CO2浓度升高对毛竹和四季竹叶片主要养分化学计量特征的影响

运用开顶式气室(OTCs)模拟大气CO2浓度升高(500、700 μmol/mol),以目前环境背景大气为对照,研究CO2浓度升高对毛竹和四季竹叶片碳(C)、氮(N)、磷(P)和钾(K)化学计量特征的影响.结果表明,毛竹和四季竹叶片C、N、P和K含量在不同的CO2浓度(对照、500、700 μmol/mol)条件下,变化范围分别为512.13～543.30、19.23～22.97、1.26～0.96和8.40～5.88 mg/g,492.13～498.02、17.97～15.37、1.05 ～0.81和4.25～5.62mg/g.相同的CO2浓度条件下,毛竹叶片C、N、P和K含量均高于四季竹,且受CO2浓度升高的影响较四季竹强烈.毛竹和四季竹叶片C/N、C/P、C/K、N/P、N/K和K/P变化范围分别依次为26.64～23.65、406.58～565.93、60.98～92.40、15.26～23.93、2.29～3.91和7.00～6.22,27.39～32.40、468.70～614.84、115.80～88.61、17.07～18.98、4.24～2.73和4.04～6.94.与环境背景大气比较,CO2浓度升高到500 μmol/mol,对毛竹和四季竹叶片C、N、P和K含量及其化学计量比并不会产生明显影响,这反映了毛竹和四季竹对高CO2浓度环境均表现出较强的适应能力.但CO2浓度升高到700 μ mol/mol,除四季竹叶片C含量无明显变化外,毛竹和四季竹叶片主要养分元素含量及其化学计量比会发生明显的适应性变化,且毛竹较四季竹变化剧烈.综上,CO2浓度升高改变了毛竹和四季竹叶片C、N、P、K含量及其化学计量比格局,尤其是CO2浓度升高到700 μmol/mol时极为明显；在养分供应上,对四季竹生长的N、P、K限制性作用和毛竹生长的N、K限制性作用没有明显影响,但明显增强了毛竹生长的P素限制性作用.

Effects of elevated CO2 on the leaf nutrient stoichiometrical characteristics in Phyllostachys edulis and Oligostachyum lubricum

Troposphere concentrations of CO₂ have been increasing rapidly as a result of human activities since pre industrial time and it’s predicted to continue rising in the future. CO₂ as substance of photosynthesis, and its enrichment has affected nutrient absorption. In this study, open top chambers (OTCs) were employed to determine the effects of elevated CO₂ on the leaf C, N, P, K stoichiometric characteristics in Phyllostachys edulis and Oligostachyum lubricum, using a split plot design with three concentration levels of  (define 350 μmol/mol) (CK),  (define 500 μmol/mol) (T1) and  (define 700 μmol/mol) (T2). The result shows that the increase of the CO₂ concentration changed the content of leaf C, N, P, K and stoichiometric characteristics in P. edulis and O. lubricum. Under the different of CO₂ concentration, the content of leaf C, N, P, K ranged in 512.13-543.30, 19.23-22.97, 1.26-0.96, 8.40-5.88 mg/g in P. edulis and 492.13-498.02, 17.97-15.37, 1.05-0.81, 4.25-5.62 mg/g in O. lubricum. So we can conclude that the contents of leaf C, N, P, and K in P.edulis are higher than in O. lubricum and the effects of elevated CO₂ concentrations in P. edulis are stronger than in O. lubricum. The leaf C/N、C/P、C/K、N/P、N/K、K/P in P. edulis ranged from 26.64 to 23.65, 406.58 to 565.93, 60.98 to 92.40, 15.26 to 23.93, 2.29 to 3.91, 7.00 to 6.22 and 27.39 to 32.40, 468.70 to 614.84, 115.80 to 88.61, 17.07 to 18.98, 4.24 to 2.73, 4.04 to 6.94 in O. lubricum. Compared with the background of environmental atmospheric, the content of leaf C, N, P, K and stoichiometric characteristics make no difference in P. edulis and O. lubricum when CO₂ concentration increase to 500 μmol/mol. But when CO₂ concentration elevated to 700 μmol/mol, the main nutrient elements and other stoichiometric characteristics of P. edulis and O. lubricum have adaptive changes and P. edulis is more strongly than O. lubricum. However the C content of O. lubricum has no significant difference. The results shows that the elevated CO₂ concentration changed the content of leaf C, N, P, K and stoichiometric characteristics of P. edulis and O. lubricum, especially when CO₂ concentration increased to 700 μmol/mol, Meanwhile, CO₂ concentration have no significant effect on the N, P, K conent of O. lubricum and N, K content on P. edulis. However, CO₂ concentration significantly enhanced the restrictive effect of P concentration to P.edulis growth.