常绿阔叶林8种乔灌木叶片氮含量及其分配与光合能力的关系

以浙江天童国家森林公园常绿阔叶林为研究对象,采用空间代替时间的方法,研究了5个不同演替阶段常见的4种乔木以及4种灌木叶片的光饱和速率(Pmax)、光合氮素利用效率(PNUE)及其与叶片氮含量(NL)、叶片氮素在细胞壁的分配比例(细胞壁N/叶片总N,NCW/NL)、氮素在光合酶中的分配比例(NR/NL)、单位面积叶干重(LMA)的相互关系。结果表明:(1)演替系列4种乔木和4种灌木各种间指标除NL外均表现出显著差异,前期种较后期种具有更高的NR/NL、PNUE、Pmax,而后期种LMA、NCW/NL、MCW/ML(细胞壁干重/叶片总干重)更大,NL在乔木各种间差异不明显,在灌木种间则差异显著;乔木种较灌木种具有更大的LMA、NCW/NL、MCW/ML,而NR/NL则较灌木小;8种植物的Pmax与NL以杨梅为最高,连蕊茶最低;苦槠具有最高的PNUE,而栲树最低。(2)随着演替的进行,前期种的NR/NL、PNUE、Pmax有减小趋势,而LMA、NCW/NL、MCW/ML逐渐增大,后期种则表现出相反的趋势。(3)NR/NL与Pmax、PNUE之间呈显著正相关关系,而LMA、NCW/NL、MCW/ML则与Pmax、PNUE、NR/NL显著负相关。研究认为,NR/NL与NCW/NL之间的负相关性及其对PNUE的影响可以在一定程度上解释树木在光合与维持两方面的权衡关系以及演替的生理机制。

Content and Allocation of Nitrogen in Leaves of 8 Tree and Shrub Species of the Evergreen Broad-leaved Forest and the Relations with Their Photosynthetic Abilities

The saturated photosynthetic rate(P_max),photosynthetic nitrogen use efficiency(PNUE),as well as their relationships with the nitrogen allocation in cell wall(N_CW/N_L),nitrogen allocation in photosynthetic enzyme(N_R/N_L) and leaf mass per unit area(LMA) of 4 trees and 4 shrubs in different successional stages of the evergreen broad-leaved forest in Tiantong National Forest Park were studied by the method of space instead of time.The result showed that:(1)There were significant differences for every index except N_L,the mean values of N_R/N_L,PNUE,P_max in earlier successional stages were higher than those in later successional stages;the species in the later successional stages had higher LMA,N_CW/N_L and M_CW/M_L.No significant differences were found among the values of N_L in the 4 trees.However,there were significant differences among the shrubs.The mean values of LMA,N_CW/N_L and M_CW/M_L in trees were higher than those in shrubs,while the N_R/N_L had an opposite tendency;the P_max and N_L of Myrica rubra were the highest,Camellia fraternal had the lowest values.Castanopsis sclerophylla had the hightest values of PNUE,Castanopsis fargesii,in the contract,the lowest.(2)With the progress of the succession,the N_R/N_L,PNUE,P_max of the earlier successional stages decrease gradually.N_CW/N_L,LMA and M_CW/M_L increase,respectively,but the species of later successional stages had a opposite trend.(3)N_R/N_L was significantly negatively correlated with the PNUE and P_max(P<0.01),respectively,while LMA,M_CW/M_L,N_CW/N_L were positively correlated with PNUE,P_max and N_R/N_L respectively(P<0.01).The research suggested that the negative correlation between N_CW/N_L and N_R/N_L and their influences on the PNUE can be explain the trade-off between the photosynthesis and persistence as well as the physiological mechanism of the succession to some extent.