Fagus

Ethnobotanical information was obtained through informed consent semi-structured interviews with key informants over the last twenty years (1989–2004) (Table 1). Informants with a sound traditional knowledge of useful wild plants, mostly elderly long-time residents, were interviewed. Open questions about wild food consumption sought to ascertain knowledge about past and present-use, mode of consumption and preparation, collection time and collection sites for each species [44 ].
For this study, data were grouped into the following categories of edible plants based on folk perceptions: "vegetables", plants whose leaves, stems or even unripe fruits or seeds were consumed; "wild fruits", plants whose fruits or seeds were consumed when ripe; home-made "liqueurs" or other alcoholic drinks; "herbal teas", used in general as a digestif; plants used for "seasoning"; and finally, "flowers" and "underground organs", eaten for their sweetness.
Every plant species mentioned by an informant within one use-category was counted as one use-report (UR) [see [45 (link)]]. For instance, the raw fruits of Prunus spinosa in Picos de Europa were reported as consumed by 17 informants and used in liqueurs by 21, totalling 38 UR. However, a total number of 27 informants cited the species as useful since some informants reported use both for liqueurs and for raw consumption of fruits. We have rejected species with only one UR because such data are less reliable and sometimes dubious for drawing comparisons.
Voucher specimens were deposited at the herbaria of the Royal Botanical Garden of Madrid (MA, Real Jardín Botánico), the University of Oviedo (FCO, Universidad de Oviedo) and the School of Agricultural Engineering at Bragança (BRESA, Escola Superior Agrária).
To estimate the cultural significance of each species, we used the Cultural Importance Index (CI), whose definition and use are discussed in another paper [see [46 ]], with the following formula:
CI=∑i=1i=NUURiN MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacH8akY=wiFfYdH8Gipec8Eeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9s8qqaq=dirpe0xb9q8qiLsFr0=vr0=vr0dc8meaabaqaciaacaGaaeqabaqabeGadaaakeaacqWGdbWqcqWGjbqscqGH9aqpdaaeWbqaamaalaaabaGaemyvauLaemOuai1aaSbaaSqaaiabdMgaPbqabaaakeaacqWGobGtaaaaleaacqWGPbqAcqGH9aqpcqaIXaqmaeaacqWGPbqAcqGH9aqpcqWGobGtcqWGvbqva0GaeyyeIuoaaaa@3F4E@
The index, which is based on previous indices [47 (link),48 ] was obtained by adding the UR in every use-category (i, varying from only one use to the total number of uses, NU) mentioned for a species, divided by the number of informants in the survey (N).
The CI was calculated for each region. For example, Foeniculum vulgare in Montesinho was reported as used in liqueurs by 10 informants, for seasoning by 32 and for herbal teas by 23. The total number of survey participants was 90.

This additive index takes into account the spread of use (number of informants) for each species and versatility, i.e. diversity of edible uses. The theoretical maximum value of the index is the total number of different edible use categories.
A mean Cultural Importance Index (mCI) of the species was used to assess wild food plant use in the Peninsular northwest as a whole. It is also useful in evaluating CI differences among the various sites. Since a null value may be due to either the species not growing in the area or growing but not being consumed, the mean value preferably needs to be calculated by considering only regions where the species grows and is available. For example, if the null values of the areas where it does not grow (Sanabria and Montesinho) are rejected, the mean value for Fagus sylvatica is 0.055; however, the figure decreases to 0.037 if all six areas are considered. Thus, the mean value takes into account species selection or rejection and availability.
To measure the cultural importance of families (CIf), we added the CI of the species from each family, following Galeano [49 ]. We preferred using the sum instead of the mean as proposed by Phillips and Gentry [48 ] so as to highlight more diverse families which would otherwise be underestimated.
When comparing the edible floras of different regions, it is crucial to differentiate between plants growing in the area but not consumed and those which cannot be consumed because they are absent. To quantify this factor, a regional selection index (RSI) was created to assess differences in edible species selection or rejection among regions. It was obtained by dividing the number of species consumed at a site by the number of species growing there. For instance, the RSI for Sanabria is 0.37 (29/78), since 29 out of 78 available species are used. A regional index for each edible category can be further calculated to assess regional differences in selection among categories. For instance, the RSI for vegetables in Sanabria is 0.19 (5 out of 27 available) versus 0.4 (10/25) for fruits.

The raw material was a mixture of 80% birch (Betula pendula) and 20% European beech (Fagus sylvatica) wood chips, provided by Södra Cell (Mörrum, Sweden). The composition of the raw material mixture, SF_{raw mat}, is presented in Table 1. The wood chips were size reduced using a knife mill (Retsch GmbH, Germany) that was fitted with a 20-mm screen and sieved to retrieve the 2–10-mm fraction.Table 1

Composition of the raw material and solid and liquid fractions after STEX pretreatment

	Raw material	HEX-treated material		STEX treated material
	SFraw mat (wt%)	SFHEX (wt%)	LFHEX (g/L)	SFSTEX (wt%)	LFSTEX (g/L)
Carbohydrates, thereof	67.6 ± 1.4	83.9 ± 0.1	na	67.1 ± 1.1	na
Glucan/glucose	39.4 ± 0.7	67.1 ± 0.1	0.4 ± 0.0	59.2 ± 0.7	2.6 ± 0.0
Xylan/xylose	22.2 ± 0.5	13.2 ± 0.0	10.1 ± 0.1	5.7 ± 0.0	43.4 ± 0.7
Arabinan/arabinose	0.6 ± 0.0	BDL	0.2 ± 0.0	BDL	0.7 ± 0.0
Galactan/galactose	1.8 ± 0.1	BDL	0.7 ± 0.0	BDL	2.2 ± 0.0
Mannan/mannose	3.7 ± 0.2	3.6 ± 0.0	0.5 ± 0.0	1.9 ± 0.0	5.7 ± 0.2
Lignin, thereof	27.2 ± 1.1	14.5 ± 0.1	na	30.4 ± 0.0	na
Acid-soluble	6.5 ± 0.0	3.4 ± 0.2	na	2.9 ± 0.1	na
Acid-insoluble	20.7 ± 1.0	11.1 ± 0.1	na	27.5 ± 0.1	na
Ash	BDL	BDL	na	BDL	na
Recovery	94.9 ± 2.5	98.4 ± 0.0	na	97.6 ± 1.1	na

Data represent mean values and standard deviation. Analyses were performed in duplicate

BDL below detection limit, na not applicable, SF solid fraction, LF liquid fraction, STEX steam explosion, HEX hydrotropic extraction

Our study site was located in a mature beech forest (Fagus sylvatica L.) c. 40 km south-west of Vienna, Austria (510 m asl). The age of the trees was on average 65 yr. The soil was a dystric cambisol (over flysh) with a pH of between 4.5 and 5.1 (CaCl₂). Organic C and total N content comprised 7.45% and 0.48% of dry soil, respectively. Despite the proximity to the city of Vienna, the site received an N input through atmospheric deposition of only 12.6 kg N ha⁻¹ yr⁻¹ (Kitzler et al., 2006 ).

The quartersawn common beech (Fagus sylvatica L.) sapwood planks, stored for two years in a room with air relative humidity of 30% and temperature 23 °C, were selected as a studied wooden substrate material. The gravimetrically determined nominal density of wood with (7.1 ± 0.4)% moisture content was (688.7 ± 24.5) kg × m^–3. The wood was mechanically processed by sawing and peripheral planing into eight samples with dimensions (400 mm × 70 mm × 20 mm) and corresponding wood grain orientation longitudinal × radial × tangential (L × R × T). The samples were furtherly divided to the smaller samples for each analysis, as schematically presented in Fig. 1. All the analyses were conducted on the surfaces with R wood grain orientation, which were manually sanded with rotational-vibrational sanding machine (paper grit P180).Figure 1

Distribution of wood samples preparation for different studies. The numbers present the sample size in individual wood grain direction (in millimeters): L—longitudinal, R—radial and T—tangential.

Seeds of Fagus sylvatica L. (European beech) were collected from the population in Gryfino, Poland (N53° 14′ 44″, E14° 32′ 47). The moisture content (MC) of seeds was calculated on a fresh weight basis using a previously described formula [26 (link)]. Freshly collected seeds had MC at the level of 29.5%. Then samples of seeds were dried on a laboratory bench at 20 °C to a 7.6% of MC that lasted up to eight days. In order to obtain MC values lower than 7.6%, seeds were placed in a drying box on blotting paper and desiccated over silica gel. Finally, beech seeds were desiccated to six levels of MC (17.2, 13.4, 10.5, 7.6, 5.9, and 4.0%). The duration of the desiccation ranged from several days to two–six weeks in the case of the lowest MC. Moisture contents of seeds were assessed by drying at 103 °C ± 2 °C for 24 h.

The forested areas (i.e., semi-natural forests, secondary forests, and plantations) comprise approximately 22.8% of the land in Hungary, the majority of which (64%) is semi-natural temperate deciduous forest (forests dominated by Quercus petraea, Q. cerris, Carpinus betulus, and/or Fagus sylvatica) [28 (link),29 (link)]. Of the total forested area in Hungary, 11% is covered by pine plantations, and 25% is planted with Robinia pseudoacacia. According to 2021 data, Ailanthus altissima covered 0.11% of the total forested area in Hungary, while Elaeagnus angustifolia covered 0.08% (National Forestry Database 2021) [30 ]. Continuous forest cover is mainly found in the mountainous and hilly areas of the country, while in the Great Hungarian Plain, riparian forests are dominant along rivers (Figure 1), although sandy areas give rise to an unaccounted percentage of non-native plantations.
The climate of the Hungarian forests is wet–temperate with a mean annual temperature of 8.0–10.5 °C; and 500–700 mm average yearly precipitation [31 ]. The main soil types in hilly forest areas are brown forest soils, while rendzina soils are present in limestone mountain areas, and ranker soils are present in volcanic and metamorphic areas [32 ].