Site-Species Allometry Equation for Theobroma cacao L. Biomass Estimation in Agroforestry Systems of Cameroon
Table 1
Models parameters and performance criteria for biomass estimation of Theobroma cacao.
Models
Model expression
N
D
a
b
c
d
RSE
RRMSE
Residual error (%)
AIC
FC
Aboveground biomass (AGB)
M1
lnB = a + b × ln (D) + ɛ
50
5–27
−1.63
1.83
0.186
0.198
3.47
−22.46
0.017
0.942
M2
lnB = a + b × ln (D × C) + Ɛ
50
5–27
−1.42
1.12
0.211
0.219
4.43
−9.72
0.022
0.925
M3
lnB = a + b × ln (D × H) + Ɛ
50
5–27
−1.41
1.1
0.209
0.212
4.31
−10.83
0.021
0.927
M4
lnB = a + b × ln (D2 × H) + Ɛ
50
5–27
−1.52
0.69
0.193
0.197
4.31
−18.65
0.019
0.937
M5
lnB = a + b × ln (D2 × C) + Ɛ
50
5–27
−1.55
0.70
0.185
0.196
3.44
−22.69
0.017
0.942
M6
lnB = a + b × ln (D) + c × ln (C) + Ɛ
50
5–27
−1.61
1.63
0.3ns
0.180
0.190
3.21
−24.50
0.016
0.945
M7
lnB = a + b × ln (D) + c × ln (H) + Ɛ
50
5–27
−1.61
1.74
0.153
0.187
0.194
3.48
−20.81
0.017
0.941
M8
lnB = a + b × ln (D2 × C) + c × ln (H) + Ɛ
50
5–27
−1.53
0.65
0.21
0.186
0.191
3.41
−21.43
0.017
0.942
M9
lnB = a + b × ln (D) + c × ln (H) + d × ln (C) + ɛ
50
5–27
−1.60
1.56
0.10ns
0.35
0.182
0.187
3.25
−22.67
0.017
0.944
Belowground biomass (BGB)
M1
lnB = a + b × ln (D) + ɛ
50
5–27
−2.65
1.65
0.278
0.316
7.92
17.78
0.039
0.855
M2
lnB = a + b × ln (D × C) + Ɛ
50
5–27
−2.49
1.03
0.275
0.306
7.70
16.87
0.038
0.857
M3
lnB = a + b × ln (D × H) + Ɛ
50
5–27
−2.42
0.98
0.301
0.372
9.56
25.79
0.045
0.829
M4
lnB = a + b × ln (D2 × H) + Ɛ
50
5–27
−2.52
0.62
0.288
0.345
8.68
21.55
0.041
0.843
M5
lnB = a + b × ln (D2 × C) + Ɛ
50
5–27
−2.60
0.64
0.267
0.293
7.20
13.67
0.036
0.866
M6
lnB = a + b × ln (D) + c × ln (C) + Ɛ
50
5–27
−2.61
1.33
0.55
0.269
0.294
7.27
15.55
0.036
0.864
M7
lnB = a + b × ln (D) + c × ln (H) + Ɛ
50
5–27
−2.67
1.76
−0.160
0.280
0.312
7.94
19.61
0.039
0.852
M8
lnB = a + b × ln (D2 × C) + c × ln (H) + Ɛ
50
5–27
−2.62
0.68
−0.190
0.269
0.290
7.21
15.37
0.036
0.864
M9
lnB = a + b × ln (D) + c × ln (H) + d × ln (C) + ɛ
50
5–27
−2.64
1.48
0.245
0.57
0.271
0.289
7.26
17.12
0.037
0.862
Total biomass (TB)
M1
lnB = a + b × ln (D) + ɛ
50
5–27
−1.31
1.79
0.164
0.169
2.68
−34.83
0.013
0.952
M2
lnB = a + b × ln (D × C) + Ɛ
50
5–27
−1.10
1.10
0.188
0.189
3.48
−21.41
0.017
0.937
M3
lnB = a + b × ln (D × H) + Ɛ
50
5–27
−2.42
0.98
0.301
0.805
−80.38
25.79
0.045
0.829
M4
lnB = a + b × ln (D2 × H) + Ɛ
50
5–27
−1.2
0.67
0.172
0.171
2.92
−29.89
0.015
0.947
M5
lnB = a + b × ln (D2 × C) + Ɛ
50
5–27
−1.23
0.68
0.161
0.164
2.57
−36.62
0.013
0.954
M6
lnB = a + b × ln (D) + c × ln (C) + Ɛ
50
5–27
−1.29
1.57
0.37
0.157
0.159
2.41
−38.68
0.012
0.956
M7
lnB = a + b × ln (D) + c × ln (H) + Ɛ
50
5–27
−1.29
1.71
0.135
0.165
0.167
2.68
−33.18
0.014
0.951
M8
lnB = a + b × ln (D2 × C) + c × ln (H) + Ɛ
50
5–27
−1.22
0.64
0.183
0.162
0.160
2.55
−35.32
0.013
0.953
M9
lnB = a + b × ln (D) + c × ln (H) + d × ln (C) + ɛ
50
5–27
−1.28
1.52
0.08ns
0.37
0.158
0.157
2.42
−36.82
0.012
0.956
B: total biomass; D: diameter; H: height of tree; C: crown diameter; N: the number of trees; a, b, c, and d: the coefficients of the variables; RRMSE: relative root mean square error; RSE: residual standard error; Adj : coefficient of determination; AIC: Akaike information criterion; and CF: correcting factor. Note. The results are significant at a 95% confidence interval. ;; and ns: nonsignificant, . value of all models: 2.2e_16. .