Jouko Meriläinen

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Growth of subarctic Scots pine (Pinus sylvestris L.) trees was investigated by a combination of process-based models and dendroecological approaches. Tree ring width indices were strongly autocorrelated and correlated with simulated photosynthetic production of the previous year and with organic matter N mineralization of the current year. An autoregressive(More)
Climatic signals were extracted from ring-width chronologies of Scots pines (Pinus sylvestris L.) from natural stands of the northern, middle, and southern parts of the boreal forest belt in Finland. The strength of the common growth signals (forcing factors) were quantifi ed as a function of time. This was achieved by mean inter-series correlations,(More)
Chrysophyte (mallomonadacean) scales were examined from the surface sediments of 18 lakes from eastern Finland, representing a wide range of limnological characteristics. Scales were always well preserved and 23 taxa were observed. The relative frequencies of the dominant taxa were plotted relative to the average autumn lakewater pH. The distribution of(More)
Diatom assemblages from the topmost sediment of 49 lakes were ordinated by means of a program for detrended correspondence analysis and reciprocal averaging (Decorana). Five lake groups were separated, each having more or less characteristic diatom assemblages and water quality. Shifts from one group to another caused by factors such as acidification,(More)
A collection of subfossil wood of Pinus sylvestris (Scots pine) was exposed to X-ray densitometry. The collection of 64 samples from the southern boreal forest zone was dendrochronologically cross-dated to A.D. 673-1788. Growth characteristics were determined by performing density profiles including the following parameters: minimum density, earlywood and(More)
Data on recenr diatom community structure and relevant environmental characteristics from the lakes and their catchments have been collected from 151 oligotrophic lakes in eastern Finland. The pattern of frequency distribution of diatoms as a function of environmental variables, including land use in the catchment, differs between diatom taxa and indicates(More)
We analyzed how the pretreatment method of Scots pine (Pinus sylvestris L.) wood specimens together with X-ray methodology applied for density analyses affect resulting tree-ring data and derived proxy-based climate information. We also evaluated whether these results from two contrasting laboratory circumstances could be homogenized by applying(More)
X-ray microdensitometry was applied to a set of Scots pinewood (i.e. low extractive content). Earlywood and latewood properties were determined as minimum and maximum densities of each tree ring and the potential influence of acetone-soluble extractives (i.e. non-structural and secondary constituents of wood) was estimated using tree-ring statistics. The(More)
Macro nutrients N, P, K, Ca, Mg, Na and S as well as heavy metals Pb, Cu, Zn, Co, Cr, Ni, Fe and Mn were analysed from a sediment core representing a 7000-year long history of a lake including the preceding brackish (Litorina Sea) and freshwater (Ancylus Lake) stages. Sediments were also analysed for sedimentary pigments, algal growth potential (AGP) of the(More)
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