Water content effects on photosynthetic response of Sphagnum mosses from the foothills of the Philip Smith Mountains, Alaska
Water content effects on photosynthetic response of Sphagnum mosses from the foothills of the Philip Smith Mountains, Alaska
复制标题
含水量对阿拉斯加菲利普·史密斯山脉山麓泥炭藓光合反应的影响
DOI：
10.1007/bf00388484
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发表时间：
1989
期刊：
影响因子：
2.7
通讯作者：
John D. Tenhunen
中科院分区：
文献类型：
--
作者：
Kevin Murray;Peter Harley;J. Beyers;H. Walz;John D. Tenhunen
在阿拉斯加布鲁克斯山脉北部山麓的草丛苔原地区，多达三分之二的年降水量可能发生在间歇性的夏季雷暴期间。泥炭藓头状花序含水量的季节变化。这取决于这些降水事件的频率和持续时间，栖息地的微地形，包括解冻的深度，以及各个物种的形态特征。研究了泥炭藓和泥炭藓的净光合作用对不同含水量的响应。在阿拉斯加北坡靠近道尔顿高速公路的草丛苔原地区，在杨柳树冠下生长的狭叶草在野外被检查。经过一段时间，在6月所需的发展光合能力，头状花序的水分含量基本上是最佳的光合作用的范围从6到10克H2O/克DW。在此范围以上，CO2吸收率降低，可能是由于限制CO2扩散到光合活性位点。在水分含量低于最佳，净光合作用迅速下降，直到达到补偿约1克H2O/克DW。根据天气条件的变化，泥炭藓样品的平均含水量在现场收集偶尔低于5克H2O/克DW。在一个特别干燥的时期，个别泥炭藓丘的含水量低于1克H2O/克DW，表明水分胁迫限制泥炭藓光合生产在这个栖息地。
SummaryIn tussock tundra areas of the foothills north of the Brooks Range, Alaska, up to two-thirds of annual precipitation may occur during intermittent summer thunderstorms. The seasonal pattern in capitulum water content of Sphagnum spp. depends on the frequency and duration of these precipitation events, on the microtopography of the habitat including depth of thaw, and on morphological characteristics of the individual species. The response of net photosynthesis to varying water content in Sphagnum squarrosum and S. angustifolium growing under willow canopies in a tussock tundra area near the Dalton Highway on the North Slope of Alaska was examined in the field. After a period in June required to develop photosynthetic capability, capitula water content was essentially optimal for photosynthesis in the range from 6 to 10 g H2O/g DW. Above this range, the rate of CO2 uptake was reduced, presumably due to limitations on CO2 diffusion to the photosynthetically active sites. At water contents below the optimum, net photosynthesis fell rapidly until reaching compensation at approximately 1 g H2O/g DW. Dependent on changes in weather conditions, average water content of Sphagnum samples collected in the field occasionally fell below 5 g H2O/g DW. During a particularly dry period, water content of individual Sphagnum hummocks fell below 1 g H2O/g DW, indicating that water stress does limit Sphagnum photosynthetic production in this habitat.