(Laurus nobilis) provides an indication of the previous existence of laurel forest. This species survives natively in Morocco, Algeria, Tunisia, Spain, Portugal, Italy, Greece, the Balkans, and the Mediterranean islands. The myrtle spread through North Africa. Tree heath (Erica arborea) grows in southern Europe, but without reaching the dimensions observed in the temperate evergreen forest of Macaronesia or North Africa. The broad-leaved Rhododendron ponticum baeticum and/or Rhamnus frangula baetica still persist in humid microclimates, such as stream valleys, in the provinces of Cádiz and Málaga in Spain, in the Portuguese Serra de Monchique, and the Rif Mountains of Morocco. The Parque Natural de Los Alcornocales has the biggest and best preserved relicts of Laurisilva in Western Europe. Although the Atlantic laurisilva is more abundant in the Macaronesian archipelagos, where the weather has fluctuated little since the Tertiary, there are small representations and some species contribution to the oceanic and Mediterranean ecoregions of Europe, Asia minor and west and north of Africa, where microclimates in the coastal mountain ranges form inland "islands" favorable to the persistence of laurel forests. In some cases these were genuine islands in the Tertiary, and in some cases simply areas that remained ice-free. When the Strait of Gibraltar reclosed, the species repopulated toward the Iberian Peninsula to the north and were distributed along with other African species, but the seasonally drier and colder climate, prevented them reaching their previous extent. In Atlantic Europe, subtropical vegetation is interspersed with taxa from Europe and North Africa in bioclimatic enclaves such as the Serra de Monchique, Sintra, and the coastal mountains from Cadiz to Algeciras. In the Mediterranean region, remnant laurel forest is present on some islands of the Aegean Sea, on the Black Sea coast of Iran and Turkey, including the Castanopsis and true laurus forests, associated with Prunus laurocerasus, and conifers such as Taxus baccata, Cedrus atlantica, and Abies pinsapo. In Europe the laurel forest has been badly damaged by timber harvesting, by fire (both accidental and deliberate to open fields for crops), by the introduction of exotic animal and plant species that have displaced the original cover, and by replacement with arable fields, exotic timber plantations, cattle pastures, and golf courses and tourist facilities. Most of the biota is in serious danger of extinction. The laurel forest flora is usually strong and vigorous and the forest regenerates easily; its decline is due to external forces. Laurel