| Habitat and Ecology: |
Canary Islands:
In the Canary Islands this species has become adapted to different habitats. In Tenerife and La Palma, J. cedrus occurs at the timberline (2,200 m), which characteristically has low precipitation and great diurnal temperature variation. Here the dominant vegetation is of shrubs Spartocytisus supranubius and Adenocarpus viscosus. In contrast, on La Gomera, which is lower in altitude, (1,150 m.) the habitat is Laurel forest which has high levels of humidity as a result of the north-east trade winds. In Gran Canaria it only occurs on Montaña del Cedro, where it grows at altitudes between 800-900 m, here the temperatures are relatively warmer. At some of the locations (La Gomera and one location on Tenerife) there is evidence of regeneration but generally recruitment appears to be relatively poor. One factor that may be related to this, is the decline in ravens (Corvus corax) that are thought to have played a significant role in seed dispersal (Nogales 1999, Remeu et al. 2009). Recent research has revealed that winter visiting Ring Ouzels (Turdus torquatus) also play a key role in seed dispersal (Remeu et al. 2009). Additional research has indicated that the Canary Islands subpopulations produce seed with relatively lower viability, possibly due to lower pollination rates resulting from fragmentation of stands (Remeu et al. 2009)
Madeira The subpopulation on Madeira occurs on exposed rock faces above the laurel forest tree-line above 1,400 m in altitude. Here it belongs to the Polysticho falcinelli-Ericetum arboreae (Capelo et al. 2004). The main components include: Erica maderinicola, Ilex perado, Laurus novocanariensis, Polystichum falcinellum, Vaccinium padifolium & Sorbus maderensis. In Madeira there have not been any studies to establish whether or not there is any regeneration, however since the removal of goats in recent years the vegetation recovery rates are very encouraging.
The current distribution pattern and the restriction to almost inaccessible sites in the Canary Islands and on Madeira reflect past human disturbance. Formerly it was more widespread.
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