VI.3.3. Limits due to the choices of environmental
indices
Some of the previous calculated environmental indices may not
have any impact on the bird distribution. However, it is also possible that the
indices used were not well adapted to the organism studied. For example, the
study of isolation through the calculation of an index of weighted connectivity
has many limits. First, as said before, the patches sampled were not as islands
of habitats surrounded by a hostile urban matrix as presumed through the IBT.
Indeed, street trees or public garden or other habitats could be find inbetween
the patches which brings a relatively high bias to the index calculation.
Second, from one bird species to another, the distances are not assumed as
equal and the study of an isolation index should be done separately for each
species regarding its eco-ethology.
IMPLICATIONS FOR CONSERVATION
«There is no catch-all conservation strategy for
wildlife conservation. Targeting a specific species of concern, a functional
group or the proper response variable will lead to greater gains in comparable
conservation efforts.» (GALITSKY, 2012)
Despite the previous limitations, our study has major
implications to help improve the efficiency of bird conservation efforts in
Bangkok. A geographic layout of the urban biodiversity hotspots was set with
the distribution of the ornithological parameters described throughout this
thesis. To protect, preserve and restore functional green infrastructures in
urban green spaces for birds, large areas should contain compact and clustered
trees separated with sufficient amount and quality of open vegetation and water
inbetween.
However, the implementation of such strategies faces
significant challenges. Increasing the size of existing urban green patches is
difficult, if not impossible in cities. Therefore, strategies to enhance
habitat diversity and resource availability for birds within the patches
appears to be a straightforward way of increasing urban bird diversity.
Furthermore, initiative like the one coming from the Bird
Conservation Society of Thailand, which explored the possibility to implement
an urban bird reserve in eastern Bangkok (ROUND , 2008), should be brought
forward as well.
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VII. CONCLUSION AND PERSPECTIVES
As there is much concern today about environmental changes, it
is essential to know how those changes affect wildlife over time, and birds
offer a great value as biological and environmental indicators (BIBBY, 1999;
GOTTSCHALK et al., 2005).
This study allowed us to conclude that in Central Bangkok, the
more an urban green space is large and with a heterogeneous landscape, the more
bird species will be numerous and the more specialized species will be found.
The influence of the water cover rates on the species abundance diversity was
demonstrated as well.
The previous results describing the bird distribution are
mostly descriptive and of little use in themselves but will be of high interest
while compared with futures bird counts conducted in a similar way. Indeed,
they will provide a quantification of urban bird diversity evolution across
time since birds are useful indicators of changes within their environment
(BIBBY, 1999; KOSKIMIES, 1989), their quantification is indispensable in order
to implement management measures or to reach a priority for future actions. It
is crucial for the Bangkok government to promote a sustainable development
within the metropolis.
As the landscape is not supposed to change in those green
areas, a landscape monitoring across time doesn't need to be implement.
However, the environmental factors could be complemented by calculating more
intrinsic environment structures within the patches with authorizations and
maps from the BMA and a scale-dependent study could also be apply.
Another clue could be the implementation of volunteer-based
surveys that provide sharing resources to facilitate science and management as
well as an avenue for urban conservation to engage a broader audience. Since
the interest for nature is growing more and more within the inhabitant of
Bangkok (pers. Obs.), initiatives of counting projects from the Bird
Conservation Society of Thailand need to be encouraged and may be
successful.
The development of sustainable cities is today the major goal
for urban landscape planners, government authorities and conservationists (WU,
2009). Programs that aim to find a sustainable balance between the today's
traditional vegetation management and more natural management need to be
implemented in order to contribute to the sustainable efforts (SHWARTZ et al.,
2013). We shall not forget that each city is a unique system and the occurring
management and planning actions should therefore be continuously evaluated to
measure their effectiveness
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