Results 1 to 10 of about 2,723,889 (322)

Solar superstorm of AD 774 recorded subannually by Arctic tree rings [PDF]

Nature Communications, 2018
Tree rings retain information of sudden variations of ancient radiocarbon (14C) content, however the origin and exact timing of these events often remain uncertain.
J. Uusitalo, L. Arppe, T. Hackman, S. Helama, G. Kovaltsov, K. Mielikäinen, H. Mäkinen, P. Nöjd, V. Palonen, I. Usoskin, M. Oinonen   +10 more
doaj   +3 more sources

Tree demography dominates long-term growth trends inferred from tree rings. [PDF]

Glob Chang Biol, 2017
Understanding responses of forests to increasing CO2 and temperature is an important challenge, but no easy task. Tree rings are increasingly used to study such responses. In a recent study, Van der Sleen et al.
Brienen RJ, Gloor M, Ziv G.
europepmc   +4 more sources

Tree-rings reveal two strong solar proton events in 7176 and 5259 BCE. [PDF]

Nat Commun, 2022
The Sun sporadically produces eruptive events leading to intense fluxes of solar energetic particles (SEPs) that dramatically disrupt the near-Earth radiation environment.
Brehm N, Christl M, Knowles TDJ, Casanova E, Evershed RP, Adolphi F, Muscheler R, Synal HA, Mekhaldi F, Paleari CI, Leuschner HH, Bayliss A, Nicolussi K, Pichler T, Schlüchter C, Pearson CL, Salzer MW, Fonti P, Nievergelt D, Hantemirov R, Brown DM, Usoskin I, Wacker L.   +22 more
europepmc   +2 more sources

Branch Rings, Thinned Rings, Tree Enveloping Rings [PDF]

Israel Journal of Mathematics, 2005
We develop the theory of ``branch algebras'', which are infinite-dimensional associative algebras that are isomorphic, up to taking subrings of finite codimension, to a matrix ring over themselves. The main examples come from groups acting on trees. In
A. C. Vieira, A. G. Abercrombie, A. M. Brunner, D. G. Quillen, D. R. Farkas, D. S. Passman, D. S. Passman, G. K. Genov, G. R. Krause, I. G. Lysionok, J. Lewin, J. P. Bell, J. S. Wilson, L. Bartholdi, L. Bartholdi, L. Bartholdi, L. Bartholdi, L. Bartholdi, L. Bartholdi, L. Bartholdi, L. Bartholdi, Laurent Bartholdi, M. Abért, M. Abért, M. Lazard, N. D. Gupta, P. M. Neumann, R. I. Grigorchuk, R. I. Grigorchuk, R. I. Grigorchuk, R. I. Grigorchuk, S. A. Amitsur, S. A. Jennings, S. N. Sidki, S. N. Sidki, T. G. Ceccherini-Silberstein, T. Y. Lam, U. Vishne, V. M. Petrogradskiî, V. M. Petrogradskiî, V. M. Petrogradskiî, V. V. Nekrashevych, W. Li, Y. Barnea, Y. Lavreniuk   +44 more
core   +5 more sources

Statistical age determination of tree rings. [PDF]

PLoS ONE, 2020
Dendrochronology, the study of annual rings formed by trees and woody plants, has important applications in research of climate and environmental phenomena of the past.
Martin Ricker, Genaro Gutiérrez-García, David Juárez-Guerrero, Margaret E K Evans   +3 more
doaj   +2 more sources

Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE. [PDF]

Nat Commun, 2018
Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of cosmogenic origin leave spatiotemporally consistent ...
Büntgen U, Wacker L, Galván JD, Arnold S, Arseneault D, Baillie M, Beer J, Bernabei M, Bleicher N, Boswijk G, Bräuning A, Carrer M, Ljungqvist FC, Cherubini P, Christl M, Christie DA, Clark PW, Cook ER, D'Arrigo R, Davi N, Eggertsson Ó, Esper J, Fowler AM, Gedalof Z, Gennaretti F, Grießinger J, Grissino-Mayer H, Grudd H, Gunnarson BE, Hantemirov R, Herzig F, Hessl A, Heussner KU, Jull AJT, Kukarskih V, Kirdyanov A, Kolář T, Krusic PJ, Kyncl T, Lara A, LeQuesne C, Linderholm HW, Loader NJ, Luckman B, Miyake F, Myglan VS, Nicolussi K, Oppenheimer C, Palmer J, Panyushkina I, Pederson N, Rybníček M, Schweingruber FH, Seim A, Sigl M, Churakova Sidorova O, Speer JH, Synal HA, Tegel W, Treydte K, Villalba R, Wiles G, Wilson R, Winship LJ, Wunder J, Yang B, Young GHF.   +66 more
europepmc   +2 more sources

Nonannual tree rings in a climate-sensitive Prioria copaifera chronology in the Atrato River, Colombia. [PDF]

Ecol Evol, 2017
In temperate climates, tree growth dormancy usually ensures the annual nature of tree rings, but in tropical environments, determination of annual periodicity can be more complex.
Herrera-Ramirez D, Andreu-Hayles L, Del Valle JI, Santos GM, Gonzalez PLM.   +4 more
europepmc   +3 more sources

Modeled Tracheidograms Disclose Drought Influence on Pinus sylvestris Tree-Rings Structure From Siberian Forest-Steppe. [PDF]

Front Plant Sci, 2018
Wood formation allows trees to adjust in a changing climate. Understanding what determine its adjustment is crucial to evaluate impacts of climatic changes on trees and forests growth.
Popkova MI, Vaganov EA, Shishov VV, Babushkina EA, Rossi S, Fonti MV, Fonti P.   +6 more
europepmc   +2 more sources

Tree rings provide a new class of phenotypes for genetic associations that foster insights into adaptation of conifers to climate change. [PDF]

New Phytol, 2018
Summary Local adaptation in tree species has been documented through a long history of common garden experiments where functional traits (height, bud phenology) are used as proxies for fitness.
Housset JM, Nadeau S, Isabel N, Depardieu C, Duchesne I, Lenz P, Girardin MP.   +6 more
europepmc   +2 more sources

Superellipse Equation Describing the Geometries of Abies alba Tree Rings [PDF]

Plants
Our previous study using 41 tree rings of one Abies alba Mill. disc indicated that the superellipse equation can accurately fit its tree-ring shape. This study further used the superellipse equation (xan+yβn=1 ) to model the geometries of 1090 tree rings
Weiwei Huang, Kehang Ma, Jiaxin Tan, Meixiang Wei, Yunjie Lu   +4 more
doaj   +2 more sources