| 摘要: |
| 【目的】研究不同林龄亚热带次生林主要树种细根的生物量、形态特性及其与土壤养分的相关关系，探讨不同林分细根生长特性差异及树种间的竞争作用，为亚热带森林的经营提供理论依据。【方法】在浙江省黄岩山选取经过皆伐后人工播种造林恢复的23年生林分及未经过人为干扰的60年生林分，每个林分中设置10个10 m×10 m的样方，每个样方中随机选取3个采样点，使用根钻法对0～20 cm土层中林分主要树种（青冈、木荷、石栎、其他木本植物）的根系样品及土壤样品进行采集，测定3个不同直径等级（D1.＞0～≤0.5 mm，D2.＞0.5～≤1 mm，D3.＞1～≤2 mm）细根的生物量及其形态特征（比根长、根长密度）,以及土壤铵态氮、硝态氮、全磷及有机质含量，并分析细根生物量及其形态特征与土壤养分的相关性。【结果】（1）细根总生物量随林龄的增加而增大，60年生林分细根总生物量显著（P＜0.05）高于23年生林分，是23年生林分的1.3倍，这种显著性差异主要由杂根（其他木本植物根系）生物量引起，而青冈、木荷、石栎的细根总生物量在2个林龄林分间无显著差异。（2）各径级细根生物量因树种和林分的不同而存在差异，60年生林分青冈D1和D2径级细根生物量分别比23年生林分高82.1%和51.1%，差异显著（P＜0.05）；木荷各径级细根生物量在2个林分间无显著差异；60年生林分石栎D1径级细根生物量是23年生林分的55.5%，差异显著（P＜0.05）；杂根各径级生物量均表现为60年生林分显著（P＜0.05）高于23年生林分，分别是23年生林分的1.5倍（D1）、1.9倍（D2）和1.9倍（D3）。（3）木荷、石栎各径级细根的比根长和根长密度在2个林龄林分间均无显著差异（P＞0.05），但青冈和杂根的细根形态在不同林龄林分间差异显著（P＜0.05），其中60年生林分D3径级比根长分别是23年生林分的1.4和1.3倍，60年生林分青冈D1、D2、D3径级根长密度分别较23年生林分增加了58.36%，41.96%和49.57%，杂根根长密度分别较23年生林分增加了44.76%，120.21%和111.31%。（4）细根总生物量与土壤养分呈显著相关关系，但在树种间和林分间有所差异，在23年生林分中,细根总生物量与土壤铵态氮、硝态氮和有机质含量呈显著或极显著正相关关系;在60年生林分中，细根总生物量与土壤铵态氮、硝态氮、全磷和土壤有机质含量呈显著或极显著正相关关系。【结论】未经过人为干扰的60年生林分细根总生物量显著高于皆伐后人工播种造林恢复的23年生林分，但更容易出现养分短缺的现象；随林龄的增加，青冈可能具有更好的适应能力和竞争能力。 |
| 关键词: 亚热带次生林 林龄 细根生物量 细根形态 土壤养分 |
| DOI： |
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| 基金项目:国家自然科学基金项目（31270489） |
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| Distribution differences of fine root biomass and morphology in subtropical secondary forest at different forest ages |
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WANG Jingbo,YU Shuiqiang,HAO Qianwei,et al
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| Abstract: |
| 【Objective】This paper studied the fine root biomass and morphological characteristics among main tree species at different forest ages,understood their correlation with soil nutrients in subtropical secondary forest and investigate the difference among different stands and competition among tree species to provide basis for the management of subtropical forests.【Method】In this study,the 23-year stand with artificial seeding after clear-cutting and 60-year stand without disturbance were selected in Huangyan Mountain,Zhejiang Province.Ten 10 m×10 m quadrats were set in each stand with 20 quadrats in total.Three sampling points were randomly selected from each quadrat.Root-drill method was used to collect root samples and soil samples of main tree species in the 0-20 cm soil layer (Cyclobalanopsis glauca,Schima superba,Lithocarpus glaber and other woody roots).Biomass and morphological characteristics (specific root length and root length density) of fine roots with different diameters （D1.＞0-≤0.5 mm，D2.＞0.5-≤1 mm and D3.＞1-≤2 mm）were studied.Ammonium nitrogen,nitrate nitrogen,total phosphorus and organic matter of soil were studied,and their correlations with biomass and morphological characteristics of fine roots were also analyzed.【Result】(1) Total fine root biomass increased with forest age.The total fine root biomass in the 60 year old stand was significantly higher than that in the 23-year stand,and that of 60-year stand was 1.3 times of that of the 23-year stand.This significant difference was only reflected on total biomass of other woody roots.There was no significant difference in total fine root biomass for three main tree species between the two stands.(2) There were significant differences in fine root biomass with different diameters,but the differences varied by tree species and forest age.Fine root biomass of C. glauca with D1 and D2 diameter classes in the 60-year stand was 82.1% and 51.1% higher than those of the 23 year stand with significant differences (P＜0.05) between them.There was no significant difference in fine root biomass of different diameters of S. superba between two stands.Fine root biomass of L. glaber with D1 diameter class in the 60-year stand was 55.5% of that in the 23-year stand with significant differences.The fine root biomass of other woody roots with different diameter classes in the 60-year stand was significantly higher (P＜0.05) than that of the 23-year stand. Fine root biomasses of the 60-year stand were 1.5 times (D1),1.9 times (D2) and 1.9 times (D3) higher compared to those of the 23 year stand.(3) There was no significant difference in specific root length and root length density of S. superba and L. glaber between two stands (P＞0.05).However,there were significant differences in fine root morphology of C. glauca and other woody roots between the two stands with different forest ages (i>P＜0.05).Specific root length with D3 diameter class in the 60 year stand was 1.4 times and 1.3 times of that of the 23-year stand.Compared with the 23-year stand,root length density of C. glauca in the 60-year stand was increased by 58.36% (D1),41.96% (D2) and 49.57% (D3),respectively.Compared with that of the 23-year stand,root length density of other woody roots in the 60-year stand was increased by 44.76% (D1)120.21% (D2) and 111.31% (D3),respectively.(4) There was significant correlations between total fine root biomass and soil nutrients,and the correlations were different between two stands and among tree species.In the 23-year stand,total fine root biomass showed significant or highly significant positive correlations with soil ammonium nitrogen,nitrate nitrogen and soil organic matter.In the 60-year stand,there were significant or highly significant positive correlations between total fine root biomass and soil ammonium nitrogen,nitrate nitrogen,total phosphorus and soil organic matter.【Conclusion】The total fine root biomass in the 60-year stand without disturbance was significantly higher than that of the 23-year stand with artificial seeding after clear cutting,but nutrient shortage was more likely to occur.With the increase of forest age,C. glauca had better adaptability and competitiveness. |
| Key words: subtropical secondary evergreen forest forest age fine root biomass fine root morphology soil nutrients |
