Stand structure and canopy metrics

Horizontal and vertical stand structure metrics (coefficients of variation, structural diversity indices, slenderness) and crown mensuration variables at plot and tree levels.

Plot-level variables

Slenderness (SLENDERNESS_MEAN) — decimal • dimensionless • output: S_mean • multi-species: sp1, sp2, sp3

Mean stand slenderness coefficient. Ratio of mean tree height to mean diameter at breast height.

Simulation breakdown: This variable is automatically expanded for each target stand species (Slenderness_SP1, Slenderness_SP2, Slenderness_SP3).
Dominant_slenderness (SLENDERNESS_DOM) — decimal • dimensionless • output: S_dom • multi-species: sp1, sp2, sp3

Dominant stand slenderness coefficient. Ratio of dominant height to dominant diameter.

Simulation breakdown: This variable is automatically expanded for each target stand species (Dominant_slenderness_SP1, Dominant_slenderness_SP2, Dominant_slenderness_SP3).
Mean_crown_d (CROWN_MEAN_D) — decimal • m • output: dc_mean • multi-species: sp1, sp2

Mean tree crown diameter in the plot.

Simulation breakdown: This variable is automatically expanded for each target stand species (Mean_crown_d_SP1, Mean_crown_d_SP2).
Do_crown (CROWN_DOM_D) — decimal • m • output: Do_crown • multi-species: sp1, sp2

Dominant crown diameter of the stand.

Simulation breakdown: This variable is automatically expanded for each target stand species (Do_crown_SP1, Do_crown_SP2).
Canopy_cover — decimal • % • output: FCC • multi-species: sp1, sp2

Canopy cover fraction. Percentage of ground covered by the vertical projection of tree crowns.

Simulation breakdown: This variable is automatically expanded for each target stand species (Canopy_cover_SP1, Canopy_cover_SP2).
Canopy_vol — decimal • m3/ha • output: V_canopy • multi-species: sp1, sp2

Apparent volume occupied by tree crowns per hectare.

Simulation breakdown: This variable is automatically expanded for each target stand species (Canopy_vol_SP1, Canopy_vol_SP2).
CCF — decimal • % • output: CCF

Stand crown competition factor (CCF). Percentage of area occupied by potential crowns of open-grown trees.
CV_dbh — decimal • % • output: CV_dbh

Coefficient of variation of the diameter at breast height distribution (%). Ratio of the standard deviation to the mean of dbh values in the plot.

Reference: Varga et al. (2005). Tree-size diversity in progression of stand development in Douglas-fir forests. Forest Ecology and Management.
CV_height — decimal • % • output: CV_h

Coefficient of variation of the height distribution (%). Ratio of the standard deviation to the mean of height values in the plot.

Reference: Varga et al. (2005). Tree-size diversity in progression of stand development in Douglas-fir forests. Forest Ecology and Management.
Shannon_dbh_index (SHANNON_DBH) — decimal • dimensionless • output: Shannon_dbh

Shannon-Weaver Diversity Index applied to dbh distribution in the plot, using 5 cm diameter classes. This positive index usually ranges from 0.5 to 5, with typical values between 2 and 3. Values below 2 are considered low in diversity, while values above 3 indicate high species diversity.

References:
- Varga et al. (2005). Tree-size diversity in progression of stand development in Douglas-fir forests. Forest Ecology and Management.
- Omoro et al. (2010). Tree biomass and soil carbon stocks in Taita Hills, Kenya. African Journal of Ecology.
- Moreno-Fernández et al. (2025). Structural diversity indices in managed forests.
Shannon_h_index (SHANNON_HEIGHT) — decimal • dimensionless • output: Shannon_h

Shannon-Weaver Diversity Index applied to height distribution in the plot, using 2.5 m height classes. This positive index usually ranges from 0.5 to 5, with typical values between 2 and 3. Values below 2 are considered low in diversity, while values above 3 indicate high species diversity.

References:
- Varga et al. (2005). Tree-size diversity in progression of stand development in Douglas-fir forests. Forest Ecology and Management.
- Omoro et al. (2010). Tree biomass and soil carbon stocks in Taita Hills, Kenya. African Journal of Ecology.
- Moreno-Fernández et al. (2025). Structural diversity indices in managed forests.
Structural_diversity_index_dbh (SQRI_DBH) — decimal • dimensionless • output: SQRI_DBH

Stand structural diversity index based on the sum of square roots of tree dbh differences (Barbeito et al., 2009).

References:
- Moreno-Fernández et al. (2025). Structural diversity indices in managed forests.
- Barbeito (2009). Natural regeneration dynamics of Pinus sylvestris L. in Central Spain.
Structural_diversity_index_height (SQRI_HEIGHT) — decimal • dimensionless • output: SQRI_HEIGHT

Stand structural diversity index based on the sum of square roots of tree height differences (Barbeito et al., 2009).

References:
- Moreno-Fernández et al. (2025). Structural diversity indices in managed forests.
- Barbeito (2009). Natural regeneration dynamics of Pinus sylvestris L. in Central Spain.

Tree-level variables

slenderness — decimal • dimensionless • output: slenderness

Individual tree slenderness coefficient. Ratio of total tree height to diameter at breast height (h / dbh).
hcb — decimal • m • output: hcb

Height to live crown base measured from ground level.
cr — decimal • % • output: cr

Live crown ratio. Percentage of total tree height occupied by the live crown.
lcw — decimal • m • output: lcw

Largest crown width. Maximum horizontal width or diameter of the live crown.
hlcw — decimal • m • output: hlcw

Height from ground level to the position of largest crown width.
mcw — decimal • m • output: mcw

Maximum horizontal crown width estimated by open-grown crown equations.
cpa — decimal • m2 • output: cpa

Crown projection area. Horizontal ground surface projection of the tree crown.
ccfl — decimal • % • output: ccfl

Crown competition factor considering only trees with larger diameter than the subject tree.

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