The Relationship Between Leaf And Vein Traits Of Robinia Pseudoacacia And Populus Bolleana In Northern Mountain Of Lanzhou

Leaves are the important part for seed plants making organic nutrients, withtranspiration, photosynthesis and respiration function and role, and are the primaryproducers of energy converters in the ecosystem, the material production of plants directlyaffected the relationship between form and function of leaves, leaves characters in turn canaffect the function of plant and basic behavior. Veins as the xylem vascular tissuecomponents of the leaves and play an important role in transporting corridor, and transportwater, nutrients and photosynthetic products for leaves, contain a dual function inphysiology and mechanics. Morphological and functional diversity of plant leaves is oftenreflected by the highly diverse network of veins. Differentiation characters of leafmorphology and veins functional traits reflect the ecological adaptation strategies thatplants formed under the pressure of natural selection, and is an important way tounderstand the mechanism of plant plasticity. Leaf biomass, formation and adaptationmechanisms of leaf size, veins network and support construction investment and otherissues have been numerously studied, hower, combining the leaf traits and veins networkfunctional traits to comprehensivly analysis and understanding the growth of leaves andadaptation strategies is still poorly studied. In view of this, in the Green base of NorthwestNormal University, Lanzhou, Robinia pseudoacacia and Populus bolleana were selectedfor study, standardized major axis estimation method(SMA) was used, analyzed therelationship between R. pseudoacacia and P. bolleana petioles, mid-rib biomass allocationand leaf size, mid-rib biomass ratio with vein density, and vein density with leaf size, inorder to systematically reveal leaf regulate carbon allocation policy by adjusting the veinnetwork construction, thus enhancing the adaptability of plants and photosynthetic gains,and comparative analysis the differences of plant growth strategy in different leaf shapesand vein type. The result showed that:(1)R. pseudoacacia was pinnate-veined ovate leaves, the leaf size was2.03-7.89cm2,the dry mass was0.035-0.095g, petiole dry mass was0.001-0.003g, mid-rib dry mass was0.002-0.007g,1°,2°,3°, minor veins densities were0.53-1.09cm/cm2,2.38-4.47cm/cm2,9.20-11.12cm/cm2,40.06-52.17cm/cm2respectively; P. bolleana was palmate-veinedleaves, the leaf size was20.86-81.74cm2, the dry mass was0.135-2.203g, petiole drymass was0.013-0.269g, mid-rib dry mass was0.017-0.251g,1°,2°,3°, minor veins densities were0.43-0.71cm/cm2?0.63-1.20cm/cm2?2.34-3.79cm/cm2,6.08-19.37cm/cm2respectively.(2)The dry mass of petiole and mid-rib in R. pseudoacacia and P. bolleana bothincreased with increasing leaf dry mass, and the increases were speeder than leaf dry mass,the increase of mid-rib dry mass were speeder than petiole dry mass, P. bolleana has morepetiole and mid-rib biomass allocation ratio than R. pseudoacacia, and more petiolebiomass allocation ratio than mid-rib.(3)The dry mass of petiole and mid-rib in R. pseudoacacia and P. bolleana bothincreased with increasing leaf area, the increase of petiole and mid-rib dry mass werespeeder than leaf area.(4)The mid-rib biomass allocation and vein density in R. pseudoacacia and P.bolleana showed strong negative scaling relationship, indicated a trade-off between midribbiomass allocation and vein density.(5)The1°,2°,3°veins showed strong negative scaling in vein density with leaf sizein R. pseudoacacia and P. bolleana, the relationship between2°vein density and leaf sizewas the most significant, but the minor veins showed no significant scaling of vein densitywith leaf size.The resources invest into support tissue in the leaf was limited by leaf size, in whichinvestment in mid-rib concerned with vein density, whereas there is a trade-off betweenvein density and leaf size, leaf regulates plant adaptability and promote photosynthesisproceeds through mutual cooperation between mid-rib, vein density, leaf size. However,the trade-off relationship exists significant differences between species, this mainlyresulted from the potential impact factors such as leaf shape and vein types, differentplants due to differences in the biological characteristics of the leaf, which will inevitablylead to plants take their own growth optimal growth model, which is the demand andinevitable result for niche differentiation of plants and compensation.