Evaluation of estimates of crown condition in forest monitoring: comparison between visual estimation and automated crown image analysis

Nakajima, Haruki; Kume, Atsushi; Ishida, Megumi; Ohmiya, Tohru; Mizoue, Nobuya

doi:10.1007/s13595-011-0132-9

Cited by 19 publications

(7 citation statements)

References 27 publications

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“…, Nakajima et al. , Boehmer et al. ) and has also been used to categorize forest health across Europe by the International Cooperative Program Forest Inventory (Eichhorn et al.…”

Section: Methodsmentioning

confidence: 99%

“…Green canopy levels were visually estimated as a proxy for the species response to drought (die-off) as the percentage of green leaves present relative to the amount in healthy individuals found in the study area. This method is standard for estimations of drought-induced die-off in ecosystems dominated by woody vegetation (Carnicer et al 2011, Galiano et al 2011, Nakajima et al 2011, Boehmer et al 2013) and has also been used to categorize forest health across Europe by the International Cooperative Program Forest Inventory (Eichhorn et al 2016). Green canopy levels were measured in the canopies of the plants that were used to estimate stand density (Appendix S3), but only species with at least 20 individuals within the stand were considered at each site to reduce stochasticity in the estimation of green canopy levels at stand level.…”

Section: Estimation Of Green Canopy Levelsmentioning

confidence: 99%

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Species climatic niche explains drought‐induced die‐off in a Mediterranean woody community

2017

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Abstract. During the last decades, plant die-off has been reported worldwide as a result of increased frequency and intensity of extreme drought events. From a niche perspective, a species performance should decrease as the climatic conditions defining a drought event differ from those characterizing the species climatic niche (the average conditions experienced by the species). Species distribution models (SDMs) can potentially be used to test the link between species performance and their climatic niche by means of climatic suitability indexes. We studied the remaining green canopy of 18 woody species co-occurring in a Mediterranean shrubland from the central Iberian Peninsula that experienced a severe die-off following an extreme drought event. We found that the suitability of the climatic conditions estimated by SDMs strongly declined for all species during the extreme drought event. Species die-off was significantly explained by the decrease in climatic suitability during the event, estimated as the ratio between the historic and the extreme event climatic suitability. Species with high occupancy levels across the landscape exhibited higher die-off likely because (1) these species have short life-span and mortality would be compensated by later high recruitment or (2) populations of rare species may have experienced local adaptation to drier conditions. Our results indicate that extreme drought events can have a negative effect, even in shrubland communities living in arid environments. Also, we develop a new approach that connects population-level responses to species climatic niches through SDMs, and it can be applied to predict community responses to strong climatic variability, such as drought events.

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“…, Nakajima et al. , Boehmer et al. ) and has also been used to categorize forest health across Europe by the International Cooperative Program Forest Inventory (Eichhorn et al.…”

Section: Methodsmentioning

confidence: 99%

Section: Estimation Of Green Canopy Levelsmentioning

confidence: 99%

Species climatic niche explains drought‐induced die‐off in a Mediterranean woody community

2017

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“…This method is standard practice for measures of drought-induced impact on ecosystems dominated by woody vegetation (e.g. Carnicer et Galiano et al, 2011;Nakajima et al, 2011;Boehmer et al, 2013). In order to facilitate comparisons between species that may exhibit different leaf phenologies, the green canopy was estimated by considering the percentage of young, thin tips of branches with no signs of decay and regularly holding up leaves (as well as checking recent leaf scars in species that drop leaves early after unfolding, such as G. scorpius).…”

Section: Recording Field Canopy Diebackmentioning

confidence: 99%

Non-structural carbohydrate dynamics associated with drought-induced die-off in woody species of a shrubland community

et al. 2018

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Our community-level study reveals that, while responses were species-specific, C stocks overall diminished in plants affected by prolonged drought and did not increase after a pulse of seasonal rain. Dynamics were faster for SS than NSC. We found limited depletion of SS, consistent with their role in basal metabolic, transport and signalling functions. In a scenario of increased drought under climate change, NSC stocks in woody plants are expected to decrease differentially in coexisting species, with potential implications for their adaptive abilities and community dynamics.

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“…It integrates intrinsic tree genetic variability, site effects, and external factors such as abiotic and biotic stresses. Crown defoliation expresses the percentage of lacking leaves with respect to an ideal healthy tree identified through photo guides (Müller and Stierlin 1990;Ferretti 1994) or local reference tree and it is measured by a proportional scale with 5% steps ranging from 0% (not defoliated) to 100% (dead tree). Alongside crown defoliation, damage symptoms (and, when evident, damaging agents) are currently assessed on leaves, branches, and trunk.…”

Section: The Level I Network In Italymentioning

confidence: 99%

Linking forest diversity and tree health: preliminary insights from a large-scale survey in Italy

et al. 2018

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Forest health is currently assessed in Europe (ICP Forests monitoring program). Crown defoliation and dieback, tree mortality, and pathogenic damage are the main aspects considered in tree health assessment. The worsening of environmental conditions (i.e., increase of temperature and drought events) may cause large-spatial scale tree mortality and forest decline. However, the role of stand features, including tree species assemblage and diversity as factors that modify environmental impacts, is poorly considered. The present contribution reanalyses the historical dataset of crown conditions in Italian forests from 1997 to 2014 to identify ecological and structural factors that influence tree crown defoliation, highlighting in a special manner the role of tree diversity. The effects of tree diversity were explored using the entire data set through multivariate cluster analyses and on individual trees, analysing the influence of the neighbouring tree diversity and identity at the local (neighbour) level. Preliminary results suggest that each tree species shows a specific behaviour in relation to crown defoliation, and the distribution of crown defoliation across Italian forests reflects the distribution of the main forest types and their ecological equilibrium with the environment. The potentiality and the problems connected to the possible extension of this analysis at a more general level (European and North American) were discussed.

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Evaluation of estimates of crown condition in forest monitoring: comparison between visual estimation and automated crown image analysis

Abstract: International audienc

Cited by 19 publications

References 27 publications

Species climatic niche explains drought‐induced die‐off in a Mediterranean woody community

Species climatic niche explains drought‐induced die‐off in a Mediterranean woody community

Non-structural carbohydrate dynamics associated with drought-induced die-off in woody species of a shrubland community

Linking forest diversity and tree health: preliminary insights from a large-scale survey in Italy

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