Autoecology of sweet-chestnut stands in Castile (Spain)

In this paper, we have established the physiographic, climatic and soil optimum and marginal habitat parameters of Castanea sativa stands in the regions of Castilla y León, Castilla-La Mancha and Madrid (Spain). Chestnut stands are usually located between 620 m and 1100 m elevation showing a wide range of variation in their rainfall, in contrast to the narrow range of temperature variation. The soils of the chestnut stands studied are mainly Cambisols, Luvisols and Umbrisols, generally highly acid, loamy or sandy-loamy and having a low C/N ratio. We have also established the interpretation criteria for ranges of the marginal habitats in relation to the optimum ones, in order to evaluate the chances of risk if the introduction of this species was carried out in an area such as the one considered in our study. Thus, the greater risk/danger would be encountered on soils whose autumn rainfall parameters are lower than 220 mm, fine earth below 16,7 %, lime lower than 20.4 %, water holding capacity lower than 38 mm, top soil organic matter lower than 2.1 %, temperature oscillations over 18.5ºC and permeability higher than 4,7. The silvicultural parameter which best describes the forestry characteristics of the Castilian chestnut stands in relation to the biotope evaluation parameters is Hart's index per number of stools, which can be satisfactorily estimated by considering slope, winter rainfall, surpluses and soil permeability