Leaf Functional Traits Differentiation and Its Trade-off Strategies of Urban Plant are Related to Atmospheric Particulate Pollution

Abstract

Background: Functional trait-based ecological research has been instrumental in advancing our understanding of understanding of environmental changes. It is still, however, unclear how the functional traits of urban plants respond to atmospheric particulate pollution, and what trade-off strategies are shown. In order to explore the variation of plant functional traits with urban atmospheric particulate pollution gradient, we divided atmospheric particulate pollution into three levels according to road distance, and measured the variation of six key leaf functional traits and their trade-off strategies. Results: Here, we show that the functional traits of plants can be used as predictors or indicators of the response of plant to urban atmospheric particulate pollution. Within studies, there was a positive correlation between leaf thickness, leaf dry matter content, leaf tissue density, stomata density and leaf dust deposition. While chlorophyll content index and specific leaf area were negatively correlated with the leaf dust deposition. Plants improve the efficiency of gas exchange by optimizing the spatial distribution of stomata of leaves. Dust deposition promotes the regular distribution of stomata. Due to the pressure of atmospheric particles, urban plant shows a trade-off relationship of economics spectrum traits at the leaf level. Taken together, these results indicate that urban atmospheric particulate pollution is the main factor causing the variation of plant functional traits. Conclusion：Under the influence of urban atmospheric particulate matter, plant show a "slow investment-return" type in the global leaf economics spectrum, with lower specific leaf area, lower chlorophyll content, larger leaf thickness, higher leaf dry matter content, higher leaf tissue density and higher stomatal density. This finding provides a new perspective for understanding the resource trades-off strategy of plants adapting to air pollution environment.