Correlation Between Leaf Traits And Leaf Water Use Efficiency Vein Of Robinia Pseudoacacia In Different Aspects Of Beishan Mountain In Lanzhou

Leaves are the main sites for plant photosynthesis,while are the hydraulic bottlenecks for whole plants.It is necessary to timely deal with the catastrophic hydraulic imbalance that may occur in the plants,which directly affects the basic behavior and function of the plant.The relations among leaf traits with plant photosynthesis,respiration,transpiration have a huge change in the different habitats and different species,but also by the transpiration of leaf structure(such as vein system,etc.).The veins as the vascular tissue and xylem components of the leaf,bearing an important function to transport the water,nutrient and photosynthetic products on the leaf.It effect the water supply and the veins of blade support efficiency on the whole leaf in a large excent.The veins with the photosynthetic rate have a closely relation,and carbon capture and water efficiency of the leaves.It reflects the basic behavior of plant adaptation to specific habitats and photosynthetic physiological functions,which have the dual functions of physiology and mechanics.In the process of photosynthesis,the leaves of the plant are inevitably lost to the surrounding atmosphere,mainly through the leaf traits and stomatal characteristics in the process of photosynthesis so that the leaf structure changes and combination to achieve leaf moisture balance.Many scholars study the leaf traits,leaf vein network system,plant photosynthetic physiological characteristics and plant water balance were studied respectively.But combine the leaf traits,leaf vein traits with photosynthetic characteristics to comprehensive analyze the physiological characteristics of plant leaves is not very profound.Therefore we choose the northern mountains of Lanzhou,and our objective was to study the changes in the relationship between venation density and stomatal traits(stomatal density and stomatal length)in Robinia pseudoacacia with changes in slope aspect.the standardized major axis(SMA)estimation method was then used to examine the relationship among between leaf density and leaf size,veins traits and stomatal density,effecting of veins on leaf water balance.Systematic eladorating the allocation mechanism of plant heterogeneity of resources.The results show that:(1)With the slope from the south to the east,west and north,the crown density,average tree height and soil moisture of the plant community displayed a pattern of increase,and photosynthetically active radiation(PAR)decreased.(2)With the slope from the south to the east,west and north,The leaf area,foliar water content and mid-rib diameter of the leaves of Robinia pseudoacacia were increased.The leaf dry weight,specific leaf weight,vein density,stomatal density showed a decreasing trend.(3)With the slope from the south to the east,west and north.The leaf net photosynthetic rate(P_n),water use efficiency(WUE),transpiration rate(T_r)and stomatal conductance(G_s)of Robinia pseudoacacia were decreasing.(4)There were significant differences in vein density with leaf area,leaf dry mass and stomatal density of Robinia pseudoacacia(P<0.05)on different slope.There are a allometry negative correlations between leaf density and leaf area on the south and north slope(p<0.01),and there are an significant difference on east and west slope(P<0.05).The slope is greater than 1 on the south,east and west slope,indicating that the increase rate of the leaf density is larger than that of the single leaf area.The slope of the northern slope is less than 1 indicating that the increase rate of leaf area is larger than that of leaf density.There was a significant positively correlation between leaf density and leaf drymass(P<0.05),and there were no significant correlations on north,east and west slope(p>0.05).The regression slope was 0.16 on south,which was close to constant velocity.Venation density of each aspect of Robinia pseudoacacia was positive correlated with stomatal density(p<0.05).There were an allometry correlations in south and north slope(p<0.01),however,there were significantly different in the east slope and the west slope(P<0.05).With the increase of leaf density,the stomatal density increased with the increase of stomatal density,and the growth rate of stomatal density was significantly smaller than that of leaf density.(5)There were significant differences in vein density,leaf water content and water use efficiency of Robinia pseudoacacia(P<0.05)on different slope.The vein density with foliar water content,water use efficiency of Robinia pseudoacacia were negatively correlated in south slope(p<0.05).There were no significant correlation in south,east and west slope(p>0.05).The regression slope was significantly less than1,indicating that leaf density the growth rate higher than leaf Water content,water use efficiency of the rate of increase.There was no significant correlation between the diameter of midrib and the water use efficiency in the four slope directions(p>0.05).The relationship between plant leaf traits and leaf water balance was affected by slope direction,and the difference of photosynthetic resources under different slope conditions was different for leaf size,leaf thickness,leaf traits,stomatal characters,leaf moisture content and water use efficiency The relationship between the various traits of the leaves,mutual control of the relationship between the control of plant adaptability and promote photosynthetic benefits.Different plants due to differences in the biological characteristics of leaves,resulting in their inevitable to take their own suitable for their own growth of the optimal growth pattern,which is the plant niche differentiation and compensation needs and inevitable results.