Research On Root And Leaf Functional Traits Of Four Larch Plantations In Jilin City

As the tree species with the largest planted area in Northeast China,larch has great ecological and economic values.Root and leaf are the most important resource acquiring organs of plants,their functional traits can reflect the resource acquisition strategies of plants.Previous studies have been conducted on the root and leaf functional traits of different life types and its response to the environment.However,the difference between root and leaf functional traits,the relationship between root and leaf economic traits,and whether they have different resource acquisition strategies when closely related tree species growing in similar environments remains to be studied.Therefore,in this study,Larix olgens,L.gmelini,L.principis-rupprechtii and L.kaempferi in Songhua Lake area of Jilin were taken as the research object,and the morphological,anatomical and chemical traits of their leaf and fine root were measured,to explore the differences of their functional traits and the relationships among leaf economic traits,root economic traits and corresponding economic traits of root and leaf,furthermore,the differences between aboveground and underground resource acquisition strategies of the four larch species were analyzed.The results are as follows:（1）There were significant differences in leaf functional traits among the four kinds of larch species.L.principis-rupprechtii had the largest specific leaf area（198.40 g/cm²）,the highest phosphorus content（1.92 mg/g）and carbon assimilation ability,the smallest dry matter content（22.26%）and tissue density（0.10 g/cm³）,and the lowest carbon content（424.55 mg/g）,its leaf resource acquisition ability was the strongest among the four larch species.L.kaempferi had the smallest specific leaf area（135.80 g/cm2）,the highest dry matter content（26.12%）and carbon content（459.52 mg/g）,and its leaf resource acquisition ability was the weakest.Among the economic leaf traits of 4 larch species,specific leaf area was negatively correlated with leaf dry matter mass and leaf tissue density,leaf thickness was positively correlated with leaf nitrogen content,leaf dry matter mass was positively correlated with leaf tissue density,and leaf C:N was negatively correlated with leaf nitrogen content and leaf thickness.The relationship between leaf economic traits of larix was affected by factors such as research scale,tree species and interspecific affinity.The tradeoff between resource acquisition and investment still existed among leaf economic traits,but it was different from the traditional leaf economic spectrum There was no significant difference in leaf resource acquisition strategies among the four larch species.（2）The changes of fine root functional traits with root order were consistent among the four larch species.The root diameter increased with the increase of root order,while the specific root length decreased gradually.The diameter of the middle column of fine roots increased while the increase of the root order,but the thickness of fine roots and the ratio of the cortex to the middle column radius of fine roots showed the opposite trend.The root N content decreased gradually with the increase of root order,while the root C:N increased with the increase of root order.The1^st order root diameter of L.kaempferi was the smallest（401.98μm）,the 5^th order root of L.gmelini was the largest（1764.72μm）;the 1^st order specific root length of Larix gmelini was the largest（47.04 m/g）,and the 5^th order of L.olgensis was the smallest（4.18 m/g）;the 1^st order root cortex of L.olgensis was the thickest（124.86μm）,and the 3^rd order root of L.kaempferi was the thinnest（70.33μm）;the 5^th order of L.gmelini had the largest stele diameter（1422.38μm）,and the 1^st order of L.principis-rupprechtii was the smallest（163.74μm）;the ratio of cortex to stele diameter of the 1^st order root for L.olgensis was the largest（1.31）,while that of the 3^rd order root of L.gmelini was the smallest（0.61）;the 1^st order root of L.olgensis had the highest nitrogen content（19.89 mg/g）,while 5^th order root of L.gmelini had the lowest（7.55 mg/g）;the 1^st order root of L.olgensis had the highest phosphorus content（1.27 mg/g）,while the 5^th roots L.kaempferi had the lowest（0.47 mg/g）;the1^st order roots of L.olgensis had the lowest C:N（22.38）,while the 5^th order roots of L.gmelini was the highest（65.81）.For 1^st order root:L.principis-rupprechtii had the highest specific root length and root tissue density with the strongest soil exploration ability.L.olgensis had the lowest specific root length and root tissue density with the weakest soil exploration ability.The thickness of root cortex,diameter of middle column and ratio of cortex to middle column radius of L.olgensis were the largest,the thickness of cortex and the ratio of cortex to radius of stele of L.kaempferi were the smallest,L.principis-rupprechtii has the smallest stele diameter.Among the root economic traits of 4 larch species:Root diameter was positively correlated with root nitrogen content,while root diameter and root nitrogen content were negatively correlated with root tissue density,root dry matter content,specific root length,and C:N.Root tissue density was positively correlated with root dry matter content,and both were positively correlated with C:N,while root dry matter content was negatively correlated with specific root length,and C:N was positively correlated with specific root length.The tradeoff between economic characters of larix root reflects two dimensions of root resource acquisition-protection and resource acquisition efficiency-life.The first-order root resource acquisition strategies of the four larch species were similar.（3）The resource acquisition strategies of larch leaf and 1^st order root were different.In conclusion,this study found that the four larch species growing in similar environments had significant differences in root and leaf functional traits,but had similar leaf resource acquisition strategies and first-order root resource acquisition strategies.The resource acquisition strategies of leaf and primary root are relatively independent.