纳帕海流域五种优势乔木树种光合速率日变化特征

为了解纳帕海流域高山环境中优势乔木树种光合速率特征及其对环境因子的响应规律,运用LI-6400便携式光合测定仪,分别测定了香格里拉纳帕海流域5种优势乔木树种净光合速率(Pn)、蒸腾速率(Tr)、水分利用效率(WUE)等主要光合生理参数日变化,并对其与环境因子的相关性进行统计分析。结果表明:(1)所测定的5种优势树种中,除川滇高山栎以外,其他4个树种的Pn均呈双峰型;5种树种Pn峰值大小依次为云杉高山松山楂清溪杨川滇高山栎,分别为21.58、21.57、15.21、14.18、11.87μmol·m~(-2)·s~(-1)。(2)树种气孔导度(Gs)和蒸腾速率(Tr)在一天之内都呈现出早晚低、中午高的规律,胞间CO2浓度(Ci)与Pn基本呈相反趋势。(3)树种WUE和LUE日均值与Pn值表现出基本一致的顺序特征,云杉和高山松相对较高,WUE分别为3.27和5.82 mmol·m~(-2)·s~(-1),LUE分别为4.42%和2.99%,川滇高山栎最低,仅为0.92 mmol·m~(-2)·s~(-1)和0.74%。(4)树种Pn对PAR和Gs的变化具有显著的响应特征。该区域树种的Pn最大值高于低海拔区域的同类树种;区域内针叶树种的WUE和LUE显著大于阔叶树种,对高山区域内相对较高的辐射环境具有更高效的适应策略;当地环湖面山上种植的大面积云杉树对区域植被的恢复具有高效的现实意义。

Diurnal variation of photosynthetic characteristics of five kinds of arbor dominant species in Napahai

In order to understand the photosynthetic physiological ecology characteristics and its response to environmen-tal factors of arbor dominant species in alpine environment of Napahai,use LI-6400 portable photosynthesis measuring system to determine the characters of diurnal change of net photosynthetic rate ( Pn) and the physiological, transpiration rate ( Tr) and water using efficiency ( WUE) and analyzed ecological factors of the 5 dominant species in Napahai. And compare the correlation analysis of photosynthesis parameters and environmental factors. The results were as follows:( 1) According to the determination of the 5 dominant tree species, daily variation of Pn of the species showed bimodal type except for Quercus aquifolioides. The level of peak value of Pn was:Picea asperata>Pinus densata>Crataegus pinnatifi-da> Populus rotundifolia>Quercus aquifolioides. The numbers of Pn were 21.583 3,21.566 7,15.208 3,14.1833 and 11.866 7μmol?m-2?s-1. (2) Tr and Gs of the species were higher in the noon and lower in the morning and evening, which are consistent with PAR. Ci was instead point to the trend of Pn. (3) The average of WUE and LUE were consist-ent with the Pn. Picea asperata and Pinus densata were relatively higher. The numbers of WUE were 3. 27 and 5. 82 mmol?m-2?s-1;the numbers of LUE were 4.42% and 2.99%. Quercus aquifolioides was the lowest, only 0.92 mmol?m-2?s-1and 0.74%. (4) Pn of the species had significant response to the change of PAR and Gs. WUE of conifer was significantly greater than broad leaved tree species; it was more efficient to the alpine environment strategy. Planting large area of Picea asperata in the mountains around the lake has efficient practical significance for the regional vegeta-tion restoration.