GapSizeFDist {ForestGapR} | R Documentation |
This function quantifies forest canopy gap size-frequency distributions and estimates power-law exponent (λ) from the Zeta distribution.
GapSizeFDist(gaps_stats,method,...)
gaps_stats |
A data.frame containing basic statistics of forest gaps. Output of ( |
method |
If method='Asner_2013' the λ is computed following the method described Asner et al. (2013) and if methods='Hanel_2017' the λ is computed following the method described in Hanel et al. (2017) |
... |
Supplementary parameters for ( |
A log-log plot of gap-size Frequency Distributions and a list containing: i) λ, ii) the gap-size Frequency Distributions and ii) method used. The λ parameter is derived for the Zeta distribution using a maximum likelihood estimator. See details section.
Hanel,R., Corominas-Murtra, B., Liu, B., Thurner, S. (2013). Fitting power-laws in empirical data with estimators that work for all exponents, PloS one, vol. 12, no. 2, p. e0170920.https://doi.org/10.1371/journal.pone.0170920
Asner, G.P., Kellner, J.R., Kennedy-Bowdoin, T., Knapp, D.E., Anderson, C. & Martin, R.E. (2013). Forest canopy gap distributions in the Southern Peruvian Amazon. PLoS One, 8, e60875.https://doi.org/10.1371/journal.pone.0060875
White, E.P, Enquist, B.J, Green, J.L. (2008) On estimating the exponent of powerlaw frequency distributions. Ecology 89,905-912. https://doi.org/10.1890/07-1288.1
#Loading raster library library(raster) # ALS-derived CHM over Adolpho Ducke Forest Reserve - Brazilian tropical forest data(ALS_CHM_DUC) # set height thresholds (e.g. 10 meters) threshold<-10 size<-c(1,10^4) # m2 # Detecting forest gaps gaps_duc<-getForestGaps(chm_layer=ALS_CHM_DUC, threshold=threshold, size=size) # Computing basic statistis of forest gap gaps_stats<-GapStats(gap_layer=gaps_duc, chm_layer=ALS_CHM_DUC) # Gap-size Frequency Distributions GapSizeFDist(gaps_stats=gaps_stats, method="Hanel_2017", col="forestgreen", pch=16, cex=1, axes=FALSE,ylab="Gap Frequency",xlab=as.expression(bquote("Gap Size" ~ (m^2) ))) axis(1);axis(2) grid(4,4)