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Final Report of Vegetation Assessment
1.4.4 Multivariate Analysis:
The cover estimates of all the species recorded from the programme sites were examined
using Two Ways Indicator Species Analysis (TWINSPAN), as a classified technique following
the procedures of Hill and Similauer (2005).
1.4.5 α, β and γ-Diversity:
The division of diversity into alpha (α), beta (β) and gamma (γ) components, to characterize
diversity on different scales was first proposed by Whittaker (1972). Alpha diversity is withinarea
diversity, measured as the number of species occurring within an area of a given size.
Gamma diversity is also a measure of within-area diversity but it refers to overall diversity
within a large region or biodiversity at the landscape level. Beta diversity is the degree of
species change along a given habitat or physiographic gradient, as such it is a measure of
between-area diversity. It is normally represented in terms of the similarity index or of species
turn-over rate (Kalin-Arroyo et al. 1995, Smith and Smith 1998, Al-Sheikh and Ghnaim
2004, Jafari et al. 2004).
α, β and γ-diversity were measured in terms of species richness, i.e., the number of species
irrespective of the relative abundance of individual species. Therefore α – diversity is simply
the number of species in one locality, the γ-diversity was calculated by adding the four α –
diversities (i.e., number of species in each locality or study site) but avoiding duplicate
counting of species common to two or more localities.
The similarity index (CC) between locality pairs was calculated by the formula:
CC = 2Ss / / Sj+Sk (SØrensen 1948)
Where Ss is the number of species common to both the localities, while Sj and Sk are the
number of species in locality 1 and locality 2, respectively.
The β – diversity was calculated as β = γ/αֿ or BD = Sc / S, in which Sc is the number of
species in a composite sample (combining α samples) and S is the mean number of species
in α-samples (Whittaker 1972). For comparing locality pairs, Sc was taken as the total number
of species in the two localities excluding duplicate counting of shared or common species,
while S was calculated irrespective of duplication.
1.4.6 Soil Analysis
Composite soil samples were taken at 15 to 30 cm depth from at least five selected transects
from each of the four sites during vegetation surveys of 2007 and 2008. These samples were
analyzed to determine physical (soil texture) and chemical parameters like EC, pH, Organic
matter, P and K.
1.4.7 Satellite Remote Sensing Based Forest Change Mapping and Monitoring
of Mangrove Forests of Keti Bundar.
GIS team of WWF – Pakistan was facilitated by the Indus For All Programme to undertake
Satellite Remote Sensing Based Forest Change Mapping and Monitoring of Mangrove
Forests of Keti Bundar during February 2008. Material and Methods and the findings of this
study are included in this report separately at pages 33 – 49.
1.4.8 Problems and threats:
Problems and threats to each site were also recognized based on discussions with local
people, concerned government officials, personal observations and literature survey; and
suggestion/recommendations were made for their mitigation.
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