Memorias de la RSEHN (segunda época)

Se analizan las causas fitogeográficas de la diversidad de los paisajes vegetales españoles y su modelado espacial resaltando seis ejes o factores como principales responsables de la misma (latitud, continentalidad, atlanticidad/mediterraneidad, altitud, factores ambientales locales e influencia antrópica).

Un análisis basado en la sistemática fitosociológica permite una aproximación cuantitativa a la diversidad de la vegetación española y una valoración de los tipos que concentran mayor riqueza.

Se presenta una clasificación geobotánica ecofisonómica de los sistemas naturales españoles diferenciando entre tipos zonales y azonales. Los sistemas zonales se han agrupado de acuerdo con su estructura en sistemas forestales, sistemas supraforestales propios de la alta montaña (“supratimberline”) y sistemas hiperxerófilos subdesérticos. Esta aproximación se completa con una tipificación de las principales etapas dinámicas de sustitución de los bosques (formaciones arbustivas, matorrales y pastizales). Las clasificaciones se presentan en forma de tablas y en ellas se aporta una referencia a la sistemática fitosociológica, correlacionada de forma prioritaria con la clasificación geobotánica ecofisonómica.

The great diversity of the Spanish Vegetation is acknowledged by botanist since the 19th Century. One of the main reasons to explain this great diversity of “plant landscapes” is the richness of the Spanish Flora. As a consequence of both, the geographical position of the Spanish territories and their great diversity of habitats, Spain has historically had an extraordinary capacity to receive taxa from different Floras. The great heterogeneity of the Spanish territories provides multiple feasible and lasting combinations from an extremely rich Flora. Other factors affecting the diversity of the Spanish plant landscapes are the complexity of the Spanish geomorphology and lithologies and its varied climatology. Moreover, on the one hand, the Iberian Peninsula is placed at the south-western border of the European continent, in a transitional area between the Circumboreal and the Mediterranean Regions. On the other hand, the Canary Islands belong to the Macaronesian Region with important relict plant landscapes from the Tertiary Era, which are quite different to the Mediterranean ones.

Thus the causes of the diversity of the Spanish plant landscapes are shown. Six axis or factors are the main responsible: latitude, continentality, Atlantic/Mediterranean influences, altitude, local environmental factors and antrophic influence.

From the analysis of the phytosociological classification of the Spanish vegetation a quantitative approximation of the diversity of the Spanish plant communities can be obtained. The azonal communities are the most diverse ones (close to one half of the total diversity, 47%). They are followed by scrubland and grassland communities (30% of the total). These are considered as substitution stages of the climacic forests, which only count 20% of the total diversity.

An ecophysiognomic geobotanic classification of the Spanish “natural systems” (sistemas naturales) is shown differentiating between zonal and azonal types. The formers are grouped in forestall systems, high mountain systems (“supra-timberline” systems) and hyper-xeric sub-desert systems. This classification is completed with the forests substitution stages (bushes and grasses). Everything is shown in tables with a reference to the phytosociological classification.