兰州市南山和北山3种乔木叶片生态化学计量特征的对比研究

Abstract

叶片生态化学计量是了解生物地球化学循环的窗口，也是认识植物的生长状况及生态适应性的关键，研究人工林叶片生态化学计量特征对进一步优化生态工程建设具有重要意义。为揭示兰州市南北两山主要绿化树种侧柏、圆柏和云杉环境适应性的异同，对其叶片生态化学计量特征进行了对比研究。结果显示：云杉、圆柏叶片C含量（496.02、497.64 g/kg）显著高于侧柏叶片（484.12 g/kg），侧柏叶片N、P含量（17.70、1.66 g/kg）均显著高于圆柏（14.04、1.42 g/kg）和云杉（15.62、1.40 g/kg）。C、N、P的变异系数均为圆柏 < 侧柏 < 云杉；云杉、圆柏叶片C ∶ N （33.32、35.42）、C ∶ P （389.57、360.52）显著高于侧柏叶片（28.17、306.07），云杉叶片N ∶ P （11.88）显著高于圆柏叶片（10.20）和侧柏叶片（10.98）。C ∶ N、C ∶ P、N ∶ P的变异系数均为圆柏 < 侧柏 < 云杉；侧柏和云杉叶片N含量与P含量正相关、与C ∶ N、C ∶ P负相关，而3种乔木叶片P含量与C ∶ P、N ∶ P负相关（且C ∶ P与N ∶ P正相关）。圆柏叶片C含量与N含量正相关，侧柏叶片C含量与N含量负相关但与叶片C ∶ N、C ∶ P正相关，侧柏和云杉叶片C ∶ N与C ∶ P正相关。冗余分析表明，SOC ∶ STN是影响3种乔木叶片化学计量的主导因子，圆柏叶片C、侧柏叶片P与SOC正相关，3种乔木叶片N都与SOC、SOC ∶ STN和SOC ∶ STP正相关；云杉叶片N，侧柏、云杉叶片P和STP负相关，而STP与侧柏叶片C ∶ P、N ∶ P及云杉叶片C ∶ N正相关；3种乔木叶片C ∶ N与SOC ∶ STN、SOC ∶ STP负相关。研究结果表明：面对养分贫瘠的土壤环境，3种乔木叶片生态化学计量的适应策略有所不同，其中云杉和圆柏采取防御策略，而侧柏采取竞争倾向策略。虽然云杉是兰州市较适宜的造林树种，但其生长与其他两种乔木一样，都受N元素的限制。;Foliar stoichiometry is a window to understand the biogeochemical cycle, as well as understand plant growth and ecological adaptability. Studying the foliar stoichiometry of artificial forests is of great significance for further optimizing ecological projects. In order to reveal the similarities and differences of the main greening species (Sabina chinensis, platycladus orientalis, Picea asperata) to environmental adaptability in the north and south mountains of Lanzhou City, the foliar stoichiometry traits of three trees were compared. The results showed that the foliar C contents of Picea asperata and Sabina chinensis (497.64 g/kg, and 496.02 g/kg, respectively) was significantly higher than that of platycladus orientalis (484.12 g/kg). The foliar N content of platycladus orientalis (17.70 g/kg) was significantly higher than that of Sabina chinensis and Picea asperata (14.04 g/kg,15.62 g/kg, respectively), and this trend was also found for foliar P content, with the former being 1.66 g/kg, and the latter two being 1.42 g/kg and 1.40 g/kg, respectively. The order of variation coefficients of C, N, and P were Sabina chinensis < platycladus orientalis < Picea asperata. The foliar C ∶ N and C ∶ P of Sabina chinensis (35.42 and 360.52, respectively) and Picea asperata (33.32 and 389.57, respectively) were both significantly higher than the C ∶ N (28.17) and C ∶ P (306.07) of platycladus orientalis. The foliar N ∶ P (11.88) of Picea asperata was significantly higher than that of Sabina chinensis (10.20) and platycladus orientalis (10.98). The order of variation coefficients of C ∶ N, C ∶ P, and N ∶ P were Sabina chinensis < platycladus orientalis < Picea asperata. The foliar N contents of platycladus orientalis and Picea asperata were positively related to the foliar P content, but were negatively related to the foliar C ∶ N and C ∶ P. The foliar P contents of the three trees were negatively related to the foliar C ∶ P and N ∶ P, with being positive correlation with each other. The foliar C content of Sabina chinensis was positively related to the foliar N content, yet for platycladus orientalis it was negatively related to the foliar N content, but positively related to the foliar C ∶ N and C ∶ P. The redundant analysis showed that foliar stoichiometry traits were mainly influenced by soil organic carbon (SOC): soil total nitrogen (STN), with the foliar C content of Sabina chinensis being positively correlated with SOC, SOC ∶ STN, and soil pH; the foliar N content of the three trees were all positively correlated with SOC, SOC ∶ STN, and SOC ∶ STP. The foliar N content of Picea asperata, and the foliar P content of platycladus orientalis and Picea asperata were negatively correlated with soil total phosphorus (STP), while the STP was positively correlated with the foliar C ∶ P and N ∶ P of platycladus orientalis and foliar C ∶ N of Picea asperata, respectively. The foliar C ∶ N values of the three trees were negatively correlated with SOC ∶ STN and SOC ∶ STP. The results suggest that three major trees have different adaptation strategies under poor nutrient habitat, with a defensive strategy for Sabina chinensis and Picea asperata, and a competitive strategy for platycladus orientalis. Though Picea asperata may be the most suitable species that were planted in north and south mountains of Lanzhou City, the growth of the three trees were all limited by STN.