Are Foliar Nutrition Status and Indicators of Oxidative Stress Associated with Tree Defoliation of Four Mediterranean Forest Species?

Abstract

Mediterranean forest ecosystems in Croatia are of very high significance because of the ecological functions they provide. This region is highly sensitive to abiotic stresses such as air pollution, high sunlight, and high temperatures alongside dry periods; therefore, it is important to monitor the state of these forest ecosystems and how they respond to these stresses. This study was conducted on trees in situ and focused on the four most important forest species in the Mediterranean region in Croatia: pubescent oak (Quercus pubescens Willd.), holm oak (Quercus ilex L.), Aleppo pine (Pinus halepensis Mill.) and black pine (Pinus nigra J. F. Arnold.). Trees were selected and divided into two groups: trees with defoliation of >25% (defoliated) and trees with defoliation of ≤25% (undefoliated). Leaves and needles were collected from selected trees. Differences in chlorophyll content, hydrogen peroxide content, lipid peroxidation and enzyme activity (superoxide dismutase, catalase, ascorbate peroxidase, non-specific peroxidase), and nutrient content between the defoliated and undefoliated trees of the examined species were determined. The results showed that there were significant differences for all species between the defoliated and undefoliated trees for at least one of the examined parameters. A principal component analysis showed that the enzyme ascorbate peroxidase can be an indicator of oxidative stress caused by ozone. By using oxidative stress indicators, it is possible to determine whether the trees are under stress even before visual damage occurs.

Grape Skin Composting Process to Recycle Food Waste: Kinetics and Optimization

“…Total carbon and nitrogen content were determined by an elemental analyzer with a spectrophotometer (LaboMed UV-VIS, Los Angeles, CA, USA) according to the method described by Lovreškov et al [ 44 ]. Measurements were performed with three repetitions, and the results are presented as the mean value ± standard deviation.…”

Application of Multivariate Regression and Artificial Neural Network Modelling for Prediction of Physicochemical Properties of Grape-Skin Compost

“…Total carbon and nitrogen were determined using an elemental analyser CNS 2000 (Leco, St Joseph, MI, USA) and a spectrophotometer (LaboMed UV-VIS, Los Angeles, CA, USA) [ 31 ].…”

Compensatory Growth and Physiological Protective Mechanisms of Populus talassica Kom. × Populus euphratica Oliv. in Response to Leaf Damage

“…For example, after mechanical damage to the hybrid poplar, which generated the accumulation of H 2 O 2 content in unwounded leaves and the significant enhancement of CAT and SOD activities, the two enzymes reached their peak at different times [52]. Under the conditions of less than 25% and more than 25% of fallen leaves, there was a significant difference in CAT, SOD, and POD of Pinus nigra, while only CAT activity showed a significant in Quercus pubescens and Pinus halepensis [53]. This trend is the same as that of the enzymatic activity induced by pine caterpillar feeding.…”