不同造林密度和冠层下杉木幼林叶片光合特性的差异研究  

Photosynthetic Characteristics of Leaves under Different Planting Densities and Canopies in Young Cunninghamia lanceolata Seedlings

作　　者：车豪 全小强 王立冬 李小玉 胥清利 梁海燕 王燕茹 马祥庆[1] 闫小莉 CHE Hao;QUAN Xiao-qiang;WANG Li-dong;LI Xiao-yu;XU Qing-li;LIANG Hai-yan;WANG Yan-ru;MA Xiang-qing;YAN Xiao-li(College of Forestry,Fujian Agriculture and Forestry University,Fuzhou,350002,Fujian,China;Fujian Pushang forest farm in Shunchang,Nanping,3532000,Fujian,China)

机构地区：[1]福建农林大学林学院,福建福州350002 [2]福建顺昌埔上国有林场,福建南平353200

出　　处：《林业科学研究》2023年第6期151-161,共11页Forest Research

基　　金：国家重点研发项目“杉木大径级无节良材培育技术”(2021YFD2201302)国家级。

摘　　要：[目的]合理的造林密度和冠层结构可有效提高林木光合效率和生长发育,研究不同造林密度下的杉木幼林不同冠层、方向和枝条部位的叶片光合特征,可为杉木大径级无节良材培育中科学界定合理的造林密度和修枝高度提供理论依据。[方法]以5年生杉木林为对象,于5个造林密度(M1:833、M2:1667、M3:2500、M_(4):3333、M_(5):6667株·hm^(-2))样地中选择3株标准木,分5个不同冠层(距离树体基部1、2、3、4、5 m处)、枝条朝向(东西和南北)、枝条叶片部位(尖端和末梢),测量光合特性值净光合速率(P_(n))、蒸腾速率(T_(r))和气孔导度(G_(s))并计算水分利用效率(WUE)。[结果]1)在冠层2 m处,P_(n)、WUE随造林密度的增加而减小,在冠层3~5 m处P_(n)、G_(s)、T_(r)、WUE随造林密度的增加呈现先升后降的趋势。2)P_(n)、G_(s)、T_(r)、WUE均随冠层的升高而显著增大,树冠5 m处的枝叶光照条件充足,光合作用较强。3)除在M_(4)、M_(5)密度下树冠2~3 m处的杉木叶片P_(n)、G_(s)、T_(r)、WUE在不同枝条部位表现为末梢叶>尖端叶外,其余的不同冠层和不同密度下的杉木叶片P_(n)、G_(s)、T_(r)、WUE在不同枝条部位表现为尖端叶>末梢叶。[结论]5个造林密度中M2密度(1667株·hm^(-2))的杉木叶片在不同冠层和枝条方向上的光合能力整体上更强,在4个冠层中各造林密度下均为树冠5 m处的杉木叶片表现出更大的光合潜力,尖端叶的光合能力强于末梢叶,东西向枝条叶片光合能力强于南北向枝条叶片。在M_(5)造林密度(6667株·hm^(-2))的冠层2和3 m处、M_(4)密度造林(3333株·hm^(-2))的冠层2 m处的枝条叶片净光合速率出现负值,即密度的增加会对林内光照资源产生影响,特别是位于低冠层的枝叶,且密度越大冠层光合能力受到的影响也越明显。[Objective]Reasonable planting density and canopy structure can effectively improve the photo-synthetic efficiency and growth of forest trees.The study of leaf photosynthetic characteristics of Cunning-hamia lanceolata seedlings in different canopy layers,directions and branch positions under different plant-ing densities can provide theoretical basis for scientifically defining reasonable planting density and prun-ing height of C.lanceolata in the cultivation of large-diameter classless trees.[Method]Three standard trees were selected from five plots with planting density(M1:833、M2:1667、M3:2500、M_(4):3333、M_(5):6667 tree·hm^(-2)),there are five different canopy layers(1,2,3,4,5 m away from the base of the tree),two differ-ent orientations of branches(east and west,north and south),and two different parts of branches and leaves(tips and endings).The net photosynthetic rate(P_(n)),transpiration rate(Tr),and stomatal conduct-ance(G_(s))were measured,and water use efficiency(WUE)was calculated.[Result]1)At 2 m of the can-opy,the P_(n) and WUE decreased with the increase of planting density,and the P_(n),G_(s),T_(r),and WUE in-creased first and then decreased at 3~5 m of the canopy.2)the P_(n),G_(s),T_(r),and WUE increased signific-antly with the increase of canopy,and the light condition of branches and leaves at 5 m of canopy was suf-ficient and photosynthesis was strong.3)Except for the leaves at 2 to 3 m of the canopy under M_(4) and M_(5) densities,P_(n),G_(s),T_(r),and WUE in terminal leaves were larger than those in tip leaves at different branch positions,P_(n),G_(s),T_(r),and WUE in the remaining leaves under different canopies and different densities showed the order of tip leaves>terminal leaves in different branch locations.[Conclusion]Among the five planting densities,the leaves at M2 density(1667 tree·hm^(-2))have stronger photosynthetic capacity in dif-ferent canopy and branch directions.In the four canopies,the leaves at 5 m of the canopy showed greater photosynthetic potential.The photosynt

关 键 词：杉木 不同造林密度 不同冠层 光合特性 

分 类 号：S725.6[农业科学—林木遗传育种]