亚热带森林光响应策略研究- - 以江西千烟洲试验站为例

Light is the primary power for the forest ecosystem. Plants have evolued a strategy of light adaptation and response. In order to reveal the light response mechanism from morphological and anatomical, physiological and biochemical characteristics, the light response of subtropical plantations at different scales such as communities, plants and leaves will be investigated through flux observations, ground-based observations and seedling cultivation experiments. Combined with flux and ground-based observations, photosynthetic production and temporal and spatial heterogeneity were discussed to reveal the relationships of photosynthetic production and light environment. Biomass allocation and photosynthetic physiological differences at different N deposition, acid rain and moisture treatments under different light environment (sunlight, canopy gaps and understory) were studied to quantify future climate change (N deposition, acid rain and drought) using seeding cultivations. The investigation of different scales light response strategy contributed to a better understanding of the basis of forest productivity, and also is crucial for the more accurate monitoring of terrestrial ecosystem carbon cycle.

光是驱动森林生态系统运行的原初动力，植物经过长期进化形成了光适应及响应策略。本课题拟采用通量观测、地面观测结合幼苗栽培实验的方法研究亚热带人工林不同尺度（群落、植株、叶片）光响应特征，旨在从形态解剖和生理生化特性方面揭示光适应性机理。通量观测和地面观测探讨光合生产与光环境时空异质性，揭示光合生产与光环境关系；幼苗栽培实验研究不同N沉降、酸雨和水分处理不同光环境下（全光照、林窗及林下）生物量分配和光合生理差异，定量未来气候变化下(N沉降、酸雨和干旱)光合生产变化及其控制机制。研究不同尺度光响应策略有助于深入认识森林生产力形成的基础，也有利于区域尺度更为精确地监测陆地生态系统碳循环。

本研究以千烟洲试验站主要造林树种湿地松(Pinus elliottii)、马尾松(P. massoniana)和杉木(Cunninghamia lanceolata)为研究对象，（1）在叶片水平上，光的有效性与年龄共同影响针叶的光合水平。上层针叶和当年生最大光合速率(Amax)、暗呼吸速率(Rd)、光饱和点(LSP)和光补偿点(LCP)普遍高于下层针叶和1年生针叶。针叶通过调整LUE来适应冠层内部光环境进行碳同化，处于弱光环境下针叶通过调整叶绿素含量、叶绿素a/b、可溶性蛋白含量和最大光化学效率(Fv/Fm)来增加碳获取。（2）在林分水平上，基于生物量法估算湿地松、马尾松和杉木3种林分的光能利用效率分别为0.18 g·MJ-1、0.20 g·MJ-1和0.34 g·MJ-1。（3）通量数据分析结果显示，千烟洲常绿针叶人工林模拟的潜在光能利用率年平均和4-10月平均较以双曲线拟合的表观量子效率分别高52.07%和17.48%。（4）湿地松幼苗全光照Pn高于遮荫环境下，但LUE不及遮荫环境下。认识不同尺度LUE主控因子对于尺度推绎和采用遥感模型估算森林生态系统NPP提供理论依据。