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Flora
The flora
of Jordan is highly diversified and considered to be very
rich if we consider the number of species in relation to the
area. The estimated number of wild vascular plants in Jordan
in 1982 was about 2100 species (Al-Eisawi, 1982). Recent collections
and estimation of species according to the updated checklist
(Al-Eisawi, 1996, in preparation) is about 2400 species. In
addition, continuous collection may raise this number to about
2500 species. Flora Palaestina as estimated by Zohary, 1962;
Zohary & Feinbrun, 1966-1984 gives a number of about 2500
species.
The elements
of the flora of Jordan are related to different biogeographical
regions. There are Mediterranean, Irano-Turanian, Saharo-Arabian
and Sudanian or Tropical elements. The reason for this is
the extreme variation in diversity within limited areas is
due to sudden ecological variations. In some cases at the
meeting points of three geographical regions there is huge
selection pressure for the species growing in that area to
adapt to such unusual conditions. Such meeting points have
often produced new taxa with different sets of characteristics
based on which endemic species have been recognized.
Status
of the flora
Although,
the flora of Jordan has been studied over the past 25 years
and a total number of about 60,000 specimens are deposited
at the herbarium at the Department of Biological Sciences,
University of Jordan, Amman, yet this collection is not systematic.
A systematic, geographical method of collection using a scale
of distribution at the country scale has never been used.
Therefore, one cannot give a geographical distribution for
any taxon at a level of 1 or 10 km².
To support
this argument, we are still adding new taxa to the flora of
Jordan whenever we visit new places or visit sites at different
seasons of the year. Borderlines between neighbouring countries
are the least surveyed and thus form a rich area for discoveries
of new taxa. Accordingly, inter-governmental co-operation
must be instigated between neighbouring countries to study
the flora of adjacent borders.
Most of
the collections made so far were not associated with co-ordinates
which can be linked in future with a geographical information
system (GIS). Recently, and with the availability of the global
positioning system (GPS), work should be accurate and complete
enough to satisfy the needs of both co-ordinated and geographical
distribution. A database system is not yet complete, although
a starting point has begun recently to give basic information
about taxa, their number, distribution and status in relation
to their availability, rarity, endemicity and uses.
A checklist
as previously mentioned was prepared in 1982 with an updated
version for the time being installed in the computer for future
publications. The dream of producing a written flora has not
yet come to reality, since such a project needs financial
support, technical facilities, human resources and the support
of a national plan. If the production of a written flora is
based on personal part-time effort, it is unlikely that this
dream will be achieved in the near future. Therefore, a national
plan for producing a written flora should be decided by the
government, since it is necessity for the determination of
the biological diversity of Jordan and for the world as a
whole. Again, the flora is badly needed to know what are the
genetic resources present in the country and what is the status
of their occurrence.
Natural
vegetation types
According
to the previous physical aspects four biogeographical regions
in Jordan are recognised as follows (Al-Eisawi, 1995). See
Map 1.
- Mediterranean
- Irano-Turanian
- Saharo-Arabian
- Sudanian
(Tropical).
Each of
the four regions has a combination of different physical aspects
reflected in the extreme variations in the components of their
biodiversity. Within the four regions, thirteen vegetation
types were recognised by Al-Eisawi (1985). Such vegetation
types comprise the major vegetation formations occurring within
the four biogeographical regions without going into smaller
vegetation formations that might occur as a result of specific
physical requirements.
Ecosystems
Two principle
ecosystems are recognized in Jordan:
- Water
ecosystems
- Terrestrial
ecosystems
(a)
Water Ecosystems
Water ecosystems are rather restricted in Jordan with a limited
marine ecosystem in the Gulf of Aqaba, as well as another
confined fresh to brackish water ecosystem in the Azraq Oasis.
There are sporadic running water systems, and aquatic vegetation
associated with them, especially around rivers, streams, water
springs and dams. In general water ecosystems are subdivided
into:
- Marine
ecosystems
- Saline
and brackish water ecosystems
- Fresh
water ecosystems
Showing
four geographical regions in Jordan
The Dead
Sea shores still show in places some vegetation associations
of highly salt-tolerant plant species such as Suaeda spp.,
Arthrocnemum spp., Juncus acutus, Juncus maritimus, Nitraria
retusa and Tamarix spp. Most of the vegetation in this area
has been destroyed and some species can be considered extinct,
endangered or rare. The vegetation in this ecosystem has suffered
a great deal for the following reasons:
- Heavy
use of the Dead Sea shore by local and international visitors
to the well-known tourist sites.
- Construction
of the Arab Potash Company workings in the area of dense
saline vegetation.
- Construction
of roads and heavy use of vehicles
- Replacement
of natural vegetation by crop cultivation and agriculture
- Construction
of hotels and touristic recreation sites.
Freshwater
plants occur at water canals, streams, and rivers, with Typha
domingensis, Phragmites australis, Salix babylonica, Nerium
oleander and Tamarix tetragyna being typical species. Azraq
Oasis is an example of a restricted water ecosystem where
fresh water and brackish water ecosystems are present side
by side. This system is very important since it occurs in
the heart of the desert and has been used over a long period
of time as a traditional site by migratory birds coming to
and returning from Northern Europe and Africa. Special types
of vegetation as well as species rare and endangered in Jordan
are restricted to this ecosystem such as Nitraria schoberi,
Halopeplis amplexicaulis, Cirsium alatum, Ruppia maritima,
R. cirrhosa, Limonium meyeri, Scirpus maritimus, Tamarix passerinoides,
Ranunculus aquatilis.
Nevertheless,
the limited ecosystem of Azraq Oasis is highly threatened
due to continuous water pumping from the water basin to the
cities of Amman and Irbid. The water table in the basin has
been lowered at least four meters due to the continuous pumping
over the last ten years. The yearly pumping of water reaches
about 50 million cubic meters, while the annual recharge of
the basin is estimated about 25 million cubic meters. Therefore
this important ecosystem has dried up over the past few years,
which is threatening a sudden collapse of the ecosystem and
its diverse biological components.
(b)
Terrestrial ecosystems
Terrestrial ecosystems in Jordan form almost 98% of the total
area of the country. They are dominated by the vast area of
the eastern desert (Badia), which comprises about 82% of the
total area of the country. Therefore, the dry ecosystem in
Jordan is the dominant type. Nevertheless, one can recognise
the following sub-types of terrestrial ecosystem:
- Mediterranean
ecosystems
a) Forest ecosystems
b) Non-forest (degraded Mediterranean) ecosystems.
2. Steppe (Irano-Turanian) ecosystems
3. Dry ecosystems
a) Sand dunes
b) Saline
c) Hammada
d) Wadi systems
The Mediterranean
ecosystems in Jordan comprise about 8-10% of the total area
of Jordan. This region is characterised by physical characteristics
that allow different forest ecosystems to grow naturally.
However the natural forest cover in Jordan at the time being
is estimated to be about 0.04%, while the reforested area
over the past 50 years does not exceed 0.04%. Therefore the
total forest cover, natural and man made, is about 0.08%.
This means that 90% of the natural forest cover has been destroyed.
This destruction is definitely associated with the loss of
many animal and plant species. The most threatened of these
are the orchid species where we have already some species
recorded as extinct.
The total
area of the destroyed forest is recognised as non-forest vegetation
type. It is usually dominated by some herbs, bushes, and rarely
very low shrubs. The dominant species, considered as an indicator
of forest destruction in the Mediterranean region, is Sarcopoterium
spinosum. However, some of these lands are badly eroded enough
to be considered as desert. Based on that it is true to say
that desertification can occur in the most unexpected places
if mismanagement of land has taken place.
The steppe
and the dry ecosystems especially in the Badia region have
been over-exploited and mismanaged. Vast areas of natural
vegetation have been wiped out through ploughing of land for
use in the cultivation of cereals, especially barley, or for
the cultivation of vegetables using irrigation. The primary
vegetation in vast areas has been totally destroyed and replaced
by noxious weeds. Often this destruction of primary vegetation
has led to the spread of diseases or pollenosis due to pollen
dispersal by such plants or to rodents feeding on these new
plants that in turn acting as secondary hosts for diseases
like Leishmania or plague. Unfortunately vast areas have been
destroyed leading to irreversible changes which cause loosening
of soil particles, erosion and thus desertification.
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