Tree differences in primary and secondary growth drive convergent scaling in leaf area to sapwood area across Europe

Petit G., von Arx G., Kiorapostolou N., Lechthaler S., Prendin A.L., Anfodillo T., Caldeira M.C., Cochard H., Copini P., Crivellaro A., Delzon S., Gebauer R., Gričar J., Grönholm L., Hölttä T., Jyske T., Lavrič M., Lintunen A., Lobo-do-Vale R., Peltoniemi M., Peters R.L., Robert E.M.R., Roig Juan S., Senfeldr M., Steppe K., Urban J., Van Camp J., Sterck F. (2018) Tree differences in primary and secondary growth drive convergent scaling in leaf area to sapwood area across Europe. New Phytologist. 218: 1383-1392.
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Doi: 10.1111/nph.15118

Resum:

Trees scale leaf (AL) and xylem (AX) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in AL : AX balance in response to climate conditions, but whether trees of different species acclimate in AL : AX in similar ways over their entire (continental) distributions is unknown. We analyzed the species and climate effects on the scaling of AL vs AX in branches of conifers (Pinus sylvestris, Picea abies) and broadleaved (Betula pendula, Populus tremula) sampled across a continental wide transect in Europe. Along the branch axis, AL and AX change in equal proportion (isometric scaling: b ˜ 1) as for trees. Branches of similar length converged in the scaling of AL vs AX with an exponent of b = 0.58 across European climates irrespective of species. Branches of slow-growing trees from Northern and Southern regions preferentially allocated into new leaf rather than xylem area, with older xylem rings contributing to maintaining total xylem conductivity. In conclusion, trees in contrasting climates adjust their functional balance between water transport and leaf transpiration by maintaining biomass allocation to leaves, and adjusting their growth rate and xylem production to maintain xylem conductance. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust

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Zero-calorie sugar delivery to roots

Ryan, M.G., Robert, E.M.R. (2017) Zero-calorie sugar delivery to roots. Nature Plants. 3: 922-923.
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Doi: 10.1038/s41477-017-0070-0

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Towards a common methodology for developing logistic tree mortality models based on ring-width data

Cailleret, M., Igler, C.I.B., Mann, H.B., Camarero, J.J., Cufar, K., Davi, H., Mészáros, I., Inunno, F.M., Peltoniemi, M., Robert, E.M.R., Suarez, M.L., Tognett, R.I., Martínez-Vilalta, J. (2016) Towards a common methodology for developing logistic tree mortality models based on ring-width data. Ecological Applications. 26: 1827-1841.
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Doi: 10.1890/15-1402.1

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A synthesis of radial growth patterns preceding tree mortality

Cailleret, M., Jansen, S., Robert, E.M.R., Desoto, L., Aakala, T., Antos, J.A., Beikircher, B., Bigler, C., Bugmann, H., Caccianiga, M., Čada, V., Camarero, J.J., Cherubini, P., Cochard, H., Coyea, M.R., Čufar, K., Das, A.J., Davi, H., Delzon, S., Dorman, M., Gea-Izquierdo, G., Gillner, S., Haavik, L.J., Hartmann, H., Hereş, A.-M., Hultine, K.R., Janda, P., Kane, J.M., Kharuk, V.I., Kitzberger, T., Klein, T., Kramer, K., Lens, F., Levanic, T., Linares Calderon, J.C., Lloret, F., Lobo-Do-Vale, R., Lombardi, F., López Rodríguez, R., Mäkinen, H., Mayr, S., Mészáros, I., Metsaranta, J.M., Minunno, F., Oberhuber, W., Papadopoulos, A., Peltoniemi, M., Petritan, A.M., Rohner, B., Sangüesa-Barreda, G., Sarris, D., Smith, J.M., Stan, A.B., Sterck, F., Stojanović, D.B., Suarez, M.L., Svoboda, M., Tognetti, R., Torres-Ruiz, J.M., Trotsiuk, V., Villalba, R., Vodde, F., Westwood, A.R., Wyckoff, P.H., Zafirov, N., Martínez-Vilalta, J. (2016) A synthesis of radial growth patterns preceding tree mortality. Global Change Biology. : 0-0.
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Doi: 10.1111/gcb.13535

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Osmolality and non-structural carbohydrate composition in the secondary phloem of trees across a latitudinal gradient in Europe

Lintunen A., Paljakka T., Jyske T., Peltoniemi M., Sterck F., Von Arx G., Cochard H., Copini P., Caldeira M.C., Delzon S., Gebauer R., Grönlund L., Kiorapostolou N., Lechthaler S., Lobo-Do-Vale R., Peters R.L., Petit G., Prendin A.L., Salmon Y., Steppe K., Urban J., Juan S.R., Robert E.M.R., Hölttä T. (2016) Osmolality and non-structural carbohydrate composition in the secondary phloem of trees across a latitudinal gradient in Europe. Frontiers in Plant Science. 7: 0-0.
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Doi: 10.3389/fpls.2016.00726

Resum:

Phloem osmolality and its components are involved in basic cell metabolism, cell growth, and in various physiological processes including the ability of living cells to withstand drought and frost. Osmolality and sugar composition responses to environmental stresses have been extensively studied for leaves, but less for the secondary phloem of plant stems and branches. Leaf osmotic concentration and the share of pinitol and raffinose among soluble sugars increase with increasing drought or cold stress, and osmotic concentration is adjusted with osmoregulation. We hypothesize that similar responses occur in the secondary phloem of branches. We collected living bark samples from branches of adult Pinus sylvestris, Picea abies, Betula pendula and Populus tremula trees across Europe, from boreal Northern Finland to Mediterranean Portugal. In all studied species, the observed variation in phloem osmolality was mainly driven by variation in phloem water content, while tissue solute content was rather constant across regions. Osmoregulation, in which osmolality is controlled by variable tissue solute content, was stronger for Betula and Populus in comparison to the evergreen conifers. Osmolality was lowest in mid-latitude region, and from there increased by 37% toward northern Europe and 38% toward southern Europe due to low phloem water content in these regions. The ratio of raffinose to all soluble sugars was negligible at mid-latitudes and increased toward north and south, reflecting its role in cold and drought tolerance. For pinitol, another sugar known for contributing to stress tolerance, no such latitudinal pattern was observed. The proportion of sucrose was remarkably low and that of hexoses (i.e., glucose and fructose) high at mid-latitudes. The ratio of starch to all non-structural carbohydrates increased toward the northern latitudes in agreement with the build-up of osmotically inactive C reservoir that can be converted into soluble sugars during winter acclimation in these cold regions. Present results for the secondary phloem of trees suggest that adjustment with tissue water content plays an important role in osmolality dynamics. Furthermore, trees acclimated to dry and cold climate showed high phloem osmolality and raffinose proportion. © 2016 Lintunen, Paljakka, Jyske, Peltoniemi, Sterck, von Arx, Cochard, Copini, Caldeira, Delzon, Gebauer, Grönlund, Kiorapostolou, Lechthaler, Lobo-do-Vale, Peters, Petit, Prendin, Salmon, Steppe, Urban, Roig Juan, Robert and Hölttä.

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A tree-centered approach to assess impacts of extreme climatic events on forests

Sass-Klaassen U., Fonti P., Cherubini P., Gričar J., Robert E.M.R., Steppe K., Bräuning A. (2016) A tree-centered approach to assess impacts of extreme climatic events on forests. Frontiers in Plant Science. 7: 0-0.
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Doi: 10.3389/fpls.2016.01069

Resum:

[No abstract available]

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