Fig. 4
From: Coordination of leaf functional traits under climatic warming in an arid ecosystem
Structural equation modeling (SEM) concerning the effects of climatic warming on key leaf functional traits and their relationships across the 4-year field warming experiment (A, across all warming treatments; B, AM; C, MW; D, SW). Solid black and red arrows represent significant positive (black) or negative (red) relationships at P < 0.05 levels, whereas dashed black and red arrows represent no significance (P > 0.05). Values above arrows indicate the standard path coefficients, and their significances at 0.05, 0.01, and 0.001 levels are marked by *, **, and ***, respectively. Arrow widths are proportional to the size of the standardized path coefficient. Percentages on rectangles or ellipses indicate the variance explained by the models. Goodness-of-fit statistics are: A χ2 = 1.64; df = 3; P = 0.44; goodness of fit index (GFI) = 1.00; root mean square error of approximation (RMSEA) < 0.001; Akaike information criterion (AIC) = 39.64; N = 124. B χ2 = 0.89; df = 2; P = 0.65; GFI = 1.00; RMSEA < 0.001; AIC = 38.89. N = 68. C χ2 = 7.39; df = 2; P = 0.25; GFI = 0.94; RMSEA = 0.29; AIC = 45.39. N = 33. D χ2 = 3.62; df = 2; P = 0.163; GFI = 0.95; RMSEA = 0.19; AIC = 41.62. N = 23. Leaf economics spectrum (LES) driven by climatic warming is shown in E–F panels. Under AM, Aarea increases, but Narea decreases with SLA, finally increasing PNUE (E). Under MW, the positive relationship of Aarea with SLA is amplified, but that of Narea with SLA is weakened, hence enhancing PNUE (F). However, under SW, the entire relationships between the leaf functional traits were largely weakened, even decoupled, consequently terminating the LES (G). Blue single arrow indicates the positive response, while red single arrow indicates the negative response. Blue double arrow indicates the positive interaction, and dotted arrow represent the decreased/cancelled relationships. The + and – signs denote the amplification and reduction, respectively