| During the long-term evolution of plants,the formation of their morphological and functional traits is not only influenced by many environmental factors,but also by the inherent heredity of species.The uniqueness of Motianling region and the extensiveness of the study of leaf traits make it very important to study the leaf traits of plants in the region of the Motianling in Minshan.In this study,vegetation survey and sample collection were carried out in the eastern part of the Mt.Motianling of Minshan by using the method of combination of sample line and sample survey.The topographic factors data and functional characteristics of plant leaves were obtained through actual investigation,collation and experimental measurement.In this study,six important leaf traits,namely leaf area,specific leaf area,leaf dry matter content,leaf carbon content,leaf nitrogen content and leaf phosphorus content,were selected to analyze the variation characteristics and biological sources of leaf traits of woody plants,in order to explore the main biological sources of leaf traits variation of woody plants.The relationship between leaf traits and topographic factors(altitude,slope,slope direction and slope position)was analyzed for revealing the response of leaf functional traits to topographic factors.At the same time,the relationship between leaf functional traits and leaf traits of woody plants at different levels(species level and community level)was compared with the change of environmental gradient,so as to explore the adjustment of plant survival strategies with environmental gradient.The research results lay a foundation for further understanding the relationship between plants and climate and the response of plants to climate change and adaptation strategies.At the same time,it accumulates small-scale basic data in typical regions with "large span" and "high concentration",which can provide a basis for the subsequent research on leaf traits and the Mortianling region.In addition,it is expected to provide some scientific basis for the restoration and reconstruction of forest ecosystem in the earth-rock mountain area of Longnan,Gansu Province.The main results of this study are as follows:(1)Variation of leaf traits and biological sources of woody plants in the eastern section of the Mt.Motianling of Minshan.In this study,the leaf traits of woody plants showed great variation,with coefficient of variation ranging from 6.65% to 127.27%.Among them,only leaf carbon content(LCC)was a low-variant trait,showing strong internal stability.Leaf area(LA),specific leaf area(SLA)and leaf phosphorus content(LPC)were all high-variant traits,while leaf dry matter content(LDMC)and leaf nitrogen content(LNC)were moderate.Although the origin of leaf traitII variation is not a single biological factor,the effects of biological factors on leaf traits are primary and secondary.In this study,the biological sources of specific leaf area(SLA)variation were family group,life type and cold tolerance in the order of primary and secondary;the biological sources of leaf dry matter content(LDMC)variation were family group,DBH,drought tolerance and height in the order of primary and secondary;the biological sources of leaf carbon content(LCC)variation were family group,cold tolerance and drought tolerance in the order of primary and secondary;and the biological sources of variation of leaf nitrogen content(LNC)were life type,cold tolerance and drought tolerance in the order of primary and secondary.For leaf phosphorus content(LPC),the biological factors alone had no significant effect on it,but the two-two interaction and the third-order interaction showed significant effect,which indicated that there was a certain stability and complexity in the variation of leaf traits,and the source of variation was not caused by a single factor.These results suggest that there may be some unclear coupling mechanism between plant functional traits and classical morphological classification,which needs further study.(2)The relationship between leaf traits and topographic factors of woody plants in the eastern part of the Mt.Motianling in Minshan.At species level and community level,leaf area(LA)decreased significantly with elevation,which indicated that elevation was the most important factor affecting leaf area(LA);As far as specific leaf area(SLA)is concerned,the most important influencing factors are altitude and slope direction;for leaf dry matter content(LDMC),the main topographic factor is slope direction;for leaf carbon content(LCC)and leaf nitrogen content(LNC),altitude and slope are the most important influencing factors;and slope position has the most significant influence on leaf phosphorus content(LPC).This indicates that the effects of topographic factors on leaf traits are not balanced,which may be related to the complexity of plant habitats.(3)Changes of the relationship between leaf functional traits of woody plants with environmental gradients in the eastern part of the Mt.Motianling of Minshan.In the highly concentrated habitats of the Motianling in Minshan,there is a general correlation between plant leaf traits at both species level and community level.Among them,some combinations of functional traits were stable at different levels,such as specific leaf area and leaf nitrogen content(SLA-LNC),leaf nitrogen content and leaf phosphorus content(LNC-LPC)were significantly positively correlated,which provided a reference for the selection of leaf traits in future large-scale(global or national scale)studies,and it also laysthe foundation for further study on the relationship between leaf traits and environmental gradient(altitude gradient),and further confirms the statement that the correlation between leaf traits is relatively stable compared with single trait.In addition,this study found that the correlation between leaf traits based on species abundance weighting was significantly better than that at species level,which may be due to the stronger adaptation strategies of communities to the environment than individual species. |
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