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

The Root Morphology and C∶N∶P Stoichiometric Characteristics of Cryptomeria japonica var.sinensis Plantations at Different Ages in Rainy Area of Western China

【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1~5级的根系形态和根功能模块的碳氮磷化学计量特征。【结果】(1)随林龄增加,柳杉1~5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。(2)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。(3)细根碳含量与磷含量呈显著负相关,与碳氮比、碳磷比呈显著正相关。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。

【Objective】 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 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 1-5grades of C.japonica var.sinensis plantations at different ages.【Result】(1)With the increase of stand age,the average diameter of grade 1-5 fine roots increased first and then decreased,the specific root length decreased 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 gradually.(2)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.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.(3)The carbon content of fine roots was significantly negatively correlated with phosphorus content,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 density.【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 balance,and can provide a theoretical basis for the sustainable management and operation of plantations.