Figure 5
Factor analysis and regressions. Graph A shows the result of the factor analysis for all the soil samples collected across China. Variables used are MAP, MAT, soil pH, CBT′, MBT′5ME and abundance of brGDGT fractions (Ia, IIa, IIa′ and IIIa′). Graph B reveals the regression between the calibrated CBT′ index and the observed soil pH values of the samples from humid to semi-humid regions of China (groups I, II, III and IV, Fig. 1). Graph C explains the relationship between the calibrated CBT′ index and the observed soil pH values from soil samples of all six groups. Graphs D and E illustrate the regressions between the calibrated MBT′5ME and the observed MAT and MAT9months of the soil samples from humid to semi-humid regions of China (groups I, II, III and IV, Fig. 1). Graph F reports the correlation between the calibrated MBT′5ME and the observed MAT based on samples from all six groups. MAT9months is the average MAT from March to November.
