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The aim of our study was to find the hydrological, precipitation and temperature signal in tree rings and selected cell parameters of European ash ( Fraxinus excelsior L.) in the floodplain forest of the Warta River. A total of 30 samples were taken at breast height, using a Pressler borer, from 15 trees (2 samples per tree) during the 2012 vegetation season. We measured the tree-ring widths, built the chronology, selected the tree that was the best correlated with the rest, and used both samples from this tree for cell analysis. For earlywood vessels, average and total density, as well as the percentage of water conductive area were calculated for the years 1950–2011. We found that high water levels during September to January of the previous year positively influence tree growth. This finding could be associated with the accumulation of nutrients, like nitrogen, in the floodplain soil, which are then used at the beginning of the growing season or earlier, when the trees transition from the true dormancy phase to relative dormancy. Temperature at the end of winter and early spring did not play a big role in tree-ring width, whereas low temperature in February negatively affected the number and the area of the earlywood cells. In addition, precipitation during the growing season, especially in June, had a positive effect on ring width. To summarize, our research showed that in the case of European ash from lowland flood-areas, river flows had a large influence on growth. Precipitation and air temperature, which both shape the river regime and directly supply forest ecosystems with water, were also important for tree growth and tree-ring structure. [ABSTRACT FROM AUTHOR]

Abstract: Tree ring width (TRW), maximum (MXD), mean (MED) and minimum (MID) wood density were investigated in samples from the vicinity of the Tuchola Forest Biosphere Reserve (Northern Poland) in an attempt to distinguish the relative importance of climate and insect attack on the growth of Norway spruce. Selected climate parameters were used for a multiple regression to predict tree-ring width during insect outbreaks. This also used AICc for model selection. Additionally, k-means clustering was then used to group the yearly data of TRW, MXD, MID and the data of insect outbreaks. The respective climate data and data on insect outbreaks during the years 1962–1996 revealed a strong influence of May precipitation on TRW and insect outbreaks on MID. Missing tree rings or narrow rings and lower MXD together with higher MID might indicate increased insect activity. [Copyright &y& Elsevier]

Research Highlights: This study used a 99-year time-series of daily climatic data to determine the climate-growth relationship for Scots Pine (Pinus sylvestris L.) growing in Northern Poland. The use of daily climatic data improved the calculated climatic response of the trees. Background and Objectives: It was hypothesised that daily temperature and precipitation data would more precisely identify climate–growth relationships than monthly data. We compared our results to a previous study conducted in the 1990s that utilised monthly precipitation and temperature data. Materials and Methods: The chronology construction and data analyses were performed using CooRecorder, CDendro and R packages (dplR, treeclim, dendrotools). Forty-nine cores from 31 trees were included in the final chronology. Results: The precipitation and temperature of March had the strongest influence upon ring-widths. Despite a statistically significant correlation between monthly temperature and ring-widths, reduction of error (RE) and coefficient of efficiency (CE) statistics confirmed that daily data better describe the effect of climate on tree rings width than monthly data. Conclusions: At this site, the growing season of Scots pine has changed with the observed association with precipitation now starting as early as February–March and extending to June–July. [ABSTRACT FROM AUTHOR]

Scots pine is an adaptable and prevalent European tree species that grows naturally throughout Europe and has been planted in a wide range of environments. Previous studies have indicated that climatic variables affect tree-ring growth patterns in this species, but it is also possible that certain aspects of the growth environment moderate this response. In order to understand the potential impact a shifting climate has on this important species, this study compared the growth response of two populations of Scots pine. Trees from similar bioclimatic regions in Hungary and Poland were compared using the hypothesis that differences in the association between climate and growth would be reflected by the degree of tree-ring width variation. We also wanted to know how changing climatic conditions influenced the temporal stability of the climate–growth signal in the most important periods for tree growth. Clear similarities in the effect of temperature and precipitation on tree-ring width variation were found between the two sites, but there were also some interesting differences. In the late winter to early spring period both populations reacted to warming with a decreasing association with temperature. Summer precipitation was shown to be the dominant factor in controlling ring-width. A decreasing trend in summer precipitation values at both Hungarian and Polish sites resulted in a weakening in correspondence for the Hungarian trees, while the Polish trees showed a significant increase in correlation with summer precipitation. The results indicated that changes in climate influenced the studied trees in different ways which has implications for the future balance of Scots pine growth in Europe. [ABSTRACT FROM AUTHOR]