Forests 2021, 12, 1361. https://doi.org/10.3390/f12101361 www.mdpi.com/journal/forests Article A Band Model of Cambium Development: Opportunities and Prospects Vladimir V. Shishov 1,2, *, Ivan I. Tychkov 1,3 , Kevin J. Anchukaitis 4,5, *, Grigory K. Zelenov 3 and Eugene A. Vaganov 2,3 1 Institute of Fundamental Biology and Biothechnology, Siberian Federal University, 660041 Krasnoyarsk, Russia; ivan.tychkov@gmail.com 2 Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Science, 660036 Krasnoyarsk, Russia; eavaganov@hotmail.com 3 Institute of Ecology and Geography, Siberian Federal University, 660041 Krasnoyarsk, Russia; zelenov.grigory@yandex.ru 4 Laboratory of Tree‐Ring Research, University of Arizona, Tucson, AZ 85721, USA 5 School of Geography, Development, and Environment, University of Arizona, Tucson, AZ 85721, USA * Correspondence: vlad.shishov@gmail.com (V.V.S.); kanchukaitis@arizona.edu (K.J.A.); Tel.: +7908211‐42‐37 (V.V.S.) Abstract: More than 60% of tree phytomass is concentrated in stem wood, which is the result of periodic activity of the cambium. Nevertheless, there are few attempts to quantitatively describe cambium dynamics. In this study, we develop a state‐of‐the‐art band model of cambium develop‐ ment, based on the kinetic heterogeneity of the cambial zone and the connectivity of the cell struc‐ ture. The model describes seasonal cambium development based on an exponential function under climate forcing which can be effectively used to estimate the seasonal cell production for individual trees. It was shown that the model is able to simulate different cell production for fast‐, middle‐ and slow‐growing trees under the same climate forcing. Based on actual measurements of cell produc‐ tion for two contrasted trees, the model effectively reconstructed long‐term cell production varia‐ bility (up to 75% of explained variance) of both tree‐ring characteristics over the period 1937−2012. The new model significantly simplifies the assessment of seasonal cell production for individual trees of a studied forest stand and allows the entire range of individual absolute variability in the ring formation of any tree in the stand to be quantified, which can lead to a better understanding of the anatomy of xylem formation, a key component of the carbon cycle. Keywords: cambium activity; cambium band; cell production; common climate signal; simulation; tree‐ring width; individual tree 1. Introduction More than 60% of tree phytomass is concentrated in stem wood, which is the result of periodic activity of the lateral meristem, that is, the cambium [1,2]. Cambium, as a self‐ sustaining system in the trunks of tree species, can exist over hundreds and even thou‐ sands of years, annually producing layers of phloem and xylem [3–5]. The term cambium is commonly used to refer to multiple cell rows that persist even during the dormancy stage. In the active phase of growth, not only does the number of cambial cells increase; there exist both initial cells and their derivatives in the cambial zone, namely the mother cells of phloem and xylem. In this stage of growth, the cambial zone is the target of and responds to both internal (e.g., hormones, peptides) and external (e.g., climate, competi‐ tion) factors, including stress‐related factors [6,7]. Despite advances in both histological and genetic studies of meristems, the mecha‐ nisms that coordinate cambium functioning as the main lateral meristem have not yet been clarified. Presumably, the balance of auxins (hormones descending from the еapical Citation: Shishov, V.V.; Tychkov, I.I.; Anchukaitis, K.J.; Zelenov, G.K.; Vaganov, E.A. A Band Model of Cambium Development: Opportunities and Prospects. Forests 2021, 12, 1361. https://doi.org/10.3390/f12101361 Academic Editors: Guy R. LaRocque, Weifeng Wang, Herman H. Shugart and Vladimir Shanin Received: 13 August 2021 Accepted: 28 September 2021 Published: 7 October 2021 Publisher’s Note: MDPI stays neu‐ tral with regard to jurisdictional claims in published maps and institu‐ tional affiliations. Copyright: © 2021 by the authors. Li‐ censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con‐ ditions of the Creative Commons At‐ tribution (CC BY) license (http://crea‐ tivecommons.org/licenses/by/4.0/).