Spectral Estimation of Soil Properties in Siberian Tundra Soils and Relations with Plant Species Composition

Table 3

Performance of model fits using spectra of samples under field conditions, evaluated with leave-one-out cross validation.

	pH	Total P (mg/100 g)	Total K (mg/100 g)	Total N (%)	Total N (%)	Total C (%)	Total C (%)	Moisture (%)
Method	PLSR	PLSR	PLSR	PLSR	SMLR	PLSR	SMLR	PLSR
No. of factors	4	2	2	2	4	4	8	1
𝑅^2	0.45	0.16	0.44	0.34	0.43	0.45	0.74	0.11
RMSE CV	0.48	34.93	314.73	0.40	0.39	8.38	6.03	12.7
RPD CV	1.35	1.09	1.35	1.24	1.28	1.37	1.90	1.05

RMSE CV: root mean square error of cross validation, RPD CV: ratio of performance to deviation of cross validation, PLSR: partial least squares regression, SMLR: stepwise multiple linear regression.