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 (D^2 × 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 (D^2 × 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	0.3^ns		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 (D^2 × 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	0.10^ns	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 (D^2 × 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 (D^2 × 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 (D^2 × 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 (D^2 × 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 (D^2 × 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 (D^2 × 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	0.08^ns	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. .