Physiological significance of forest tree defoliation: Results from a survey in a mixed forest in Tuscany (central Italy)

Pollastrini, Martina; Feducci, Matteo; Bonal, Damien; Fotelli, Mariangela N.; Geßler, Arthur; Grossiord, Charlotte; Guyot, Virginie; Jactel, Hervé; Nguyen, Diem; Radoglou, K.; Bussotti, Filippo

doi:10.1016/j.foreco.2015.11.018

Cited by 37 publications

(24 citation statements)

References 72 publications

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“…In the first months after the drought event, evergreen trees retain the dead leaves, so, at least in the short period, the amount of dry leaves on the plant is a better indicator of drought impact than defoliation. Defoliation levels were close to those observed in previous surveys carried out on Mediterranean forests in Tuscany, on forests not affected by drought (Pollastrini et al, 2016). The results presented in Table 1 suggest therefore that Q. ilex, with a significantly higher amount of dead leaves, is more drought sensitive than P. latifolia, in line with a large body of evidence on the comparative behavior of these two species under stress conditions (Peñuelas et al, 1998(Peñuelas et al, , 2000Barbeta et al, 2013;Rosas et al, 2013;Sperlich et al, 2015).…”

Section: Discussionsupporting

confidence: 87%

Widespread Crown Defoliation After a Drought and Heat Wave in the Forests of Tuscany (Central Italy) and Their Recovery—A Case Study From Summer 2017

Pollastrini

Puletti²,

Selvi

et al. 2019

Front. For. Glob. Change

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An anomalous event of drought and heat occurred in central Italy during the summer of 2017. Based on the SPI (Standardized Precipitation Index) and data from the European Space Agency, this event started in November 2016 and was characterized by a strong reduction of precipitation and soil moisture, especially in lowland areas with Mediterranean climate. The aim of this case report were to describe the impact of this event on representative forest communities in central Italy, to analyze the different responses of deciduous and evergreen tree and shrub species in contrasting environmental conditions and to assess their subsequent capacity of recovery or, if not, mortality. Trees suffered severe impacts consisting of widespread crown defoliation, leaf desiccation, crown dieback and whole tree mortality. Deciduous tree species (Fagus sylvatica, Quercus pubescens, Quercus cerris) shed their leaves during the summer, but apical buds and twigs were preserved. This allowed these species to produce new shoots in the following year (2018) and to restore the canopy closure of the stands. Mediterranean evergreen broadleaves, such as Quercus ilex and Phillyrea latifolia suffered of total or partial crown desiccation with wilting leaves and branch dieback. These species partially resprouted in 2018 from axillary and latent buds. The case presented here is discussed within the wider context of the impacts of climate change on Mediterranean forests. Future research directions should include an effective forest monitoring system that combines terrestrial and remote sensing surveys, ad hoc field climate change experiments and silvicultural trials from the perspective of proactive management for the adaptation of forests to future climatic conditions.

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Section: Discussionsupporting

confidence: 87%

Widespread Crown Defoliation After a Drought and Heat Wave in the Forests of Tuscany (Central Italy) and Their Recovery—A Case Study From Summer 2017

Pollastrini

Puletti²,

Selvi

et al. 2019

Front. For. Glob. Change

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“…In addition, previous studies have also described strong species identity effects on crown defoliation (e.g., Bussotti et al, 2018;Pollastrini et al, 2016). Thus, identity and diversity may affect tree defoliation.…”

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confidence: 94%

Tree diversity mitigates defoliation after a drought‐induced tipping point

Sousa-Silva

Verheyen

Ponette

et al. 2018

Global Change Biology

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Understanding the processes that underlie drought-related tree vitality loss is essential for anticipating future forest dynamics, and for developing management plans aiming at increasing the resilience of forests to climate change. Forest vitality has been continuously monitored in Europe since the acid rain alert in the 1980s, and the intensive monitoring plots of ICP Forests offer the opportunity to investigate the effects of air pollution and climate change on forest condition. By making use of over 100 long-term monitoring plots, where crown defoliation has been assessed extensively since 1990, we discovered a progressive shift from a negative to a positive effect of species richness on forest health. The observed tipping point in the balance of net interactions, from competition to facilitation, has never been reported from real ecosystems outside experimental conditions; and the strong temporal consistency of our observations with increasing drought stress emphasizes its climate change relevance. Furthermore, we show that higher species diversity has reduced the severity of defoliation in the long term. Our results confirm the greater resilience of diverse forests to future climate change-induced stress. More generally, they add to an accumulating body of evidence on the large potential of tree species mixtures to face manifold disturbances in a changing world.

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“…The sampling and assessment of adult trees in forest conditions poses specific problems, such as the standardization of sampling procedures, the variability of the parameters considered within the plant and the stand, and the role of ecological and structural features in modifying the Impacts. These methodological issues have been addressed in [5,27,29,87] for the assessment of chlorophyll a fluorescence properties. Thanks to the results of these studies, we can now select the most robust and reliable parameters to assess the physiological vitality of trees and to interpret them in relation to the functional traits and ecological behavior of a tree species.…”

Section: Discussionmentioning

confidence: 99%

“…The maximum quantum yield of primary photochemistry (F V /F M ), which is the most commonly used fluorescence parameter, is easily measurable in field conditions with different kinds of instruments [20] and has been probed and determined to be useful for characterizing responses and the adaptation of plants to stress [25]. ChlF analysis, with special reference to prompt fluorescence [26], has been extensively applied in forests [5,[27][28][29], and the relationships between ChlF parameters, crown defoliation, and foliar traits have been explored extensively [30,31]. ChlF fluorescence can also be assessed by means of remote sensing techniques [32].…”

Section: Crown Conditions and Growthmentioning

confidence: 99%

“…There are discussions about the physiological significance of defoliation and its suitability for describing the overall crown condition [5]. Some additional analytical parameters can be taken into consideration for the more effective assessment of the crown condition in relation to climatic stress impacts on individual trees and on forest stands.…”

Section: Introductionmentioning

confidence: 99%

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Traditional and Novel Indicators of Climate Change Impacts on European Forest Trees

Bussotti

Pollastrini

2017

Forests

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Abstract:The concern for the fate of forest ecosystems under climate change demands the development of a prompt and effective system for detecting the impacts of pressure factors, such as rising temperatures, drought conditions, and extreme climatic events. In ongoing European monitoring programs, the health condition of trees is only assessed visually as a matter of course and there is limited evidence that enhanced crown defoliation implies physiological disturbance and reduced tree growth. The progress of the research makes it possible to apply methods developed in experimental conditions in forests for the fast and reliable assessment of impacts and of stress conditions. In this review, we analyze the most promising indicators of tree and forest health (at individual plant and ecosystem levels) for their potential application in forest ecosystems and their ability to support and integrate the traditional visual assessment, provide information on influential factors, and improve the prediction of stand dynamics and forest productivity.

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Physiological significance of forest tree defoliation: Results from a survey in a mixed forest in Tuscany (central Italy)

Cited by 37 publications

References 72 publications

Widespread Crown Defoliation After a Drought and Heat Wave in the Forests of Tuscany (Central Italy) and Their Recovery—A Case Study From Summer 2017

Widespread Crown Defoliation After a Drought and Heat Wave in the Forests of Tuscany (Central Italy) and Their Recovery—A Case Study From Summer 2017

Tree diversity mitigates defoliation after a drought‐induced tipping point

Traditional and Novel Indicators of Climate Change Impacts on European Forest Trees

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