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Biological
spectrum with some other ecological attributes of the flora
and vegetation of the Asir Mountain of South West, Saudi
Arabia
Mohammad Al-Yemeni and Hassan
Sher*
Department of Botany and Microbiology, College of Science,
King Saud University, Riyadh, Kingdom of Saudi Arabia.
*Corresponding author. E-mail:
hassan.botany@gmail.com.
Accepted 27 July, 2010 |
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Based on the current available information on the
flora and vegetation of the Asir mountain of SW Saudi
Arabia, spectra on life form and some other ecological
attributes were analyzed and reviewed in different
sub-ecosystem of the investigated area. The floristic list
of Asir Mountain of the Kingdom of Saudi Arabia consists of
189 species belonging to 74 families, 65 dicotyledons (dicots),
4 monocotyledons (monocots), while gymnosperms and
pteridophytes were represented by one family each.
Asteraceae was the dominating family in the study area.
According to the Raunkiaerian life form therophytes (36.5%)
followed by hemicryptophytes (15%) and geophytes (12.5%)
were dominant in the area. Chaemophytes 6.5%,
mesophanerophytes 3%, megaphanerophytes 2%,
nanophaneorophytes 13% and climbers 1.5% contribution in the
establishment of vegetation structure in the study area. In
leaf size spectra, the analysis revealed that microphylls
(38.5%) followed by nanophylls (24%), leptophylls (13.5%),
mesophylls (12%), macrophylls (3%) and megaphylls (1%)
construct the vegetation belt of the area. The biological
spectrum of the high altitude was characterized by
phanerophytes mainly representing nanophanerophytic followed
by hemicryptophytic and geophytic species. These were
increasing with the rise in elevation while the
megaphanerophytic species were decreasing. The vegetation
cover in general and the tree layer in particular were
observed very rare and sparse. The grassland vegetation is
characterized by the largest percentage of hemicryptophytes.
In this region, the vegetation expression was predominantly
evergreen, although the tree flora has considerable elements
of deciduous species. The dominance of phanerophytes appears
to be due to high rainfall, temperature and low biotic
pressure. However, the population of therophytic species was
increasing in highly grazed and eroded areas.
Key words:
Biological spectrum, Asir mountain, leaf size, life form,
biotic and abiotic factors. |
