Silviculture and Cinegetics Review - Societatea Progresul Silvic

FORESTRY BELTS SILVICULTURE AND CINEGETICS REVIEW XVII/30/2012
mentioned for the first time in 924 AD, as a result of the
thinning of oak forests by cutting, controlled fire and
grazing with goats. Trees were maintained in a certain
proportion, so that from the same land surface can be
obtained the necessary wood, grass for grazing animals,
cereal crops and others.
complete abandonment of transhumance, partial
substitution of sheep with cattle due to lack of pastors,
decrease in food stocks and grazing periods, allowed by
the socio-economic adjustments of the agricultural
politics are the most important factors for this situation
(Olea, San Miguel, 2006).
In time, goats were replaced by cattle, sheep, horses and
pigs. By maintaining optimum animal load per hectare
throughout, this agroforestry system is kept under
control and perfect ecological and economical balance
for all its structural components:
trees+pastures+animal+agricultural crops.
2.2. Role of stand in the agroforestry system
Dehesa is similar to African savannah (with dry
summers, and not rainy like the typical savannah) where
stand plays a fundamental role in the overall balance,
and offering indirect services and goods. However, it
contributes to the overall productivity of dehesa with
acorns, sprouts, and supply of feed for animals, cork,
mushrooms, pollen and many other resources.
Stand is an essential component in the dehesa, and as
such management should be seen as integrated with the
semi-natural pasture and animals.
This is the most important approach to dehesa, since
natural regeneration is poor or lacking. Almost
Photo. 1. The role of stand in the agroforestry system
In addition, the situation is even more difficult because
of fewer trees due to the so-called “seca” (tree dryness
due to attack of fungi dispersed by climatic, edaphic and
biological conditions) (Table 5).
Table 5. Main characteristics of the Spanish dehesa stand and appropriate management type (by Olea and San Miguel,
2006)
Main role
Stability: structure, landscape, climate, reduce erosion, water and nutrients cycle, shelter,
biodiversity, carbon fixation, culture etc. Perennial species can be considered as permanent
forage species for livestock and wildlife.
Species
Quercus ilex rotundifolia ,(=Q.ilex ballota), Q suber (xerophytes and perennial), Quercus
faginea, Q. pyreneica and other dominant species
Density
(15) 20- 100( 200) mature trees /ha
Degree of crown coverage (5) 10-50 ( 70) %
Degree of base coverage (stems)
Production
2-10 (15) m 2 /ha
Firewood : 800-5000 kg/ha per one rotation (10-15 years)
Acorn : (100) 200 – 600 (800) kg/ ha with differences between years
Cork ( only Q. suber ) : 500 – 1500 (2000) kg/ha per one rotation (9-12 years)
Branches from cutting: 400-1500 kg /ha/year.
Planting seedlings is important in the colder climate dehesa where acorn production is lower.
Silvicultural rotation
Treatments
Areas of natural regeneration : stand senescence ( 150 years for Q. suber and 250-300 years
for other species)
Crown forming cuts in: 10-15 years
Cork peeling in: 9-12 years
The lack of stand natural regeneration in dehesa is by far the greatest threat to survival. In
addition, “ seca” makes a lot of damages.
2.3. The role of permanent pastures The most important managerial goal in a dehesa is
extensive growth of animals. However, natural pastures,
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