散射辐射对亚热带人工针叶林光能利用率的影响  

The impacts of changes in diffuse radiation on light use efficiency in a subtropical plantation coniferous forest

作　　者：卫楠 张弥[1] 王辉民[2] 张雷明[2] 温学发[2] 刘寿东[1] 

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室气候与环境变化国际合作联合实验室气象灾害预报预警与评估协同创新中心耶鲁-南京信息工程大学大气环境研究中心,南京210044 [2]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室,北京100101

出　　处：《生态学报》2017年第10期3403-3414,共12页Acta Ecologica Sinica

基　　金：国家自然科学基金青年基金(31200377);中国科学院战略性先导科技专项项目(XDA05050208);高等学校博士学科点专项科研基金新教师类课题(20123228120003)

摘　　要：地表接受的太阳辐射中散射辐射的改变是影响森林生态系统光能利用率(Light Use Efficiency,LUE)的重要因素。以千烟洲亚热带人工针叶林为研究对象,利用30 min通量和常规气象观测数据,以晴空指数(kt)和地表接受的散射辐射(S_f)占太阳总辐射(S_0)的比值(S_f/S_0)为指标,分析了2003—2012年生长旺季(6—8月)散射辐射变化对千烟洲亚热带人工针叶林光能利用率的影响,并利用改进的光响应曲线模型分析了散射辐射变化对植被光合特性的影响。研究结果表明:2003—2012年生长旺季中,kt在0.6—0.7范围内的LUE比kt在0.4—0.5范围内的LUE平均减少了44.66%;S_f/S_0在70%—85%之间的LUE比S_f/S_0在55%—70%之间的LUE平均提高了22.24%。由此可以看出,与晴朗天空相比,多云及气溶胶增加导致的散射辐射增加可使该生态系统的LUE提高。并且,未受到高温干旱影响的2005、2006、2008、2009、2010及2012年散射辐射下该生态系统的初始量子效率αf比直接辐射下的αr平均增加了0.63 g CO2/mol;而10年间所有年份散射辐射下的光饱和时的潜在最大光合作用速率比直接辐射下平均提高了0.81 mg CO_2m^(-2)s^(-1),说明散射辐射可使该生态系统植被光合能力提高。Changes in diffuse radiation received at the ground surface impact light use efficiency （LUE） of the forest ecosystem. In this study, we focused on a subtropical plantation coniferous forest at Qianyanzhou. Based on 30 min flux data, routine meteorological data, and two indexes, clearness index （kt） and the ratio （Sf/S0） of diffuse radiation （Sf） to global solar radiation （S0）, we analyzed the impacts of changes in diffuse radiation on light use efficiency in this ecosystem during the mid-growing season （June to August） from 2003 to 2012. Moreover, applying the modified light response model, we investigated effects of changes in diffuse radiation on vegetation photosynthetic characteristics. The results indicated that the LUE decreased by a mean of 44.66% in kt range of 0.6 to 0.7 during the mid-growing season from 2003 to 2012,compared that in kt range of 0.4 to 0.5. In the same period, the LUE increased by a mean of 22.24% in Sf/S0 range of 70% to 85%, compared to that in Sf/S0 range of 55% to 70%. These results indicated that LUE was higher under cloudy skies and aerosol loading increase conditions than that under clear sky conditions. Moreover, the initial quantum efficiency （αf） increased by a mean of 0.63 gCO2/mol under diffuse radiation, comparing with that （αr） under direct radiation in 2005, 2006, 2008, 2009, 2010, and 2012 during the mid-growing season without drought stress. Regardless of where the water stress occurred, the capacity of a canopy to resist photosynthetic saturation at high levels of PAR （βf） was greater under diffuse radiation than βr under direct radiation by a mean of 0.81 mgCO2 m-2 s-1. The results verified that diffuse radiation improved the photosynthetic capacity of the forest ecosystem.

关 键 词：光能利用率 散射辐射 晴空指数 千烟洲亚热带人工针叶林 

分 类 号：S718.5[农业科学—林学]