Common Ash (Fraxinus excelsior L.)

Douglas, G. C.; Pliūra, Alfas; Dufour, Jean; Mertens, Patrick; Jacques, Dominique; Fernandez-Manjares, Jean; Buiteveld, J.; Parnuta, Gheorghe; Tudoroiu, Marin; Curnel, Yannik; Thomasset, Muriel; Jensen, V.; Knudsen, Martin; Foffová, Elena; Chandelier, Anne; Steenackers, Marijke

doi:10.1007/978-94-007-6146-9_9

Cited by 11 publications

(15 citation statements)

References 67 publications

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“…F . excelsior is one of the tree species silviculturally managed in the last 30–40 years in Europe, mostly due to its high quality wood [ 94 ]. It is also extensively used in urban landscape planting because of the aesthetic characteristics desired from urban trees such as autumn colour, attractive bark and flowers [ 95 ].…”

Section: Discussionmentioning

confidence: 99%

Gene flow of common ash (Fraxinus excelsior L.) in a fragmented landscape

2017

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Gene flow dynamics of common ash (Fraxinus excelsior L.) is affected by several human activities in Central Europe, including habitat fragmentation, agroforestry expansion, controlled and uncontrolled transfer of reproductive material, and a recently introduced emerging infectious disease, ash dieback, caused by Hymenoscyphus fraxineus. Habitat fragmentation may alter genetic connectivity and effective population size, leading to loss of genetic diversity and increased inbreeding in ash populations. Gene flow from cultivated trees in landscapes close to their native counterparts may also influence the adaptability of future generations. The devastating effects of ash dieback have already been observed in both natural and managed populations in continental Europe. However, potential long-term effects of genetic bottlenecks depend on gene flow across fragmented landscapes. For this reason, we studied the genetic connectivity of ash trees in an isolated forest patch of a fragmented landscape in Rösenbeck, Germany. We applied two approaches to parentage analysis to estimate gene flow patterns at the study site. We specifically investigated the presence of background pollination at the landscape level and the degree of genetic isolation between native and cultivated trees. Local meteorological data was utilized to understand the effect of wind on the pollen and seed dispersal patterns. Gender information of the adult trees was considered for calculating the dispersal distances. We found that the majority of the studied seeds (55–64%) and seedlings (75–98%) in the forest patch were fathered and mothered by the trees within the same patch. However, we determined a considerable amount of pollen flow (26–45%) from outside of the study site, representing background pollination at the landscape level. Limited pollen flow was observed from neighbouring cultivated trees (2%). Both pollen and seeds were dispersed in all directions in accordance with the local wind directions. Whereas there was no positive correlation between pollen dispersal distance and wind speed, the correlation between seed dispersal distance and wind speed was significant (0.71, p < 0.001), indicating that strong wind favours long-distance dispersal of ash seeds. Finally, we discussed the implications of establishing gene conservation stands and the use of enrichment planting in the face of ash dieback.

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Section: Discussionmentioning

confidence: 99%

Gene flow of common ash (Fraxinus excelsior L.) in a fragmented landscape

2017

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“…Due to the tall vertical structure of forests, parts of the canopy can be turbulently decoupled from the overlying atmosphere. If this decoupling is not properly taken into account in abovecanopy flux measurements, it can lead to incorrect estimates of gas fluxes, in turn reducing the accuracy of estimates of the net ecosystem exchange of CO 2 or of evaporation (Fitzjarrald and Moore, 1990;Alekseychik et al, 2013;Jocher et al, 2017).…”

Section: Conclusion and Recommendationsmentioning

confidence: 99%

“…If the flow above the canopy is (partly) decoupled from the within-canopy flow, above-canopy observations are a poor representative of the overall dynamics (Jocher et al, 2017). This will affect the interpretation of onsite above-canopy flux measurements such as heat, water vapor, and CO 2 (Fitzjarrald and Moore, 1990). Especially when determining the net ecosystem exchange of CO 2 , decoupling has to be taken into account (Jocher et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Decoupling of a Douglas fir canopy: a look into the subcanopy with continuous vertical temperature profiles

et al. 2020

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Abstract. Complex ecosystems such as forests make accurately measuring atmospheric energy and matter fluxes difficult. One of the issues that can arise is that parts of the canopy and overlying atmosphere can be turbulently decoupled from each other, meaning that the vertical exchange of energy and matter is reduced or hampered. This complicates flux measurements performed above the canopy. Wind above the canopy will induce vertical exchange. However, stable thermal stratification, when lower parts of the canopy are colder, will hamper vertical exchange. To study the effect of thermal stratification on decoupling, we analyze high-resolution (0.3 m) vertical temperature profiles measured in a Douglas fir stand in the Netherlands using distributed temperature sensing (DTS). The forest has an open understory (0–20 m) and a dense overstory (20–34 m). The understory was often colder than the atmosphere above (80 % of the time during the night, >99 % during the day). Based on the aerodynamic Richardson number the canopy was regularly decoupled from the atmosphere (50 % of the time at night). In particular, decoupling could occur when both u*<0.4 m s−1 and the canopy was able to cool down through radiative cooling. With these conditions the understory could become strongly stably stratified at night. At higher values of the friction velocity the canopy was always well mixed. While the understory was nearly always stably stratified, convection just above the forest floor was common. However, this convection was limited in its vertical extent, not rising higher than 5 m at night and 15 m during the day. This points towards the understory layer acting as a kind of mechanical “blocking layer” between the forest floor and overstory. With the DTS temperature profiles we were able to study decoupling and stratification of the canopy in more detail and study processes which otherwise might be missed. These types of measurements can aid in describing the canopy–atmosphere interaction at forest sites and help detect and understand the general drivers of decoupling in forests.

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“…The assessed traits were: (1) disease incidence ratio (the ratio between the number of symptomatic trees and the total number of trees in a family); (2) health condition of an individual tree (scored between 1 -tree with dry stem and branches -and 5 -externally healthy tree -, Pliura et al 2011); (3) survival ratio (the ratio between the number of living and dead trees in a family); (4) seedling height; (5) total length of necroses on leader and lateral shoots in an individual plant; and (6) total length of necrotic lesions formed on leader and lateral shoots and stem of an individual plant. Bud flushing phenology was assessed in beginning of May 2014 when all phases were present and distribution of scores was closest to normal, using a categorical scale of five degrees (points) adopted from Douglas et al (2013): 5 -very early; 4 -early; 3 -of moderate earliness; 2 -late; and 1 -very late flushing.…”

Section: Assessment Of Tree Biometric Parameters and Sanitary Conditionsmentioning

confidence: 99%

Genetic variation of Fraxinus excelsior half-sib families in response to ash dieback disease following simulated spring frost and summer drought treatments

Pliūra¹,

Lygis²,

Marčiulynienė³

et al. 2016

iForest

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Ten juvenile Fraxinus excelsior half-sib families from two Lithuanian populations have been tested in the controlled environment for their response to ash dieback disease caused by Hymenoscyphus fraxineus, detecting changes of genetic variation and heritability, as well as estimating genotype by environment (G×E) interaction and phenotypic plasticity following artificial spring frost and summer drought treatments. In 2014, a batch of 200 four-year-old ash seedlings was used for each treatment and control (no treatment). Health condition, bud flushing phenology and height were assessed for each seedling, and disease incidence and survival ratios were assessed for each family both before (at the beginning of the vegetation season) and after the treatments (at the end of the vegetation season). Disease incidence ratio increased from 0.77-0.80 up to 0.90-0.95. Tree mortality rates during one vegetation season were significantly lower in the frost treatment (21%) than in the drought treatment (25%) or control (31%). None of the tested F. excelsior families were completely resistant to ash dieback, although significant among-family differences in disease incidence and damage rates suggest an additive mode of gene action and thus a quantitative resistance to the disease. Neither disease incidence rates, nor tree health condition scores differed significantly among the applied treatments (including control) indicating in general a negligible effect of the simulated adverse conditions on health status of the ash seedlings. However, G×E interaction was found to be significant (at P > 0.05) for disease incidence, length of necrotic shoots and tree survival, implying that susceptibility of ash families to the dieback disease unequally depends on environmental conditions, and indicating a presence of genetic variation in plasticity and reaction norms of the tested families across environments (treatments). Substantially increased coefficients of additive genetic variation and heritability in health condition following both frost and drought treatments and compared to control showed that simulated stress conditions may noticeably contribute to expression of differences among the tested F. excelsior families in their resistance traits, thus enabling a better evaluation of performance of different families, an effective family selection for resistance, and achievement of a marked genetic gain.

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Common Ash (Fraxinus excelsior L.)

Cited by 11 publications

References 67 publications

Gene flow of common ash (Fraxinus excelsior L.) in a fragmented landscape

Gene flow of common ash (Fraxinus excelsior L.) in a fragmented landscape

Decoupling of a Douglas fir canopy: a look into the subcanopy with continuous vertical temperature profiles

Genetic variation of Fraxinus excelsior half-sib families in response to ash dieback disease following simulated spring frost and summer drought treatments

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