Comparative study on mineral nutrient resorption efficiency of Fraxinus velutina plants with different diameter classes
In order to study the nutrient cycling process of Fraxinus velutina plantation,the nutrient resorption of N,P,K,Ca and Mg in male plants of F.velutina with different diameter classes was systematically analyzed.The result showed that N,P and K in leaves were obviously resorbed by other tissues before abscission,while Ca and Mg were further enriched in the leaves.The nutrient resorption efficiencies of N in F.velutina plants were mostly in the range of 40%-60%,the nutrient resorption efficiencies of Ca were mainly distributed between(-10%)and(-40%),however,the range of nutrient resorption efficiencies of other elements were relatively dispersed.Compared with the plants of larger diameter class,the plants of small diameter class of F.velutina had higher N resorption efficiencies and lower K resorption efficiencies.There was a highly significant positive correlation between leaf N and P nutrient resorption efficiency of F.velutina.During the defoliation stage,the organic N and P fractions of senescent leaves were hydrolyzed into amino acids and inorganic P respectively and then transported out,and these two physiological processes were simultaneous and closely related,and this was also the main reason why N and P resorption efficiencies were closely related.The nutrient resorption efficiency of Ca and Mg also showed a significant positive correlation.Ca and Mg were important structural elements in cell wall and chlorophyll molecule respectively,and these two elements often accumulated continuously in the senescent leaves,which was called"negative resorption",indicating that the transfer processes of these two elements in plants were similar and correlated.The N/P ratios of the fresh leaves of the young F.velutina trees were more than 16,while when the diameter of F.velutina was more than 10 cm,the N/P ratios were mostly less than 14,which indicated that with the increase of forest age,the P limitation in the plantation gradually changed into N limitation.The above results indicate that the application amount of nitrogen fertilizer should be gradually increased with the growth of forest age.The above research results can provide a theoretical reference for further understanding the nutrient cycle process of F.velutina.
Fraxinus velutinanutrient resorptiondiameter classmineral elements
万方数据
维普
