Birch sap extraction and short-term physiological responses in Betula celtiberica forests of north-western Spain

Introduction In recent years, birch sap has gained attention due to its applications in different sectors. However, the ecological impact of sap extraction and its implications for ecosystem sustainability remain insufficiently explored. This study focuses on the sustainable management of Betula celtiberica sap extraction in the Reserva de la Biosfera de los Valles de Omaña y Luna (RBVOyL). Methods The effects of sap extraction on tree physiology were assessed by measuring water potential and chlorophyll fluorescence. In parallel, the biochemical composition of the sap was analyzed to characterize its biocompounds and evaluate their potential commercial uses. Practices for sustainable and responsible sap collection were also considered. Results Sap extraction did not produce negative effects on tree physiological status, as neither water potential nor chlorophyll fluorescence showed adverse responses 1 month after extraction. In addition, the volume of sap obtained and the concentrations of biocompounds detected support its potential use as a food and cosmetic resource. Discussion Birch sap could represent a viable, sustainable and natural product for small-scale production in the study region, contributing to the diversification of local economic activities. Nevertheless, further research is required to assess the long-term effects of sap extraction and its broader potential as a forest resource.