R/height.korf.R

In sitree: Single Tree Simulator

height.korf <- function (common.vars,
                         this.period,
                         tr,
                         dbh.inc.mm, ...) 
{
  spp <- common.vars$spp
  height <- next.height <- rep(NA, nrow(tr$data$dbh.mm))

  ## height this.period according to korf
  height[spp == 'spruce'] <- 1017.27 *
    exp(-12.697 * tr$data$dbh.mm[spp == 'spruce',this.period]^ (-0.3562))
  
  height[spp == 'pine'] <- 299.34 *
    exp(-34.2159 * tr$data$dbh.mm[spp == 'pine',this.period]^ (-0.6932))
  
  height[spp %in% c('birch', 'other')] <- 714.0037 *
    exp(-11.0299 * tr$data$dbh.mm[spp %in% c('birch', 'other'),this.period]^ (-0.347))

  ## height next.period according to korf
  next.height[spp == 'spruce'] <- 1017.27 *
    exp(-12.697 * (tr$data$dbh.mm[spp == 'spruce',this.period] +
                     dbh.inc.mm [spp == 'spruce'])^ (-0.3562))
  
  next.height[spp == 'pine'] <- 299.34 *
    exp(-34.2159 * (tr$data$dbh.mm[spp == 'pine',this.period] +
                     dbh.inc.mm [spp == 'pine'])^ (-0.6932))
  
  next.height[spp %in% c('birch', 'other')] <- 714.0037 *
    exp(-11.0299 * (tr$data$dbh.mm[spp %in% c('birch', 'other'), this.period]+
                      dbh.inc.mm [spp %in% c('birch', 'other')]) ^ (-0.347))
  
  ## height should never be below 13
  ##height[height < 13] <- 13
  height.inc.dm <- next.height - height

  return(height.inc.dm)
  
}