1、第 41 卷 第 2 期2023 年 4 月四川农业大学学报Journal of Sichuan Agricultural UniversityVol.41 No.2Apr.2023华西雨屏区不同林龄柳杉人工林的根系形态和碳氮磷化学计量特征李婧，洪宗文，熊仕臣，李宇，刘宣，李冬青，李晗，谭波，徐振锋，游成铭*（长江上游林业生态工程四川省重点实验室/长江上游森林资源保育与生态安全国家林业和草原局重点实验室/华西雨屏区人工林生态系统研究长期科研基地/四川农业大学生态林业研究所，成都 611130）摘要：【目的】为揭示不同根序的根系形态及碳氮磷化学计量特征在林木不同生长阶段的差异。【方法】以华西雨屏
2、区中龄林（13 a）、成熟林（33 a）和过熟林（53 a）的柳杉人工林为研究对象，对比分析不同林龄柳杉15级的根系形态和根功能模块的碳氮磷化学计量特征。【结果】随林龄增加，柳杉15级细根直径、比根长和比表面积整体上分别呈先增后减，先减后增和逐渐降低的趋势，而根组织密度则无明显变化规律；随根序增加，同一林龄细根直径整体呈增加趋势，而比根长和比表面积均逐渐降低。随林龄增加，柳杉细根碳含量整体呈先增后减的趋势，磷含量、碳氮比和碳磷比呈先减后增的规律，氮磷比无显著变化。并且，吸收根的氮含量整体高于运输根，运输根的碳含量、碳氮比和碳磷比均高于吸收根。细根碳含量与磷含量呈显著负相关，与碳氮比、碳磷比呈显
3、著正相关。氮含量与磷含量、氮磷比、比根长和比表面积显著正相关，与碳氮比、碳磷比、直径和组织密度显著负相关。【结论】柳杉人工林细根形态和化学计量特征在不同生长阶段和根序上均具有较强的可塑性。研究结果有助于深入认识林木资源吸收策略与养分平衡规律，可为人工林的可持续经营与管理提供理论依据。关键词：华西雨屏区；柳杉；林龄；细根；化学计量特征中图分类号：S718.5 文献标志码：A 文章编号：1000-2650（2023）02-0257-09The Root Morphology and CNP Stoichiometric Characteristics of Cryptomeria japonica
4、 var.sinensis Plantations at Different Ages in Rainy Area of Western ChinaLI Jing，HONG Zongwen，XIONG Shichen，LI Yu，LIU Xuan，LI Dongqing，LI Han，TAN Bo，XU Zhenfeng，YOU Chengming*（Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province/National Fores
5、try and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River/Long-Term Research Station of Alpine Forest Ecosystems/Institute of Ecology&Forestry，Sichuan Agricultural University，Chengdu 611130，China）Abstract:【Objecti
6、ve】This study aims to reveal the difference of root morphology and carbon（C），nitrogen（N）and phosphorus（P）stoichiometry characteristics of roots at different orders for tree at different growth stages.【Method】Taking the Cryptomeria japonica var.sinensis plantations of middle-aged forests（13 a），mature
7、 forests（33 a）and over-mature forests（53 a）in Rain Area of Western China as the research objects，this study compared and analyzed the root morphology and root function modules of 1-5 grades of C.japonica var.sinensis plantations at different ages.【Result】With the increase of stand age，the average di
8、ameter of grade 1-5 fine roots increased first and then decreased，the specific root doi:10.16036/j.issn.1000-2650.202205182收稿日期：2022-05-30基金项目：国家自然科学基金（32071745，31870602，31901295）；四川省应用基础研究基金（2021YJ0340）；四川农业大学科研兴趣小组（2022105）。作者简介：李婧，硕士研究生。*责任作者：游成铭，讲师，主要从事森林生态学研究，E-mail：。四川农业大学学报第 41 卷 length decre
9、ased first and then increased，and the specific surface area decreased gradually，while the root tissue density showed no obvious change.With the increase of root order，the average fine root diameter of the same stand age increased，while the specific root length and specific surface area decreased gra
10、dually.With the increase of stand age，the carbon content of C.japonica var.sinensis fine roots as a whole showed a trend of increasing first and then decreasing，the P content，C/N ratio，and C/P ratio showed a trend of decreasing first and then increasing，and the N/P ratio did not change significantly
11、.Moreover，the N content of the absorptive root was higher than that of the transportive root，while the carbon content，C/N ratio，and C/P ratio of the transportive root were all higher than the absorptive root.The carbon content of fine roots was significantly negatively correlated with phosphorus con
12、tent，but was significantly positively correlated with the C/N ratio and C/P ratio.The N content was significantly positively correlated with P content，N/P ratio，specific root length and specific surface area，and was significantly negatively correlated with C/N ratio，C/P ratio，diameter and tissue den
13、sity.【Conclusion】In summary，the fine root morphology and stoichiometry of C.japonica var.sinensis plantation have strong plasticity at different growth stages and root orders.The results of the study are helpful for in-depth understanding of the strategy of forest resource absorption and nutrient ba
14、lance，and can provide a theoretical basis for the sustainable management and operation of plantations.Keywords:Rain Area of Western China；Cryptomeria japonica var.sinensis plantation；stand age；fine root；stoichiometric characteristics细根是林木获取水分、养分和转移碳到土壤的功能器官，对森林生态系统的生产力及碳和养分循环具有重要调控作用1-4。细根形态(如直径、比根长
15、和组织密度等)是影响植物生产力的重要指标，对维持根系的功能具有重要作用5-6。例如，根系直径与根系寿命和周转有关，而比根长和比表面积可以表征根系对养分的吸收效率和利用效率5。碳氮磷化学计量特征是研究植物体内元素分配及其耦合关系的有效手段，反映了植物资源利用效率和生态适应策略7-8。例如，细根碳含量可以揭示植物根系构建消耗的碳同化产物9，氮、磷含量是揭示植物养分库和生理活性的重要指标10，并且氮磷比可以用于诊断林木潜在的养分限制状态11-13。因此，研究细根形态和碳氮磷生态化学计量特征有助于深入认识林木资源吸收策略与养分平衡规律，可为人工林的可持续经营与管理提供理论依据。目前国内外对细根的定义划
16、分主要有3种，分别是按照直径特定的阈值(如，0.5 mm、1 mm或 2 mm)、根序级以及根功能模块(如，吸收根和运输根)划分2,14-15。越来越多的研究表明，植物细根较小的内部构造和功能具有高度的异质性，简单地用直径定义细根的方法难以量化其形态、结构和生理的可塑性和多样性16-17。根系是由不同形态和功能的多个分支结构的远端根构成，相较于直径，细根结构和功能与根序及根功能模块联系更为紧密16-17。例如，位于根系远端的吸收根易于菌根定殖、但寿命短，主要负责水分和养分的探测和吸收，而运输根的寿命相较更长，主要执行养分运输、储存及其对植物的固定18。以往研究发现，细根直径和根组织密度随根序的增加而增加，而比根长、氮磷含量则相反19-20。近年来，国内外学者已对不同树种根系形态和化学性状在根序级和根功能模块的差异进行了大量报道3,21-22，但缺乏林龄对细根形态和化学计量特征影响的研究。林龄作为林分结构的主要特征之一，不同生长阶段的林木可以通过改变土壤的养分资源有效性和养分需求量23，进而改变林木细根形态和细根碳氮磷化学计量特征。首先，林龄可通过改变林分结构、微环境、凋落物归还、根系分