Study On Functional Traits Of Ferns From Different Habitats In Wuyi Mountain

Plant functional traits reflect the plant's response to the growth environment and can be used to characterize plant adaptation and survival strategies to the external environment.As the oldest vascular plant,ferns represent a unique evolutionary path of vascular plants and play an important role in the structure and function maintenance of the entire forest ecosystem.However,most of the current researches on plant functional traits are focused on seed plants,and the functional traits of ferns and their response to the environment needs to be further studied.The Wuyi Mountains in Jiangxi preserve the typical mid-subtropical primordial forest ecosystem,the distribution of ferns is very extensive,and it is an ideal area for studying the functional characteristics of ferns.Therefore,in order to explore the functional traits and correlations of various organs of ferns in different habitats,this study collected 45 species of ferns in 4 habitats(especially evergreen broad-leaved forest,bamboo forest,tea field,and streamside)in Wuyi Mountain,Jiangxi.In order to explore the main structural,metabolic and nutrient characteristics and their correlations of fern leaves and fine roots in different habitats,the main functional traits of their leaves and fine roots are measured.The main results of this work were as follows:(1)In terms of the relationships between leaf functional traits,in general,the leaf biomass and leaf area of ferns all show an allometric growth relationship with a slope of less than 1.0,and the results support the hypothesis of "diminishing returns";compared with seed plants,the leaf mass per area of ferns,area-based photosynthesis and nitrogen content are lower than the median value of seed plants,but the relationship between fern leaf traits is roughly the same as that of seed plants;Among different habitats,the leaf mass per area,photosynthetic characteristics and non-structural carbohydrate characteristics are all expressed as follows: tea field > bamboo forest > streamside >evergreen broad-leaved forest;in addition,the tea field has a higher photosynthetic nitrogen and phosphorus utilization efficiency,and the streamside has a higher leaf nitrogen and phosphorus content.In general,the leaf mass per area was significantly negatively correlated with mass-based photosynthesis and photosynthetic nitrogen and phosphorus utilization efficiency(P < 0.05),while photosynthetic nitrogen and phosphorus utilization efficiency was significantly positively correlated with leaf carbon isotope content(P < 0.001).There was a significant positive correlation between leaf nitrogen and phosphorus content(P < 0.001),and these two traits were also significantly related with leaf nitrogen to phosphorus ratio(P < 0.001).Except for N:P and N and N:P,the relationship between leaf traits has a common allometric growth index in different habitats,indicating that the overall habitat has not changed the trade-off mechanism between fern leaf traits.(2)In terms of the relationships between the fine root functional traits,among different habitats,ferns in streamside have larger specific root length and specific root area,higher fine root nitrogen and phosphorus content,and lower root tissue density,ferns in bamboo forest have higher fine root carbon content and larger root tissue density.Generally speaking,the fine root diameter is significantly negatively correlated with the specific root length and specific root area(P < 0.001),and the specific root length is significantly positively correlated with the specific root area(P < 0.001),which was significantly negatively correlated with root tissue density(P < 0.001),and there was also a significant negative correlation between specific root area and root tissue density(P < 0.001).Root nitrogen content was positively correlated with root phosphorus content(P < 0.001),and these two traits were also significantly related with root nitrogen to phosphorus ratio and the specific root length(P < 0.001).The relationship between fine root traits does not have a common allometric growth index in different habitats,indicating that the fine root traits have greater variability and uncertainty compared with leaf traits.(3)In terms of the relationship between leaf-root functional traits,on the whole,the stoichiometric characteristics of leaves and fine roots are significantly different,and the nutrient content(C,N,P content)of the leaf part is higher.The root tissue density of fine roots was significantly negatively correlated with specific leaf area and leaf nitrogen content(P < 0.05),and the nitrogen content of fine roots was significantly positively correlated with specific leaf area(P < 0.05),and the nitrogen content,phosphorus content,and nitrogen-phosphorus ratio between leaves and fine roots were significantly positively correlated(P < 0.001).(4)In terms of the resource trade-off strategies,there was an economics spectrum in the leaves,roots and whole plants of ferns.Ferns in different habitats have different resource trade-off strategies: most of the fern species in the streamside were distributed at the end of the "faster investment and return",and tended to adopt a acquisitive strategy;most of the fern species in the bamboo forest were distributed at the end of the "slower investment and return",and tended to adopt a conservative strategy;while the evergreen broad-leaved forest and tea field fern species were distributed on both sides of acquisition and conservation.In summary,habitat will affect the functional traits of ferns,and the functional traits between leaves and roots were closely correlated.Species in different habitats have formed different life strategies in the process of adapting to the environment.The results of the study were helpful to understand the mechanism of interaction among various traits of ferns in Wuyi mountain,which can provide a basis for the living environment needs of existing ferns and provide references for the protection of biodiversity.