Special Issue "Advances in Forest Ecophysiology: Stress Response and Ecophysiological Indicators of Tree Vitality"

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Plant Response to Abiotic Stress and Climate Change".

Deadline for manuscript submissions: 31 October 2022 | Viewed by 4301

Special Issue Editor

Dr. Nenad Potočić
E-Mail Website
Guest Editor
Croatian Forest Research Institute, Division of Forest Ecology, Cvjetno naselje 41, 10450 Jastrebarsko, Croatia
Interests: tree mineral nutrition; crown condition and foliar injury; biochemical stress indicators

Special Issue Information

Dear Colleagues,

The changing climate and air pollution are among the greatest threats to the health and functioning of forest ecosystems, jeopardizing their ecological and economic functions and services. The impact of increasing temperatures and extreme weather events (droughts, storms, and temperature and precipitation extremes) on the vitality of forest trees is often difficult to separate from the impact of nitrogen deposition, tropospheric ozone, or heavy metals, as they can exhibit synergistic effects. For example, forest soil acidification, atmospheric N deposition, and climate change are all partly responsible for the continuous decrease in foliar P concentrations in Europe, causing reduced tree growth.

A better understanding of physiological processes influencing tree vitality under the changing climate and air pollution pressures requires considerable research efforts and constant advancements in research methods and approaches.

The use of indicators is elementary in modern forest ecophysiology research, as it enables us to effectively measure the stress response of trees and helps us estimate the level of damage to trees and forest ecosystems.

For this Special Issue, we welcome original research papers dealing with ecophysiological indicators of the response of forest trees to environmental stress. Examples of such indicators are photosynthetic activity and other biochemical stress indicators, nutrients in different tree compartments, leaf loss, tree growth and tree mortality, visible symptoms of stress in foliage, and microscopical markers of stress. We also welcome reviews of recent advances in forest ecophysiology.

Please note that due to increased interest, the decision was made to prolong the submission deadline for this Special Issue. We are now looking forward to receive your manuscripts until the 31st October 2022.

Dr. Nenad Potočić
Guest Editor

Manuscript Submission Information

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Keywords

  • climate change
  • air pollution
  • dieback
  • leaf injury
  • growth
  • water and nutrient uptake
  • photosynthesis
  • oxidative stress

Published Papers (6 papers)

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Research

Article
Do Different Tree-Ring Proxies Contain Different Temperature Signals? A Case Study of Norway Spruce (Picea abies (L.) Karst) in the Eastern Carpathians
Plants 2022, 11(18), 2428; https://doi.org/10.3390/plants11182428 - 17 Sep 2022
Viewed by 241
Abstract
One of the most important proxy archives for past climate variation is tree rings. Tree-ring parameters offer valuable knowledge regarding how trees respond and adapt to environmental changes. Trees encode all environmental changes in different tree-ring parameters. In this study, we analyzed how [...] Read more.
One of the most important proxy archives for past climate variation is tree rings. Tree-ring parameters offer valuable knowledge regarding how trees respond and adapt to environmental changes. Trees encode all environmental changes in different tree-ring parameters. In this study, we analyzed how air temperature is encoded in different Norway spruce tree-ring proxies along an altitude gradient in an intramountain valley of the Carpathians. The study area, in the Gheorgheni region, Romania (Eastern Carpathians), has a mountain climate with a frequent temperature inversion in winter. The climate–growth relationship was analyzed for two contrasting altitudes: low elevation, i.e., below 1000 m a.s.l., and high elevation, i.e., above 1500 m a.s.l. Two local weather stations, one in the valley and the other on the upper part of the mountains, provide daily temperatures (Joseni—750 m a.s.l. and Bucin—1282 m a.s.l.). The bootstrap Pearson correlation between cumulative daily temperature data and three tree-ring proxies (tree-ring width—TRW, basal area increment—BAI, and blue intensity—BI) was computed for each series. The results show that elevation modulates the climate response pattern in the case of BI, and remains relatively similar for TRW and BAI. The winter temperature’s positive influence on spruce growth was observed in both TRW and BAI chronologies. Additionally, the BAI chronology highlights a positive relationship with summer temperature. The highest correlation coefficient (r = 0.551, p < 0.05, n = 41) was recorded between BI residual chronology from high elevation series and summer/autumn temperature from the upper-part weather station for a cumulative period of 59 days (the second half of August to the beginning of October). Our results show that, for this intramountain valley of the Eastern Carpathians, different tree-ring proxies capture different climate signals. Full article
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Article
Visible Foliar Injury and Ecophysiological Responses to Ozone and Drought in Oak Seedlings
Plants 2022, 11(14), 1836; https://doi.org/10.3390/plants11141836 - 13 Jul 2022
Viewed by 554
Abstract
To verify the responses of visible foliar injury (VFI), we exposed seedlings of three oak species for 4.5 months in an open air facility, using differing ozone (O3) and drought treatments: O3 (three levels from ambient to ×1.4 ambient), and [...] Read more.
To verify the responses of visible foliar injury (VFI), we exposed seedlings of three oak species for 4.5 months in an open air facility, using differing ozone (O3) and drought treatments: O3 (three levels from ambient to ×1.4 ambient), and drought (three levels of irrigation from 40% to 100% field capacity). We related the accumulated phytotoxic O3 dose (POD1) and cumulative drought index (CDI) to the O3 and drought VFI and assessed growth increment (height, diameter, leaf number), biomass (of all organs), and physiological parameters: net photosynthesis per plant (Pn), photosynthetic nitrogen (PNUE) and phosphorus use efficiency (PPUE)). The results indicated that an increase in POD1 promoted O3 VFI in Quercus robur and Quercus pubescens, while Quercus ilex was asymptomatic. The POD1-based critical level at the onset of O3 VFI was lower for Q. robur than for Q. pubescens (12.2 vs. 15.6 mmol m−2 POD1). Interestingly, drought reduced O3 VFI in Q. robur but increased it in Q. pubescens. Both O3 and drought were detrimental to the plant biomass. However, Q. robur and Q. pubescens invested more in shoots than in roots, while Q. ilex invested more in roots, which might be related to a hormetic mechanism. Pn, PNUE and PPUE decreased in all species under drought, and only in the sensitive Q. robur (PPUE) and Q. pubescens (PNUE) under O3. This study confirms that POD1 is a good indicator to explain the development of O3 VFI and helps a differential diagnosis of co-occurring drought and O3 VFI in oak forests. Full article
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Article
Species-Level Differences in Osmoprotectants and Antioxidants Contribute to Stress Tolerance of Quercus robur L., and Q. cerris L. Seedlings under Water Deficit and High Temperatures
Plants 2022, 11(13), 1744; https://doi.org/10.3390/plants11131744 - 30 Jun 2022
Viewed by 406
Abstract
The general aim of this work was to compare the leaf-level responses of different protective components to water deficit and high temperatures in Quercus cerris L. and Quercus robur L. Several biochemical components of the osmotic adjustment and antioxidant system were investigated together [...] Read more.
The general aim of this work was to compare the leaf-level responses of different protective components to water deficit and high temperatures in Quercus cerris L. and Quercus robur L. Several biochemical components of the osmotic adjustment and antioxidant system were investigated together with changes in hormones. Q. cerris and Q. robur seedlings responded to water deficit and high temperatures by: (1) activating a different pattern of osmoregulation and antioxidant mechanisms depending on the species and on the nature of the stress; (2) upregulating the synthesis of a newly-explored osmoprotectant, dimethylsulphoniopropionate (DMSP); (3) trading-off between metabolites; and (4) modulating hormone levels. Under water deficit, Q. cerris had a higher antioxidant capacity compared to Q. robur, which showed a lower investment in the antioxidant system. In both species, exposure to high temperatures induced a strong osmoregulation capacity that appeared largely conferred by DMSP in Q. cerris and by glycine betaine in Q. robur. Collectively, the more stress-responsive compounds in each species were those present at a significant basal level in non-stress conditions. Our results were discussed in terms of pre-adaptation and stress-induced metabolic patterns as related to species-specific stress tolerance features. Full article
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Article
Effects of Climate on Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) Growth Southeast of the European Alps
Plants 2022, 11(12), 1571; https://doi.org/10.3390/plants11121571 - 14 Jun 2022
Viewed by 482
Abstract
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is a non-native tree species in Slovenia with the potential to partially replace Norway spruce in our native forests. Compared to spruce, it has several advantages in terms of volume growth, wood quality and tolerance to drought. [...] Read more.
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is a non-native tree species in Slovenia with the potential to partially replace Norway spruce in our native forests. Compared to spruce, it has several advantages in terms of volume growth, wood quality and tolerance to drought. This is important given the changing climate in which spruce is confronted with serious problems caused by increasing temperatures and drought stress. At three sites (one on non-carbonate bedrock and deep soils, and two on limestone with soil layers of varying depths), 20 Douglas-fir and 20 spruce per site were sampled in order to compare their radial growth response to climate and drought events. The radial growth of Douglas-fir exceeds that of spruce by about 20% on comparable sites. It is more responsive to climate than spruce. Above-average temperatures in February and March have a significant positive effect on the radial growth of Douglas-fir. In recent decades, above-average summer precipitation has also had a positive influence on the radial growth of Douglas-fir. Compared to spruce, Douglas-fir is less sensitive to extreme drought events. Our results indicate that Douglas-fir may be a good substitute for spruce in semi-natural managed forest stands in Slovenia. The planting of Douglas-fir should be allowed in Slovenian forests, but the proportion of it in forest stands should be kept lower than is the case with spruce today. Full article
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Article
Impact of an Extremely Dry Period on Tree Defoliation and Tree Mortality in Serbia
Plants 2022, 11(10), 1286; https://doi.org/10.3390/plants11101286 - 11 May 2022
Viewed by 540
Abstract
This paper presents research results on forest decline in Serbia. The results were obtained through monitoring defoliation of 34 tree species at 130 sample plots during the period from 2004 to 2018. This research aimed to determine whether the occurrence of defoliation and [...] Read more.
This paper presents research results on forest decline in Serbia. The results were obtained through monitoring defoliation of 34 tree species at 130 sample plots during the period from 2004 to 2018. This research aimed to determine whether the occurrence of defoliation and tree mortality were caused by drought. Defoliation was assessed in 5% steps according to the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) methodology. All the trees recorded as dead were singled out, and annual mortality rates were calculated. To determine changes in air temperature and precipitation regimes during the study period, we processed and analysed climatic data related to air temperature and precipitation throughout the year and in the growing season at 28 main weather stations in Serbia. Tree mortality patterns were established by classifying trees into three groups. The first group of trees exhibited a gradual increase in defoliation during the last few years of monitoring, with dying as the final outcome. The second group was characterised by sudden death of trees. The third group of trees reached a higher degree of defoliation immediately after the first monitoring year, and the trees died after several years. Tree mortality rates were compared between years using the Standardised Precipitation Evaporation Index (SPI) and the Standardised Precipitation Evapotranspiration Index (SPEI), the most common methods used to monitor drought. The most intensive forest decline was recorded during the period from 2013 to 2016, when the largest percentage of the total number of all trees died. According to the annual mortality rates calculated for the three observation periods (2004–2008, 2009–2013, and 2014–2018) the highest forest decline rate was recorded in the period from 2014 to 2018, with no statistically significant difference between broadleaved and coniferous tree species. As the sample of coniferous species was small, the number of sample plots should be increased in order to achieve better systematic forest condition monitoring in Serbia. The analysis of the relationship between defoliation and climatic parameters proved the correlation between them. It was noted that the forest decline in Serbia was preceded by an extremely dry period with high temperatures from 2011 to 2013, supporting the hypothesis that it was caused by drought. We therefore conclude that these unfavourable climatic conditions had serious and long-term consequences on forest ecosystems in Serbia. Full article
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Article
Defoliation Change of European Beech (Fagus sylvatica L.) Depends on Previous Year Drought
Plants 2022, 11(6), 730; https://doi.org/10.3390/plants11060730 - 09 Mar 2022
Cited by 2 | Viewed by 759
Abstract
European beech (Fagus sylvatica L.) forests provide multiple essential ecosystem goods and services. The projected climatic conditions for the current century will significantly affect the vitality of European beech. The expected impact of climate change on forest ecosystems will be potentially stronger [...] Read more.
European beech (Fagus sylvatica L.) forests provide multiple essential ecosystem goods and services. The projected climatic conditions for the current century will significantly affect the vitality of European beech. The expected impact of climate change on forest ecosystems will be potentially stronger in southeast Europe than on the rest of the continent. Therefore, our aim was to use the long-term monitoring data of crown vitality indicators in Croatia to identify long-term trends, and to investigate the influence of current and previous year climate conditions and available site factors using defoliation (DEF) and defoliation change (ΔDEF) as response variables. The results reveal an increasing trend of DEF during the study period from 1996 to 2017. In contrast, no significant trend in annual ΔDEF was observed. The applied linear mixed effects models indicate a very strong influence of previous year drought on ΔDEF, while climate conditions have a weak or insignificant effect on DEF. The results suggest that site factors explain 25 to 30% DEF variance, while similar values of conditional and marginal R2 show a uniform influence of drought on ΔDEF. These results suggest that DEF represents the accumulated impact of location-specific stressful environmental conditions on tree vitality, while ΔDEF reflects intense stress and represents the current or recent status of tree vitality that could be more appropriate for analysing the effect of climate conditions on forest trees. Full article
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Metal- and Organ-Specific Tolerance to Heavy Metal Induced Stress Is Mediated by Antioxidant Enzyme’s Activities, Proline, Polyamine, and Plant Hormones Levels in Poplar Species
Authors: Marko Kebert 1; Saša Orlović1; Vanja Vuksanović 2; Saša Kostić 1; Biljana Kiprovski 3; Martina Zorić 1; Francesca Rapparini 4; Luisa Neri 4; Stefania Biondi 5
Affiliation: 1 Institute of Lowland Forestry and Environment, University of Novi Sad, Serbia; 2 Faculty of Agriculture, University of Novi Sad, Serbia; 3 Institute of Field and Vegetable Crops, Novi Sad, Serbia; 4 Bioeconomy Institute (IBE), Department of Bio-Agrifood Science (DiSBA), National Research Council (CNR), Italy; 5 Department of Biological, Geological, and Environmental Sciences (BiGeA), University of Bologna, Italy
Abstract: Beside anthropogenic factor, by causing altered precipitation patterns, climate change will indirectly affect the increase of heavy metals in soils due to hydrological effects and enhanced leaching (i.e. Cd and Ni), especially in the vicinity of mines and smelters. Phytoextraction as a well-known, powerful “green” technique for environmental clean-up that is using plants to extract, sequester and/or detoxify heavy metals, significantly contributes to removing these persistent inorganic pollutants from soils. Poplar species due to its fast growth features, high transpiration rate, large biomass, feasible reproduction present great candidate to be used in phytoextraction technology but the consequences of concomitant oxidative stress upon plant metabolism and the mechanism of the poplars’ tolerance to heavy metal induced stress are not completely understood so far. In this study, cuttings of poplar species (Populus deltoides) were exposed to two different concentrations (maximum allowed amount (MAA) for soil and tripled MAA according to National legislation) of two heavy metals (Cd2+ and Ni2+) that were separately applied to the soil to estimate effects of heavy metal upon accumulation of free and conjugated polyamines, plant hormones (abscisic acid-ABA and indole-3-acetic acid-IAA) and proline as well as activities of different enzyme’s activities at root and leaf levels. By using selected ion monitoring (SIM) mode of gas chromatography with mass spectrometry (GC/MS) coupled with isotopically labelled technique, amounts of ABA and IAA were quantified, while polyamine amounts were determined by using high performance liquid chromatography with fluorometric detection after derivatization with dansyl-chlorid. Obtained results showed that poplar species responded to elevated concentration of heavy metals in soils by exhibiting metal- and organ-specific tolerance. Knowledge about tolerance mechanism is of great importance for the development of phytoremediation technology and afforestation programs for polluted soils.

Title: Crown Defoliation and Radial Increment among Decayed and Undecayed Norway Spruce Trees
Authors: Povilas Žemaitis; Emilis Armoška
Affiliation: Lithuanian Research Centre for Agriculture and Forestry, Instituto al. 1, Akademija, LT-58344 Kėdainiai distr., Lithuania
Abstract: Heterobasidion annosum (Fr.) Bref. is a major root and butt rot causing fungal pathogen, responsible for widespread economic and ecological damage within the natural distribution of Norway spruce (Picea abies (L.) Karst) in Europe. Though butt rot causes tree decline, the exact degree to which H. annosum interacts with vitality indicators like tree crown condition and tree radial increment is still unclear. To shine light on the interaction between butt rot and crown defoliation, radial increment as indicators of vitality, assessment among decayed and undecayed Norway spruce trees within twenty Norway spruce stands was performed. This study showed that butt rot causes Norway spruce vitality decline expressed as reduction in radial increment and increased crown defoliation. Decayed trees showed a radial increment reduction of 8.7 and 10.9 percentage points over the last five-year and last twenty-year period prior to the assessment compared to undecayed trees. Also, decayed trees had 8.5 pp higher crown defoliation compared with undecayed trees. Undecayed trees show a stand age dependent defoliation relationship – defoliation increased with increasing stand age; however, decayed trees do not show a stand age dependent defoliation relationship, indicating changes in the effect-response framework for decayed trees.

Title: How Does Mistletoe Drive the Host’s Growth, Storage, and Water Use Efficiency? Response of the Scots Pine Growing in Mesotrophic Conditions
Authors: Radosław Jagiełło 1; Janusz Olejnik 2; Marek Urbaniak 2; Kaludia Ziembińska 2; Paweł Szmyt 1; Henrik Hartmann 3
Affiliation: 1 Faculty of Forestry an Wood Technology, Poznań University of Life Sciences; 2 Faculty of Environmental and Mechanical Engineering, Poznań University of Life Sciences; 3 Max Planck Institute for Biogeochemistry
Abstract: Hemiparasitic xylem-typing pine mistletoe attracts considerable interest because it spreads rapidly across Europe. Droughts, generally regarded as the primary cause of tree decline, are heightened under the additional impact of hemiparasite exacerbating problems with hydraulics and nutrition. This work aims to contribute to our knowledge of host growth, storage and water relations in response to mistletoe infestation. Thus we determined growth dynamics, concentration of non-structural carbohydrates and carbon isotope ratio (δ13C) in tree rings to estimate ecophysiological parameters related to tree vitality. We observed a sharp difference in growth between mistletoe-infested and healthy trees. We observed significantly higher levels of starch in the outermost rings of infested trees. No noteworthy differences were found for intrinsic water-use efficiency (iWUE). Although, there has been an apparent increasing trend of iWUE over the last fifteen years, indicating general water limitation to pine trees in the studied region. We indicated that downregulation in growth is a stress indicator of great importance. Our findings suggest that while grappling with water and nutrients leak, trees may prioritise carbon allocation to storage and keep stable iWUE or cannot use stored energy to grow due to water and nutrient limitations.

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