_applied sciences_  
_Article_  
**Linking Thermal Indices, Productivity, Phenotypic Traits, and Stressors for Assessing the Health of Centennial Traditional Olive Trees**  
[PERSON] 1,*(c), [PERSON] 1, [PERSON] 2 and [PERSON] 1(c)  
1 Biodiversity Conservation Laboratory, Department of Environment, University of the Aegean,  
81132 Mytilene, Greece; [EMAIL_ADDRESS] (A.K.); [EMAIL_ADDRESS] (P.G.D.)  
2 Department of Zoology and Marine Biology, Faculty of Biology, National and Kapodistrian University of Athens, 15772 Athens, Greece; [EMAIL_ADDRESS]  
Correspondence: [EMAIL_ADDRESS]  
**Featured Application: Integrating infrared thermography with olive tree traits and their stressors enhances centennial olive tree monitoring and management in Mediterranean traditional agroecosystems.**  
**Abstract: Centennial olive trees, integral components of traditional Mediterranean agroecosystems, hold immense value as repositories of biodiversity and cultural heritage due to their physiological attributes and life history, making them crucial for the conservation of High Nature Value ancient olive orchards. However, they are increasingly confronted with physiological challenges exacerbated by various biotic and abiotic stressors jeopardizing their health and productivity, underscoring the urgency for ongoing monitoring and conservation measures to secure their long-term existence. To monitor these challenges, in recent years, the adoption of non-invasive techniques like infrared thermography (IRT) has become prevalent. In this study, we aimed to comprehensively assess the health state of traditional centennial olive trees, with a particular focus on their productivity. To achieve this, we monitored 44 centennial olive trees from a traditional olive grove on the island of Navos, Greece, a representative location for Mediterranean olive groves, during the period from 2017 to 2020. We established connections between a set of trunk and canopy thermal and humidity indices, phenotypic traits, and the two most prevalent stressors affecting olive trees not only within the context of the island but also more broadly in similar Mediterranean environments worldwide: the olive leaf spot disease (OLS) and crop water stress, assessed through the crop water stress index (CWSI). To evaluate their interrelationships, we initially assessed intraspecific thermal and humidity pattern variations, and we developed linear and logistic regression models to gain insights into the factors influencing olive tree productivity, water stress, and the OLS presence. Results indicated that combining thermal and humidity indices can substantially explain olive tree productivity, water stress, and OLS, providing a valuable tool for assessing and monitoring the health and overall state of centennial olive trees, while offering a comprehensive approach to understanding the complex interactions shaping traditional olive grove dynamics. By identifying key indicators such as tree thermal patterns and water stress levels, olive growers and conservations can make informed decisions to enhance the vitality and longevity of these culturally and ecologically significant trees.**  
**Keywords: traditional olive groves; infrared thermography; trunk thermal indices; canopy thermal indices; crop water stress index; olive leaf spot disease; Navos**