中文摘要：

近年发现宝天曼锐齿栎（Quercus aliena var. acuteserrata）成熟林难以更新，通过对锐齿栎幼苗不同遮阴处理下生长、非结构性碳（NSC）和光合作用进行研究，为理解宝天曼锐齿栎树种的更新困难和加强锐齿栎林的科学抚育提供理论依据。本研究通过搭建遮阴棚对盆栽锐齿栎幼苗设置遮阴处理，并用中午开放遮阴网的方法模拟光斑，设置了对照（自然光照）、遮阴80%中午开放1 h（T80-1）、一直遮阴80%（T80）、遮阴98%中午开放1 h（T98-1）、一直遮阴98%（T98）5处理，测定了遮阴后锐齿栎幼苗的干物质量、比叶面积、NSC浓度、存活率、光合光响应曲线参数、光合日变化、荧光参数等指标。结果表明：遮阴处理的幼苗干物质量和NSC浓度都显著低于对照，模拟光斑处理使幼苗NSC浓度显著高于一直遮阴处理的幼苗；遮阴严重的T98处理使幼苗出现了较高的死亡率；在高光强下，T80、T98-1、T98的净光合速率（Pn）因非气孔限制显著低于对照；且T98的光化学反应能力最低；遮阴后锐齿栎幼苗表现出一定的遮阴适应性，如光饱和点（LCP）和暗呼吸速率（Rd）降低，T98的Pn高于T98-1。本研究证明，在严重遮阴环境下锐齿栎幼苗易因难以维持碳的收支平衡而死亡，但光斑缓解了遮阴对幼苗碳储备的不利影响，对塑造幼苗在高光照条件下的光合能力也有显著作用。

英文摘要：

In recent years, it has been found that Quercus aliena var. acuteserrata mature forests in Baotianman Mountains in southwestern Henan Province in China are difficult to regenerate. This study aims to explore the reasons why Q. aliena could not well regenerate by investigating the effects of different light environments on photosynthetic characters and nonstructural carbohydrate （NSC） of Q. aliena seedlings, and to discuss the impact of sunfleck on Q. aliena regeneration. In this study, sunfleck was simulated by opening shading apparatus at noon every day. Five treatments were set up： control （CK, natural sunlight） and four shading treatments including shade by 80% with opening one hour at noon （T80-1）, shade by 80% （T80）, shade by 98% sunshine with opening one hour at noon （T98-1） and shade of 98% sunshine （T98）. Dry matter yield, NSC of Q. aliena seedlings, gas exchanges in photosynthetically active radiation （PAR） under 1500 μmol·m-2·s-1, photosynthesisPAR curves, diurnal variation of photosynthesis and chlorophyll fluorescence parameters of the leaves were measured. The dry matter yield and total NSC content of Q. aliena seedlings in shaded treatments were significantly lower than those of CK. The NSC content of seedlings under simulated sunfleck treatments was significantly higher than that of the seedlings with corresponding only shading treatments. Serious shading treatment （T98） resulted in higher death rate of seedlings. Different light environments had significant effects on photosynthetic capacity of Q. aliena seedlings. The net photosynthetic rates （Pn） of T80, T98-1 and T98 were significantly lower than CK under high PAR because of nonstomatal limitation in the shading treated seedlings. The efficiency of photochemical reaction of T98 was the lowest among all treatments. Q. aliena seedlings showed the ability of shade tolerance to some degree, such as lower lig