Search

Partial and preliminary results obtained from a Spanish forest formation dynamics study are presented in this paper. Seven land squares located in different land classes and selected according to a fitoclimatological gradient (Allue, 1990), have been diacronically analyzed using aerial photointerpretation and spatial analysis with G.I.S. techniques. As an overall trend, polarization in forest pattern evolution has been detected: Fragmentation and diversification have occurred in coastal and/or periurban areas, and homogenization and extensification have occurred in inner and remote areas., En este artículo se presentan resultados parciales obtenidos en un estudio sobre la dinámica de las formaciones forestales de la España mediterránea. Siete cuadrículas de 14 Km2 situadas en clases territoriales representativas de todo el espectro de subtipos fitoclimáticos de Allue (1990), se han estudiado mediante la interpretación diacrónica de fotogramas aéreos, integración y análisis espacial en sistemas de información geográfica. Del análisis de los resultados se concluye que se ha producido una clara polarización en la dinámica evolutiva de las formaciones forestales, con fragmentación y diversificación en las zonas litorales y/o próximas a núcleos urbanos, y homogeneización con extensificación en las más interiores y alejadas de las zonas urbanas, todo ello con independencia de la esencia fitoclimática de las zonas analizadas.

A nation-wide Land Classification of Spain useful for renewable resources assessment, inventory and research, has been developed at INIA after several successful experiences carried out at regional level. The construction of this classification mainly aimed to provide a land model based on physical factors with undoubted forestry significance that are nonchanging at human life span. Because of the size of Spain (504.750 km2), its ecological diversity and available cartographic information, we had to design an original land classification method showing he following features: a) Divisive hierarchical multifactor framework in four progressive phases with increasing resolution power (25, 4, 1 and 0,25 km2 sample size) ad source map scale (1/400.000, 1/200.000, 1/50.000 and 1/10.000), and decreasing land coverage in accordance with land variability. b) Climatic, geological, and physiographic attributes actively used in land classes definition process, and biological, current land use, soil or remote sensing information passively used as land classes test. c) Twinspan multivariate analysis applied in order (1) to detect the main existing multifactor gradient (2) to arrange and classify the sample squares (3) to identify squares throughout the analysed land using a reduced number of indicator attributes. In the first phase, an ecoregionalization process took place, and eight main ecoregions were defined and delimited by means of 570 sample squares of 25-km2 size, characterized by 174 climatic, geological, and physiographic attributes. The resulting ecoregions showed highly significant correlation with phytosciological taxa distribution. The second phase has been developed separately for each ecoregion. After its completion, 252 Land Classes have been defined using a systematically selected sample of 5450 squares of 4 km2. Afterwards, 125000 squares have been identified and all the Spanish Land Classes were mapped and forestry characterized by means of an ARC-INFO Geographical Information System. The obtained framework can be used in different scale forest studies. At present, it has been successfully used in studies on native and nonnative forests (Pinus nigra plantations, Quercus suber woodlots, etc.). Important ecological and silvicultural features have appeared highly dependent on the Land Classification. As a consequence, land suitability maps for different forestry purposes have been designed., En este trabajo se presenta una Clasificación Territorial de España, basada en la consideración conjunta e integrada de aquellos factores ecológicos de carácter físico que tienen indudable significación forestal y que son relativamente constantes a escala de la vida humana. Dado el tamaño, la diversidad ecológica y la cartografía disponible, se ha diseñado un método original de Clasificación Territorial. La estructura de clasificación obtenida en su aplicación a España puede ser usada en estudios forestales con distintas escalas de trabajo. Hasta el momento ha sido utilizada con éxito en estudios de bosques de especies tanto autóctonas como exóticas (Quercus suber, Pinus nigra). Tras estas aplicaciones, se ha puesto en evidencia la dependencia de importantes aspectos ecológicos y selvícolas respecto de la clasificación. En consecuencia, han sido diseñados mapas de idoneidad territorial para distintos propósitos forestales.