X hits on this document

PDF document

The Forest Map of Spain 1:200,000. Methodology and analysis of general results - page 4 / 16





4 / 16

The Forest Map of Spain 1:200,000


of the generalized occurrence of high mountain vege- tation. Nowadays, the exact altitudinal belt boundary may be not clearly delimited due to the alteration caused by ancestral grazing exploitation of most mountain areas and the lack of direct meteorological data. More- over, there are differences among mountain ranges and comparing the exposure (sunny or shady hillslopes). In the Pyrenees, Montserrat (1990, 1992) locate it at (2,300) 2,500 m; Díaz et al. (1998) set it out at (1,700) 1,800 m in the Cantabrian mountains, as well as in Moncayo (Iberian Range) according to Villar (1990); and Allué (1996) deduced the altitude of (1,800) 2,100 m in the Central Range. Plant covers are dominated by microthermal and hygrophile species which constitute either scrubs or graminoid communities and, further uphill, semideserts and rocky deserts.

Taiga-like Type or Mountain Needleleaf Forests domain (T). Strictly speaking, Taiga-like refers to conifer forests in northern regions at sub-arctic latitudes, but it can be equivalently applied to needleleaf woodlands of the high mountain belts in middle latitudes, like in Spain. This type is located, when existing, immediately below the High Mountain ype.This characteristic conifer area in the Mediterranean region is so recognized by several authors such as Quezel (1982). It occupies cold climate areas with regular long periods of frost and cool summers, with no water shortage (Ruiz de la Torre, 1990). The growth period is longer than in the High Mountain Type, but it is too short and there are too many frosts for Deciduous angiospermae trees to dominate. Its width varies between (1,500) 1,600 and (2,300) 2,500 m in the Pyrenees (Montserrat, 1990,

  • 1992)

    ; 1,500 and 2,100 m in the Central Range (Allué,

  • 1996)

    and above (1,400) 1,500 m in the southern Ibe-

rian Range (López Leiva, 1995). Relatively microthermal and hygrophile species (mainly genera Abies, Pinus and in a lesser extent, Juniperus and Taxus) prevail in the arboreous plant covers.

Deciduous Type or Deciduous Forests domain (C). This belongs to mild or cold winter climates and warm or warm-hot summer thermic pattern with no water shortage (Ruiz de la Torre, 1990). The growth period is longer than for the Taiga-like and allows the predomi- nance of deciduous angiospermae trees. It is spread throughout all northern regions with atlantic climate, although it is also interspersed in mediterranean Spain. Thus, the potential area is located along the Cantabrian range (below timberline) and in the whole litoral strip from Galicia to Navarra, therefore located between 0 and (1,700) 1,800 m (Díaz, 1998) and in central Py-

renees between (1,000) 1,200 and 1,600 m. Genera Quercus, Fagus, Betula and Tilia are dominant.

Subsclerophyll Type or Subsclerophyll (submedi- terranean) Forests domain (S). In climates with a cold or mild-cold winter and a warm summer, subdry or at least having a subdry period (Ruiz de la Torre, 1990) which lasts less than 3 months. Generally speaking, this type is found between 800 and 1,500 m in medi- terranean Spain; in addition, there are scarce patches in the atlantic region, almost at sea level. Broadleaf semirigid, semideciduous or deciduous tree species dominate o co-dominate, like species of genera Quercus, Acer and some Pinus and Juniperus.

Sclerophyll Type or Sclerophyll Forests domain (E). In climates with mild to cold, wet to subdry winter and a hot, dry period of 3-5 months which includes the whole summer or it is centred in part of it (Ruiz de la Torre, 1990). It is located from sea level up to 800 (1,500) and more. The prevalence corresponds to evergreen tree species with small, hard leaves of genera Quercus, Olea, along with Pinus and Juniperus.

Hyperxerophile ype or Hyperxerophile Plant Covers domain (H). It occupies potential forested areas, but only at the transitional boundary towards places inside a non forest fringe, where tree species cannot constitute large woodstands due to arid climate conditions. It belongs to mild and cold regions, with drought during almost the entire year or periodical sequences of consi- derably dry years (Ruiz de la Torre, 1990). It is located from sea level up to 800 m. Currently, these areas undergo a considerable antropic degradation which, along with the abundance of interspersed special soil (salts and gypsum), makes the possibility of sparse arboreous covers occurrence still more difficult. Its most representative tree species belong to genera Pinus, Tetraclinis and Juniperus.

The Canary Islands are shared by 5 zonal types (Fig. 4). High Mountain Type or Above Timberline Belt (S). Only present in Tenerife and La Palma. Its vegetation has a more arid physiognomy than the ones located immediately below. The thermic pattern is colder, with large temperature contrasts among seasons and between mornings and nights. Its width varies from 2,000-2,500 m up to the highest summits (Ruiz de la Torre, 1990). Plant covers are made up of several scrubs domina- ted by species of genera Spartocytisus, Adenocar- pus, Pterocephalus, Echium etc. and the lychen Gri- minia.

Alize tradewinds forests Type (SA). Found in Gran Canaria, Tenerife, La Gomera, and El Hierro and loca-

Document info
Document views83
Page views89
Page last viewedMon Jan 23 05:02:02 UTC 2017