Study On The Adapted Strategy Of Ferns Based On Leaf Functional Traits

Plant functional traits can reflect the change of environment and have an impact on ecosystem function.As a link between plants and the environment,functional traits can be used to explore the adaptation of plants to the environment.Ferns have important research value for that,as an early group of plants to leave water and successfully landed,they belong to both primitive vascular plants and higher sporophytes,and form a link between bryophytes and seed plants.During the evolutionary history of 400 million years,ferns have experianced four mass extinction events,and each time,they diversified and adapted to the new environment.At present,ferns are widely distributed and have various ecological types.Most of them grow under forest,some habitate forest margins or epiphyte on tree trunks.In order to explore the ecologial strategies of ferns in different environments,we collected 234 fern samples as experimental materials in this study.Eight functional traits reflecting different leaf function and plant strategy were measured: Leaf Area,Petiole Length,Leaf Mass per Area,Leaf Nitrogen Concentration,and the density,length,width and the ratio of length to width of stomata.We analysed correlations between functional traits,and compared these functional traits among different ecological types of ferns and among fern groups adapting to different environmental light intensity.The results show that:1.Correlation analysis between functional traits showed that correlations among functional traits in these forest understorey ferns are in accordance with patterns reported for seed plants.We found that foliar leaf mass per area(LMA)decrease with leaf area(Area),nitrogen concentration per unit mass(Nmass)and petiole length(PL);Area increases with Nmass and PL.It embodies the trade-off between the close relationship between leaf functional traits.2.Comparison among growth types of terrestrial,epiphytic,lithophytic and vining showed that:(a)terrestrial ferns that grow understorey tend to have larger Area,higher Nmass,and lower LMA,which help to capture more light in shaded and moist environment.(b)For ferns growing in the rock crevices and the canopy epiphytes,they reduce the Area,increase the LMA and shortening the petiole length,so as to avoid the damage caused by the strong light and low water availability.3.According to different light intensity divisions,when studying the changes of fern stomatal response to the environment,it was found that: When the light intensity is high,the ferrite stomata are in a state of small aspect ratio but high density,in order to respond quickly to changes in the environment and reduce the transpiration rate of the leaves.Under the forest,the ambient light intensity is weak,and the air humidity is high.The fern's stomatal aspect ratio is large and the density is small,not sensitive to moisture.Compared with angiosperms,ferns have lower stomatal density than angiosperms,and their stomata area is higher than that of angiosperms.In summary,this study begins with measuring the leaf functional traits of ferns,analyzes the differences in environmental requirements of different ecological types of ferns,and explores the suitable strategies for ferns in constant environmental changes,and also reveals functions.The ecological indication of traits provides a basis for the living environment needs of existing ferns and provides an important reference for the protection of biodiversity.