古生态研究组知识库

The function and morphology of plant leaves typically differ according to leaf habit (evergreen vs deciduous), and these differences have been thought to respond divergently to climatic conditions. While the variations in leaf margins with leaf habit and their respective correlation with climate have been investigated, limited investigation has been conducted on other leaf physiognomic characters. In the present study, we studied 2111 evergreen and 1001 deciduous native woody dicotyledons, investigating how the occurrences of 21 leaf physiognomic characters vary with leaf habit in humid regions of China. We then analysed these leaf characters of evergreen and deciduous species and climate correlations using canonical correspondence analysis based on 498 and 521 calibration datasets, respectively. Our results show that most of leaf physiognomic characteristics differed significant between evergreen and deciduous species in terms of the percentage values and the ordination diagrams. The leaf physiognomic distribution of both evergreen and deciduous species exhibited remarkable differences in response to climate. The lobed, small (nano- and microphyll), obtuse apex, reflex base, wide (length: width ratio <= 2:1) and ovate shape leaves predominated in deciduous species and occurred in colder and drier climates, while untoothed, large (noto- and mesophyll), reflex apex, acute base, narrow (L:W ratio = 2-4:1) and elliptic shape leaves predominated in evergreen species and occurred in warmer and wetter climates. This distribution pattern was primarily influenced by winter temperature and precipitation. The leaf physiognomic characteristics of evergreen and deciduous species display distinct responses to winter climatic variables across humid regions of China, revealing differences in environmental tolerance between the two leaf habits. This also suggests that the East Asian winter monsoon especially influences the leaf physiognomic characters of both evergreen and deciduous species in China. Furthermore, our findings suggest that in addition to leaf margins, leaf habit could confound correlations between other leaf physiognomic characters and climate, potentially affecting the accurate prediction of paleoclimate in China using multivariate leaf physiognomy approaches.