Tree canopy defoliation can reveal growth decline in mid-latitude temperate forests

Ferretti, Marco; Bacaro, Giovanni; Brunialti, Giorgio; Calderisi, Marco; Croisé, Luc; Frati, Luisa; Nicolas, Manuel

doi:10.1016/j.ecolind.2021.107749

Cited by 16 publications

(13 citation statements)

References 64 publications

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“…5a, b, Table 3, Functions 6 and 8). Our results are in line with the findings of Waring (1987), Dobbertin (2005) and Ferretti et al (2021) who stated that insect defoliation affects the photosynthetic processes and reduces stem growth. Furthermore, due to the varying distances between the curves, we found that the growth losses, with decreasing leaf area and increasing crown perforation, were smaller at the lower end of the diameter range compared to the upper end of the diameter range (Fig.…”

Section: Defoliation and Tree Growth Losssupporting

confidence: 93%

“…They found out that growth was inversely related to defoliation. Even lightly defoliated trees showed a significant reduction in growth (Ferretti et al 2021). Both of our foliationdescribing parameters correlated with the basal area increment, which was calculated within the same year directly after defoliation had taken place.…”

Section: Defoliation Detection By Tlsmentioning

confidence: 58%

“…In addition, stem growth is easy and accurate to measure in the field on the same tree that we used to calculate the foliation. The results of Ferretti et al (2021) suggest that even slight and moderate variations in defoliation may have a significant impact on tree and forest growth. They found out that growth was inversely related to defoliation.…”

Section: Defoliation Detection By Tlsmentioning

confidence: 97%

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Assessment of defoliation and subsequent growth losses caused by Lymantria dispar using terrestrial laser scanning (TLS)

Jacobs

Hilmers

Leroy

et al. 2022

Trees

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Key message TLS scans of three surveys before, during and after gypsy moth gradation, allowed high-resolution tracking of defoliation and subsequent inter-annual growth losses on an individual tree level. Abstract Foliation strongly determines all tree growth processes but can be reduced by various stress factors. Insect defoliation starts at variable times and is one stress factor that may affect photosynthetic processes and cause immediate reactions like refoliation, which are difficult to detect by surveys repeated at 1-year intervals. This study used a large-scale field experiment in German oak/mixed forests affected by gypsy moths (Lymantria dispar) to test the use of terrestrial laser scanning (TLS) for detecting inter-annual foliation and growth losses at the individual tree level caused by the gypsy moth. The experiment comprised two levels of gypsy moth defoliation risk, high (H) and low (L), as well as two pest control treatment levels: spraying with the insecticide Mimic (M) or unsprayed control (C). The factorial design consisted of four treatment combinations (HC, HM, LC, and LM), applied to 11 spatial blocks with a total of 44 plots. The TLS approach detected the defoliation caused by the gypsy moth, estimated as leaf area and crown perforation parameters. For the first time, TLS-derived tree foliation was evaluated based on inter-annual stem growth. Leaf area and crown perforation showed a correlation of + 0.6 and – 0.35, respectively, with basal area increments. Furthermore, this study revealed subsequent growth losses in the same year due to defoliation. Our results show that TLS can offer new opportunities to develop new indicators that monitor foliation at the individual tree level. The crown perforation can describe defoliation or the tree’s vitality based on one scanning campaign, whereas the leaf area needed at least two.

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Section: Defoliation and Tree Growth Losssupporting

confidence: 93%

Section: Defoliation Detection By Tlsmentioning

confidence: 58%

Section: Defoliation Detection By Tlsmentioning

confidence: 97%

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Assessment of defoliation and subsequent growth losses caused by Lymantria dispar using terrestrial laser scanning (TLS)

Jacobs

Hilmers

Leroy

et al. 2022

Trees

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“…Climate impacts can trigger defoliation processes in various types of forests [ 14 ]. Defoliation of tree crowns is the most widely used parameter for the assessment of forest vitality [ 30 , 31 , 32 , 33 ]. The percentage of tree damage is determined based on the visual assessment of the lack of assimilation organs (i.e., percentage of defoliation).…”

Section: Introductionmentioning

confidence: 99%

Impact of an Extremely Dry Period on Tree Defoliation and Tree Mortality in Serbia

Češljar

Jovanovic

Brašanac-Bosanac

et al. 2022

Plants

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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.

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“…Defoliation is an unspecific parameter, integrating the intrinsic genetic variability of trees, site effects (soil fertility, climatic features, structure and composition of the forest stand) and external factors such as abiotic and biotic stresses [2,3]. The real significance of defoliation and its consequences on physiological functioning and growth, however, is not clear, although several studies have addressed this issue, often reaching contrasting results [4][5][6][7][8]. Defoliation is not necessarily equivalent to physiological damage and can be considered indicative of the dynamic equilibrium of a tree in its own environment, and we assume that the physiological responses may depend not only on the levels of defoliation itself, but also on year-by-year differences and species-specific strategies to cope with stress.…”

Section: Introductionmentioning

confidence: 99%

Defoliation, Recovery and Increasing Mortality in Italian Forests: Levels, Patterns and Possible Consequences for Forest Multifunctionality

Bussotti

Papitto²,

Martino³

et al. 2021

Forests

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Forest health and multifunctionality are threatened by global challenges such as climate change. Forest health is currently assessed within the pan-European ICP Forests (International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests) programme through the evaluation of tree crown conditions (defoliation). This paper analyses the results of a 24-year assessment carried out in Italy on 253 permanent plots distributed across the whole forested area. The results evidenced a substantial stability of crown conditions at the national level, according to the usual defoliation thresholds Defoliation > 25% and Defoliation > 60%, albeit with species-specific patterns. Within this apparent temporal stability, an increased fraction of extremely defoliated and dead trees was observed. Extreme defoliation mostly occurred in years with severe summer drought, whereas mortality was higher in the years after the drought. The results for singular species evidenced critical conditions for Castanea sativa Mill. and Pinus species, whereas Quercus species showed a progressive decrease in defoliation. Deciduous species, such as Fagus sylvatica L., Ostrya carpinifolia Scop. and Quercus pubescens Willd. suffer the loss of leaves in dry years as a strategy to limit water loss by transpiration but recover their crown in the following years. The recurrence of extreme heat waves and drought from the beginning of the XXI century may increase the vulnerability of forests, and increased tree mortality can be expected in the future.

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Tree canopy defoliation can reveal growth decline in mid-latitude temperate forests

Cited by 16 publications

References 64 publications

Assessment of defoliation and subsequent growth losses caused by Lymantria dispar using terrestrial laser scanning (TLS)

Assessment of defoliation and subsequent growth losses caused by Lymantria dispar using terrestrial laser scanning (TLS)

Impact of an Extremely Dry Period on Tree Defoliation and Tree Mortality in Serbia

Defoliation, Recovery and Increasing Mortality in Italian Forests: Levels, Patterns and Possible Consequences for Forest Multifunctionality

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