Andrews T J, Muller G J
Australian Institute of Marine Science, P.M.B. No. 3, M.S.O., 4810, Townsville, Australia.
Oecologia. 1985 Feb;65(3):449-455. doi: 10.1007/BF00378922.
Photosynthetic gas exchange properties of leaves of the mangrove, Rhizophora stylosa Griff., were investigated in order to assess its productivity and gain some insight into the constraints set upon it by the saline habitat. Mature trees of this dominant species were studied in their natural, tidal-forest environment at Hinchinbrook Is., North Queensland for two periods during the dry season. Individual leaves were enclosed in a chamber wherein environmental conditions were varied. CO assimilation, transpiration and environmental parameters were monitored during daylight hours by instrumentation housed in a mobile laboratory mounted on a barge. Analysis of the daily course of leaf gas exchange revealed a CO assimilation capacity comparable with that of many glycophytic trees. Photosynthesis was strongly influenced by leaf temperature as well as photon flux density. There was a strong and steadily increasing inhibition of gas exchange as leaf temperatures and, consequently, the leaf to air VPD increased. CO assimilation rates and leaf conductances to water vapour diffusion were strongly correlated, resulting in nearly constant internal CO concentrations in the leaves under the full range of conditions. The effect of leaf orientation in minimizing the leaf-to-air temperature difference was striking. The close coordination between stomatal conductance and CO assimilation rate in this mangrove results in high water use efficiency. This sparing use of water may be an important factor underlying the high salinity tolerance of mangroves.
为了评估红树植物红海榄（Rhizophora stylosa Griff.）的生产力，并深入了解盐碱生境对其的限制因素，对其叶片的光合气体交换特性进行了研究。在旱季的两个时间段里，对北昆士兰欣钦布鲁克岛自然潮汐森林环境中的这种优势树种的成年树木进行了研究。将单叶置于一个可改变环境条件的气室内。白天，通过安装在驳船上的移动实验室中的仪器监测二氧化碳同化、蒸腾作用和环境参数。对叶片气体交换日进程的分析表明，其二氧化碳同化能力与许多甜土植物树木相当。光合作用受到叶片温度以及光量子通量密度的强烈影响。随着叶片温度以及叶-气蒸汽压差（VPD）的升高，气体交换受到强烈且持续增强的抑制。二氧化碳同化速率与叶片对水汽扩散的传导率密切相关，在所有条件下叶片内部二氧化碳浓度几乎保持恒定。叶片取向在最小化叶-气温差方面的作用显著。这种红树植物气孔导度与二氧化碳同化速率之间的紧密协调导致了高水分利用效率。这种对水分的节约利用可能是红树植物耐高盐性的一个重要因素。
