Figure 5. Principal
component analysis of fine root traits (means of total soil layers) of
the four species along rock fragment content gradient and years of
growth. The proportion explained of Axis 1 and Axis 2 are 45.40% and
20.82%, respectively. Solid black lines indicate six fine root
functional traits. The confidence circle represents the 95% confidence
interval between growth years (a), yellow is 2nd, the green is3rd and
the red is 4rd. The confidence circle represents the 95% confidence
interval between species (b), the red is A. (Artemisia
vestita ), the green is B. (Bauhinia brachycarpa ), the
yellow is S. (Sophora davidii ) and the blue is C.(Cotinus szechuanensis ). Abbreviations for root traits are as
follow: βF , β of fine root; FRB, fine root biomass; RLD,
fine root length density; SRL, specific fine root length; RD, root
diameter; RTD, fine root tissue density.