摘要
【目的】探讨不同树种叶片的呼吸作用特性及其影响因素,通过呼吸作用的差异量化叶片碳通量估计的影响,以期揭示不同树种叶片呼吸作用的差异以及光对暗呼吸产生的抑制作用。【方法】选取北美地区温带针阔混交林中的尖叶扁柏、刚松、脂松、乔松和铁杉5个常绿树种叶片为试验材料,测量叶片的光响应CO_2响应和呼吸温度响应曲线及叶片结构和生化指标;采用线性回归分析叶片呼吸特性同结构、生化及生理指标间的关系,并运用气孔-光合作用耦合模型和测量得到的参数模拟试验期间叶片碳同化速率。【结果】1）不同树种间叶片比叶面积（SLA）和单位面积氮含量（N_（area））呈显著差异,但单位质量氮含量（N_（mass））差异不显著。叶片单位面积呼吸速率（R_（area））呈现明显种间差异,但同样受到叶片结构性状的调控;2）叶片呼吸同叶片氮含量、净碳同化速率（A）以及SLA间存在显著正相关关系;3）光对5个树种叶片暗呼吸作用均表现出一定的抑制作用,光下线粒体呼吸速率（R_L）同暗呼吸速率（R_n）的比值在0.39~0.90之间。R_L/R_n同Rubisco酶的最大氧化速率（v_（o1500））和最大羧化速率（v_（c1500））均呈显著正相关。此外R_L还和R_n之间具有较强的相关性;4）物种间呼吸作用的Q_（10）为1.44~2.24,不同树种间呼吸作用的总活化能（E_0）虽有差异,但变化幅度较小;5）使用固定的Q_（10）（2.0）并假定R_L=R_n对5个树种叶片碳同化量的模拟均造成一定影响,但影响的方向和大小在物种间各不相同。而此种简化对叶片碳同化量之和造成的影响较小。【结论】不同树种的呼吸生理特性存在种间差异。呼吸速率的种间差异不仅和叶片氮含量有关,同时还和叶片结构形状关系密切。光对暗呼吸的抑制作用受到Rubisco酶羧化和氧化的调控,反映出叶片光合生理和呼吸生理的内在联系。忽视叶片呼吸特性的种间差异及光对暗呼吸的抑制作用将可能导致错误的估计叶片的碳通量,此类误差将会在冠层、生态系统及全球尺度上增大。
【Obiective】This study aimd to investigate the interspecies variation in leaf respiratory characteristics and its underpinning factors,and quantify the impacts of such variation on the estimation of leaf carbon flux. 【Method 】Five evergreen species of Chamaecyparis thyoides,Pinus rigida,P. resinosa,P. strobes and Tsuga canadensis,which are common to temperate coniferous-broadleaf forest of Northern America,were chosen in this study. Leaf light photosynthetic response curves,and CO_2 response curves and respiration temperature response curve as well as leaf morphological and biochemical traits were measured. Using linear regression, we analyzed the relationship among leaf respiratory characteristics,leaf structural,biochemical and physiological attributes. A coupled stomata-photosynthesis model was adopted to simulate the dynamic of leaf level carbon flux during the experimental period. 【Result】Our results showed：（ 1） Interspecific difference was found in leaf area-based nitrogen content（ Narea）,but not in mass-based nitrogen content（ N_（mass））. Likewise,there was obvious difference in the area-based respiration rate（ Rnarea）was highly regulated by leaf morphological traits; 2） Leaf respiration rate could be well explained by its nitrogen content. Moreover,a positive relationship was also found among R,maximum net carbon assimilation rate（ A） and specific leaf area（ SLA）; 3） Light inhibited leaf dark respiration in all species investigated,with the ratio of mitochondrial respiration under daylight to dark respiration rate（ R_L/ R_n） spanning from 0. 39 to 0. 90. The R_L/ Rnratio was positively correlated with maximum oxygenation rate（ v_（o1500）） and carboxylation rate（ v_（c1500）） of Rubisco. In addition,strong correlation was also found between leaf Rnand R_L; 4） Q_（10） of dark respiration ranged from 1. 44 ~ 2. 24. Activation energy of respiration（ E_0） varied among species,but the variation was marginal; 5） With using fixed Q_（10） and assuming R_L= Rnaffected the estimation of leaf carbon flux was affected in all 5 species,but the extent and magnitude of influence were species-specific. The sum of carbon flux for the 5 species was only slightly affected. 【Conclusion 】In summary,those results clearly demonstrated that leaf respiratory characteristics were species-specific. Factors underlying the inter-specific variation include leaf nitrogen content and leaf morphological traits. The light inhibition of dark respiration was regulated by Rubisco carboxylation and oxygenation,reflecting that leaf photosynthesis and respiration were inter-related. Simulating leaf level carbon flux without considering the effects of Q_（10） and light inhibition of dark respiration would lead to incorrect outcomes in terms of leaf carbon gain.Apparently,such error will be undoubtedly magnified when scale up to canopy,ecosystem or global level.
出处
《林业科学》
EI
CAS
CSCD
北大核心
2016年第4期1-10,共10页
Scientia Silvae Sinicae
基金
国家自然科学基金项目(30900192
30570300)
国家外专局-教育部"111计划"项目(B08044)
中央民族大学自主科研项目(MUC2011ZDKT09)
关键词
温带
针阔叶混交林
常绿树种
呼吸作用
温度
temperate zone
deciduous-evergreen mixed forest
evergreen species
respiration
temperature
作者简介
冯金朝为通讯作者。
