Selection from the list of topics

What do the numbers stand for?
What is the purpose of the standard error?
When are two results statistically different?
When is it not sufficient to consider only the standard error?
Two types of changes?
Change analyses: When are the results (not) additive?
Why is a dot (“.”) sometimes given in the cells for standard error or estimated value?
Why are no standard error values shown in some tables?
Negative values for growing stock, increment or fellings?

1. What do the numbers stand for?

The tables mainly show results that were calculated using statistical methods from the data of the sample inventory of the National Forest Inventory (NFI). Such results always consist of two figures: (1) the estimated value and (2) the sampling error, the so-called standard error.

Example 1: Estimated value and standard error

NFI5

volume of deadwood (stemwood)
ownership (2 categories)

regional demarcation: production region

unit: m³/ha

evaluation area: accessible forest without shrub forest

grid: 1.4 km grid, subgrids 1-5

state 2018/26
	production region
	Jura		Plateau		Pre-Alps		Alps		Southern Alps		Switzerland
ownership (2 categories)	m³/ha	±%	m³/ha	±%	m³/ha	±%	m³/ha	±%	m³/ha	±%	m³/ha	±%
public	30	10	17	13	37	9	36	6	26	10	30	4
private	27	17	20	12	50	10	32	8	39	13	34	5
total	29estimated value	9standard error	19	9	44	7	35	5	29	8	32	3

The tables usually show the relative (percentage) standard error (“±%”), but occasionally – in the case of estimated percentages – the absolute standard error (“±”).

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2. What is the purpose of the standard error?

The standard error can be used to define confidence intervals around the estimated value, which contain the true value of the population with a certain statistical certainty.

The statistical certainty is:

68% if the confidence interval is calculated using the standard error
(68% confidence interval = estimated value ± standard error), and
95% if the confidence interval is calculated using twice the standard error
(95% confidence interval = estimated value ± 2 × standard error*)

Example 2: Calculating confidence intervals

LFI5
volume of deadwood (stemwood)
ownership (2 categories)
regional demarcation: production region
unit: m³/ha
evaluation area: accessible forest without shrub forest
grid: 1.4 km grid, subgrids 1-5
state 2018/26
	production region
	Jura
ownership (2 classes)	m³/ha	±%
public	30	10
private	27	17
total	29	9

Question
What are the 68% and 95% confidence intervals of the above estimates?

Procedure

Calculate the absolute standard error (= relative standard error × estimated value / 100)
Calculate the confidence intervals
- 68% confidence interval = estimated value ± absolute standard error
- 95% confidence interval = estimated value ± 2 × absolute standard error

Answer

			Step 1	Step 2

ownership (2 categories)	volume of deadwood Jura NFI5
	estimated value	standard error		confidence interval
		relative	absolute	68%	95%
	m³/ha	±%	±m³/ha	m³/ha	m³/ha
public	30	10	3	27-33	24-36
private	27	17	5	22-32	17-37
total	29	9	3	26-32calculated with the standard error, i.e. 29 ± 3	23-35calculated with twice the standard error, i.e. 29 ± 2 × 3

The volume of deadwood in the Jura is between 26 and 32 m³/ha with a statistical certainty of 68% and between 23 and 35 m³/ha with a statistical certainty of 95%.

The 95% confidence interval is larger than the 68% confidence interval. This results in higher statistical certainty with the 95% confidence interval.

Example 3: Visualisation of the 68% and 95% confidence intervals

Data: see example 2

When interpreting the results, one must define the level of statistical certainty that one would like to apply to the statement.

The 68% confidence interval is generally used in the National Forest Inventory (NFI).

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3. When are two results statistically different?*

This can be checked by comparing the confidence intervals of two estimated values:

If the 68% confidence intervals of two estimates do not overlap, it can be assumed with some certainty that the two populations differ.
If the 95% confidence intervals of two estimates do not overlap, it can be assumed with high certainty that the two populations differ.

Example 4: Interpretation of two results from the same inventory

NFI5
growing stock (stemwood)
ownership (2 categories)
regional demarcation: production region
unit: m³/ha
evaluation area: accessible forest without shrub forest
grid: 1.4 km grid, subgrids 1-5
state 2018/26
	production region
	Jura		Plateau		Pre-Alps		Alps		Southern Alps		Switzerland
ownership (2 categories)	m³/ha	±%	m³/ha	±%	m³/ha	±%	m³/ha	±%	m³/ha	±%	m³/ha	±%
public	331	3	311	3	405	4	300	3	256	5	314	2
private	387	5	432	4	454	4	348	4	285	6	398	2
total	345	2	363	2	431	2	314	2	262	4	343	1

	case 2						case 1

case 1

Question
Is the growing stock per hectare greater in the Alps than in the Southern Alps?

Procedure

Calculate the absolute standard errors
Calculate the confidence intervals depending on the desired level of statistical certainty:
- 68% confidence intervals (some certainty; absolute standard error)
- 95% confidence intervals (high certainty; twice the absolute standard error)
Assess whether the confidence intervals corresponding to the desired level of statistical certainty do not overlap

Answer

ownership (2 categories)	growing stock NFI5
	Alps					Southern Alps
	estimated value	standard error		confidence interval		estimated value	standard error		confidence interval
		relative	absolute	68%	95%		relative	absolute	68%	95%
	m³/ha	±%	±m³/ha	m³/ha	m³/ha	m³/ha	±%	±m³/ha	m³/ha	m³/ha
total	314	2	6	308-320	302-326	262	4	10	252-272	242-282

Neither the 68%-confidence intervals nor the 95%-confidence intervals overlap (pairs of values in ).

In this case, the level of statistical certainty selected has no influence on the result.

Overall, this means that there is high statistical certainty that the growing stock per hectare is greater in the Alps than in the Southern Alps.

Case 2

Question
Is the growing stock per hectare greater in the Plateau than in the Jura?

Procedure

See case 1.

Answer

ownership (2 categories)	growing stock NFI5
	Jura					Plateau
	estimated value	standard error		confidence interval		estimated value	standard error		confidence interval
		relative	absolute	68%	95%		relative	absolute	68%	95%
	m³/ha	±%	±m³/ha	m³/ha	m³/ha	m³/ha	±%	±m³/ha	m³/ha	m³/ha
total	345	2	7	338-352	331-359	363	2	7	356-370	349-377

The 68%-confidence intervals do not overlap (pairs of values in ).
In contrast, the 95%-confidence intervals overlap (pairs of values in ).

In this case, the level of statistical certainty selected has an influence on the interpretation of the results. At the 68% confidence interval level, the conclusion is that the growing stock per hectare is higher in the Plateau than in the Jura. At the 95% confidence interval level, however, this conclusion cannot be drawn.

Considering both confidence interval levels, it can be said that there is some, but not high, statistical certainty that the growing stock per hectare is greater in the Plateau than in the Jura.

The confidence intervals can also be used to determine whether a value estimated with a sample from the National Forest Inventory (NFI) deviates from a target value (e.g. from Swiss forest policy) or whether a change between two inventories is statistically certain.

Example 5: Interpretation of two results from different inventories

ownership (2 categories)	growing stock Plateau*
	NFI4		NFI5
	m³/ha	±%	m³/ha	±%
public	340	3	309	3
private	447	4	432	4
total	386	2	363	2
* accessible forest without shrub forest NFI4/NFI5

Question
Has the growing stock per hectare in the Plateau decreased from NFI4 to NFI5?

Procedure

Calculate the absolute standard errors
Calculate the confidence intervals depending on the desired level of statistical certainty:
- 68% confidence intervals (some certainty; absolute standard error)
- 95% confidence intervals (high certainty; twice the absolute standard error)
Assess whether the confidence intervals corresponding to the desired level of statistical certainty do not overlap.

Answer

ownership (2 categories)	growing stock Plateau*
	NFI4					NFI5
	estimated value	standard error		confidence interval		estimated value	standard error		confidence interval
		relative	absolute	68%	95%		relative	absolute	68%	95%
	m³/ha	±%	±	m³/ha	m³/ha	m³/ha	±%	±	m³/ha	m³/ha
public	340	3	11	329-351	318-362	309	3	11	298-320	287-331
private	447	4	16	431-463	415-479	432	4	17	415-449	398-466
total	386	2	8	378-394	370-402	363	2	9	354-372	345-381
* accessible forest without shrub forest NFI4/NFI5

The 68%-confidence intervals do not overlap in the public forest and the total forest (pairs of values in ), but they do in the private forest (pairs of values in ). At the certainty level of the 68% confidence intervals, it can be concluded that the growing stock per hectare in the public forest and the total forest of the Plateau has decreased. For the private forest the decrease is not statistically certain at this level.

The 95%-confidence intervals overlap in all three categories. At the certainty level of the 95% confidence intervals, it is therefore not certain that the growing stock has decreased, even for the public forest and total forest.

See also examples 6 and 7, in which changes between two inventories are interpreted using the more sensitive metric of net change.

For many target variables in the NFI, it is possible to determine whether a change between two inventories is statistically certain, not only by comparing the states in the two inventories (see example 5), but also by analysing the net change** between the two inventories.

To do this, one must first define the level of statistical certainty that one would like to apply to the statement (as done above):

A net change has occurred with some certainty if the relative standard error is less than 100% or if the confidence interval calculated with the absolute standard error (68% confidence interval) does not include the value 0.
A net change has occurred with high certainty if twice the relative standard error is less than 100% or if the confidence interval calculated with twice the absolute standard error (95% confidence interval) does not include the value 0.

Example 6: Interpretation of net changes with the relative standard error

ownership (2 categories)	change in growing stock from NFI4 to NFI5, Plateau*
	estimated value	standard error
	m³/ha	±%
public	-34	30
private	-9	147
total	-23	34
* accessible forest without shrub forest NFI4/NFI5

Question
Has the growing stock per hectare in the Plateau decreased from NFI4 to NFI5?

Procedure

Define the level of statistical certainty (68% or 95% confidence interval)
Determine whether:
- the relative standard error is less than 100% (certainty level of the 68% confidence interval)
- twice the relative standard error is less than 100% (certainty level of the 95% confidence interval)

Answer

ownership (2 categories)	change in growing stock from NFI4 to NFI5, Plateau*
	estimated value	standard error
		single	double
	m³/ha	±%	±%
public	-34	30	60
private	-9	147	294
total	-23	34	68
* accessible forest without shrub forest NFI4/NFI5

The single relative standard error is less than 100% for both the public forest and the total forest (highlighted values). For the private forest, however, it is greater than 100% (highlighted values). At the certainty level of the 68% confidence interval, it can be concluded that the growing stock in the Plateau has decreased in the public forest and in total. For the private forest, on the other hand, the decrease in stock is not statistically certain at this level.

The same conclusion is reached in this example with the certainty level of the 95% confidence interval, as twice the relative standard error is again less than 100% for both the public forest and the total forest.

Overall, this means that there is high statistical certainty that the growing stock per hectare has decreased in the public forest in the Plateau, as well as overall. For private forests, on the other hand, the decrease in stock is not statistically certain (as twice the relative standard error and the relative standard error are both less than 100%).

Example 7: Interpretation of net changes with the absolute standard error

ownership (2 categories)	change in growing stock from NFI4 to NFI5, Plateau*
	estimated value	standard error
	%	±
public	-10	3
private	-2	3
total	-6	2
* accessible forest without shrub forest NFI4/NFI5

Question
Has the growing stock per hectare in the Plateau decreased from NFI4 to NFI5?

Procedure

Define the level of statistical certainty (68% or 95% confidence interval)
Calculate the confidence interval based on the defined certainty level
- 68% confidence interval with the absolute standard error
- 95% confidence interval with twice the absolute standard error
Determine whether the corresponding confidence interval does not include the value 0

Answer

ownership (2 categories)	change in growing stock from NFI4 to NFI5, Plateau*
	estimated value	standard error		confidence interval
		single	double	68%	95%
	%	±	±	%	%
public	-10	3	6	-13 to -7	-16 to -4
private	-2	3	6	-5 to +1	-8 to +4
total	-6	2	4	-8 to -4	-10 to -2
* accessible forest without shrub forest NFI4/NFI5

Neither the 68% nor the 95% confidence interval includes the value 0 for the public forest or for the total forest. At both certainty levels, this leads to the conclusion that the growing stock in the Plateau has decreased in the public forest and in total. For the private forest, on the other hand, the decrease in stock is not statistically certain (as the confidence intervals include the value 0).

Net changes can be interpreted using the absolute or relative standard error (see examples 6 and 7). It is advisable to use the absolute standard error if the estimated value in the table is shown as a percentage (%; as in example 7), and the relative standard error if the estimated value in the table is shown in absolute terms (m³, m³/ha, pc, m²; as in example 6). This means that the standard error can be taken directly from the table and does not need to be converted.

To assess whether a change is statistically certain, it is advisable to analyse the net change between the two inventories wherever possible. Net changes are more sensitive than status comparisons, which makes it easier to detect differences statistically. See examples 6 and 7 (net change) and 7 (comparison of two results from different inventories).

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4. When is it not sufficient to consider only the standard error?

The National Forest Inventory (NFI) is a sample-based large-scale inventory whose sample areas are arranged on a grid with a mesh size of 1.4 km × 1.4 km. The NFI was designed in such a way that the growing stock for Switzerland as a whole can be predicted with a maximum standard error of 1%.

If results are requested for individual regions or for individual classes, the standard error quickly becomes much larger. This is because the number of sample areas and subjects (e.g. sample trees, young forest plants, pieces of deadwood) analysed for the queried combination of variable expressions* is considerably lower than for the total.

Example 8: Standard error and combination of variable expressions

region	growing stock
	total		maple		sycamore		Norway maple
	estimated value	standard error	estimated value	standard error	estimated value	standard error	estimated value	standard error
	m³/ha	±%	m³/ha	±%	m³/ha	±%	m³/ha	±%
Switzerland	343	1	12	5	11	5	1	20
production region "Plateau"	363	2	15	10	14	11	0	50
Canton of Aargau	289	7	15	20	13	20	1	63

The standard error increases as the level of detail increases.

Large standard errors are to be expected if:

forest districts are selected as the regional demarcation or results for small cantons (e.g. Appenzell Innerrhoden, Nidwalden) are queried,
a classification variable with many classes is selected (e.g. tree species in 56 classes),
several classification variables are combined with each other (e.g. main tree species and development stage).

Large standard errors are an indication that the estimate may have been based on too small a number of sample areas or subjects and that the result of the estimate therefore may not be reliable.

For the target variable “number of stems of young forest plants with browsing damage” (browsing intensity), an uncertain estimate is not necessarily recognisable by a large standard error. This is because this target variable is a quotient estimator**, which is – due to the survey method – only based on a small number of assessed young forest plants for rarer tree species (e.g. pine, larch, Arolla pine, oak, chestnut). Accordingly, for this target variable one should always check how many young forest plants were assessed for the individual estimates. As a rule of thumb, at least 30 young forest plants per estimate should have been assessed for browsing in order to obtain a reliable estimate.

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5. Two types of changes?

There are two types of changes in the National Forest Inventory (NFI):

The first type of change involves specific target variables for change components such as increment, fellings or mortality. These target variables are only available for two consecutive measurement cycles, e.g. NFI4 to NFI5. When change components are analysed, the classification variable expression of the second measurement cycle is generally assigned to the first measurement cycle. These analyses therefore do not take into account any change in the expression (e.g. from private to public ownership) from the earlier to the later measurement cycle.
In the second type of change, the difference in target variables, such as stem number, growing stock or forest area, is used to calculate the net change between two measurement cycles. These target variables are usually used to represent states, e.g. that in NFI5, but can also show the net change between any two measurement cycles, e.g. between NFI1 and NFI5. In these net change analyses, the change in expression is taken into account for some of the classification variables, including “tree condition” and “forest, non-forest”. In this way, it can be seen, for example, that the forest area has increased. For the remaining classification variables, the expressions are regarded as static. This means that the most recent state – whether it was assessed in a measurement cycle (e.g. “primary forest function NFI5”) or taken from an external data source (e.g. “protection forest [2022]”) – is assigned to all measurement cycles.

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6. Change analyses: When are the results (not) additive?

The results are:

additive if they are reported as the total change between two measurement dates. For example, the fellings for the various production regions reported in cubic metres (m³) can be added together to obtain the total fellings for Switzerland.
not additive if they are reported as a change per year (e.g. m³/year). For example, the fellings for the various production regions reported in cubic metres per year (m³/year) cannot be added together to obtain the total fellings for Switzerland.

Example 9: : Additivity/non-additivity of changes

	growing stock: total change between NFI4 and NFI5 (in 1000 m³)*
	Jura		Plateau		Pre-Alps		Alps		Southern Alps		Switzerland
higher/lower altitude zone	1000 m³	±%	1000 m³	±%	1000 m³	±%	1000 m³	±%	1000 m³	±%	1000 m³	±%
lower altitude zone	-3759.0	28	-4909.1	36	-1025.2	133	-317.1	195	3464.1	31	-6546.3	42
higher altitude zone	574.3	117	-328.0	62	1093.0	123	7128.4	21	666.7	93	9134.3	24
total	-3184.7	40	-5237.1	34	67.9	2805	6811.3	23	4130.8	30	2588.1	136
	* accessible forest without shrub forest NFI4/NFI5
	additive

	growing stock: annual change between NFI4 and NFI5 (in 1000 m³/year)*
	Jura		Plateau		Pre-Alps		Alps		Southern Alps		Switzerland
higher/lower altitude zone	1000 m³/year	±%	1000 m³/year	±%	1000 m³/year	±%	1000 m³/year	±%	1000 m³/year	±%	1000 m³/year	±%
lower altitude zone	-421.1	28	-560.6	36	-115.7	133	-35.9	195	389.5	31	-740.7	42
higher altitude zone	64.7	117	-38.3	62	122.4	123	810.4	21	74.9	93	1032.7	24
total	-357.3	40	-598.4	34	7.6	2805	773.8	23	464.4	30	292.7	136
	* accessible forest without shrub forest NFI4/NFI5
	not additive

The non-additivity of changes expressed per year arises because the total change is divided by the average number of years between the two measurement dates in the domain* under consideration, and this average number of years varies slightly depending on the domain.

Example 10: Average number of years per domain

domain		mean number of years*
production region	higher/lower altitude zone
Mittelland	-	8.75
Plateau	higher altitude zone	8.56
Plateau	lower altitude zone	8.76
Southern Alps	-	8.90
Southern Alps	higher altitude zone	8.90
Southern Alps	lower altitude zone	8.89
* between the NFI4 and NFI5 measurements in the accessible forest without shrub forest

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7. Why is a dot (“.”) sometimes given in the cells for standard error or estimated value?

In the calculation of a results table, data is not always available for all combinations of variable expressions*. In most cases, this indicates that the variable estimated with the relevant target variable does not occur or only occurs very rarely. The value 0 is then usually used. However, as this value is not based on any direct measurements, a dot (“.”) is given for the associated standard error. If reference is made to the assumed value of 0 in the calculation, e.g. in the case of percentages or certain change estimates, no value can be used. In this case, a dot (“.”) is given for the estimated value and the standard error.

For example, no Arolla pines have yet been found and measured in the Plateau in the National Forest Inventory (NFI) (growing stock of Arolla pine by production region). It can therefore be assumed that the values are missing because the Arolla pine actually does not occur in the Plateau, and therefore the growing stock in that region must be 0.

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8. Why are no standard error values shown in some tables?

The data in these tables originates from a complete survey and not from a sample inventory. Accordingly, it is not necessary to specify a standard error because there is no uncertainty due to sampling.

The forest road network survey that the National Forest Inventory (NFI) periodically carries out with the local forestry services is an example of such a complete survey.

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9. Negative values for growing stock, increment or fellings?

A negative value is possible if the result could only be calculated on the basis of a few trees. The estimate is therefore not reliable. This is also reflected in the standard error, which is usually extremely large for negative stock, increment or felling values.

Negative values can occur because, when the stemwood volume of the tally trees is determined, the volume estimated solely on the basis of the diameter at breast height (DBH) (tariff volume) is adjusted using the volume of the tally trees estimated on the basis of DBH, diameter at 7 m height and tree height. This procedure enables an unbiased and more accurate calculation of the stemwood volume. However, it can lead to negative values for all target variables that are based on the stemwood volume of the tally trees (e.g. growing stock, increment, fellings) if the number of tally trees in the selected combination of variable expressions* is small.

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NFI1
number of stems
diameter at breast height (10 classes) · main tree species
regional demarcation: production region
unit: 1000 n
evaluation area: accessible forest without shrub forest
grid: 1.4-km grid
state 1983/85
		production region
		Jura		Plateau		Pre-Alps		Alps		Southern Alps		Switzerland
diameter at breast height (10 classes)	main tree species	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%
n/a	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	0	.	0	.	0	.	0	.	0	.	0	.
	fir	0	.	0	.	0	.	0	.	0	.	0	.
	pine	0	.	0	.	0	.	0	.	0	.	0	.
	larch	0	.	0	.	0	.	0	.	0	.	0	.
	Arolla pine	0	.	0	.	0	.	0	.	0	.	0	.
	other conifers	0	.	0	.	0	.	0	.	0	.	0	.
	beech	0	.	0	.	0	.	0	.	0	.	0	.
	maple	0	.	0	.	0	.	0	.	0	.	0	.
	ash	0	.	0	.	0	.	0	.	0	.	0	.
	oak	0	.	0	.	0	.	0	.	0	.	0	.
	sweet chestnut	0	.	0	.	0	.	0	.	0	.	0	.
	other broadleaves	0	.	0	.	0	.	0	.	0	.	0	.
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	0	.	0	.	0	.	0	.	0	.	0	.
12-20 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	8328	10	13171	9	18619	6	26790	4	3099	13	70007	3
	fir	6436	7	5180	10	7247	7	3042	12	449	27	22353	4
	pine	534	31	515	32	459	44	6655	12	88	51	8252	10
	larch	68	43	394	48	21	71	3788	10	1450	15	5721	8
	Arolla pine	0	.	0	.	43	100	1412	17	0	.	1455	17
	other conifers	397	39	483	29	114	35	483	38	0	.	1477	19
	beech	12765	6	11010	6	9048	7	5930	9	6538	11	45291	3
	maple	2607	9	2275	16	2375	10	2548	12	400	22	10206	6
	ash	1879	14	2917	11	2601	14	1733	16	1173	19	10304	6
	oak	1425	24	1920	22	183	36	756	23	1306	25	5590	12
	sweet chestnut	0	.	49	82	0	.	71	59	7450	11	7570	11
	other broadleaves	3201	11	4470	11	4133	13	7613	9	8897	8	28314	4
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	37641	4	42384	4	44843	4	60820	3	30850	5	216539	2
21-30 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	5205	8	7643	7	13556	6	20232	4	2281	13	48918	3
	fir	4110	8	3565	9	4684	7	1544	12	198	33	14101	4
	pine	752	21	561	20	298	35	3686	11	202	47	5499	8
	larch	116	43	230	34	0	.	3171	9	1217	15	4733	8
	Arolla pine	0	.	0	.	62	75	1251	15	10	100	1324	15
	other conifers	39	62	108	32	10	100	30	58	0	.	187	25
	beech	9180	5	6879	6	5209	7	3080	10	2395	12	26743	3
	maple	1648	9	1431	12	1421	11	1208	13	143	35	5851	5
	ash	1307	13	1742	11	1292	13	673	20	316	28	5329	7
	oak	1058	18	1272	14	117	41	241	35	583	26	3272	10
	sweet chestnut	0	.	78	88	0	.	29	58	2398	13	2505	13
	other broadleaves	1401	12	1819	12	796	16	1655	13	2648	11	8320	6
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	24815	3	25328	3	27448	3	36800	3	12392	5	126783	2
31-40 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	4056	7	7513	6	9957	5	13553	4	1561	13	36640	2
	fir	2887	8	2622	8	3184	7	985	12	187	35	9865	4
	pine	949	14	1187	13	127	31	1655	11	148	53	4066	7
	larch	42	54	226	23	26	59	2567	8	820	14	3680	7
	Arolla pine	0	.	0	.	9	100	711	15	5	100	725	15
	other conifers	0	.	74	43	0	.	10	100	0	.	85	40
	beech	5008	5	3955	6	3212	8	1358	11	831	13	14364	3
	maple	622	13	399	18	505	17	334	18	26	54	1886	8
	ash	457	16	1089	11	502	18	214	24	62	45	2325	8
	oak	428	19	699	13	32	49	66	46	231	28	1456	10
	sweet chestnut	0	.	0	.	0	.	36	53	603	16	639	15
	other broadleaves	416	17	515	15	168	34	434	18	572	16	2105	8
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	14865	3	18279	3	17721	3	21923	3	5046	6	77834	1
41-50 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	2758	6	4585	5	6121	4	7712	4	991	11	22168	2
	fir	1479	7	1649	8	2112	7	590	12	166	25	5996	4
	pine	484	15	772	12	158	35	667	13	23	71	2105	7
	larch	23	52	125	23	37	46	1737	7	490	12	2412	6
	Arolla pine	0	.	0	.	0	.	304	17	4	100	308	17
	other conifers	0	.	79	50	0	.	0	.	0	.	79	50
	beech	2094	6	2029	7	1352	9	660	12	322	15	6457	4
	maple	127	18	161	20	119	22	104	21	4	100	514	10
	ash	125	21	360	14	125	22	40	37	10	72	660	10
	oak	180	19	415	15	13	58	57	35	34	38	698	11
	sweet chestnut	0	.	4	100	0	.	8	71	379	17	390	17
	other broadleaves	97	28	166	21	44	32	106	27	66	29	479	12
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	7367	3	10344	3	10082	3	11983	3	2489	6	42266	2
51-60 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	1201	8	1941	7	2837	6	3642	5	465	13	10086	3
	fir	535	11	604	11	890	9	348	14	66	33	2443	5
	pine	139	22	272	16	29	61	212	24	15	50	668	12
	larch	16	50	59	26	36	46	980	9	274	14	1365	7
	Arolla pine	0	.	0	.	4	100	118	21	0	.	122	21
	other conifers	0	.	29	42	0	.	0	.	0	.	29	42
	beech	563	11	668	10	538	13	266	16	130	23	2165	6
	maple	27	50	49	29	33	39	16	50	0	.	125	20
	ash	44	33	128	21	22	45	15	61	0	.	209	16
	oak	116	28	188	16	19	50	4	100	26	61	353	14
	sweet chestnut	0	.	0	.	0	.	4	100	146	21	150	21
	other broadleaves	29	42	66	29	4	100	42	40	34	36	175	18
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	2670	5	4004	4	4410	4	5648	4	1157	7	17889	2
61-70 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	345	12	445	11	854	8	1160	8	195	20	2999	5
	fir	172	16	139	17	317	14	69	26	33	39	729	8
	pine	16	61	43	35	15	59	38	39	0	.	111	22
	larch	0	.	23	47	10	72	337	13	78	27	448	12
	Arolla pine	0	.	0	.	0	.	43	33	0	.	43	33
	other conifers	4	100	8	71	4	100	0	.	0	.	16	50
	beech	139	19	269	15	69	27	83	26	53	28	614	10
	maple	22	45	0	.	0	.	4	100	0	.	26	41
	ash	21	52	12	58	4	100	0	.	0	.	37	37
	oak	9	71	69	29	25	51	0	.	5	100	108	23
	sweet chestnut	0	.	0	.	0	.	0	.	54	32	54	32
	other broadleaves	4	100	8	71	5	100	8	71	8	71	33	36
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	730	8	1016	7	1303	7	1742	6	427	12	5218	3
71-80 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	107	23	125	20	262	16	457	11	100	24	1052	8
	fir	73	26	61	28	115	21	35	37	16	60	301	13
	pine	0	.	4	100	0	.	4	100	0	.	8	71
	larch	4	100	4	100	0	.	142	19	32	35	182	17
	Arolla pine	0	.	0	.	0	.	51	32	0	.	51	32
	other conifers	0	.	4	100	0	.	0	.	0	.	4	100
	beech	23	41	61	29	26	41	8	71	37	46	156	19
	maple	0	.	6	100	7	71	9	72	4	100	26	42
	ash	0	.	18	51	0	.	0	.	0	.	18	51
	oak	4	100	44	32	0	.	4	100	0	.	51	29
	sweet chestnut	0	.	0	.	0	.	4	100	80	37	84	35
	other broadleaves	0	.	4	100	0	.	0	.	0	.	4	100
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	211	17	329	13	411	13	715	9	269	17	1935	6
81-90 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	20	45	24	41	32	35	124	18	27	38	229	13
	fir	8	71	8	71	51	29	12	58	10	72	88	22
	pine	0	.	4	100	0	.	0	.	0	.	4	100
	larch	0	.	4	100	0	.	54	28	9	71	66	25
	Arolla pine	0	.	0	.	0	.	8	71	0	.	8	71
	other conifers	0	.	0	.	0	.	0	.	0	.	0	.
	beech	4	100	47	30	4	100	11	58	0	0	67	25
	maple	0	.	0	.	4	100	4	100	0	.	8	71
	ash	0	.	0	.	0	.	0	.	0	.	0	.
	oak	8	71	20	45	0	.	0	.	0	.	28	38
	sweet chestnut	0	.	0	.	0	.	0	.	27	41	27	41
	other broadleaves	0	.	5	100	0	.	0	.	0	.	5	100
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	40	31	112	21	91	21	213	14	73	24	530	9
91-100 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	8	71	7	71	16	50	45	33	8	71	85	23
	fir	7	71	4	100	8	71	12	58	0	.	32	35
	pine	0	.	0	.	0	.	0	.	0	.	0	.
	larch	0	.	0	.	0	.	12	58	4	100	16	50
	Arolla pine	0	.	0	.	0	.	4	100	0	.	4	100
	other conifers	0	.	0	.	0	.	0	.	0	.	0	.
	beech	0	.	8	71	0	.	0	.	0	.	8	71
	maple	0	.	0	.	0	.	0	.	0	.	0	.
	ash	0	.	0	.	0	.	0	.	0	.	0	.
	oak	0	.	7	71	0	.	0	.	0	.	7	71
	sweet chestnut	0	.	0	.	0	.	4	100	36	39	40	37
	other broadleaves	0	.	0	.	0	.	0	.	0	.	0	.
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	16	50	27	38	24	41	77	24	48	33	192	15
>100 cm	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	0	.	0	.	8	71	22	55	12	75	42	38
	fir	4	100	0	.	0	0	0	.	15	59	18	51
	pine	0	.	0	.	0	.	0	.	0	.	0	.
	larch	0	.	0	.	0	.	12	58	8	71	20	45
	Arolla pine	0	.	0	.	0	.	8	71	0	.	8	71
	other conifers	0	.	0	.	0	.	0	.	0	.	0	.
	beech	0	.	0	.	0	.	0	.	4	100	4	100
	maple	0	.	0	.	0	.	0	.	0	.	0	.
	ash	0	.	0	.	0	.	0	.	0	.	0	.
	oak	0	.	4	100	0	.	0	.	0	.	4	100
	sweet chestnut	0	.	0	.	0	.	0	.	59	34	59	34
	other broadleaves	5	100	0	.	0	.	0	.	4	100	9	71
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	9	72	4	100	8	71	41	36	101	24	163	19
total	n/a	0	.	0	.	0	.	0	.	0	.	0	.
	spruce	22030	5	35456	4	52263	4	73736	3	8740	9	192225	2
	fir	15709	5	13831	6	18607	5	6637	9	1141	21	55925	3
	pine	2874	12	3358	10	1086	29	12917	9	476	40	20712	6
	larch	269	30	1062	23	130	35	12801	6	4382	10	18643	5
	Arolla pine	0	.	0	.	117	82	3910	12	19	82	4047	12
	other conifers	440	39	785	22	129	32	523	36	0	.	1876	17
	beech	29778	4	24926	4	19460	6	11396	8	10310	10	95870	2
	maple	5053	7	4321	11	4463	8	4226	10	577	23	18641	4
	ash	3832	11	6265	8	4546	11	2676	14	1561	17	18881	5
	oak	3227	16	4638	12	389	24	1128	22	2185	20	11567	8
	sweet chestnut	0	.	131	86	0	.	155	43	11231	10	11517	9
	other broadleaves	5152	9	7053	9	5151	12	9857	8	12230	8	39444	4
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.
	total	88364	2	101827	2	106341	2	139963	2	52852	3	489347	1

Table citation

Abegg, M.; Ahles, P.; Allgaier Leuch, B.; Cioldi, F.; Didion, M.; Düggelin, C.; Fischer, C.; Herold, A.; Meile, R.; Rohner, B.; Rösler, E.; Speich, S.; Temperli, C.; Traub, B.,
2023: Swiss national forest inventory - Result table No. 1326954. Birmensdorf, Swiss Federal Research Institute WSL

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