100 m alt.
Soil reaction (pH) and degree of base saturation (V%)
will undergo corresponding changes with the rise in
altitude of the bar of the bioclimatic indicators more
active for vegetation (Maruşca, 2007).
Changes much slower in the soil will cause the
productivity of natural vegetation and crops to be quite
low although more favorable conditions of heat will be
in the future in higher elevations.
1.4. Forecast of mountain grassland productivity
As a result of climate and soil physic-chemical
properties changes, altitude grassland productivity will
change as to reach a maximum between 1600 and 1800
m compared to the current 1000 -1200 m altitude, that is
with 600 m higher (Table 4).
In turn, level of productivity will be lower than the
current one due to the reduction with approx. 45 cm of
soil thickness and more pronounced acidity by 0.9 units.
Table 4. Forecast of grassland productivity at an increase of average air temperature by 3 0 C (year 2070)
Possible
Natural grassland productivity
floors
Dry matter production Average Specific Livestock production
(zones) Altitude
(DM) t/ha
grazing consumption weight increase (kg/ha)
after (m) Unfertilized N 100 P 50 K 5 period kg DM/kg Unfertilized N 100 P 50 K 5
decades
0 (days) gain
0
kg/ha
kg/ha
Spruce 2200- 2400 1.8 4.8 100 30 60 160
Spruce 2000-2200 2.3 6.0 115 28 80 220
Spruce + 1800-2000 2.8 7.2 130 26 100 280
Beech
Beech 1600-1800 3.3 7.4 145 24 130 310
Beech 1400-1600 2.8 6.8 160 22 120 310
Sessile oak 1200-1400 2.3 6.2 175 20 110 310
Oaks 1000-1200 1.8 5.6 160 18 100 310
Forest 800-1000 1.3 5.0 130 16 80 310
steppe
Steppe 600-800 0.8 4.4 100 14 60 310
Gradients for 100 m altitude
1800-2400 - 0.25 - 0.6 - 7.5 + 1.0 - 10 - 30
1200-1800 + 0.25 + 0.3 - 7.5 + 1.0 + 5 0
600-1200 + 0.25 + 0.3 + 15.0 + 1.0 + 10 0
Through organic – mineral fertilization with N 100 P 50 K 50
kg/ha on the most productive grasslands of 1600 –
1800 m altitude production increases from 3.3 t/ha DM
to 7.4 t/ha DM (224 %) where after conversion in
animal products can be obtain 310 kg /ha gain in live
weight in an average grazing period of 145 days.
Grazing period ranges between 100 days at 600 - 800 m
altitude due to the dry period, same on the 2200 – 2400
m altitude corridor where there is a shorter vegetation
period. The maximum grazing period of 175 days is
reached at 1200-1400 m altitude. Due to altitude, the
specific consumption per 1 kg gain increases by 1 kg
DM for each 100 m altitude, and from 14 kg at 600 –
800 m to 30 kg at 2200 – 2400 m altitude.
Due to the decrease of active temperatures by altitude
and the increase of precipitation it is created a heathumidity
balance between 600 and 1800 m altitude,
interval where grassland productivity is expressed as
live weight gain remaining constant at about 300 kg /ha
on medium fertilized surfaces. Soil and climate
conditions in the mountain area more adverse to
traditional agricultural crops by altitude, requires the
development of better grazing livestock on natural
pastures and the practice on a larger scale of agro
tourism, like the Alpine countries.
2. The Iberian agroforestry system (Dehesa)
2.1. Importance and evolution
The most famous agroforestry system is the Spanish
dehesa that was established since the Neolithic being
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