施肥和灌溉对‘新林1号’杨人工林叶根及土壤碳氮磷化学计量特征的影响

王瑞雪; 庞忠义; 彭彦辉; 李潇; 赵曦阳; 王宏星

doi:10.11929/j.swfu.202603006

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施肥和灌溉对‘新林1号’杨人工林叶根及土壤碳氮磷化学计量特征的影响

Effects of fertilizer and irrigation on the C, N and P stoichiometry of leaf−root−soil in Populus cathayana × canadasis ‘Xinlin1’

摘要

摘要: 以10年生‘新林1号’杨人工林为研究对象，设置3个施肥水平：1000 g尿素·株⁻¹（N）、1000 g复合肥·株⁻¹（F）和0 g·株⁻¹（CK）和3个灌溉水平：-20 kPa阈值灌溉（I₂₀）、-33 kPa（I₃₃）阈值灌溉和未灌溉（I₀），测定杨树叶片、根系和根际土的碳和养分含量，并计算碳氮磷化学计量比。结果表明：施肥和灌溉显著增加叶片和根系的全氮（TN）和全磷（TP）含量，降低C/N、C/P，其中I₂₀F处理下叶片TN（29.8 g·kg⁻¹）和TP（1.8 g·kg⁻¹）含量最高，显著高于I₀CK下叶片TN和TP含量；I₂₀F处理的C/P和N/P最低，分别为266.4、15.7，显著低于其他处理。施肥对土壤养分含量和化学计量比均有显著影响（除了TC和C/N）；灌溉仅对根际土壤的TP、AP、AK含量和N/P有显著影响，其中I₂₀F处理下根际土壤TP（0.5 g·kg⁻¹）、AP（11.4 mg·kg⁻¹）、AK（218.3 mg·kg⁻¹）含量最高，与I₀CK相比，分别提高了28.9%、44.8%、15.6%。 ‘新林1号’杨的胸径和材积的年增长量与叶片和根系的TN和TP含量、土壤的TP、AP、AK含量呈显著正相关，与叶片和根系的C/N、C/P及土壤N/P呈显著负相关；随机森林结果表明叶片和根系的TP含量、叶片C/P是影响林木生长的最重要的因子。施肥和灌溉显著增加叶片、根系和根际土壤养分含量，改变化学计量特征，I₂₀F处理下叶片和根系TN和TP含量、根际土壤TP、AP、AK含量达到最大，且叶片和根系C/P和土壤N/P最低。充足的水分条件（-20 kPa阈值灌溉）配施复合肥是促进‘新林1号’杨生长的最佳水分耦合措施。

Abstract:
A 10-year-old 'Xinlin1' poplar plantation was selected as the research object. Three fertilization levels were set: 1000 g urea per tree (N), 1000 g compound fertilizer per tree (F),
and 0 g per tree (CK), and three irrigation levels: -20 kPa threshold irrigation (I₂₀), -33 kPa threshold irrigation (I₃₃), and no irrigation (I₀). The carbon and nutrient contents of poplar leaves, fine roots, and rhizosphere soil were measured, and the C, N and P stoichiometry were calculated. The results showed that: Fertilization and irrigation significantly increased the total nitrogen (TN) and total phosphorus (TP) contents in leaves and roots, and decreased C/N and C/P. The I₂₀F treatment had the highest leaf TN (29.8 g·kg⁻¹) and TP content (1.8 g·kg⁻¹), which were significantly higher than those under the I₀CK treatment. The C/P and N/P ratios were the lowest under the I₂₀F (266.4 and 15.7) treatment, which were significantly lower than those under other treatments, with reductions of 26.3% and 5.3% compared to the I₀CK treatment. Fertilization significantly affected soil nutrient contents and stoichiometric ratios, except for TC and C/N. Irrigation only significantly affected the AP and AK contents, and N/P ratio of the rhizosphere soil of 'Xinlin1' poplar. Under the I₂₀F treatment, the rhizosphere soil TP (0.5 g·kg⁻¹), AP (11.4 mg·kg⁻¹), and AK (218.3 mg·kg⁻¹) contents were the highest, which were 28.9%, 44.8%, and 15.6% higher than those under the I₀CK treatment (TP: 0.4 g·kg⁻¹; AP: 7.9 mg·kg⁻¹; AK: 188.9 mg·kg⁻¹), respectively. Correlation analysis results indicated that the annual growth of the diameter at breast height and volume of 'Xinlin1' poplar were significantly positively correlated with the TN and TP contents of leaves and roots, as well as the TP, AP, and AK contents of soil, and significantly negatively correlated with the C/N and C/P ratios of leaves and roots and the N/P ratio of soil. Random forest results showed that the TP contents of leaves and roots and the C/P ratio of leaves were the most important factors affecting tree growth. Fertilization and irrigation significantly increased the nutrient contents of leaves, roots, and rhizosphere soil, and changed the stoichiometric characteristics. The TN and TP contents of leaves and roots and the TP, AP, and AK contents of rhizosphere soil were the highest under the I₂₀F treatment, and the C/P ratios of leaves and roots and the N/P ratio of soil were the lowest. Sufficient water conditions (-20 kPa threshold irrigation) and compound fertilizer application is the best water and fertilizer measures to promote the growth of 'Xinlin1' poplar.

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