| For plants, the leaf anatomical traits (leaf morphology traits, vein density, stomata sizeand density, trichomes types and density) were closely related with transpiration andphotosynthesis. They are the results of adaption for environmental factors during long-term evolution. There were many reports about leaf traits and characters. In regionalscales, yet there is no general conclusion about the relationships between leaf traits, thevariation pattern along a climate gradient, the main factors that drive the variations andhow do leaf traits respond to climate changes. They were important in ecology researchfield, and had important theoretical significance in understanding how plant respondedto climatic changes, community composition changes as well as plant migration. Theywould guide the resonable forest management under climatic change conditions.Orienatal oak (Quercus variabilis) was the most wide distributioned tree species ineastern Asia (19–42°N、97–140°E，50–2000m a.s.l). Oriental oak had importanteconomic value (timber, cork, fruits and so on), biological diversity, environmentalprotection, urban and rural landscape function et al. The natural environment oforiental oak distributed sites were complex due to the large distribution area, and theoriental oak growing in different sites formed geographical populations with differentgenetic composition. This made oriental oak be an ideal plant species for investigatingthe relationship between leaf traits and environmental factors.We examined both the variation in leaf size, LMA, leaf petiole length, leaf veindensity, stomatal size and density, leaf trichome density and other leaf traits of orientaloak (Quercus variabilis) from44in situ Populations include the mainland of China,Taiwan Island, Zhoushan Archipelago, Korea Peninsula and Japan Archipelago across temperate-subtropical biomes. We investigated the variation patterns of leaf traits andinvestigated the relationships between leaf traits and environmental factors. Theresponse of leaf traits to environmental changes were also examined by commongarden experiment with seedlings of15populations from different provenances grownin a common garden. The main results were as follows:1) Leaf morphogy traits of oriental oak significantly differed among different insitu populations (P <0.001), and the differences among common garden populationsreduced after two years growing in common garden except for leaf petiole length.Particularly, leaf length（P=0.160） and leaf area （P=0.105）had no significantdifference among common garden populations. Leaf length to width was negativelycorrelated with latitude for in situ populations (r~2=0.134, P=0.015). Leaf length,width and petiole length showed negative correlations with longitude for in situpopulations (r~2=0.132, P=0.016for leaf length; r~2=0.109, P=0.028for leaf width;r~2=0.289, P <0.001for leaf petiole length). While leaf morphology traits wereindependent of latitude and longitude of origins (P=0.081–0.949). Leaf morphologytraits were invariant with MAP (P=0.070–0.511). Leaf length to width rationegatively correlated with MAT (r~2=0.135, P=0.014). Leaf length and leaf length towidth ratio were significantly negatively correlated with MDSH (r~2=0.207, P=0.002for leaf length and r~2=0.278, P <0.001for leaf length to width ratio). Additionally,leaf length and leaf length to width were negatively correlated with soil Kconcentrations (r~2=0.131, P=0.033for leaf length and r~2=0.235, P=0.003for leaflength to width). We concluded that the main factor that affected leaf morphology wasMDSH, secondly was MAT by multiple regression analysis. Leaf morphology traits oforiental oak were sensitive to climatic factors. The variances in field observed in thisstudy were mainly due to environmental differences among different sampling sites.The heritability of leaf morphology traits variations caused by environment was low.2) Minor vein density (≥3rdorder) of oriental oak decreased significantly with theincreasing latitude (r~2=0.63and P <0.001) for the in situ populations, and this patternremained unchanged for the garden-Populations (r~2=0.63and P <0.001). Minor veindensity both positively correlated with mean annual precipitation (MAP) and mean annual temperature (MAT) of the origins for both the garden-Populations (r~2=0.29, P=0.04and r~2=0.35, P=0.02, respectively) and the in situ Populations (r~2=0.30, P <0.001and r~2=0.53, P <0.001, respectively). Leaf vein density significantly positivelycorrelated with mean daily sunshine hours (MDSH) of the origins for the in situpopulations (r~2=0.24, P=0.001), but were invariant for the common gardenpopulations (r~2=0.23, P=0.07). Minor vein density significantly increased with leaflength and leaf length to width for in situ populations (r~2=0.12, P=0.02and r~2=0.36,P <0.001, respectively). Leaf minor vein density were negatively correlated with leaflength (r~2=0.44, P=0.007). Additionally, leaf minor vein density showed a negativelyrelationships with soil K and Ca concentrations (r~2=0.16, P=0.02and r~2=0.21, P=0.007, respectively). MAT and leaf shape were the main factors that had directed effecton leaf minor vein density of oriental oak through Path Coefficient analysis, whileMAP and MDSH had strong in-directed effects. These results implied that leaf veindensity was a genotypic trait for adapting for local climatic factors, and this trait did notsensitively respond to temporal change in growing conditions.3) Stomatal density and SOI of in situ populations decreased with longitude (r~2=0.098, P=0.039of stomata density; r~2=0.120, P=0.021of SOI), while stomataldensity and SOI were independent of longitude, and have no significant differencesamong15garden populations (P=0.278–0.540). Stomatal density was significantlynegatively correlated with MAP of the origins (r~2=0.157, P=0.008), but wereinvariant with other climatic factors for the in situ populations (P=0.321–0.740).Compared with stomatal density, leaf SOI was more sensitive to climatic factors. SOIshowed a negative relationship with MAT (r~2=0.12, P=0.02) and MAP (r~2=0.39, P <0.001), and a positive correlation with mean monthly solar radiation (MMSR) of theorigins for the in situ populations (r~2=0.16, P=0.011). For the common gardenpopulations, both stomatal density and SOI were invariant with climatic factors oforigins (P=0.101–0.775). Stomatal density was negatively correlated with stomatal length (r~2=0.236, P=0.001) and stomatal width-to-length (r~2=0.266, P <0.001)across in situ populations. Both of stomatal density and SOI were positively correlatedwith leaf dry mass per area (LMA) and leaf petiole length (r~2=0.199–0.299, P=<0.001–0.002) for the in situ populations, while no significant correlation for thegarden populations (P=0.056–0.568). SOI was positively correlated with soil Ca (r~2=0.18, P=0.012) and K concentrations for the in situ populations (r~2=0.15, P=0.019). Stomatal Rpvalue was significantly positively correlated with latitude for the insitu populations (r~2=0.210, P=0.002), while showed no correlations for the commongarden populations (r~2=0.006, P=0.781). Stomatal Rpvalue were negativelycorrelated with MAP of the origins (r~2=0.160, P=0.007), positively correlated withstomatal length and width for the in situ populations (r~2=0.231–0.235, P=0.001).The main factors that affected stomatal density and SOI of oriental oak were stomatalsize, LMA and MAP by multiple regression analysis. The main factors influencingstomatal Rpvalue were stomatal length and MAP. The present results implied thatstomatal density of oriental oak were genetically adaptive to long-term ecologicalenvironments and had high flexibilities in response to temporary climatic changes. Thestomatal Rpvalue was relatively stable, environmental factors influenced the stomatalRpvalue in some extent, but did not change the non-random distribution pattern ofstomata.4) Leaf trichome density of oriental oak had significant differences among in situpopulations (P <0.001), while had no significant differences among15gardenpopulations (P=0.521). Trichome density was invariant with latitude, longitude andaltitude of the origins for both in situ and common garden populations (P=0.107– 0.650). Leaf trichome density was significantly negatively correlated with MAP (r~2=0.159, P=0.007), positively correlated with MMSR (r~2=0.095, P=0.053) and wasinvariant with other climatic factors for in situ populations (P=0.074–0.613).Trichome density was independent of climatic factors of origins for common gardenpopulations (P=0.404–0.985). Leaf trichome density was significantly positivelycorrelated with leaf petiole length (r~2=0.145, P=0.0110) and LMA (r~2=0.235, P=0.001), and significantly positively correlated with stomatal density (r~2=0.510, P <0.001) for in situ populations. Leaf LMA and MAP were the main factors that affectedleaf trichome density of oriental oak. The present study suggested that the leaf trichomeand stomata may be two leaf traits that have coevolution relationships during long-termenvironmental adaptation. Leaf trichome density of oriental oak was very sensitive toenvironmental changes and had strong phenotypic plasticity. |
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