Communicated by Îzaks Raðals Dendroclimatological research has been perfomed in Latvia after a break of about 25 years. The growth pattern of Scots pine (Pinus sylvestris L.) in six districts of western Latvia is analysed in relation to climatic factors (monthly and seasonal mean air temperature and precipitation). Applying various statistical techniques, it was observed that in this area the growth of pine on mineral soils with normal moisture conditions has been affected most significantly by the mean air temperature during the period from the second half of January to the first half of April of the same year. Thus, the period when mean air temperature is the most significant influence is similar across an area at least from Lithuania (inclusive) to southern Scandinavia, while further north it ismean summer air temperature that gradually becomes the determining factor in the radial growth of pine. Also the quality of the dendrochronological signal in tree-ring chronologies of pine growing in the environmental conditions of Latvia was determined and signature years during the 20th century were identified, when the majority of pines throughout the territory of the Baltic States exhibit a similar change in annual radial growth.

An Iron Age timber settlement which, in view of the defensive structures uncovered, is described as a lake fortress, on an island in Lake Āraiši, north-eastern Latvia, was excavated in 1965-69 and 1975-79 by teams led by Jānis Apals, who distinguished five construction phases. Dendrochronological analysis produced a c. 100-year floating chronology for Norway spruce (Picea abies (L.) Karst.) timbers from the earliest phase. A 14 C wiggle-match was undertaken to obtain an absolute date range for the final year of the floating chronology, and thus for the construction of the settlement. Ten blocks of wood from one timber, each comprising 6-11 years and collectively spanning the whole 93-year tree-ring series, were dated by AMS. Using the IntCal13 calibration data, there is a 95% probability that the felling date of this timber falls in the range 775-784 cal AD. It appears, however, that the AD 775 spike in the atmospheric 14 C level occurred within the 6-year span of the last sample. On this basis, we can narrow the date of construction to 776-780 cal AD. This date is significantly earlier than those reported in previous publications.

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In the course of archaeological excavations and supervision work in the historical centre of Rīga (Old Rīga), revetments built at various times along the former River Rīga or Rīdzene have so far been discovered in at least 11 sites, and revetments along the bank of the River Daugava have been found in at least three sites. The absolute age of stretches of revetment along both banks of the River Rīga (Rīdzene) and along the right bank of the River Daugava, discovered in the course of recent archaeological excavations, has been determined using the dendrochronological dating method. This article brings together the results obtained thus far in the dating of these structures. Although only some of the discovered stretches of historical waterfront have been dated, this information has given a significantly more precise picture of the building history of the waterfronts along the banks of both rivers, and thus also of the development of the historical ports of Rīga. This indicates the importance and necessity of continuing this research.

Single-year 14C sampling of a spruce log from the timber platform on which the Āraiši lake-fortress was built dates this timber exactly, by synchronization with AD 774/5 Miyake event. Dendrochronological synchronisms between the dated log and other timbers provide annual precision for the construction of the site. The felling date obtained, AD 835, is 50–60 years later than that proposed previously (Meadows and Zunde 2014) on the basis of a wiggle-match between 14C ages of decadal blocks and the IntCal13 calibration curve (Reimer et al. 2013), although the same 14C data favor a felling date in the AD 830s when wiggle-matched to IntCal20 (Reimer et al. 2020). Our results appear to confirm doubts expressed by Philippsen et al. (2022) about IntCal20 values from ca. AD 825-835.