Fate of organic solvent-soluble extractives and arabinogalactan during brown rot degradation of Siberian larch heartwood

This dataset contains measurement data from the following publication: Belt, T.; Harju, A.; Venäläinen, M.; Kilpeläinen, P. (2024) Fate of organic solvent-soluble extractives and arabinogalactan during brown rot degradation of Siberian larch heartwood. European Journal of Wood and Wood Products. DOI: 10.1007/s00107-024-02146-3. The data consist of mass loss and extractive content data for samples derived from two different decay tests. The decay tests and measurement procedures are described in brief below; further details can be found in the publication.

Decay test 1 was a stacked-sample test. Sample blocks were prepared from fresh Siberian larch heartwood and Scots pine sapwood. The decay test was conducted in test tubes over nutrient agar inoculated with Coniophora puteana or Rhodonia placenta. Each tube (N =5) received 7 heartwood or sapwood blocks stacked on top of each other (sample positions 1-7 from top to bottom). After decay, the mass losses of all larch heartwood and pine sapwood samples were measured. The decayed larch heartwood samples were individually ground to powder and extracted with methanol to obtain organic solvent-soluble extractives and with cold water to obtain arabinogalactan.

Decay test 2 was a time-series test. Increment cores were obtained from 5 Siberian larch trees, with 8 cores obtained from each tree. Core pieces were cut from outer heartwood and split lengthwise to produce two halves: one half for the decay test and the other to act as an undecayed extractive content control. The decay test was conducted on petri dishes containing nutrient agar inoculated with C. puteana or R. placenta. One core half from each tree exposed to C. puteana and one exposed to R. placenta were removed from the decay test after 10, 20, 27 and 36 days of incubation. After decay, the mass losses of all decay test core halves were measured. The decay test and control core halves were individually ground to powder and extracted with methanol to obtain organic solvent-soluble extractives and with cold water to obtain arabinogalactan.

Organic solvent-soluble extractives in the methanol extracts were analysed by GC-MS after trimethyl silylation of the extracts. A total of 13 extractive compounds were identified and quantified in the extracts: 5 fatty acids (palmitic, linolenic, linoleic, oleic, and stearic acid), 6 resin acids (isopimaric, pimaric, palustric, dehydroabietic, abietic, and neoabietic acid), and 2 flavonoids (dihydrokaempferol and taxifolin). Arabinogalactan in the cold water extract was analysed by GC-FID after acid methanolysis. Arabinogalactan was determined as the sum of arabinose and galactose obtained by methanolysis.

The “Decay test 1.csv”-file gives the sample identifiers (ID, sample type, test fungus, tube number, sample position), and mass losses of the larch heartwood and pine sapwood samples, and the extractive contents of the larch heartwood samples. Extractive content data are given for all fatty acids, resin acids, and flavonoids quantified in the methanol extracts, and for arabinose and galactose quantified in the cold water extracts. Extractive contents are given on a decayed wood basis (mg/g decayed wood).

The “Decay test 2.csv”-file gives the sample identifiers (ID, sample type, test fungus, tree number, core number, decay test time), mass losses, and extractive contents of the decayed and control larch heartwood core halves. Extractive content data are given for all fatty acids, resin acids, and flavonoids quantified in the methanol extracts, and for arabinose and galactose quantified in the cold water extracts. Extractive contents are given on a decayed wood basis (mg/g decayed wood).