Leaf hydraulic traits of larch and ash trees in response to long-term nitrogen addition in northeastern China  

兴安落叶松和水曲柳叶片水力性状对长期氮添加的响应

作　　者：Ying Jin Chuankuan Wang Zhenghu Zhou Jiacun Gu 

机构地区：[1]Center for Ecological Research,Northeast Forestry University,Harbin 150040,China [2]Key Laboratory of Sustainable Forest Ecosystem Management—Ministry of Education,Northeast Forestry University,Harbin 150040,China [3]School of Forestry,Northeast Forestry University,Harbin 150040,China

出　　处：《Journal of Plant Ecology》2021年第6期1105-1114,共10页植物生态学报（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(31901278);the National Science and Technology Support Program of China(2011BAD37B01);the Program for Changjiang Scholars and Innovative Research Team in Universities(IRT_15R09).

摘　　要：Aims Atmospheric nitrogen(N)deposition influences tree hydraulic architecture and thus the growth and survival;but the responses of leaf hydraulic traits remain uncertain,and may vary with species or plant functional types.Methods We used the 16-year N addition experiment(10 g N m−2 year−1)on Fraxinus mandshurica(ash,broadleaf angiosperm)and Larix gmelinii(larch,conifer gymnosperm)plantations in northeastern China and examined the effect of N addition on their leaf hydraulics.We measured the leaf pressure–volume traits by the bench drying method and quantified the maximum leaf hydraulic conductance(K_(leaf_max))and resistance to embolism(P50leaf)by the timed rehydration method.Important Findings Larch had higher K_(leaf_max)and stronger drought tolerance(i.e.,lower relative water content at turgor loss point(RWC_(tlp))and modulus of elasticity(ε),and more negative P50leaf)than ash.N addition increased the leaf osmotic potential at turgor loss(πtlp)and full turgor(π0),and leaf capacitance(Cleaf_mass)for ash but not for larch,indicating that ash is more sensitive to N addition.N addition consistently increased K_(leaf_max)and P50leaf values for both species.πtlp andπ0 were positively while Cleaf_mass was negatively correlated with leaf density(LD)for ash.K_(leaf_max)was positively but P50leaf was negatively related with LD for larch.There were negative relationships between K_(leaf_max)and P50leaf for both species.Overall,our findings suggest that long-term N addition decreases the leaf drought tolerance for these two important tree species,which improve the understanding of the tree hydraulic performance under N deposition.大气氮沉降影响树木水力结构,进而影响树木的生长和生存。然而,目前关于叶片水力性状对氮沉降的响应尚不明确,而且该响应可能与物种或植物功能型有关。本研究以中国东北地区水曲柳(Fraxinus mandshurica,阔叶被子植物)和兴安落叶松(Larix gmelinii,针叶裸子植物)人工林为研究对象,利用长达16年的施氮(10 g N m^(−2)yr^(−1))试验研究了氮添加对两种树种叶片水力性状的影响。用自然干燥法测定了叶片压力-容积曲线,用复水动力学法量化了叶片最大水力导度(K_(leaf_max))和抗栓塞阻力(P50leaf)。研究结果表明,与水曲柳相比,兴安落叶松具有较高的K_(leaf_max)和较强的干旱容忍性(即较低的质壁分离点的相对含水量(RWC_(tlp))和弹性模量(ε),较负的P50leaf)。此外,氮添加增加了水曲柳的叶膨压损失点水势(πtlp)、叶饱和含水量时的渗透势(π0)和叶水容(Cleaf_mass),但对兴安落叶松的这些性状影响不显著,表明水曲柳对氮添加更敏感。氮添加增加了水曲柳和兴安落叶松的K_(leaf_max)和P50leaf。水曲柳的πtlp和π0均与叶密度(LD)正相关,而Cleaf_mass与LD负相关。兴安落叶松的K_(leaf_max)与LD正相关,P50leaf与LD负相关。两个树种的K_(leaf_max)与P50leaf均呈负相关关系。我们的研究表明,长期氮添加降低了这两个重要造林树种的叶片干旱容忍性,这一发现加深了我们对氮沉降背景下树木水力表现的理解。

关 键 词：nitrogen deposition pressure–volume traits leaf hydraulics Larix gemelinii Fraxinus mandshurica 

分 类 号：S714[农业科学—林学]