FIGURE CAPTIONS
FIGURE 1 Conceptual model of the role of ECM symbionts in plant
N and P uptake
FIGURE 2 Schematic diagram of variation partitioning in
determining the effects of soil variables, climate factors, and ECM
traits on root and foliar nutrient variables. Values in diagram
represents the explained variations in each category of factors and
various interactions.
FIGURE 3 Analysis of structural equation models (SEMs) on root
and foliar nutrient variables. *, P < 0.1; **, P<0.05; ***, P<0.01. Standardized path coefficients
(δ) were showed on line arrows. R2 value represents
the proportion of total variance explained for the specific dependent
variable. (a1): SEMs depicting the regulatory pathway of the controls in
root P; (a2): SEMs depicting the regulatory pathway of the controls in
root N; (a3): SEMs depicting the regulatory pathway of the controls in
root N:P; (b1): SEMs depicting the regulatory pathway of the controls in
leaf P; (b2): SEMs depicting the regulatory pathway of the controls in
leaf N; (b3): SEMs depicting the regulatory pathway of the
controls in leaf N:P. ECM-PC1: the first principal components of ECM
traits by PCA; ECM-PC2: the second principal components of ECM traits by
PCA. MAT: the mean annual temperature; MAP: the mean annual
precipitation. Soi-PC1: the first principal components of soil factors
principal component analysis (PCA); Soi-PC2: the second principal
components of soil factors by PCA.
FIGURE 4 Redundancy analysis (RDA) ordination biplot of ECM
traits and root nutrients (a) and foliar nutrients (b).
Cratio: Colonization ratio of ECM fungi; CE: ECM roots
with contact exploration type; ECMtips: ECM root tips
per unit root biomass; FRB: Fine root biomass; MDE: ECM roots with
medium exploration type; MDI: Morphology diversity index;
Root-tipsratio: the ratio of the living to dead root
tips; SA: superficial area of ECM; SDE: ECM roots with short distance
exploration type; MiNR1: sampling at 3077 m asl . in Miyaluo
Nature Reserve; MiNR2: sampling at 3612 m asl . in Miyaluo Nature
Reserve; WaNR1: sampling at 3070 m asl . in Wanglang Nature
Reserve; WaNR2: sampling at 3150 m asl . in Wanglang Nature
Reserve; WoNR1: sampling at 2850 m asl . in Wolong Nature Reserve;
WoNR2: sampling at 3000 m asl . in Wolong Nature Reserve; WoNR3:
sampling at 3194 m asl . in Wolong Nature Reserve; WoNR4: sampling
at 3413 m asl . in Wolong Nature Reserve; WoNR5: sampling at 3593
m asl . in Wolong Nature Reserve.
FIGURE 5 The significant relationships of root and foliar
nutrients with soil exploration types. (a): the regressions of root P
and the colonization ratio of CE; (b): the regressions of root P and the
colonization ratio of SDE; (c): the regressions of root N and the
colonization ratio of SDE; (d): the regressions of sqrt(root P) and
sqrt(the colonization ratio of MDE); (e): the regressions of root N:P
and the colonization ratio of MDE; (f): the regressions of foliar N:P
and the colonization ratio of MDE. CE: ECM roots with contact
exploration type; SDE: ECM roots with short-distance; MDE: ECM roots
with medium exploration type.
FIGURE 6 A conceptual model of the intervention of ECM
symbiosis on root and foliar N and P nutrients in A. faxoniana .
I: The primary effects of ECM symbiosis on root nutrients. Root N and P
nutrients could both be strongly affected by ECM symbiosis, but the
effects were stronger on root P than root N; II: Indirect mediation of
ECM symbiosis on foliar N and P nutrients driven by the nutrient
limitation signals from leaves to roots; III: Changes in foliar N and P
nutrients caused by variations in ECM strategies. Changes in ECM
foraging strategies imposed greater influences on foliar P than foliar