麻栎和闽楠幼苗叶功能性状及生物量对光照和施肥的响应

Responses of leaf functional traits and biomass of Quercus acutissima and Phoebe bournei seedings to light and fertilization

光照和养分条件是影响植物生长的重要环境因子,不同生活型植物对环境异质性的响应机制不同。以落叶阔叶树种麻栎和常绿阔叶树种闽楠幼苗为研究对象,设置2个光照梯度(全光照和45%全光照)和4个施肥梯度(不施肥、氮磷供应比为5、15和45)共8种处理,研究光照和施肥及其交互作用对麻栎和闽楠生物量和叶形态、生理及化学性状的影响,并探讨了叶功能性状和生物量的关系。结果表明:(1)光照、施肥及其交互作用对光合气体交换参数(除水分利用效率外)、叶绿素荧光参数、叶形态指标(除比叶面积外)、单位质量叶氮含量和根冠比影响显著(P<0.05)。此外,光照和施肥对地上生物量和总生物量影响显著(P<0.05)。(2)全光照显著增加了麻栎和闽楠单株总叶面积和地上、地下生物量及总生物量(P<0.05),而遮荫降低了非光化学猝灭系数、光合氮利用率和根冠比,增加了单位质量叶氮含量。(3)在全光照处理中,施肥显著增加了麻栎和闽楠水分利用效率(P<0.05);在遮荫处理中,氮磷供应比45显著增加了麻栎和闽楠净光合速率和水分利用效率(P<0.05)。(4)麻栎和闽楠在全光照中倾向于资源获取策略,在遮荫中偏向于资源保守策略。在光照和施肥处理中,麻栎和闽楠单株总叶面积与地上生物量均显著正相关(P<0.05)。总之,单株总叶面积是预测麻栎和闽楠幼苗地上生物量变化的稳定指标,施肥有助于增加低光环境下麻栎和闽楠幼苗的生态适应能力。

The light and nutrient conditions are important environmental factors that affect plant growth, and plants of different life forms have different responses mechanisms to environmental heterogeneity. The seedlings of the deciduous broad-leaved tree species Quercus acutissima Carruth. and the evergreen broad-leaved tree species Phoebe bournei(Hemsl.) Yang were selected as the research objects, and a total of 8 treatments were formed by setting 2 light gradients(the full light and 45% full light) and 4 fertilization gradients(no fertilization, the nitrogen and phosphorus supply ratio of 5, 15 and 45). In this paper, we study the effects of light, fertilization and their interaction on the biomass and leaf morphology, physiological and chemical properties of the Quercus acutissima and Phoebe bournei, and explore the relationship between leaf functional traits and plant biomass. The results showed that:(1) light, fertilization and their interaction had significant effects on photosynthetic gas exchange parameters(except for water use efficiency), chlorophyll fluorescence parameters, leaf morphology indicators(Un-including specific leaf area), unit mass leaf nitrogen content, and root shoot ratio. In addition, light and fertilization showed significant impacts on above ground biomass and total biomass(P<0.05).(2) The treatment of full light significantly increased the total leaf area, aboveground biomass, underground biomass and total biomass of the Q. acutissima and P. bournei(P<0.05), while the treatment of shading reduced the non-photochemical quenching coefficient, photosynthetic nitrogen-use efficiency and root shoot ratio, but increased the unit mass leaf nitrogen content.(3) In the full light treatment, fertilization significantly promoted the water use efficiency of the Q. acutissima and P. bournei(P<0.05). In the shading treatment, the nitrogen and phosphorus supply ratio of 45 markedly increased the net photosynthetic rate and water use efficiency of the Q. acutissima and P. bournei(P<0.05).(4) The Q. acutissima and P. bournei preferred resource acquisition strategies in the full light condition and preferred resource conservation strategies in shading condition. In the light and fertilization treatments, the total leaf area of the Q. acutissima and P. bournei were significantly positively correlated with aboveground biomass(P<0.05). In short, the total leaf area was a stable indicator for predicting changes in the aboveground biomass of the seedings of Q. acutissima and P. bournei. The fertilization was helpful to increase the ecological adaptability of the seedings of Q. acutissima and P. bournei. in a low light environment.