ForestElementsR (version 2.0.1)

stand_level_increment: stand_level_increment

Description

Calculate periodic annual stand level increments from time-ordered vectors of appropriate stand sum variables. Typically the variable of interest is a stand's wood volume per unit area, but it works equally for stand basal area and biomass.

Usage

stand_level_increment(time, x_remain, x_remove)

Value

A vector of the annual increments for the stand level variable of interest corresponding to the input vector time. The increments always relate to the period from (and including) the corresponding point in time back to (and excluding) the previous point in time. Thus, the first element of the output vector is always NA. If the input vectors are of length 1 only, the function consequently returns NA.

Arguments

time

Vector of points in time. Must be unique and in ascending order

x_remain

Vector of the variable of interest (typically wood volume) for the remaining stand. "Remaining stand" means the amount which is actually there at the corresponding point in time. The vector x_remaing must be arranged corresponding to the input vector time.

x_remove

Vector of the variable of interest (typically wood volume) for the removal stand. Each entry in this vector represents the amount removed up to and including the corresponding point of time, but after the previous point in time.

Details

The input vector x_remove is to be understood as the amount removed up to (or at) the corresponding points in time and after the preceding points in time in the time input vector. The resulting increments are to be understood in a similar way: The entries in the increment vector relate to the period between the entry at the same position in the time input vector and the time entry at the position before. Therefore, the first element of the resulting increment vector is always NA.

Examples

 # Stand age, remaining and removal volume (m³/ha)
 age        <- seq(20, 70, 5)
 vol_remain <- c(65, 118, 175, 233, 293, 355, 416, 476, 534, 589, 642)
 vol_remove <- c(16,  29,  35,  39,  39,  39,  38,  37,  36,  35,  34)

 stand_level_increment(age, vol_remain, vol_remove) # m³/ha/yr

 # Works also with basal area (m²/ha)
 age        <- seq(20, 60, 5)
 ba_remain  <- c(26.0, 30.1, 32.5, 34.2, 35.5, 37.1, 38.7, 40.3, 41.9)
 ba_remove  <- c( 0.0,  5.0,  5.9,  5.4,  5.1,  4.2,  3.3,  3.0,  2.7)

 stand_level_increment(age, ba_remain, ba_remove) # m²/ha/yr