Geoscience Reference
In-Depth Information
value of using bryophyte community information
for
in extended dry periods during the summer.
The influence of the Mediterranean climate is
particularly evident in the Sic o mountain range
located in the central-western area of Portugal.
The entire study area (Figure 12.1) is mountainous
(up to 1500 m altitude) and characterized by steep,
headwater streams dominated by bedrock and
boulders, fast currents and sequences of pools,
riffles, waterfalls and rapids.
Aquatic macrophytes found in these headwater
systems depend on their ability to attach firmly
to the stream-bed substratum, resist scouring and
tolerate low nutrient levels. These communities
are of great phyto-geographical importance owing
to the colonization routes during the Iberian
Peninsula formation (S ergio, 1990) and the
refuge nature of the area during the final glacial
phase of the late Quaternary
fluvial
and
ecological
assessments
of
these
watercourses at a regional scale.
Study area
In biogeographical terms, north-west Portugal is
at the western-most edge of the Euro-Siberian
Region and is also located at the northern border
of the Mediterranean Region (Costa
et al
., 1998).
The climate is wet and temperate, with annual
precipitation of 600-3000 mm and a mean daily
temperature range of 7-17
◦
C.Thec imate s
strongly influenced by the moderating effect
of the Atlantic Ocean but there is considerable
intra-annual
variability
of
precipitation
and
period (Petit
et al.,
consequently
in
river
flows,
which
can
result
Figure 12.1
Location of the study area and stream segments in relation to: (a) Europe: (b) the Iberian Peninsula;
(c) Portugal. (A-F: represents the TWINSPAN groups to which bryophyte communities were assigned — see
Figure 12.2).
