Coxson D S
Kanamaskis Centre for Environmental Research, University of Calgary, T2N 1N4, Calgary, Alberta, Canada.
Oecologia. 1987 Sep;73(3):454-458. doi: 10.1007/BF00385264.
The response of net photosynthesis to temperature, moisture, and light was examined in thalli of the tropical basidiomycete lichen Cora pavonia from recent lahar flows on the volcanic summit La Soufrière (Guadeloupe, French West Indies). Although thalli of C. pavonia are typically exposed to only low light intensities and isothermal temperature conditions under prevailing cloud/shroud conditions on La Soufrière, their photosynthetic response matrix reveals an unexpected breadth of response. The temperature optimum of net photosynthetic uptake in C. pavonia rises from 6°C at a photon flux area density of 25 μmol m s PAR to 27°C at 1000 μmol m s PAR, with rates of maximal net photosynthetic uptake exceeding 25 mg CO g h. Net photosynthesis was optimal at thallus moisture contents of 250 to 350 percent water content by weight, declining only slightly in fully saturated thalli. These response patterns pose an apparent paradox, as on most days they will act to severely restrict net photosynthetic uptake by thalli of C. pavonia on La Soufrière. This paradox is discussed in context of those selective pressures faced by lichen thalli in later successional stages as well as those imposed by brief periods of atypical weather conditions.
对来自瓜德罗普岛（法属西印度群岛）苏弗里耶尔火山山顶近期火山泥流上的热带担子地衣科帕沃尼亚珊瑚地衣（Cora pavonia）叶状体的净光合作用对温度、湿度和光照的响应进行了研究。尽管在苏弗里耶尔盛行的云层/遮蔽条件下，帕沃尼亚珊瑚地衣的叶状体通常仅暴露于低光照强度和等温温度条件下，但其光合响应矩阵显示出意想不到的广泛响应。帕沃尼亚珊瑚地衣净光合吸收的最适温度从光子通量面积密度为25 μmol m² s⁻¹ 时的6°C升至1000 μmol m² s⁻¹ 时的27°C，最大净光合吸收速率超过25 mg CO₂ g⁻¹ h⁻¹。净光合作用在叶状体水分含量为250%至350%（重量）时最为适宜，在完全饱和的叶状体中仅略有下降。这些响应模式构成了一个明显的悖论，因为在大多数日子里，它们会严重限制苏弗里耶尔岛上帕沃尼亚珊瑚地衣叶状体的净光合吸收。本文结合地衣叶状体在演替后期面临的选择压力以及非典型天气条件短暂时期所施加的压力，对这一悖论进行了讨论。
