Early detection of cork oak decline in Mediterranean forests using TreeTalker®Cyber physiological monitoring

Mediterranean cork oak forests are increasingly threatened by abiotic and biotic stressors, with Phytophthora emerging as a major cause of tree decline. This study presents preliminary results from an ongoing monitoring experiment aimed at investigating the effects of Phytophthora infection on hydraulic functioning and growth dynamics of cork oak (Quercus suber L.) in a stand located in central Sardinia (Italy). Two experimental theses were considered: healthy trees and declining trees affected by Phytophthora.

Ten trees were continuously monitored starting from May 2025 using TreeTalker®Cyber devices (five per thesis) to measure sap flow velocity, stem radial growth, and microclimatic variables, including air temperature, relative humidity, and vapour pressure deficit (VPD). High-frequency physiological data were integrated with atmospheric conditions to assess differences in tree water use and growth performance between the two theses.

Preliminary results showed a substantial reduction in sap flow magnitude and altered diurnal patterns in declining trees compared to healthy individuals. In addition, declining trees exhibited a pronounced reduction in stem radial growth compared to healthy individuals, indicating a combined impairment of hydraulic functioning and growth processes associated with Phytophthora infection. These findings demonstrate the potential of IoT-based proximal sensing for detecting early physiological signals of tree decline and support its application in forest health monitoring.