Table 3.

Distribution of the best fitted sub-models of root diameter spectrum with regard to the four functions

Soil depth	Data for fitting	Total no. of equations	Zone I: lowest global MSE				Zone II: lowest MSE of fine roots			Zone III: lowest MSE of coarse roots
			Exponential	Weibull	Gompertz	Log normal	Weibull	Gompertz	Log normal	Weibull	Gompertz	Log normal
]0·0, 0·2] m	Mini-monolith	25	0	2	2	21	4	4	17	1	8	16
]0·2, 0·4] m	Root trench	24	0	2	7	15	6	12	6	3	6	15
]0·4, 0·6] m	Root trench	24	0	5	3	16	10	11	3	4	5	15
]0·6, 0·8] m	Root trench	24	0	6	7	11	13	8	3	4	8	12
]0·8, 1·0] m	Root trench	24	0	3	18	3	20	2	2	2	18	4

Unit: number (No.) of equations.

Within each group (the three or four values in the same line and the same zone), the highest number of equations is underlined.

When the MSE is decomposed into fine roots (Zone II) and coarse roots (Zone III), only the three two-parameter functions (i.e. Weibull, Gompertz and log-normal CDFs) are compared.