Chemistry Reference
In-Depth Information
3. The wild plants and adaptations
Qatar is a small country with more than 4/5 of its boundary surrounded by a coastline
(Figure 1), and the combinations of many environmental factors including drought and
salinity, and high evapo-transpiration, irradiance, and temperatures do not allow many
plants to grow and survive in this region. The flora of Qatar has been placed into one of five
main habitat groups [10]: (1) xerophytes of rock and gravel deserts where the conditions are
very dry, (2) halophytes of saline areas such as salt marshes, coastal sands, sabkhas and
oolitic sands, (3) xerophytic species grow in natural silt and sand depressions where water
retention is higher than those purely xerophytes, (4) species adapted at deep sand where
water is available under the surface, and (5) species receiving artificial irrigation such as
farms, gardens and sewage ponds. Also, the coastal line has been classified into five
halophytic plant communities: (1) mangrove intertidal community, (2) low salt marsh
coastal community, (3) high salt marsh coastal community, (4) sandy coastal community,
and (5) sandy-rocky coastal community [5]. The coastline of the State of Qatar encompasses
unique ecosystem of vegetated sand beaches alternating with bays of aquatic halophytes
and mangroves, followed inland by members of some families like chenopodiaceae, which
are considered as halophytes and/or xerophytes. These plants have various morphological
and anatomical modifications, and physiological and biochemical characteristics that could
have contributed to their adaptation to the harsh environment in this region [9].
The checklist of plants in the State of Qatar has been reviewed many times, some reports
[11] listed 213 species, while others [12] gave a list of 260 species, then the monograph of
Batanouny [6] listed 301 species in 207 genera and 55 families. Recently, Norton and his
colleagues [10] have increased the list of wild plants to nearly 400 species of which about 270
species are likely to be truly native. Some other references can be found in the last
publication to updating the checklist of the wild plants in the Gulf region and in the State of
Qatar. Most of these plants have been recognized as either xerophytes or halophytes; well
adapted to dry and/or saline environments.
3.1. Xerophytic plants
Many plants at the coastal line and throughout the Qatari land are characterized as
xerophytes, include:
Cyperus conglomeratus
,
Oligomeris linifolia
,
Helianthemum lipii
,
Tetraena
qatarense
,
Ochradenus baccatus
and many others. These plants have various mechanisms to
cope with drought and water stressed soils
(A) Drought - Escaping xerophytes
These plants germinate, grow, and flower within a short period of time after fairly heavy
rainfall. They produce seeds before the dry season, and therefore, they resist dry season
during the seed stage [13, 14]. Examples of such plants:
Polycarpaea
spicata
and
Senecio
desfontanei
. Almost all ephemerals that germinate and grow in the desert after the summer
rainfall are C4 plants, while plants that germinate after the autumn rainfall are C3 plants
[13]. Most escaper plants survive the dry period in the desiccation - tolerant seed stage.
