摘要
用Li-6400便携式光合测定系统(Li-CorInc.,USA)对海南岛热带山地雨林恢复演替先锋建群种黄桐(EndospermumchinenseBenth.)叶片的气体交换特征及其对环境的响应进行了测定。结果表明:(1)净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(E)日变化均为双峰型曲线。出现"午睡"原因是光合有效辐射(PPFD)不足和Gs的关闭,不是强光抑制和水分胁迫。(2)叶片Pn大小与Gs、E、PPFD、气温(Ta)和叶面温度(Tl)等为密切的正比关系,与胞间CO2浓度(Ci)、大气CO2浓度(Ca)和大气相对湿度(RH)等相关度极低甚至是负相关,光饱和点(LSP)较高,表现出阳性树种特性。(3)短期高Ca作用会引起Gs、E的降低和Pn增高。Ca倍增,则Pn提高了70%,E降低4.43%,水分利用效率(WUE)提高78%。(4)叶片Pn日平均值和日最大值分别达6.40±0.17、11.60μmolCO2/(m2·s),表现出速生性。
To investigate how will leaf gas change of species response to environmental factors during the succession of tropical regeneration forest, we choose the dominant tree species, Endospermum chinense Benth as our study case. Leaf gas change characteristics and its responses were measured with Li6400 portable photosynthesis system (LiCor Inc.,USA) in Jianfengling, Hainan Island. Netphotosynthesis, stomatal conductance and transpiration are all exhibited a bimodal diurnal pattern and the first peak is reached during the time of 8:00~10:00; the other subpeak is reached at 14:00. There is a noon break of photosynthesis during 12:00~13:00 due to the absence of irradiance and the closure of part stomata. Although photosynthetic rate is affected by the interaction of such environmental factors and how much this interaction is still to be studied, there is a strong linear relationship between the net photosynthetic rate(Pn) and stomatal conductance (Gs), transpiration rate (E), photosynthetic photon flux density (PPFD), air temperature (Ta) and leaf temperature. No evident relation is found between Pn and intercellular CO2 concentration (Ci), atmospheric CO2 concentration (Ca) and relative humidity (RH) and no strong limitation of such factors contributed to photosynthesis. The light response experiment of Endospermum chinense shows the characteristics of high light saturation point(LSP) with 1683μmol/(m2·s) and low light compensation point (LCP)with 15~25μmol/(m2·s). The shortterm response of leaves to CO2 enrichment resulted in decreasing of stomatal conductance, transpiration and increasing of Pn. Doubled growth concentration of CO2 can enhance Pn by 70%, water use efficiency(WUE) by 78% and decrease transpiration by 443%. Endospermum chinense has a high daily average Pn of 640±017μmolCO2/(m2·s) and daily maximum Pn of 1160μmolCO2/(m2·s), which testified its fastgrowing characteristics.
出处
《生态学报》
CAS
CSCD
北大核心
2003年第9期1765-1772,共8页
Acta Ecologica Sinica
基金
国家林业局热带林业研究重点实验室开放基金资助项目(1999)
海南尖峰岭热带林生态系统定位研究站资助项目(2001-08)~~
关键词
气体交换
光合环境
优势树种
热带雨林
leaf gas exchange
photosynthetic environment
dominant tree species
tropical rain forest
