DROUGHT SENSITIVITY OF CASTANEA SATIVA: CASE STUDY OF SUMMER 2003 IN THE SOUTHERN ALPS

Abstract

The post-cultural dynamics of abandoned chestnut stands and diseases, such as chestnut blight and ink-disease, have been recognized as major drivers of the natural withdrawal of the chestnut tree. Climate warming causing drought might interact with these dynamics and accelerate the disappearing of the chestnut tree from former cultivated sites. The summer of 2003 was by far the hottest on record in Switzerland. Several chestnut stands were damaged by a combination of the heat and a significant precipitation shortfall in the Southern Alps. Between August and October 2003, these areas were mapped and examined for possible correlations with the geomorphologic site conditions. As expected, the drought and heat especially impacted stands in unfavourable settings with shallow soil and on forest edges. Forest edge effects seem to be even more relevant as the exposure. Although damage remained within limits, the 2003 summer drought showed that Castanea sativa does not have an effective mechanism to protect itself against over-transpiration in extremely hot and dry weather. This may raise new questions about the ecological plasticity of the chestnut tree in view of possible climate changes.