Leaf Morphological And Anatomical Traits From Tropical To Cold-temperate Forest Plants:Latitude Pattern And Influence Factors

Leaf traits may reflect the adaptation mechanisms of plants to the external environment. In this study, we investigated leaf morphological and anatomical traits in nine cold-temperate to tropical forests along a 4,200 km transect to test how they vary across latitudinal gradients and their influencing factors. Here, we combined with leaf morphology, anatomical structure of dominant tress (according to relative important value)from large scale to investigate the latitude patterns of leaf traits. Then we examined leaf anatomical traits of 917 common plant species from tropical to cold-temperate forests along the north-south transect of eastern China to quantify the variation in leaf anatomical traits at the levels of species, plant functional groups and community, and to revel the main factors influencing leaf anatomical trait at large scale, and try to establish the linkage between leaf anatomical traits and ecosystem functions in natural communities. The main findings of this study were as fellowed:(1) The results showed that leaf dry weight decreased (P<0.05), while specific leaf area increased (P<0.05) with increasing latitude. Stomatal length and stomatal density did not change significantly, while stomatal pore area index increased (P<0.05) with increasing latitude. The palisade-leaf mesophyll thickness ratio increased (P<0.01), while the spongy-leaf mesophyll thickness ratio decreased with increasing latitude (P<0.01). Climate and leaf nutrients were the main factors that regulated leaf morphological and anatomical traits. Furthermore, we identified positive correlations between leaf area and leaf dry weight, leaf thickness and palisade mesophyll thickness (P<0.01), but negative correlations between stomata length and stomatal density (all Ps<0.01). The observed negative correlations represented the adapt mechanisms of leaves through their morphological and anatomical traits. These findings provided new insights into the responses of leaf morphological and anatomical traits to climate changes and important parameters for future model optimization.(2) For all 917 plant species, leaf anatomical traits present significantly latitude trends at species, plant life form and community levels(P<0.05), while aggregated values of leaf traits at plant life form and community level present different latitude trends compare to species level. Temperature and precipitation appeared to be the main factors influencing adaxial epidermis thickness, abaxial epidermis thickness, palisade-spongy tissue ratio, and spongy tissue-leaf thickness ratio, which explained 33%-72% of the total variation in latitudinal patterns. In addition, abaxial epidermis thickness, leaf thickness, palisade-spongy tissue ratio, and palisade tissue-leaf thickness ratio were all significantly correlated with de Martonne’s aridity index. More importantly, leaf anatomical traits were significantly correlated with gross primary production and water use efficiency, suggesting that leaf anatomical traits considered in this study should be correlated with their ecosystem functions. Latitudinal trends in leaf anatomical traits at large geographical and communities scales are first presented here and verified the real linkage between leaf traits measured at leaf scale and ecosystem functions at natural condition.