Xylogenesis of Scots Pine in an Uneven-Aged Stand of the Minusinsk Depression (Southern Siberia)

Abstract

Tree-ring formation studies are important for assessing the impact of environmental factors on tree growth at intra-seasonal resolution. This information is necessary for understanding plant acclimatization to current and expected climate changes. Little is still known about how tree age may affect the duration and rate of annual ring formation. In this study, we investigated tree-ring formation in Scots pine (Pinus sylvestris L.) trees of different ages (30- and 95-year-old trees) from the foreststeppe zone in Southern Siberia. The main objectives were 1) to estimate the timing of cambial activity by distinguishing the phases of division, enlargement, wall thickening, and maturation of tracheids and 2) to compare the anatomical structure of the tracheids forming the annual rings of the differently aged trees. Stem tissue was sampled weekly from April to September 2014. The results showed a 1-2 week difference in duration of the phases of xylem formation between the groups; in addition, the ring width of the young trees was slightly narrower. The size of the tracheids of the entirely formed ring (i.e. the results of the enlargement phase) did not differ between the groups whereas the dynamics of the cell-wall thickness showed significant differences. The data obtained in the present study can provide references to calibrate process-based models linking environment to wood formation. These data can be used to benchmark time-explicit simulated measurements of annual ring increment and cell anatomical structure against the corresponding parameters of mature trees growing under natural conditions

Small fluctuations in cell wall thickness in pine and spruce xylem: Signal from cambium?

“…However, it is logical to expect increased N as a result of increased duration of cambial activity, making the lower boundary of these estimations more realistic. Indeed, direct observations of seasonal kinetics in the study region showed that the maximum number of cells in the zone of cell wall thickening occurred in August (i.e., for latewood), which accounted for 20-34% of the total cell production, i.e., 20-34 and 10-17 cells, respectively, for the given examples of N ( [40] and unpublished data). This finding can…”

“…We also used earlier 10-day observations of pine xylem phenology under relatively similar conditions (2013 and 2014, 53.65˚N 91.58˚E, 320 m a.s.l. ; [10,40]) to overcome low temporal resolution of local data, and compared these observations with the temperature data from the Minusinsk weather station (53.68˚N 91.67˚E, 260 m a.s.l., 9 km from site).…”

“…The comparison of the seasonal kinetics of conifer xylogenesis in the study region during several seasons ( [10,40], also unpublished data) with the corresponding temperature series showed that the threshold temperatures coinciding with the onset of cambial activity are approximately 8˚C for both species (cf. range of threshold temperatures 5.6-8.5˚C reported by Rossi et al [46]).…”

“…However, this estimation can be exceeded if spring is particularly early (cf. early onset of pine cambial activity on April 11 (101 DOY) and its duration of 110 days in 2014 at the other site [40]).…”

What Quantitative Anatomy Can Provide for Kinetics of Xylogenesis: Analysis of Cell Radial Diameters

“…В течение сезона роста фиксируется постепенный переход клеток из камбия в зону растяжения, затем в зону одревеснения клеточной стенки, что в итоге заканчивается потерей клетки протоплазмы и включением ее в формирующуюся водопроводящую систему -ксилему (Гамалей, 1972;Larson, 1994;Vaganov et al, 2006;Olano et al, 2014;Prendin et al, 2017). Особенности кинетики каждого этапа в конечном итоге отражаются в окончательных анатомических характеристиках трахеид: радиальном размере и толщине клеточной стенки (Ваганов и др., 1985;Camarero et al, 2010;Martin-Benito et al, 2013;Cuny et al, 2014;Rossi et al, 2014 (Rossi et al, 2006;Ziaco, Biondi, 2016;Fonti et al, 2020 2009,2010). Эта система позволяет измерять размеры клеток и их частей (Munro et al, 1996).…”