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Final Report of Vegetation Assessment
the mangroves but they are also nutrient-rich. The most extensive and luxurious mangroves
are invariably associated with mud and muddy soil found along deltaic coasts, in lagoons and
along estuarine shorelines (Saenger 2002). Both freshwater flow and silt load of Indus river
continued to decrease with the construction of dams and barrages upstream. According to
Saifullah (1997), the annual silt load at Kotri barrage has decreased from 200 million tons to
50 million tons during 1955 to 1984. The sediment reaching the delta has been as low as 10
million tons/year (Meadow and Meadow 1999). The uprooting of mature Avicennia trees due
to erosion observed during present study appears to be due to the lack of deposition of fresh
sediment, further aggravated by the sea level rise due to global warming resulting in the
receding coast-line and sea intrusion. The lack of sediment deposition has far reaching
effects. The natural land subsidence rates in river deltas are higher than other parts of the
coast, which are normally compensated by the new sediment deposition, but the lack of
sediment may result in local relative sea level rise and intrusion of salt water in the inland
aquifers leading to biodiversity loss in coastal ecosystems (Haq 1999). It means that in case
of general rise in sea level, the actual sea level rise would be greater for the deltas resulting in
a greater inundation than other parts of coast, thus greater destruction and dislocation of
people. These effects would be even more severe in the absence of mangroves.
The increase in salinity of the area is also indicated by the inland vegetation. Aeluropus
lagopoides, Arthrocnemun macrostachyum, Halostachys belangerana and Tamarix indica are
recognized as dominant species in Two Way Indicator Species Analysis (TWINSPN), which
are all halophytic species. Besides these Salvadora persica, another halophytic species is
also fairly common. Floristically as well, Chenopodiaceae and Tamaricaceae (all halophytes)
are among the larger families, and among grasses about ten species are halophytes. It is
interesting that Hoekstra et al. (1997) reported Tamarix dioica from the salt marshes of Indus
delta but we did not find this species in delta area, neither any of its specimen is recorded
from this area in the Flora of Pakistan. It therefore appears to be a case of misidentification.
Similarly, the Arthrocnemum indicum mentioned by Hoekstra et al. (1997) must be actually
Arthrocnemum macrostachyum, as the former is a rare species on Pakistan coast (Flora of
Pakistan No. 204). The primary productivity in terms of DMY and carrying capacity were found
to be quite low indicating that the ecosystem cannot sustainably support any large number of
livestock.
2.5.1 Problems & Threats:
Keti Bundar is of great ecological and economic significance because of the mangrove
ecosystems. These ecosystems almost entirely support shrimp and fishery production that
earn 100 million US $ annually (Saifullah 1997). Normally mangrove ecosystems are pristine
and do not require much management unless ecological processes are disrupted. In spite of
overwhelming importance of mangroves in Pakistan, little attention has been paid to their
management. Mangroves are disappearing at an alarming rate and main causes of such rapid
decline are rooted among unawareness among policy makers, authorities and public at large
(Saifullah 1997). Keti Bundar is one of the major towns in Indus delta that is facing a multitude
of environmental degradation and loss of livelihood opportunities for the locals. Some of the
serious problems leading to ecological degradation in this area are briefly described below.
2.5.1.1 Deficiency of Fresh Water Flow form Indus River: This is probably the most serious
problem of Indus delta as a whole. Mangroves occur preferably in deltaic regions of the world
because they grow better in low saline water and soft alluvial substrate. Their productivity
increases proportionately with the increase of fresh water (Saifullah 1997). There has been a
continuous decrease in Indus River discharge ever since the creation of Pakistan mainly
because of extension in irrigated agriculture that forced to construct more upstream dams and
barrages. Flow of River Indus has decreased from 150 MAF (before construction of dams and
barrages) to a meager amount of 10 MAF. Gradual decrease in fresh water has triggered the
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