Main Phases of Wood Formation in Chestnut (Castanea sativa) in Central Italy - Comparison of Seasons 2008 and 2009

We present wood formation in chestnut (Castanea sativa) during the growing seasons 2008 and 2009, compare its dynamics in the two years and discuss possible effects on wood quality. To this purpose, microcores containing wood, cambium and phloem were collected at weekly intervals from 10 chestnut trees growing at the Cimini mountains near Viterbo, Central Italy. In 2008, the onset of wood formation started before the first sampling on 17 April 2008. Onset of lignification of the first formed vessels was observed around 23 April (day of the year DOY 113.8 ± 5.3) and the first latewood vessels were observed around 5 June 2008 (DOY 156.5 ± 7.7). Latewood formation continued until 29 September 2008 (DOY 273.9 ± 10.5) when the terminal cells of the newly formed xylem ring were fully lignified. In 2009, the main phases of wood formation generally occurred earlier than in 2008. The expansion of earlywood vessels was observed around 10 April (DOY 99.7 ± 6.1), the onset of lignification around 22 April (DOY 111.9 ± 7.4) and the first latewood vessels around 28 May 2009 (DOY 147.9 ± 4.7). Lignification of the last formed cells was completed by 26 September 2009 (DOY 273.9 ± 10.5). The average duration of tree-ring formation was 161 days in 2008 and 169 days in 2009, the average ring widths were 3296 ± 1514 μm in 2008 and 3166 ± 1073 μm in 2009, and latewood percentages comprised 76% and 74% of the 2008 and 2009 tree-rings, respectively. The small differences in timing of wood formation phases in the two study years are probably due to small variations in climatic conditions between the two years and they did not seem to have a major impact on ring widths and latewood percentages, which are two important parameters affecting wood quality in ring porous wood species.