1 Tr - Chioglossa

112
que explotan los bancos de semillas, que constituyen
el recurso trófico dominante en estos
medios durante el invierno (p. ej., Tellería y Santos,
1985; Tellería el al., 1992).
Muchos de los trabajos de restauración de
terrenos afectados se han orientado hacia el
mantenimiento de una cubierta herbácea con
apariencia de "pradera", eliminándose las especies
de matorrales colonizadoras por motivos
"estéticos" (I.T.G.E., 1989). El manejo posterior
de estos terrenos suele incluir la plantación de
especies arbóreas, a menudo ornamentales y frecuentemente
exóticas, las cuales, a causa del
deficiente sustrato edáfico, suelen mostrar un
escaso desarrollo y una elevada mortalidad (Gil
Bueno, 1994). Tales manejos posteriores generalmente
incrementan los costes de la restauración
y resultan ineficaces.
Si los trabajos de rehabilitación de zonas afectadas
por actividades extractivas (o incluso de
otras áreas que han sufrido impactos similares,
como los desmontes y taludes de los grandes
viales de comunicación) se orientan hacia la
recuperación de los hábitats naturales y a que
éstos sean ocupados de nuevo por las comunidades
animales que habían sido eliminadas, será
decisivo el que se favorezca el proceso de la
sucesión natural de la vegetación. Sólo ésta
garantizará el desarrollo de los procesos de edafogénesis
que permitan la instauración de una
vegetación diversificada (Bradshaw, 1983;
Brenner el al., 1983; Guitián Ojea, 1995) y, en
último término, el que la diversidad animal
retorne a los valores que tenía antes del impacto.
SUMMARY
Colonizalion of spoil henches of an opencasl lignile
mine in northwest Spain h.,>, bird communities
Colonization by birds of the spoil benches of the Meirama
opencast lignite mine in northwest Spain was
studied over the 1I years following the start of the
revegetation process. At Meirama, spoil benches are
initially fertilized and hydroseeded with apasture
mix, but are subject to little subsequent management
CHIOGLOSSA. 1 (1996)
and are gradually colonized by scrub vegetation characteristic
of the region. Bird censuses were carried
out in May (reproductive season) and in December
(winter season) of 1995 on six plots on spoil benches
ranging in age from Oto 1I years. Bird recolonization
is particularly rapid after the first 2 - 3 years posthydroseeding,
and is clearly closely related to habitat
development due to revegetation and natural succession.
The establishment of bird communities on Meirama
mine spoils is typically dependent on the establishment
of native plant communities. The pioneer
colonists identified are typical grassland bird species
(1 - 3 years post-hydroseeding). Following colonization
by these pioneer species other bird species only
appeared when the scrub layer was well developed
(from the fourth year onward). Some species (such as
typically woodland bird species) were not detected
until the 7 - II years post-hydroseeding, by which
time the vegetation cover tends to be a dense scrub
with relatively high plant species diversity (from 7 ­
10 years onward) 01' tree communities dominated by
Alnus, Salix and Betula develop along the bank of a
larger drainage ditch (from the eleven year onward).
Bird species composition was relatively similar to
that in natural surrounding areas in the oldest (seven
to ten-year-olds) spoil plots.
Key words: colonization, disturbed land, opencast
mining, restoration, revegetation, spoil benches, succesion.
BIBLIOGRAFÍA
Arnold. G. W. (1983). The influence of ditch and
hedgerow structure, length of hedgerows, and
area of woodland and garden on bird numbers on
farmland. J. App/. Eco/., 20: 731-750.
Bejcek, V. (1988). Communities of small terrestrial
mammals on the spoil hanks in the Most Basin.
Yysoká Skola Zemedelská, Praha.
Bejcek. V. Y Stastny, K. (1982). Sucession uf hird
communilies 0/1 spoi/ hanks after surface hrown
coal mining. XVIII Congressus Internationalis
Ornithologicus, págs. 166-167. Moscow.
Bejcek, Y. y Tyrner, P. (1980). Primary sucession and
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banks after surface mining of lignite in the Most
basin (NW Bohemia). Folia Zool., 29: 67-77.
Blanco, M. D., Casas, A., Cives, J., Galán, P., Gil, F.,
González, M. Y., Guitián, F., Leirós, M. c., Saá.