A map of Andalusian biodiversity has been created by using a number of
normalized and specialized environmental variables from the Andalusian
Environmental Information Net (SinambA). The most important variables refer to
the fauna, flora, vegetation and characterization of land use. The index which
presents itself – differentiated for natural or semi-natural zones and cultivated
zones responds to a classic measure of biodiversity: “variation and relative
abundance of habitats and species”. In this way, it has been considered that the
diversity of habitats, defined by the maximum number of different plant
communities that can be recognized in a single geographical area and type of
land use, is akin to the abundance of species and that the structural diversity,
which takes into account the number of existing vegetation strata and the
abundance of each of these, contributes in a decisive way to the creation of a
global diversity indicator. Finally, information about the presence and distribution
of the principal taxons of fauna and flora in Andalusia has also been included.
The Land Cover 2000 project has been a central pillar in the elaboration of this
map of biodiversity.
INTRODUCTION
There are many ways of measuring biodiversity, from the most classic and easily
understood – the bigger the number of species, the larger the biodiversity is – to
more complex systems, which imply the use of many variables, and whose
comprehension requires a higher analytical capacity.
On the other hand, the greatest problem nowadays for the calculation of indexes
or indicators of biodiversity that result operational is the absence of normalized
data, especially when you’re dealing with a territory as big as Andalusia.
Because of this, a series of normalized variables from the SinambA have been
used in order to create the map of biodiversity.
The most important ones are the variables that refer to the characterization of
territorial use, as the fundamental tool to territorialize the rest of the variables, the
vegetation, emphasizing the relative typology and distribution of the plant
communities, the distribution of the principal taxa of fauna and flora, or the
degree of danger of the natural or semi-natural habitats, obtained using other
variables in SinambA. All of the variables have been integrated and analyzed in a
Geographical Information System, giving, as a result, the map of biodiversity that
is being presented.
OBJECTIVES
The main objective is to generate a model that evaluates the biodiversity thanks
to the normalized variables existing in the SinambA that would help to obtain a
cartography at an adequate scale from this source, and develop an evaluation
and continuation of this cartography.
MATERIALS AND METHODS
The presented cartography tries to show the variation and relative abundance of
habitats and species. To do so, a combination of data from different sources and
different scales has been used. On one side, an index of vegetation diversity has
been calculated – phytocenotic diversity – thanks to the habitat diversity,
understood by the maximum number of different plant communities that can be
found in a specific geographic area and land cover type, and the structural
diversity, which contemplates the existing vegetation strata and the abundance of
each of these strata.
Combining both factors, habitats diversity and structural diversity, the
phytocenotic diversity has been calculated. Only the structural diversity has been
used in cultivated areas, since the followed methodological process excludes, in
these areas, the calculation of the habitats diversity. This index represents not
only the variety and complexity of the vegetation strata, but also the possibility of
sheltering a certain number of plant communities with what will constitute a
relative indicator of the existing floral diversity (phytocenotic diversity). Although, it
is important to make a little matization: the information used for the index calculation
comes from areas with some protection figure, so, for being able to generalize the index
to the total region, it has been necessary to ponderate it from the degree of danger of
the natural or semi-natural habitats, refered to the Andalusia existing landscape
typologies, variables generated by the SinambA.
The distribution and abundance of the principal taxa of fauna and flora have been
added to compliment this index.
Calculation of habitat diversity
At the most basic level, the diversity of habitats is nothing more that the number
of different types of habitats in a specific geographical area (Magurran, 1989).
Thus, for the correct interpretation of this characteristic, it is necessary to adopt a
system to classify the different types of habitats.
In this way, the Environmental Ministry is elaborating a work program called
Mapping and Evaluation of the Vegetation, Fauna and Flora at a derailed scale of
Andalusian forestal ecosystems – whose finalization is expected in 2006 for
1,500,000 ha. – which implies more than 33% of the forest area of the region.
This cartography is based on the phytosociological methodology suggested by
(Braun-Blanquet, 1979) that classifies the vegetation habitats of Andalusia.
Each of the mosaic pieces identified in the vegetation cartography at a scale of
detail contains information about the natural and semi-natural habitats that they
contain, being relatively easy to calculate a diversity index for habitats, as the
maximum number of different habitats contained in a mosaic piece. It has been
necessary to extrapolate this information to the forestal territories that do not
have mapping of vegetation. The extrapolation process was made using the
correlation of the available data for more than 1,500,000 ha. that had already
been analyzed with the respective Land Cover 2000 Andalusian map units.
Calculation of structural diversity
The number of vertical strata and the abundance of vegetation in these strata
have been used for the calculation of the structural diversity. This information is
collected in a semi-detailed scale (1:50,000) in the Land Cover 2000 Andalusian
map integrated into SinambA.
In order to obtain the structural diversity value, two parameters have been
considered: variety of strata and occupation of territory. The latter was also
obtained from two parameters: vertical development and land cover of
vegetation.
The integration of the structural diversity and the habitat diversity will give place
to an index named phytocenotic index.
Calculation of the specific diversity of vertebrates
To obtain the value of the specific diversity, data from the Atlas of Vertebrates,
which was made by the National Inventory of Habitats and Taxons, realized by
the Environmental Ministry, was used.
The Shannon-Weaver index (Krebs, 1985) was used as an index which takes
into account the proportional abundance of species.
Representation of the diversity of the flora taxa
An adaptation of the bio-geographic typology of Andalusia defined by (Rivas
Martinez et al, 1997) to the landscape units has been used as a base for the
representation of the diversity of flora taxa and their endemic nature. (Figure 1).
Figure 1. Adjustment of the bio-geographic units on the Landsat satellite image.
On this base, the diversity of taxa and the degree of their endemic nature has
been represented, thanks to the data obtained from the revision of a large
amount of bibliographic sources: (Blanca et al., 1999), (Hernandez et al., 1999),
(Hernandez et al., 1994), (Rodriguez et al., 2002), (Rivas et al., 1997).
RESULTS
The resulting map is the union of all of the variables, whose calculation has been
explained throughout this text. In this way, the base of this map constitutes the
index of phytocenotic diversity in natural or semi-natural areas, and the index of
structural diversity in cultivated areas. Atop this information, the proportional
abundance of vertebrate taxa, has been added through the use of isolines
(uniting areas with the same proportion of abundance) calculated from the
Shannon-Weaver index. The bio-geographic zoning in the region constitutes the
skeleton over which the abundance and endemic nature of the principal flora and
fauna taxa in Andalusia are represented.
(Figure 2.)
No evaluated areas
Structural diversity
(Cultivated areas)
Final result: Biodiversity Map of Andalusia
Structural diversity
biodiversity
(Natural areas)
Normalized Shannon index for vertebrates
vertebrtesnormalidado de vertebrados
Biogeographic region limits
Information about taxa
Figure 2. Summary of intermediate results and processes to obtain a biodiversity
map.
BIBLIOGRAPHY
Braun-Blanquet, J. (1979): Fitosociología: Bases para el estudio de las
comunidades vegetales H. Blume Ediciones. Madrid.
Consejería de Cultura y Medio Ambiente. Agencia de Medio Ambiente. Junta de
Andalucía. (1994). Protección de la flora en Andalucía. Hernández Bermejo, J.
E., Clemente Muñoz, M (Eds.)
Consejería de Medio Ambiente. Junta de Andalucía (1999). Libro rojo de la flora
silvestre amenazada de Andalucía. Tomo I, especies en peligro de extinción.
Blanca, G., Cabezudo, B., Hernández-Bermejo, J.E. Herrera, C.M. Muñoz, J. y
Valdés, B. (eds.).
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pp. 52-59.
Krebs, Charles J. (1985). Ecología, estudio de la distribución y la abundancia.
Editorial Harla. México.753 pp.
MacArthur R. H., and E. O. Wilson. (1967). The theory of island biogeography.
Princeton University Press, Princeton.
Magurran A. E. (1989): Diversidad ecológica y su medición. Ediciones vedrà.
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