Garraf Natural Park: Human Activity and Vegetation Adaptation
Most of the Garraf has a typical southern Mediterranean
landscape. The vegetation is a dense scrub of one to three metres in height,
some of African origin. Garraf is the most northerly area of Europe where this
The vegetation on the coastal slopes tends to be MAQUIS - a
dense tangle of undergrowth usually found in impermeable areas or where soils
are damper. Maquis is from the French word meaning 'resistance' relating to the
armoured protection of the species.
Where the underlying rock is permeable, such as limestone,
GARRIGUE vegetation is found. This is less dense and lower lying scrub which
includes many aromatic plants such as rosemary and lavender.
In the drier and hotter interior of the Garraf, the holm (or
evergreen) oak and laurestine dominate in the damper valleys. Vegetation has
adapted to the dry, hot conditions and poor soils where water drains away
rapidly. Where the shrubs have leaves, these are evergreen, which enables the
plants to make full use of the relatively short periods favourable to growth in
spring and autumn. Adaptations such as leathery leaves, long roots and the
ability to close the leaf around the stomata helps survival through the summer
Some species have all their leaves reduced to spines to reduce
evapo-transpiration, such as the Kermes Oak, Gorse, Juniper and Heather.
Broom has no leaves, transpiring through its green stem. Plants
with flat, hard, waxy and leathery leaves that provide insulation include
Mock-Privet, Laurestine and Rosemary.
The stomata of the Evergreen Oak is able to close to preserve
moisture. Other plants, such as the Rock Rose shrivel their leaves in times of
drought to reduce evapo-transpiration. Some plants accumulate large quantities
of water within their structures, such as the Prickly Pear, Cat's Claw and the
Strong aromas and resins repel animals. Such plants include
Rosemary, Lavender and Thyme.
Some of the plant species are particularly resistant to fire.
When their stems above ground are completely destroyed they are able to send up
Carritx, normally only found on the North African coast,
probably arrived in the Garraf from seeds dropped by migratory birds.
The lack of vegetation cover is due to past human activity on
the Garraf — the grazing of goats and growing of crops. There is much evidence
of the terraces or ‘Feixes’. Overgrazing and over-cultivation led to soil
erosion that removed the soil essential for tree regeneration.
Trees not only protected the soil from heavy rain and erosion.
They also provided shade and the shelter they offered from the wind helped
increase humidity levels, especially because of the water vapour received by
evaporation and transpiration from the tree foliage, the undergrowth and the
soil surface. The blanket of moister air would, in turn, prevent rapid
evaporation from the ground. Beneath the tree canopy therefore, the soil would
remain relatively cool and moist during the hot summer days even after weeks of
With the felling or grazing of the forest, the soil would have
been exposed to the wind and sun and dried to a considerable depth in only a few
days. Also the leaf-fall which had persistently supplied new humus to the
surface layers was now cut off; no longer were mineral nutrients being drawn by
the plant roots from deep within the soil and then returned to the soil through
leaf decay. The nutrient cycle was therefore altered as well as the water cycle.
Without humus, the soil lost its ‘stickiness’ or adhesive qualities. The
winter rains were able to run off the surface carrying the soil particles away.
In a very short time, bare rock was exposed, and where pockets of soil remain,
these are poor in humus and prone to drought.
The ‘terra rossa’ or red soils are often said to be
characteristic of the Mediterranean region. They are widespread on the Garraf.
The redness is due to the presence of iron (ferrous) oxide (Fe²0³),
one of the products of weathering of the limestone through the action of
naturally-acidic rain water. Were there more humus in the soil, the redness
would be obscured and the whole aspect of the Garraf (and much of the
Mediterranean landscape) would be very different.
Today, fire is a main controlling influence. In the past, it
has been common practice to clear the land for farming by burning the
vegetation. Fires are also started today by careless visitors, arson and
lightning strikes. Burning favours shrubs like the lentisk and the cistus which
can shoot freely from the base of the stems no matter how often they are burned.
The saplings of trees, on the other hand, cannot survive.
Vegetation and Human Value
The red fruit gives an oil that can be consumed. It has been
considered an aphrodisiac. The fruit also provides an indelible ink. An incision
in the stem produces a green, very aromatic liquid, with an odour similar to
turpentine. This is called the Turpentine of Kios. Its taste is slightly bitter
but not unpleasant. Chewing the fruit strengthens the gums and whitens the
The fruit ripens at the end of August, turning from green to
black. It is poisonous. A short time after eating it, you would experience
violent stomach pains, vomiting, kidney and respiratory failure and death. In
very small doses, the plant is used as a laxative.
The green fruit is very bitter. The ripe fruit is black and the
oil is used for cooking. It is a popular medicine. The leaves are used to
relieve high blood pressure and also for hypoglycaemia.
The fruit is very nutritious and is used in cattle feed. It has
been used for human consumption in the past. The pods are rich in calcium and
sugars and can be eaten fresh, dried or crushed. It can be made into an omelette
(tortilla). The fruit can be substituted for cocoa in the manufacture of
chocolate and the seeds have sometimes been used as a substitute for coffee. The
seeds (quilates or carats) were used in ancient times to weigh gold. The quality
of gold plating today is still measured in carats (in fractions of 24).
The berries are poisonous, but in low doses are used to treat
kidney diseases and as a stimulant. Oil obtained from the wood (oil of Miera) is
used as an antiseptic. The reddish timber is highly valued by cabinet-makers.
The acorns are used as animal feed. They are bitter but have
been eaten by people in times of food shortage. Roasted, they lose their
bitterness and can be used as a coffee substitute. Cochineal colouring (for
materials) is also obtained from them.
Its location in The Garraf is unique in Europe - it marks its
most northerly site in the continent. The palm dates are edible, but not
popular. The leaves have been used for hat and basket weaving and making brooms
and rope. It is protected by law.
HOLM (or EVERGREEN) OAK
The acorns are very bitter, but toasted, they lose this taste.
They are used as animal feed. The bark is used as a dye for wool, giving a
The fruit is poisonous, producing inflammation of the mouth,
vomiting and diarrhoea. It is used as a medicine but its rapid toxicity in
higher doses causes it to be rarely used today.
It is an important forestry tree, planted to help prevent soil
erosion in arid zones. The pine cone can be eaten, but is very oily. The bark is
rich in tannin dye.
The fruit can be eaten, but too many produces headaches as the
ripe ones contain alcohol! It is used to make alcoholic drinks, sweets and
The fruit is edible, but remove the spines first! Alcohol can
be made from the fruit pulp. It can be used to make a deliciously refreshing