纯林和混交林3种植物光合特征研究

Study on Photosynthetic Characteristics of 3 Tree Species in Pure and Mixed Forests

为探究不同造林模式下植物光合生理响应机制,精准提升人工林改造水平,使用Li-6400XT对黄土丘陵区纯林和混交林中油松、连翘、柠条叶片光合作用日变化及光响应曲线进行测定。结果表明:造林模式并未对3个树种净光合速率日变化趋势产生影响,仅对3个树种净光合速率日变化均值产生影响,具体表现为油松(混交连翘)>油松(混交柠条)>油松(纯林)、连翘(纯林)>连翘(混交油松)、柠条(混交油松)>柠条(纯林);在不同造林模式下,影响因子中仅空气相对湿度与净光合速率的关系显示出差异;当光合有效辐射为2000μmol/(m^(2)·s)时,所有测定植物叶片净光合速率趋于饱和,与纯林相比,油松(混交连翘)、油松(混交柠条)、柠条(混交油松)的净光合速率分别提高了42.1%、10.5%和74.0%,连翘(混交油松)的净光合速率降低了40.4%;采用4种光响应模型拟合光响应曲线,结果显示直角双曲线修正模型效果最优,油松(混交连翘)、油松(混交柠条)光合参数均高于油松纯林,柠条(混交油松)高于柠条纯林。上述结果说明,在黄土丘陵区,相较于纯林,油松与柠条的混交林可加强植物各自的光合能力,环境适应性更强,更适合在该区栽植。

To explore the physiological response mechanism of plant photosynthesis under different afforestation modes and improve the plantation forests precisely.In this study,Li-6400XT was used to determine the diurnal changes and light response curves of leaf photosynthesis of Pinus tabuliformis,Forsythia suspensa,and Caragana korshinskii in pure and mixed forests in loess hilly areas.The results showed that the afforestation model did not affect the daily change trend of the net photosynthetic rate(Pn)of the 3 plants and tree species,but only affected the average daily Pn change of the 3 plants species.Pine(mixed Forsythia suspensa)>Pine(mixed Caragana korshinskii)>Pine(pure forest),Forsythia(pure forest)>Forsythia(mixed Pine),Caragana korshinskii(mixed Pine)>Caragana korshinskii(pure forest);in different afforestation modes,only the relationship between Pn and air relative humidity shows a difference;when the photosynthetically active radiation(PAR)is 2000μmol/(m^(2)·s),Pn of all tested plant leaves tends to be saturated.Compared with pure forest,the Pn of Pine(mixed Forsythia suspensa),Pine(mixed Caragana korshinskii)and Caragana korshinskii(mixed Pine)increased by 42.1%,10.5%and 74.0%,respectively,and the Pn of Forsythia(mixed pine)decreased by 40.4%;four light response models are used to fit the light response curve,and the results show that the right-angle hyperbolic correction model(MRH)has the best effect after fitting.The photosynthetic parameters of Pine(mixed Forsythia suspensa)and Pine(mixed Caragana korshinskii)are higher than Pine(pure forest),and Caragana korshinskii(mixed Pine)is higher than Caragana korshinskii(pure forest).Mixed afforestation is more beneficia to the photosynthesis of Pinus tabulaeformis and Caragana korshinskii and can increase the plant environment adaptability and promote plant growth.