Needle characteristics of Lebanon cedar (Cedrus libani A.Rich.): degradation of epicuticular waxes and decrease of photosynthetic rates with increasing needle age

Güney, Aylin; Zimmermann, R.; Krupp, Anna; Haas, Klaus

doi:10.3906/tar-1507-63

Cited by 4 publications

(5 citation statements)

References 17 publications

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“…We thus assume that the top three canopy layers of leaf area index (LAI; m 2 leaf m −2 ground ) mainly consist of sun-adapted foliage (i.e., sun leaves) with Hg uptake rates corresponding to the uptake rates measured at top canopy. Leaf area indices and vertical foliar biomass distribution differ among tree species (Fichtner et al, 2013;Hakkila, 1991;Sharma et al, 2016;Tahvanainen and Forss, 2008;Temesgen et al, 2005). We did not apply a height correction for tree species with a LAI ≤ 3.…”

Section: Correction Factor For Foliar Hg Uptake Flux As a Function Ofmentioning

confidence: 99%

“…Consequently, a physiologically less active older needle accumulates less Hg(0). Additionally, adsorption of Hg(0) to needle wax layers as a possible nonstomatal uptake pathway might be minimized in older needles, because aging needles suffer from cuticular wax degradation (Burkhardt and Pariyar, 2014;Güney et al, 2016). As older needles exhibited higher Hg concentrations than younger needles, the Hg re-emission flux might increase with age.…”

Section: Effect Of Needle Age On Foliar Hg Uptakementioning

confidence: 99%

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A bottom-up quantification of foliar mercury uptake fluxes across Europe

et al. 2020

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Abstract. The exchange of gaseous elemental mercury, Hg(0), between the atmosphere and terrestrial surfaces remains poorly understood mainly due to difficulties in measuring net Hg(0) fluxes on the ecosystem scale. Emerging evidence suggests foliar uptake of atmospheric Hg(0) to be a major deposition pathway to terrestrial surfaces. Here, we present a bottom-up approach to calculate Hg(0) uptake fluxes to aboveground foliage by combining foliar Hg uptake rates normalized to leaf area with species-specific leaf area indices. This bottom-up approach incorporates systematic variations in crown height and needle age. We analyzed Hg content in 583 foliage samples from six tree species at 10 European forested research sites along a latitudinal gradient from Switzerland to northern Finland over the course of the 2018 growing season. Foliar Hg concentrations increased over time in all six tree species at all sites. We found that foliar Hg uptake rates normalized to leaf area were highest at the top of the tree crown. Foliar Hg uptake rates decreased with needle age of multiyear-old conifers (spruce and pine). Average species-specific foliar Hg uptake fluxes during the 2018 growing season were 18 ± 3 µg Hg m−2 for beech, 26 ± 5 µg Hg m−2 for oak, 4 ± 1 µg Hg m−2 for pine and 11 ± 1 µg Hg m−2 for spruce. For comparison, the average Hg(II) wet deposition flux measured at 5 of the 10 research sites during the same period was 2.3 ± 0.3 µg Hg m−2, which was 4 times lower than the site-averaged foliar uptake flux of 10 ± 3 µg Hg m−2. Scaling up site-specific foliar uptake rates to the forested area of Europe resulted in a total foliar Hg uptake flux of approximately 20 ± 3 Mg during the 2018 growing season. Considering that the same flux applies to the global land area of temperate forests, we estimate a foliar Hg uptake flux of 108 ± 18 Mg. Our data indicate that foliar Hg uptake is a major deposition pathway to terrestrial surfaces in Europe. The bottom-up approach provides a promising method to quantify foliar Hg uptake fluxes on an ecosystem scale.

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Section: Correction Factor For Foliar Hg Uptake Flux As a Function Ofmentioning

confidence: 99%

Section: Effect Of Needle Age On Foliar Hg Uptakementioning

confidence: 99%

A bottom-up quantification of foliar mercury uptake fluxes across Europe

et al. 2020

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show abstract

“…Consequently, a physiologically less active older needle accumulates less Hg(0). Additionally, adsorption of Hg(0) to needle wax layers as a possible nonstomatal uptake pathway might be minimized in older needles because ageing needles suffer from cuticular wax degradation (Burkhardt and Pariyar, 2014;Güney et al, 2016). As older needles exhibited higher Hg concentrations than younger needles, the Hg re-emission flux might increase with age.…”

Section: Effect Of Needle Age On Foliar Hg Uptakementioning

confidence: 99%

A bottom-up quantification of foliar mercury uptake fluxes across Europe

Wohlgemuth¹,

Osterwalder²,

Joseph³

et al. 2020

Preprint

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Abstract. The exchange of gaseous elemental mercury, Hg(0), between the atmosphere and terrestrial surfaces remains poorly understood mainly due to difficulties in measuring net Hg(0) fluxes on the ecosystem scale. Emerging evidence suggests foliar uptake of atmospheric Hg(0) to be a major deposition pathway to terrestrial surfaces. Here, we present a bottom-up approach to calculate Hg(0) uptake fluxes to aboveground foliage by combining foliar Hg uptake rates normalized to leaf area with species-specific leaf area indices. This bottom-up approach incorporates systematic variations in crown height and needle age. We analyzed Hg content in 583 foliage samples from six tree species at 10 European forested research sites along a latitudinal gradient from Switzerland to Northern Finland over the course of the 2018 growing season. Foliar Hg concentrations increased over time in all six tree species at all sites. We found that foliar Hg uptake rates normalized to leaf area were highest at the top of the tree crown. Foliar Hg uptake rates decreased with needle age of multi-year old conifers (spruce and pine). Average species-specific foliar Hg uptake fluxes during the 2018 growing season were 18 ± 3 µg Hg m−2 for beech, 26 ± 5 µg Hg m−2 for oak, 4 ± 1 µg Hg m−2 for pine and 11 ± 1 µg Hg m−2 for spruce. For comparison, the average Hg(II) wet deposition flux measured at 5 of the 10 research sites during the same period was 2.3 ± 0.3 µg Hg m−2, which was four times lower than the site-averaged foliar uptake flux of 10 ± 3 µg Hg m−2. Scaling up site-specific foliar uptake rates to the forested area of Europe resulted in a total foliar Hg uptake flux of approximately 20 ± 3 Mg during the 2018 growing season. Considering that the same flux applies to the global land area of temperate forests, we estimate a foliar Hg uptake flux of 108 ± 18 Mg. Our data indicate that foliar Hg uptake is a major deposition pathway to terrestrial surfaces in Europe. The bottom up approach provides a promising method to quantify foliar Hg uptake fluxes on an ecosystem scale.

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“…For analysis of sapwood area, between twenty-two and twenty-four mature C. libani trees of different size and age were randomly chosen per sampling site. None of the selected tree individuals had any visible damage (Güney et al, 2016). DBH was measured in two directions and then averaged.…”

Section: Study Area and Tree Selectionmentioning

confidence: 99%

Sapwood Area Related to Tree Size, Tree Age, and Leaf Area Index in Cedrus libani

Güney

2018

Bilge International Journal of Science and Technology Research

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Sapwood includes the water conducting part of the stem which transports water and minerals from roots to leaves. Studies using sap flow gauges have to determine the area of the sapwood in order to scale measured sap flow densities to the tree or stand level. The aim of this study was to investigate the relationship between sapwood area at breast height and other tree parameters which are easy to measure of the montane Mediterranean conifer Cedrus libani, including a total number of 92 study trees of different size and age. The study was conducted at four different stands situated between 1000 and 2000 m altitude in the Elmalı Cedar Research Forest of Antalya, SW-Turkey. Sapwood area of the study trees was determined by extracting two tree cores from opposite directions of the stem using an increment borer and by visually assessing the wet part of the core. Parameters measured besides sapwood area were diameter at breast height, stem radius without bark, sapwood depth, tree basal area, tree height, tree age, and projected crown area. Furthermore, at each stand, leaf area index (LAI) was determined using hemispherical photographs of the forest canopy. The most significant relationship was found between stem radius without bark and sapwood area (R 2 : 0.94) followed by tree basal area and sapwood area (R 2 : 0.90). Although it was the second best predictor, tree basal area should be used to estimate sapwood area when estimating stand transpiration since it can be measured faster and without giving damage to the tree. Mean sapwood area and mean site-specific LAI showed a significant positive correlation. The findings of this study can be used in ecophysiological studies when transpiration rates of C. libani are measured using sap flow gauges.

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Needle characteristics of Lebanon cedar (Cedrus libani A.Rich.): degradation of epicuticular waxes and decrease of photosynthetic rates with increasing needle age

Cited by 4 publications

References 17 publications

A bottom-up quantification of foliar mercury uptake fluxes across Europe

A bottom-up quantification of foliar mercury uptake fluxes across Europe

A bottom-up quantification of foliar mercury uptake fluxes across Europe

Sapwood Area Related to Tree Size, Tree Age, and Leaf Area Index in Cedrus libani

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