Selection of a table or map

2018/26

2004/06

Horizontal distance that the timber travels on a road with limited truck drivability to the point of sale (timber yard or railway station) in four classes. Restricted truck access means that the road cannot be used by trucks with fewer than 4 axles due to permanent bottlenecks or places with a load capacity of less than 28 tonnes. Reference: Forest Service Survey (MID 3060: Vortransportlinie)

Altitude above sea level in classes of 200 m. Reference: Digital height model DHM 25 from Swisstopo

Altitude above sea level in classes of 400 m. Reference: Digital height model DHM 25 from Swisstopo

Altitudinal vegetation belts in the system used in the guidelines for monitoring the sustainability and performance of protection forests (NaiS; Frehner et al. 2005) – in ten classes, whereby the classes «hyperinsubric», «colline» and «colline with beech» and «lower and upper montane» only occur in the Southern Alps (S), the classes «submontane», «lower montane», «upper montane» only in the Northern Alps (N) and the classes «high montane», «subalpine» and «upper subalpine» on both sides of the Alps. The information is based on the altitudinal vegetation belts determined by experts (accessible forest sample plots of NFI4 on the 1.4-km network; Arge Frehner et al. 2020), as well as on the altitudinal vegetation belts modelled for the period 1981-2010 (other sample plots; Zischg et al. 2021). n/a: located above the forest boundary modelled by Zischg et al. and sometimes in the area of lakes, which were relatively roughly cut out by Zischg et al.

Altitudinal vegetation belts in the system used in the guidelines for monitoring the sustainability and performance of protection forests (NaiS; Frehner et al. 2005), reduced to three classes. The variable represents a simplification of the NaiS altititudinal vegetation belts in six classes (NAISHSTKOMB6KL) in which the class «hyperinsubric and colline» is mearged with «submontane» to form the class «hyperinsubric, colline, submontane», the class «lower and upper montane» with «high montane» to form the class «montane» and the class «subalpine» with «upper subalpine» to form the class «subalpine». The information is based on the altitudinal vegetation belts determined by experts (accessible forest sample plots of NFI4 on the 1.4-km network; Arge Frehner et al. 2020), as well as on the altitudinal vegetation belts modelled for the period 1981-2010 (other sample plots; Zischg et al. 2021). n/a: located above the forest boundary modelled by Zischg et al. and sometimes in the area of lakes, which were relatively roughly cut out by Zischg et al.

Altitudinal vegetation belts in the system used in the guidelines for monitoring the sustainability and performance of protection forests (NaiS; Frehner et al. 2005), reduced to six classes. The variable represents a simplification of the NaiS altitudinal vegetation belts with ten classes (NAISHSTKOMB) in which the classes «hyperinsubric» and «colline» are merged with «colline with beech» to form the class «hyperinsubric and colline» and the class «lower montane» with «upper montane» and «lower/upper montane» to form the class «lower and upper montane». The information is based on the altitudinal vegetation belts determined by experts (accessible forest sample plots of NFI4 on the 1.4-km network; Arge Frehner et al. 2020), as well as on the altitudinal vegetation belts modelled for the period 1981-2010 (other sample plots; Zischg et al. 2021). n/a: located above the forest boundary modelled by Zischg et al. and sometimes in the area of lakes, which were relatively roughly cut out by Zischg et al.

Aspect, classified into the following five classes: North, East, South, West and indeterminate. «Indeterminate» means that the slope is ≤10%. Reference: Field Survey (MID 191: Azimut der Exposition)

Aspect, classified into the following nine classes: North, North-East, East, South-East, South, South-West, West, North-West and indeterminate. «Indeterminate» means that the slope is ≤10%. Reference: Field Survey (MID 191: Azimut der Exposition)

Basal area of standing living trees and shrubs ≥12 cm in diameter at breast height (dbh) per hectare – in four classes. Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Ecological value of the forest as a habitat for animals and plants – in three classes. Its value as a biotope is based on the three indicators «naturalness of the proportion of conifers», «diversity of woody species» and «structural diversity».

Type of certificate: FSC and/or PEFC (NFI4, NFI5) or FSC and/or Q (PEFC) (NFI3). Reference: Forest Service Survey (MID 602: Zertifizierungs-Label)

Measure of inter-tree crowding of the tree crowns in a stand. Reference: Field Survey (MID 266: Schlussgrad)

Proportion of the ground area covered by tree crowns according to the aerial photo interpretation – in five 20-percent classes. The percentage is calculated using the 25 grid points on the interpretation area (50 × 50 m). Reference: aerial photo interpretation

Proportion of the ground area that is covered by established regeneration, i.e. by living coniferous and broadleaved trees ≥1.3 m in height and 11.9 cm in diameter at breast height (dbh). Reference: Field Survey (MID 273: Deckungsgrad der gesicherten Verjüngung)

Proportion of ground area covered by ferns, grasses, herbs, Rubus species, (tall) herbaceous perennials and dwarf shrubs (e.g. vaccinia, Alpenrose or juniper). Reference: Field Survey (MID 278: Bodenvegetations-Deckungsgrad).

Proportion of the ground area covered by trees and shrubs with a height of 0.5-3.0 m and by branches of taller individuals of the same species in the same area. Reference: Field Survey (MID 277: Strauchschicht-Deckungsgrad)

Proportion of the ground area covered with berry bushes (blackberry, raspberry, blueberry, cowberry, bog bilberry, and cranberry). Reference: Field Survey (MID 279: Beerensträucher-Deckungsgrad)

Degree of damage to forest stands in six classes, derived from the mean degree of damage to trees and shrubs ≥12 cm in diameter at breast height (dbh) weighted with the basal area. Reference: Field Survey (MID 1027: Baumschadenart, MID 1018: Baumzustand)

Proportions of conifers and broadleaves making up the stand structure, classified according to their proportional basal areas into four classes: pure conifer forest: 91-100 % conifers, mixed conifer forest: 51-90 % conifers, mixed broadleaved forest: 11-50 % conifers and pure broadleaved forest: 0-10 % conifers. Reference: Field Survey (MID 265: Mischungsgrad)

Stage of stand development, defined by the dominant diameter at breast height (dbhdom = dbh of the 100 largest [thickest] trees per hectare). Young growth/thicket: dbhdom <12 cm, pole timber: dbhdom 12-30 cm, young timber: dbhdom 31-40 cm, medium timber : dbhdom 41-50 cm, old timber: dbhdom >50 cm, mixed: trees of different development stages, no development stage predominant or groups of different development stages covering < 500 m². Reference: Field Survey (MID 261: Entwicklungsstufe)

Ecological value of the forest stand according to the number of woody species present, as well as the presence of woody species of special ecological importance (willows, birches, alders, native poplars, native oaks, chestnut, cherry tree, Malus spp., Pyrus spp., Sorbus spp. and Scots pine) in the upper layer – in three classes. Reference: Field Survey (MID 50: Baumart, MID 65: Schicht)

Indication of whether alien woody species (tree or shrub neophytes) ≥12 cm in diameter at breast height (dbh) dominate the growing stock, i.e. account for at least 50% of the growing stock – in two classes. Reference: Field Survey (MID 50: Baumart, MID 1018: Baumzustand, MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Indication as to whether invasive or non-invasive alien woody species («tree or shrub neophytes») ≥12 cm in diameter at breast height (dbh) dominate the growing stock, i.e. account for at least 50% of the growing stock – in three classes. The classification as «invasive» is based on the 2022 publication «Invasive alien species in Switzerland» of the Federal Office for the Environment (FOEN) (UW-2220-E). Reference: Field Survey (MID 50: Baumart, MID 1018: Baumzustand, MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Indication as to whether introduced woody species (tree- or shrub-like neophytes) ≥12 cm in diameter at breast height (dbh) dominate the growing stock, i.e. account for at least 50% of the growing stock, classified into the three classes: «not dominated by introduced species», «dominated by introduced species other than black locust», «dominated by introduced, invasive black locust». Black locust is the only invasive introduced species that has been recorded separately in all NFI inventories to date. The classification as «invasive» corresponds to the publication «Alien species in Switzerland» of the Federal Office for the Environment (FOEN) from 2022 (UW-2220-E). Reference: Field Survey (MID 50: Baumart, MID 1018: Baumzustand, MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Mean age of the 100 largest standing living trees and shrubs ≥12 cm in diameter at breast height (dbh) per hectare – in five classes. Reference: Field Survey (MID 826: Baumalter)

Diameter at breast height (dbh) of the 100 largest (thickest) standing living trees and shrubs ≥12 cm dbh per hectare – in eight classes. Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Mean diameter at breast height (dbh) of the 100 largest standing living trees ≥12 cm in diameter at breast height (dbh) per hectare – in five classes. Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Location inside or outside the catchment area of a spring whose water is fed either directly and unfiltered into the drinking-water supply, or is used at least temporarily or partially as drinking water for the public. Reference: Forest Service Survey (MID 603: Wald im Einzugsgebiet von gefassten Trinkwasserquellen)

Distance - measured horizontally - that the timber is transported from the felling site to a road that is at least 2.50 m wide and dimensioned for an axle load of at least 10 tonnes - in four classes. Any hauling on a road does not count to the extraction distance. Reference: Forest Service Survey (MID 3000: Rückelinie)

Combination of the 18 groups of NaiS site types, each with a similar objective for the main tree species (NAISGGROB20), into 10 large associations known as «forest formations». *As the characterisation of the site types in the NaiS-NFI project is on a small scale, it is possible that non-forest site types such as meadow, pasture and rock may be present in sample plots that are classified as «forest» in NFI. Similarly, «forest without shrub forest“ may also contain «shrub forest» site types.

Forest functions of considerable local importance according to forest plans or an assessment by the local forest service. It's possible for there to be several forest functions of considerable local importance at the same time. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'agricultural use' according to forest plans or an assessment by the local forest service. The forest function 'agricultural use' generally includes wooded pastures and nut orchards. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'drinking-water protection' according to forest plans or an assessment by the local forest service. The forest function «drinking-water protection» generally includes groundwater protection zones and drinking-water catchment areas. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'game protection' according to forest plans or an assessment by the local forest service. As a rule, the forest function 'game protection' includes seasonal grazing areas and game reserves. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'landscape protection' according to forest plans or an assessment by the local forest service. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'military' according to forest plans or an assessment by the local forest service. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'nature conservation' according to forest plans or an assessment by the local forest service. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function «protection against natural hazards» according to forest plans or an assessment by the local forest service. The term «natural hazards» refers to avalanches, rockfall, landslides, landslides and channel processes. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'recreation' according to forest plans or an assessment by the local forest service. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'timber production' according to forest plans or an assessment by the local forest service. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Presence of the forest function 'windbreak' according to forest plans or an assessment by the local forest service. The forest function 'windbreak' generally includes the forests or forest strips that protect agricultural land against wind. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Intensity of forest management, classified in three classes according to site quality and the time of the last treatment. Reference: Forest Service Survey (MID 607: Anzahl Jahre seit dem letzten Eingriff); modelled site quality (total growth performance according to Keller 1978)

Indication as to whether forest planning documents exist at the local level (operational plan, silvicultural project, etc.) and/or at the cantonal level (forest development plan or regional/cantonal forest plan). These documents provide the basis for the forest manager to make silvicultural or operational decisions, irrespective of the year they were produced. Reference: Forest Service Survey (MID 2028: lokale forstliche Planungswerke, MID 803: Stand der Waldentwicklungspläne WEP)

Classification of forests into 12 classes («types») according to their development, structure and management. Unlike in the 17-class forest-type classification, in this 12-class classification all development stages (from young growth to timber) are subsumed in the class «uniform high forest». Reference: Field Survey (MID 255: Nutzungskategorie, MID 257: Waldtyp nach Aufnahmeanleitung LFI, MID 260: Waldform, MID 267: Bestandesstruktur, MID 261: Entwicklungsstufe)

Classification of forests according to their establishment, structure and management into 17 classes («types»). In contrast to the forest typology with 12 classes, the forest typology with 17 classes defines each development stage (young growth to timber) as an individual class. Reference: Field Survey (MID 255: Nutzungskategorie, MID 257: Waldtyp nach Aufnahmeanleitung LFI, MID 260: Waldform, MID 267: Bestandesstruktur, MID 261: Entwicklungsstufe)

Classification of the forest according to the forest decision and accessibility into the three classes «accessible forest without shrub forest», «inaccessible forest without shrub forest» and «shrub forest».

Type of forest in two classes: «forest without shrub forest» or «shrub forest». Reference: Field Survey (MID 816) or - if the forest is inaccessible – aerial photo interpretation

Land cover, classified as one of three categories: 'forest without shrub forest', 'shrub forest' and 'non-forest', based on the NFI forest definition. Reference: Field Survey (MID 816), or if inaccessible, aerial photo interpretation.

Zones around groundwater wells and groundwater recharging facilities that are designated by the canton as in the public interest for protecting drinking water. How strict the property restrictions and/or management requirements are depends on the protection zone,. The variable reflects the protection zone categories applicable since 2016 in accordance with Art. 121 of the Waters Protection Ordinance (SR 814.201) and the status of designation by the cantons on 8 July 2022 (download of data from geodienste.ch).

Value of the forest stand as a habitat – in three classes, derived from the attributes: development stage, crown closure, stand structure, proportion of old timber, degree of damage to the stand, presence of forest or stand edge, occurrence and type of gaps in the stand, degree of cover of the herb layer, degree of cover of berry bushes as well as the occurrence of stumps, lying deadwood, snags and piles of branches. Reference: Field Survey (various attributes)

Habitat quality assessed according to the types of deadwood present. It is considered «high» if the three deadwood types «snagss», «branch and wood piles» and «stumps and lying deadwood» are present on the interpretation area, «moderate» if two types are present, and «low» if none or only one type is present.

Indication as to whether the timber harvesting (felling, processing, extraction and hauling) is carried out wholly or in part by the forest enterprise itself or by a contractor. If an intervention has been carried out since the last Inventory, the information is based on the actual type of operation; if no intervention has been carried out, it is based on the type of operation that the district forester thinks would have been carried out at the time of the current Inventory. Reference: Forest Service Survey (MID 351: Ausführung der Holzernte)

Areas in higher and lower altitude zones classified according to the system used for altitudinal vegetation belts in the guidelines for monitoring the sustainability and performance of protection forests (NaiS; Frehner et al. 2005). The boundary between the higher and lower altitudes runs between the «upper montane» and «lower montane» levels on the Northern Alps and between the «high montane» and «upper/lower montane» levels to the Southern Alps. The information is based on the altitudinal vegetation belts determined by experts (accessible forest sample plots of NFI4 on the 1.4-km network; Arge Frehner et al. 2020), as well as on the altitudinal vegetation belts modelled for the period 1981-2010 (other sample plots; Zischg et al. 2021). n/a: located above the forest boundary modelled by Zischg et al. and sometimes in the area of lakes, which were relatively roughly cut out by Zischg et al.

Located in/outside a groundwater protection zone. The cantons demarcate groundwater protection zones around groundwater wells and groundwater recharging facilities to protect drinking water where this is in the public interest. The indicator variable combines the various protection zone categories in force since 2016 in accordance with Art. 121 of the Waters Protection Ordinance (SR 814.201) into one class. Data status: 8 July 2022 (download from geodienste.ch).

Machines or tools used for felling and processing the trees. If an intervention has taken place since the last Inventory, the data is based on the means actually used. If no intervention has taken place, it is based on the means that would have been used in the case of an intervention at the time of the current Inventory, according to the district forester's assessment. Reference: Forest Service Survey (MID 352: Art der Holzernte)

Correspondence between the actual proportion of conifers in a stand and the postulated natural proportion of conifers in the corresponding potential natural vegetation (PNV). Reference: NaiS site types, aggregated into groups with similar mixing and regeneration objectives («Gfein») according to the NaiS-NFI project (Arge Frehner et al. 2020) for the PNV; classification of the proportion of conifers according to the Kienast method; Field Survey (MID 50: Baumart, MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Number of natural hazard processes that can occur simultaneously in forest designated «protection forest» by the cantons (as of 2022) according to the harmonised criteria of SilvaProtect-CH (as of 2022). The following four natural hazard processes can be considered: rockfall, avalanches, hillslope debris flows/landslides, channel processes. Reference: GIS data from the FOEN, 2022

Number of standing living trees and shrubs ≥24 cm in diameter at breast height (dbh) – in classes of 100. Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang, MID 1018: Baumzustand)

Number of standing living trees and shrubs ≥36 cm in diameter at breast height (dbh) – in classes of 100. Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang, MID 1018: Baumzustand)

Number of standing living trees and shrubs ≥12 cm in diameter at breast height (dbh) per hectare – in classes of 100. Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang, MID 1018: Baumzustand)

Number of tree and shrub species in the upper stand layer – in six classes. The information refers to the relevant stand on the interpretation area (50 × 50 m) and only takes into account species with a cover ≥5%. Reference: Field Survey (MID 242: Baumart in der Oberschicht)

Classification of forest stands according to the dominant diameter at breast height (dbhdom), i.e. the 100 largest (thickest) standing living trees per hectare, as: «old timber stand» (dbhdom >50 cm) or «not old timber stand». Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Forest ownership, classified according to the two categories: 'public' and 'private'. Reference: Forest Service Survey (MID 365: Eigentum)

Ownership of the forest, categorised according to the 7 types 'federal government', 'canton', 'municipality', 'citizens' community', 'corporation', 'individual private ownership' and 'company'. Reference: Forest Service Survey (MID 365: Eigentum)

Sample plots with/without traces of grazing by livestock pasturing in the relevant stand on the interpretation area (50 × 50 m), as well as intensity and recency of pasturing based on the occurrence and freshness of pasturing signs, especially tracks and droppings. Reference: Field Survey (MID 205: Beweidungsintensität)

Tree species group (conifers or broadleaves) with the larger basal area. For the calculation, the standing living trees and shrubs ≥12 cm in diameter at breast height (dbh) were taken into account. Reference: Field Survey (MID 1018: Baumzustand, MID 50: Baumart, MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Main tree species with the largest basal area. For the calculation, the standing living trees and shrubs ≥12 cm in diameter at breast height (dbh) were taken into account. Reference: Field Survey (MID 1018: Baumzustand, MID 50: Baumart, MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Type of the most important forest function relevant for managing the forest according to forest plans or an assessment by the local forest service during NFI4 (2009-2017). Reference: Forest Service Survey (MID 911: Vorrangfunktion 2)

Type of the most important forest function relevant for management according to forest plans or an assessment by the local forest service during NFI5 (2018-2026). Reference: Forest Service Survey (MID 911: Vorrangfunktion 2)

Presence of the primary function «nature and landscape conservation», classified into the four classes: «landscape protection», «nature conservation», «game protection» or «other» according to forest plans or an assessment by the local forest service during NFI5 (2018-2026). Reference: Forest Service Survey (MID 911: Vorrangfunktion 2)

Presence of the primary function: «nature conservation» according to forest plans or an assessment by the local forest service during NFI5 (2018-2026). Reference: Forest Service Survey (MID 911: Vorrangfunktion 2)

Proportion of conifers in the basal area of standing living trees and shrubs ≥12 cm in diameter at breast height (dbh) – in four classes. Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang)

Percentage of sanitary/salvage fellings in total fellings - in three classes. Reference: Forest Service Survey (MID 344: Anteil Zwangsnutzung)

Area in/outside a forest that provides protection against avalanches which the cantons designated «protective forest» according to the harmonised criteria of SilvaProtect-CH in 2022. Reference: GIS data from FOEN, 2022

Area in/outside a forest that provides protection against channel processes which the cantons designated «protective forest» according to the harmonised criteria of SilvaProtect-CH in 2022. Reference: GIS data from FOEN, 2022

Area in/outside a forest that provides protection against hillslope debris flows/landslides which the cantons designated «protective forest» according to the harmonised criteria of SilvaProtect-CH in 2022. Reference: GIS data from FOEN, 2022

Area in/outside a forest that provides protection against rockfall processes which the cantons designated «protective forest» according to the harmonised criteria of SilvaProtect-CH in 2022. Reference: GIS data from FOEN, 2022

Area inside/outside the protective forest that the cantons had designated in 2022 according to the harmonised criteria of SilvaProtect-CH (Losey & Wehrli 2013). In 2022, Canton Aargau had not yet designated its protective forest. Reference: GIS data from FOEN, 2022

Main reason for sanitary/salvage felling. Reference: Forest Service Survey (MID 345: Ursache der Zwangsnutzung)

Proportion of the area covered by regeneration, i.e. broadleaved and coniferous trees ≥10 cm in height and ≤11.9 cm in diameter at breast height (dbh), in six classes. The feature is available as of NFI2 (1993-1995). Reference: Field Survey (MID 270: Verjüngungs-Deckungsgrad)

Terrain topography - in five classes. Reference: Field Survey (MID 192: Relief)

Type of forest reserve («natural forest reserve», «special forest reserve“ or «other forest»), based on the forest reserves as designated by the cantons (as of 2023) and the forest/non-forest decision of the respective Inventory. Reference: GIS data from FOEN, 2023, and Field Survey (MID 816) or – if the forest is inaccessible – aerial photo interpretation

Presence of non-forestry buildings and facilities, such as railway lines, main roads, power- and pipelines or residential areas, which potentially impede logging, i.e. tree felling and processing. Reference: Field Survey (MID 207: Einschränkungen für die Holzhauerei)

Indication as to whether a silvicultural treatment took place since the last inventory. Reference: Forest Service Survey (MID 611: Art alle Eingriffe seit Referenzdatum)

Production capacity of the site in kilograms per hectare and year based on the total mean increment (TMI) according to Keller (1978) - in four classes. Low: TMI ≤1500 kg/(ha/year), moderate: TMI 1501-3000 kg/(ha/year), good: TMI 3001-4500 kg/(ha/year), very good: TMI >4500 kg/(ha/year).

Forest area under the same management – in eight classes. Several forest owners form a management unit («enterprise») if they have joined forces to manage their forests permanently (and not just for one logging operation). Reference: Forest Service Survey (MID 410: Grösse der Bewirtschaftungseinheit)

Slope in classes of 20%. Reference: Digital height model DHM 25 from Swisstopo

Slope in classes of 40%. Reference: Digital height model DHM 25 from Swisstopo

Presence of a forest function that is locally very important according to forest plans or an assessment by the local forest service – in two classes (present/absent). Forest functions include e.g. timber production, protection against natural hazards, nature conservation and drinking water protection. Reference: Forest Service Survey (MID 327: Spezielle Waldfunktionen)

Age of the stand – in classes of 20 years. Reference: Field Survey (MID 264: Bestandesalter)

Age of the stand – in classes of 40 years. Reference: Field Survey (MID 264: Bestandesalter)

Density of a stand – in four classes. The Stand Density Index (SDI) is calculated on the basis of the number of stems per hectare of trees and shrubs ≥12 cm in diameter at breast height (dbh) and the mean diameter. Reference: Field Survey (MID 60: Brusthöhendurchmesser, MID 62: Umfang, MID 1018: Baumzustand)

Stand in which the existing regeneration is very important because it is most likely to form the future main stand. In NFI, this is understood to mean the development stage young growth/thicket, regeneration under shelterwood and selection-type high forest. Reference: Field Survey (MID 261: Entwicklungsstufe, MID 433: Waldbauliche Beurteilung, MID 267: Bestandesstruktur); Forstdienstbefragung (MID 611: Art alle Eingriffe seit Referenzdatum)

Classification of tree collectives into three classes in order to distinguish small collectives (group [500-900 m²] and groves [1000-4900 m²]) from stands in the sense of silvicultural theory (≥5000 m²). Reference: Field Survey (MID 259: Bestandesgrösse)

Mechanical resistence of a stand to abiotic and biotic stresses within the next 10 to 20 years – in three classes. Reference: Field Survey (MID 310: Gesamtstabilität)

Vertical structure (stratification) of a stand, defined on the basis of the degrees of cover of the upper, middle and lower layers. Reference: Field Survey (MID 267: Bestandesstruktur)

Indication as to whether the current main stand (i.e. the trees of the upper layer) originated from natural regeneration (100% natural regeneration), artificial regeneration (<20% natural regeneration) or mixed regeneration (20-99% natural regeneration). Reference: Forest Service Survey (MID 404: Art der Bestandesentstehung)

Status and type of certification. Reference: Forest Service Survey (MID 319: Art der Zertifizierung)

Status of the forest development plan or a comparable cantonal forest planning document. Reference: Forest Service Survey (MID 803: Stand der Waldentwicklungspläne)

Information on whether the forest road network has been completed or whether an improvment is in progress (construction, project planning) or planned according to the current transportation system plan. Reference: Forest Service Survey (MID 614: Erschliessungsabsichten)

Techniques used in timber harvesting, i.e. for felling, processing and extracting trees – in twelve classes. If timber has been harvested since the last Inventory, the information is based on the procedures actually used. If, on the other hand, no harvesting has taken place, it is based on the procedures which, according to the district forester's assessment, would have been used in the case of an intervention at the time of the current Inventory. Abbreviations: LO: logging, EX: extraction, PS: pre-skidding, FE: felling, PRO: processing, CH: chopping, AS: assortment, FT: full tree. Reference: Forest Service Survey (MID 352: Art der Holzhauerei, MID: 3001: Rückemittel)

Number of years since the last silvicultural treatment – in classes of ten years. Silvicultural treatments include harvesting and tending interventions, planting and afforestation, as well as sanitary and safety interventions. Reference: Forest Service Survey (MID: 607: Anzahl Jahre seit dem letzten Eingriff)

Number of years since the last silvicultural treatment in classes of five or ten years. Silvicultural treatments include harvesting and tending interventions, planting and afforestation, as well as sanitary and safety interventions. Reference: Forest Service Survey (MID: 607: Anzahl Jahre seit dem letzten Eingriff)

Number of years until the next silvicultural treatment according to the forest planning schedule. Silvicultural treatments include harvesting and tending interventions, planting and afforestation, as well as sanitary and safety interventions. Reference: Forest Service Survey (MID 337: Zeitpunkt des nächsten Eingriffs)

Sample plots with/without traces of livestock pasturing in the relevant stand on the interpretation area (50 × 50 m). Traces could be: presence of pasturing livestock, faeces, fresh tracks, resting places, torn hairs and traces of browsing or fraying, and indication of the livestock class in the case of pasturing. Reference: Field Survey (MID 204: Beweidungsart)

Information about the large- and small-scale infrastructure used for the extraction and transport of timber. Reference: Forest Service survey (MID 326: Erschliessungskonzept)

Indication of how the stand is likely to be treated in the next intervention, taking into account local forest functions and planning. Reference: Forest Service Survey (MID 335: Art des nächsten Eingriffs)

Type of stand establishment, with natural and artificial regeneration distinguished. Reference: Field Survey (MID 275: Verjüngungsart)

Year in which the forest was (re)afforested during past centuries – in classes of ten years. Reference: Forest Service Survey (MID 332: Jahr der Aufforstung)

Year in which the forest was (re)afforested in earlier periods in six classes: before 1851; 1851-1900; 1901-1950; 1951-2000; 2001-2020; oe «no afforestation/afforestation unknown». Reference: Forest Service Survey (MID 332: Jahr der Aufforstung)

Year in which the forest development plan or a comparable cantonal planning document was put into effect – in six classes. Reference: Forest Service Survey (MID 804: Kalenderjahr der Inkraftsetzung des Waldentwicklungsplans WEP)

Sample plots without/with grazing and year when last grazed on by livestock. Reference: Forest Service Survey (MID 341: Jahr der letzten Beweidung)

Regional demarcation with the forest districts as a unit. This variable is based on a survey of the cantonal forest services in winter 2022/2023.

Area designated in both NFI4 (2009-2017) and NFI5 (2018-2026) as «accessible forest without shrub forest» (a.f.w.s.f.), i.e. «forest without shrub forest» that can be accessed on foot and is situated in a forest that the cantons designated «protective forest» in 2022 according to the harmonised criteria of SilvaProtect-CH (Losey & Wehrli 2013).