Browsing by Subject "long-term data"

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  • Voutilainen, Ari; Arvola, Lauri Matti Juhani (2017)
    In order to improve our understanding of the connections between the biological processes and abiotic factors, we clustered complex long-term ecological data with the self-organizing map (SOM) technique. The available 21-year long (1990–2010) data set from a small pristine humic lake, in southern Finland, consisted of 27 meteorological, physical, chemical, and biological variables. The SOM grouped the data into three categories of which the first one was the largest with 12 variables, including metabolic processes, dissolved oxygen, total nitrogen and phosphorus, chlorophyll a, and taxonomical groups of plankton known to exist in spring. The second cluster comprised of water temperature and precipitation together with cyanobacteria, algae, rotifers, and crustacean zooplankton, an association emphasized with summer. The third cluster was consisted of six physical and chemical variables linked to autumn, and to the effects of inflow and/or water column mixing. SOM is a useful method for grouping the variables of such a large multi-dimensional data set, especially, when the purpose is to draw comprehensive conclusions rather than to search for associations across sporadic variables. Sampling should minimize the number of missing values. Even flexible statistical techniques, such as SOM, are vulnerable to biased results due to incomplete data.
  • Kurhinen, J.; Bolshakov, V. N.; Delgado, M.; Prokhorov, I.; Ovaskainen, Otso (НИЦ НБ РС(Я), 2019)
    The article is devoted to the international project — “The Eurasian Chronicle of Nature: a large-scale analysis of changing ecosystems”, the history of the project from 2011 to 2019 is given. The significance of the long-term data of the “Annals of Nature” of the protected areas when studying the dynamics of the biological diversity of the biota of Eurasia, including the assessment of the effects of climate change, is emphasized.