Figure 1.
Particle size distribution of the two soil textures.
(A) Sandy soil. (B) Clay soil. Data were obtained from particle size measurement by a laser diffraction system (Sympatec GmbH, System-Partikel-Technik, Clausthal- Zellerfeld, Germany).
Figure 2.
Schematic diagram of the experiment.
(A) Plan form of experimental device; (B) plan form of water pool; (C) cross section of water pool; (D) photograph of water pool; (E) water valve; (F) plan form of pot; (G) cross section of pot; (H) photograph of pot; and (I) photograph of experimental plants. The experimental devices (A) were constructed by cement. Each device was divided into 2×8 cells. Each cell contained a pot and a water pool. Each pot (1 m ×1 m ×1 m) was located between two water pools (0.6 m ×1 m ×1 m). The steel mesh (covered with nylon) was used to separate the pot from the water pools, and all water pools in the device were connected by PVC pipes (the length of PVC was 1.2 m; A, G). The left pools were also connected with right pools by PVC pipes (C). Thus the water could run-through the whole device. The left pots were filled with sandy soils, and the right pots with clay soils (G, I).
Figure 3.
Three steps and four types in making inferences about two lines.
Four types: (A) Change is defined as the slopes are not equal in the two soil textures; (B) Shift 1 is defined as the slopes are equal but the intercepts are differences in the two soil textures; (C) Shift 2 is defined as the slopes are equal, and the intercepts are no differences in the two soil textures, but are shifted in location along common slope SMA lines; (D) Overlap is defined as no difference in slopes, no difference in intercept and no shift location along common slope SMA lines.
Figure 4.
Average values of LMR, SMR and RMR in the two soils over ontogeny.
Bars represent average values ± CV, n = 60. Different letters indicate differences (p≤0.05) of biomass allocation to leaves, stems and roots between the two soils.
Figure 5.
Specific root length and root/leaf ratio in the two soil textures at four growth stages.
(A) SRL; (B) root length/leaf area ratio. Bars represent average values ± SE, n = 15. Different lower-case and capital letters indicate differences (p≤0.05) between growth stages and between soil textures, respectively.
Figure 6.
Allometric plots for plant size, LMR, RMR and SMR.
Data for individual slopes and intercepts are given in Table 1. The SMA regression (using SMATR package of R) was used to test the slope and intercept heterogeneity at α = 0.05 (where slopes or intercepts non-heterogeneous, P>0.05) between the two soil textures: (A) Slopes non-heterogeneous, P = 0.73; Intercepts heterogeneous: LMR higher at a given plant size in clay soil treatment (P<0.001). (B) Slopes non-heterogeneous, P = 0.47; Intercepts heterogeneous: RMR lower at a given plant size in clay soil treatment (P<0.001). (C) Slopes non-heterogeneous, P = 0.54; Intercepts non-heterogeneous: SMR was equal at a given plant size between clay and sandy soil treatment (P = 0.13); (D) LMR versus SMR. Slopes non-heterogeneous, P = 0.41; Intercepts heterogeneous, P<0.001; (E) RMR versus SMR. Slopes non-heterogeneous, P = 0.33; Intercepts heterogeneous, P<0.001; and (F) LMR versus RMR. Slopes non-heterogeneous, P = 0.69; Intercepts non-heterogeneous, P<0.001.
Table 1.
Test for common slope and intercept between the clay and sandy soil textures.
Figure 7.
Allometric plots for plant traits.
Data for individual slopes and intercepts are given in Table 1. The SMA regression (using SMATR package of R) was used to test the slope and intercept heterogeneity at α = 0.05 (where slopes or intercepts non-heterogeneous, P>0.05) between the two soil textures: (A) Leaf mass versus plant size. Slopes non-heterogeneous, P = 0.32; Intercepts heterogeneous: leaf mass was higher at a given plant size in clay soil treatment (P<0.001); (B) Root mass versus plant size. Slopes non-heterogeneous, P = 0.056; Intercepts heterogeneous: root mass was lower at a given plant size in clay soil treatment (P<0.001); (C) Stem mass versus plant size. Slopes non-heterogeneous, P = 0.05; Intercepts non-heterogeneous: stem mass was equal at a given plant size between clay and sandy soil treatment (P = 0.49); (D) Leaf area versus plant size. Slopes non-heterogeneous, P = 0.055; Intercepts heterogeneous: leaf area was higher at a given plant size in clay soil treatment (P<0.001); (E) Root length versus plant size. Slopes non-heterogeneous, P = 0.054; Intercepts heterogeneous: root length was lower at a given plant size in clay soil treatment (P<0.001); and (F) Diameter of basal stem versus plant height. Slopes non-heterogeneous, P = 0.08; Intercepts non-heterogeneous: diameter of basal stem was equal at a given plant height between clay and sandy soil treatment (P = 0.08).
Figure 8.
Relationships between plant size and SLA, SRL in the two soil textures.
(A) SLA vs. plant size. (B) SRL vs. plant size. Data for individual slopes and intercepts are given in Table 1. The SMA regression (using SMATR package of R) was used to test the slope and intercept heterogeneity at α = 0.05 (where slopes or intercepts non-heterogeneous, P>0.05) between the two soil textures: (A) Slopes non-heterogeneous, P = 0.12; Intercepts heterogeneous: SLA lower at a given plant size in clay soil treatment (P<0.001). (B) Slopes non-heterogeneous, P = 0.28; Intercepts non-heterogeneous: SRL was equal at a given plant size between clay and sandy soil treatment (P = 0.77).
Figure 9.
Nested design and variance components of LMR, RMR and SMR based on nested ANOVAs.
(A) Nested design. (B) Variance components. Three-level nested ANOVAs: one level was groups, different soil textures; the next level was subgroups, the different plant size categories; and within subgroups, the replications in each plant size category.