Geography Reference
In-Depth Information
development of cartography. It was considered of interest to note the state or degree of
consolidation of urban or under urban development, as this is one aspect that has changed
in the whole Madrid Region from the 70's of last century.
We then crossed the two land-use maps by means of techniques of overlapping and digital
layer intersection, thus comparing the information from both years. The result was a new
map on which each patch showed the land use observed in both years. Thus, we identified
all the types of changes that had taken place in the PNA during the 35-year period. Then it
was possible to know if each type of vegetation or land use in each part of the territory has
changed or not. Results allowed us to identify a set of changes occurred in the PNA during
these 35 years.
Then we calculated the percentage of the area that has changed in the whole PNA and for
each type of dynamic [28, 48]. These percentages allowed us to establish categories of
dynamism that distinguished zones of more or less changing and map its spatial
distribution. Finally, we used categories of dynamism map (1:12,500 scale) to select three
locations. We conducted a more detailed study about natural dynamic of territory [49-51],
using a set of ecological parameters as indicators of structure and organization of territory.
A more detailed study allowed us to recognize and map 23 types of land uses. These were
the result of consider at the same time land uses and vegetation units. Using this criterion
we obtained categories as Dehesas
of Quercus ilex
subsp.
ballota
i.e.
In each selected locations, we calculated relative frequencies of each land use type using
their abundance, and graphed their relative frequency profile in 1975 and 2009. Each profile
has been defined by three parameters: the richness of land uses, R(u), calculated as the
number of different categories of land uses in the corresponding year [52]; Shannon's
diversity, H'(u), expressed in bits [27]; and Pielou's evenness, E(u) [53].
Evenness is the proportion between observed diversity value and maximum diversity value
that would be possible to reach with the registered R(u). High values of E(u) indicate an
even land use distribution, that means that there are not a dominating land use in the
territory. To the contrary, low values of E(u) are indicating that one or a small set of land
uses are more frequent [54].
In order to complete the study of evolution of territorial structure and organization, we
analyzed ecological connectivity and fragmentation in each selected location in 1975 and 2009.
We calculated ecological connectivity (c) of territory according to a set of permeability
values assigned to each land uses. These permeability values were established taking into
account matter and energy flows (genes, seeds, species, etc.) through two adjacent land uses
[55-57], and assessing the quality of each land uses according to landscape functionality,
forestry value, cultural value, among others.
Finally, we calculated fragmentation of territory (f) according to the variation in patches
number occurred between 1975 and 2009 at each selected locations. We focused on
boundary effect caused by human land uses. Results were mapped.
