220
Regional Environmental Changes: Application to Soil Erosion Modeling
where:
Di = tree diameter measured at 1.30 m,
n = number of samples,
= mean diameters,
Sdm = mean diameter spread.
The Sd m value was divided into the mean diameter and expressed, in percentage, as
follows:
(3.4 ).
The correlation (Fig. 3) between the height percentage spread and the last
parameter was calculated using the regression procedure (r 2 =0.88).
In conclusion, the correlation between the Sdm % and the trees in the last two layers
was calculated, confirming that it is possible to replace the height index with that
of the diameters. The regression obtained in this case (r 2 =0.78) is also good
(Fig. 4).
3
CONCLUSION
If one takes into account the results obtained in the case of the forest types
(Western Alps coniferous forests) examined, the diameter measurements are
sufficient to identify the stratification degree of the forest.
As expected, the lower Shr % values obtained describe a mono-stratified
community; on the other hand, the spread values proportionally increase with an
increase of the forest complexity, allowing one to place each forest in its proper
structural type group.
The obtained index (Fig. 5) is included in a theoretical range of 0 to 100, where 0
indicates mono-stratified forest, while 100 indicates a hypothetical maximum
variability (multi-stratified forest). A single layer forest shows guide values of
between 18 and 35 (this being the case of almost all the Pinus sylvestris forests
examined); guide values of between 36 and 55 characterize quite an irregular
height distribution; the higher values consist of forests where the different height
classes are mixed, such as the Abies alba more natural forests surveyed.
The environmental quality index, in relation to the forest stability determined by
the forest structure analysis, presents several advantages:
it is surveyed rapidly;
it can be objectively determined;
it is separated from considerations based on a single experiment or the
analysis of the data surveyor;
• it enables one to obtain complete and easy information for land
management use.
Regional Environmental Changes: Application to Soil Erosion Modeling
where:
Di = tree diameter measured at 1.30 m,
n = number of samples,
= mean diameters,
Sdm = mean diameter spread.
The Sd m value was divided into the mean diameter and expressed, in percentage, as
follows:
(3.4 ).
The correlation (Fig. 3) between the height percentage spread and the last
parameter was calculated using the regression procedure (r 2 =0.88).
In conclusion, the correlation between the Sdm % and the trees in the last two layers
was calculated, confirming that it is possible to replace the height index with that
of the diameters. The regression obtained in this case (r 2 =0.78) is also good
(Fig. 4).
3
CONCLUSION
If one takes into account the results obtained in the case of the forest types
(Western Alps coniferous forests) examined, the diameter measurements are
sufficient to identify the stratification degree of the forest.
As expected, the lower Shr % values obtained describe a mono-stratified
community; on the other hand, the spread values proportionally increase with an
increase of the forest complexity, allowing one to place each forest in its proper
structural type group.
The obtained index (Fig. 5) is included in a theoretical range of 0 to 100, where 0
indicates mono-stratified forest, while 100 indicates a hypothetical maximum
variability (multi-stratified forest). A single layer forest shows guide values of
between 18 and 35 (this being the case of almost all the Pinus sylvestris forests
examined); guide values of between 36 and 55 characterize quite an irregular
height distribution; the higher values consist of forests where the different height
classes are mixed, such as the Abies alba more natural forests surveyed.
The environmental quality index, in relation to the forest stability determined by
the forest structure analysis, presents several advantages:
it is surveyed rapidly;
it can be objectively determined;
it is separated from considerations based on a single experiment or the
analysis of the data surveyor;
• it enables one to obtain complete and easy information for land
management use.