As characteristic communities of coastal dunes (Crawford 1989; Goldstein et al.
1996), juniper woodlands are structurally open communities, with only a few
woody plant species. Those juniper communities show variations in the composition of plant species over the Mediterranean Basin (Géhu et al. 1990). These
variations are also apparent along the southwestern coast of Spain, where several
factors seem to control the woody plant composition of juniper communities on
different spatial scales (Muñoz-Reinoso 2003). On a large scale, climate and soil
texture play an important role in controlling the soil water availability for plants,
and in separating the xerophytic communities of Huelva, with Halimium
commutatum and Stauracanthus genistoides among others, from the mesic communities of Cádiz, with Chamaerops humilis, Phillyrea angustifolia, Olea europaea, and Quercus coccifera.
On a smaller scale, sand mobility, pH values, and calcium carbonate content
allow plant communities of the sand dunes and cliffs to be distinguished. Sandy
dunes showed a moderate to high sand mobility, higher pH values, and high
content in calcium carbonate, while cliffs showed a higher proportion of silt.
Dunes were characterized by species such as Ononis natrix, Sideritis arborescens,
and Clematis flammula, while Cistus ladanifer, C. crispus or Ulex australis
characterized cliff communities.
Finally, the coastal pine plantations play an important role in modifying local
environmental conditions, mainly decreasing sand mobility and salt spray deposition, which induces important changes in plant communities, such as the replacement of Armeria pungens, Artemisia chritmifolia or Scrophularia frutescens with
Halimium halimifolium. Tekke and Salman (1995) have referred to the effects of
pine plantations on the landscape, geomorphology, soils, and ecology of coastal
ecosystems. Sand stabilization (the final purpose of pine plantations) results in the
disappearance of the species adapted to a moving substrate, and the reduction in salt
spray deposition under the pine tree canopy. Thus, these pine plantations allow
colonization by species that are less tolerant to coastal stress, such as Rhamnus
lycioides.
Differences in controlling environmental factors are not only shown by plant
composition, but also by the richness and diversity of the species (Muñoz-Reinoso
2004). The harsher environment of coastal dunes produces a low diversity of woody
species, and juniper communities are characterized by Helichrysum picardii,
Armeria pungens, Thymus carnosus, Sideritis arborescens, and Corema album. On
the cliffs, the elevation of the coast reduces the environmental stress promoted by
the salt spray; then, the richness and diversity of the species increase and the
composition of plant species is mainly controlled by lithology and climate (water
availability).
Pinus pinea plantations attenuate the effect of the harsh coastal physical
environment, causing the disappearance of endemic juniper woodland vegetation
and promoting the establishment of landward species. Salt spray deposition falls
off to less than 20 % of windward deposition (Fig. 9.3, Muñoz-Reinoso
unpublished), and species of stabilized dunes such as Halimium halimifolium and
Rosmarinus officinalis replace the species adapted to a moving substrate.
9 Restoration of Andalusian Coastal Juniper Woodlands
149
1996), juniper woodlands are structurally open communities, with only a few
woody plant species. Those juniper communities show variations in the composition of plant species over the Mediterranean Basin (Géhu et al. 1990). These
variations are also apparent along the southwestern coast of Spain, where several
factors seem to control the woody plant composition of juniper communities on
different spatial scales (Muñoz-Reinoso 2003). On a large scale, climate and soil
texture play an important role in controlling the soil water availability for plants,
and in separating the xerophytic communities of Huelva, with Halimium
commutatum and Stauracanthus genistoides among others, from the mesic communities of Cádiz, with Chamaerops humilis, Phillyrea angustifolia, Olea europaea, and Quercus coccifera.
On a smaller scale, sand mobility, pH values, and calcium carbonate content
allow plant communities of the sand dunes and cliffs to be distinguished. Sandy
dunes showed a moderate to high sand mobility, higher pH values, and high
content in calcium carbonate, while cliffs showed a higher proportion of silt.
Dunes were characterized by species such as Ononis natrix, Sideritis arborescens,
and Clematis flammula, while Cistus ladanifer, C. crispus or Ulex australis
characterized cliff communities.
Finally, the coastal pine plantations play an important role in modifying local
environmental conditions, mainly decreasing sand mobility and salt spray deposition, which induces important changes in plant communities, such as the replacement of Armeria pungens, Artemisia chritmifolia or Scrophularia frutescens with
Halimium halimifolium. Tekke and Salman (1995) have referred to the effects of
pine plantations on the landscape, geomorphology, soils, and ecology of coastal
ecosystems. Sand stabilization (the final purpose of pine plantations) results in the
disappearance of the species adapted to a moving substrate, and the reduction in salt
spray deposition under the pine tree canopy. Thus, these pine plantations allow
colonization by species that are less tolerant to coastal stress, such as Rhamnus
lycioides.
Differences in controlling environmental factors are not only shown by plant
composition, but also by the richness and diversity of the species (Muñoz-Reinoso
2004). The harsher environment of coastal dunes produces a low diversity of woody
species, and juniper communities are characterized by Helichrysum picardii,
Armeria pungens, Thymus carnosus, Sideritis arborescens, and Corema album. On
the cliffs, the elevation of the coast reduces the environmental stress promoted by
the salt spray; then, the richness and diversity of the species increase and the
composition of plant species is mainly controlled by lithology and climate (water
availability).
Pinus pinea plantations attenuate the effect of the harsh coastal physical
environment, causing the disappearance of endemic juniper woodland vegetation
and promoting the establishment of landward species. Salt spray deposition falls
off to less than 20 % of windward deposition (Fig. 9.3, Muñoz-Reinoso
unpublished), and species of stabilized dunes such as Halimium halimifolium and
Rosmarinus officinalis replace the species adapted to a moving substrate.
9 Restoration of Andalusian Coastal Juniper Woodlands
149