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由于砍伐、林火等形成的林缘是典型的生态过渡区,并以高生物多样性和快速变化的光环境为最显著特征。研究植物在林缘附近不同光环境下对光能和水分的利用特征有利于在个体层次揭示林木更新、森林群落动态的生理生态学基础,具有重要意义。蒙古栎是长白山地区落叶阔叶林及阔叶红松林中的常见阳性树种。通过对长白山白桦林林缘及附近蒙古栎的野外观测研究,结果表明:①林冠对林缘光照等的影响随距离林缘远近的不同而不同。林缘及附近区域的光环境存在巨大差异,温度和水分条件等也有显著变化。②蒙古栎光合的日进程为单峰型,净光合速率的高峰值达20μmolCO2·m-2·s-1,未见明显午休;林外蒙古栎的净光合速率及日光合总量均大于(或远大于)林缘和林内的净光合速率及日光合总量,表明蒙古栎在林外强光下生长最快;此外,对低光的高效利用显示蒙古栎可在林内低光环境正常生长。③蒙古栎在不同光环境下蒸腾速率的日进程为单峰型,林外最高可达近8mmolH2O·m-2·s-1。虽然蒙古栎在林外的蒸腾速率、日蒸腾量及水分利用率均较高,但与林内弱光环境相比,水分利用率增加的趋势略有降低,这是蒙古栎对林外强光环境的一种适应。④蒙古栎叶片的气孔导度随光照的增加而增大,这有利于植物在强光下增加净光合速率和蒸腾速率,有利于植物在强光下快速生长。另外,蒙古栎的叶片胞间CO2浓度从早至晚呈增加趋势;随日PAR总量的增加,蒙古栎的叶片胞间CO2浓度呈降低趋势。弱光环境下胞间CO2浓度的增加,有利于植物固定CO2、增加对光能和水分的利用效率。
Because of cutting, forest fire formed by the edge of the forest is a typical ecological transition zone, and to high biological diversity and rapidly changing light environment as the most significant features. It is of great significance to study the characteristics of light and water utilization of plants in different light environments near the edge of forest so as to reveal the physiological and ecological basis of forest regeneration and forest community dynamics at the individual level. Quercus mongolica is a common positive species in deciduous broad-leaved and broad-leaved Korean pine forests in Changbai Mountain. Through the field observation of the birch forest edge of Changbai Mountain and the nearby Quercus mongolica, the results showed that: ① The impact of canopy on the light edge of forest edge varied with the distance from forest edge. There is a huge difference in the light environment between the edge of the forest and the surrounding area, as well as temperature and moisture conditions. ② The daily process of photosynthesis of Quercus mongolica is unimodal and the peak value of net photosynthesis rate reaches 20μmolCO2 · m-2 · s-1. No significant midday break is observed. The net photosynthetic rate and total photosynthetic rate of Quercus mongolica is greater than Or far greater than) the net photosynthetic rate and total photosynthesis in the forest edge and forest, indicating that Quercus mongolica grows fastest under strong light in the forest. In addition, the efficient use of low light shows that Quercus mongolica can grow normally in low light environment . ③ The daily process of transpiration rate of Quercus mongolica under different light conditions is unimodal, and the highest up to nearly 8mmolH2O · m-2 · s-1 outside the forest. Although the transpiration rate, daily transpiration and water use efficiency of Quercus mongolica were higher in the forest, the trend of increase of water use efficiency slightly decreased compared with the low light environment in the forest, A kind of adaptation. ④ Stomatal conductance of Quercus mongolica leaves increased with the increase of light intensity, which was conducive to the increase of net photosynthetic rate and transpiration rate of plants in bright light, which was conducive to rapid plant growth in bright light. In addition, the intercellular CO2 concentration in leaves of Quercus mongolica tended to increase from early to late. With the increase of total daily PAR, the intercellular CO2 concentration in Quercus mongolica decreased. Under low light environment, the increase of intercellular CO2 concentration is conducive to plant CO2 fixation and increase the utilization efficiency of light energy and water.