Estimating Productivity, Detecting Biotic Disturbances, and Assessing the Health State of Traditional Olive Groves, Using Nondestructive Phenotypic Techniques

Abstract

Conservation of traditional olive groves through effective monitoring of their health state is crucial both at a tree and at a population level. In this study, we introduce a comprehensive methodological framework for estimating the traditional olive grove health state, by considering the fundamental phenotypic, spectral, and thermal traits of the olive trees. We obtained phenotypic information from olive trees on the Greek island of Lesvos by combining this with in situ measurement of spectral reflectance and thermal indices to investigate the effect of the olive tree traits on productivity, the presence of the olive leaf spot disease (OLS), and olive tree classification based on their health state. In this context, we identified a suite of important features, derived from linear and logistic regression models, which can explain productivity and accurately evaluate infected and noninfected trees. The results indicated that either specific traits or combinations of them are statistically significant predictors of productivity, while the occurrence of OLS symptoms can be identified by both the olives’ vitality traits and by the thermal variables. Finally, the classification of olive trees into different health states possibly offers significant information to explain traditional olive grove dynamics for their sustainable management.

An (Un)Expected Threat for a Regionally Near-Threatened Species: A Predation Case of a Persian Squirrel on an Insular Ecosystem

“…The island's climate is typical Mediterranean, characterized by cool-moist winters and warm-dry summers [29]. Lesvos, a hilly island with a maximum altitude of 968 m, encompasses a variety of different habitat types, including extensive areas of Coniferous and Broadleaved forests mainly in the central part, traditional olive groves and grazing land in the eastern and southern part [30], while in its western and northern parts the island consists of shrubby vegetation and phrygana (Figure 1). Due to its vicinity to Asia Minor, the island's diversity is influenced from the east, and thus, hosts a high number of biota, including the Persian squirrel.…”

“…mainly in the central part, traditional olive groves and grazing land in the eastern and southern part [30], while in its western and northern parts the island consists of shrubby vegetation and phrygana (Figure 1). Due to its vicinity to Asia Minor, the island's diversity is influenced from the east, and thus, hosts a high number of biota, including the Persian squirrel.…”

Linking Thermal Indices, Productivity, Phenotypic Traits, and Stressors for Assessing the Health of Centennial Traditional Olive Trees

“…On the one hand, these anomalies within the tree's structure give rise to a diverse array of microhabitats, offering refuge to numerous species [7,13,40] and thus play a pivotal role in supporting biodiversity [41,42]. On the other hand, the emergence of cavities and deteriorating wood poses challenges to the olive tree's health [43][44][45] and productivity as it matures [46]. Such challenges have the potential to impede nutrient and water transport within the tree [47][48][49], consequently affecting its productivity, fruit yield, and overall vigor [50,51].…”

“…Among these non-invasive techniques, infrared thermography (IRT), a subset of remote sensing techniques [77][78][79], plays a pivotal role in evaluating tree physiology, facilitating early detection of stress factors [80,81] and precise interventions to ensure tree health [82,83] and productivity [46]. IRT captures temperature variations across different structures of the tree, including the canopy and trunk, providing valuable insights for identifying early signs of physiological stress stemming from factors like water deficiency [84][85][86][87] or diseases [88].…”

Estimation of Characteristic Parameters of Grape Clusters Based on Point Cloud Data

“…Weight, size, and volume are important phenotypic parameters. They can be used not only as an indicator of plant growth vigor but also as a parameter for estimating traits (Wang and Chen, 2020a ; Zevgolis et al, 2021 ). Table grapes are plants with variable spatial structures and complex geometric shapes.…”