partitionBEFsp {partitionBEFsp}

partitionBEFsp: A package for calculating the Loreau & Hector 2001 BEF partition.

Description

The partitionBEFsp (or "partitioning Biodiversity-Ecosystem Functioning as sample-level and population-level estimates" package) is a collection of functions that can be used to estimate selection and complementarity effects, sensu Loreau & Hector 2001 (Nature 412:72-76), even in cases where data are only available for a random subset of species (i.e. incomplete sample-level data). A full derivation and explanation of the statistical corrections used here is available in Clark et al. 2019, Estimating Complementarity and Selection Effects from an Incomplete Sample of Species.

Source

Loreau, M., and Hector, A. (2001). Partitioning selection and complementarity in biodiversity experiments. Nature 412:72-76.

Examples

#Monoculture biomasses for 57 species
M<-c(57.57, 2.33, 306.25, 172.42, 351.48, 280.15, 216.93,
     1.30, 397.73, 185.57, 19.81, 162.45, 36.23, 42.48,
     3.16, 250.12, 5.30, 58.06, 172.93, 210.50, 253.78,
     15.96, 218.62, 282.00, 342.73, 242.18, 49.39, 100.00,
     112.20, 181.50, 61.98, 428.82, 911.55, 80.60, 206.75,
     108.25, 58.45, 154.55, 114.58, 144.38, 273.98, 25.41,
     148.82, 48.27, 35.62, 168.45, 157.98, 100.47, 31.12,
     9.86, 247.57, 182.32, 16.20, 251.30, 118.73, 137.65,
     149.93)

#Polyculture biomasses for a community of 57 species
P<-c(31.82, 0.06, 6.93, 6.75, 0.00, 0.11, 0.00,
     10.95, 0.19, 0.58, 0.01, 0.52, 21.72, 16.20,
     0.00, 0.09, 3.42, 0.00, 0.02, 3.18, 8.86,
     0.03, 0.02, 0.00, 10.14, 8.93, 4.53, 0.00,
     0.00, 0.02, 8.80, 0.31, 21.47, 0.34, 14.52,
     0.15, 0.00, 17.17, 66.55, 1.65, 0.44, 0.17,
     7.11, 0.45, 5.37, 7.66, 4.37, 0.00, 120.08,
     144.61, 0.00, 0.00, 0.00, 8.33, 93.18, 0.58,
     1.77)


#calculate DRY
DRY<-calculate_DRY(M=M, P=P, Q=length(M))

####################################
# Example 1: Classic partition
####################################

#calculate classic partition for full community
classic_partition(DRY=DRY, M=M)

#note that sum of partition equals the change in yield,
#but only if sample-size corrected covariance isn't used
N<-length(M)
cp_F<-classic_partition(DRY=DRY, M=M, uncorrected_cov = FALSE)
cp_T<-classic_partition(DRY=DRY, M=M, uncorrected_cov = TRUE)
cp_C<-classic_partition(DRY=DRY, M=M, uncorrected_cov = "COMP")

sum(P-M/N) #observed - expected yield
cp_F$S+cp_F$C #default
cp_T$S+cp_T$C #non-sample-size corrected
cp_C$S+cp_C$C #compromise

#also note that compromise only perfectly equals change in yield
#if Q = N (i.e. if the entire community is sampled)

sum(unlist(classic_partition(DRY=DRY, M=M, uncorrected_cov = "COMP", N=length(DRY), Q=N)))
sum(unlist(classic_partition(DRY=DRY, M=M, uncorrected_cov = "COMP", N=length(DRY), Q=N*2)))


####################################
# Example 2: Estimate population-level statistics
####################################
#estimate population-level partition for full community using only 30 species
set.seed(25123)
smp<-sample(30)
DRY_sample<-DRY[smp]
M_sample<-M[smp]
sample_to_population_partition(DRY=DRY_sample, M=M_sample, N=length(M_sample), Q=57)
#note - SP and CP are relatively close to the classic partition for the full community,
#whereas SS and CS are not.

#Repeat procedure for samples of between 2 and 57 species:
N_sample<-2:57
SP_est<-numeric(length(N_sample))
CP_est<-numeric(length(N_sample))

for(i in 1:length(N_sample)) {
  #sample N random species
  smp<-sample(1:57, N_sample[i])

  pop_est<-sample_to_population_partition(DRY=DRY[smp], M=M[smp], N=N_sample[i], Q=57)
  SP_est[i]<-pop_est$SP
  CP_est[i]<-pop_est$CP
}

#Plot estimates vs. true value (dotted line)
plot(N_sample, SP_est, type="b"); abline(h=classic_partition(DRY=DRY, M=M)$S, lty=3, col=2)
plot(N_sample, CP_est, type="b"); abline(h=classic_partition(DRY=DRY, M=M)$C, lty=3, col=2)
#note - estimates are noisy, but converge to the true value as N approaches Q.


####################################
# Example 3: Estimate sample-level statistics
####################################

#estimate expected value of sample-level statistics for a random sample of 30 species
#based on the full population of Q species
population_to_sample_partition(DRY=DRY, M=M, N=30, Q=57)

#Repeat procedure for samples of between 2 and 57 species:
N_sample<-2:57
SS_est<-numeric(length(N_sample))
CS_est<-numeric(length(N_sample))

for(i in 1:length(N_sample)) {
  pop_est<-population_to_sample_partition(DRY=DRY, M=M, N=N_sample[i], Q=57)
  SS_est[i]<-pop_est$SS
  CS_est[i]<-pop_est$CS
}

#Plot estimates vs. true value (dotted line)
plot(N_sample, SS_est/N_sample, type="b")
abline(h=classic_partition(DRY=DRY, M=M)$S/57, lty=3, col=2)
#note - expected value of SS/N = SP/Q for all N
plot(N_sample, CS_est/N_sample, type="b")
abline(h=classic_partition(DRY=DRY, M=M)$C/57, lty=3, col=2)
#note - expected value of CS/N is a biased estimate of SP/Q, especially for small N


####################################
# Example 4: Estimate confidence intervals
####################################
smp_ci<-sample_to_population_partition(DRY=DRY, M=M, Q=57, nboot=1000)
smp_ci$confint$bootdat_summary