Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14850, USA.
Physiol Plant. 2012 Apr;144(4):346-56. doi: 10.1111/j.1399-3054.2012.01566.x. Epub 2012 Mar 5.
In arid regions, biomes particularly responsive to climate change, mosses play an important biogeochemical role as key components of biocrusts. Using the biocrust moss Syntrichia caninervis collected from the Nevada Desert Free Air CO₂ Enrichment Facility, we examined the physiological effects of 10 years of exposure to elevated CO₂, and the effect of high temperature events on the photosynthetic performance of moss grown in CO₂-enriched air. Moss exposed to elevated CO₂ exhibited a 46% decrease in chlorophyll, a 20% increase in carbon and no difference in either nitrogen content or photosynthetic performance. However, when subjected to high temperatures (35-40°C), mosses from the elevated CO₂ environment showed higher photosynthetic performance and photosystem II (PSII) efficiency compared to those grown in ambient conditions, potentially reflective of a shift in nitrogen allocation to components that offer a higher resistance of PSII to heat stress. This result suggests that mosses may respond to climate change in markedly different ways than vascular plants, and observed CO₂-induced photosynthetic thermotolerance in S. caninervis will likely have consequences for future desert biogeochemistry.
在干旱地区，生物群系对气候变化特别敏感，苔藓作为生物结皮的关键组成部分，发挥着重要的生物地球化学作用。本研究使用从内华达荒漠免费空气 CO₂ 增浓设施采集的苔藓物种——犬尾藓，研究了暴露在高浓度 CO₂ 下 10 年对苔藓的生理效应，以及高温事件对 CO₂ 富集空气中生长的苔藓光合作用性能的影响。暴露在高浓度 CO₂ 下的苔藓的叶绿素含量下降了 46%，碳含量增加了 20%，氮含量和光合作用性能没有差异。然而，当暴露在高温（35-40°C）下时，与在环境条件下生长的苔藓相比，来自高 CO₂ 环境的苔藓具有更高的光合作用性能和光系统 II（PSII）效率，这可能反映了氮分配到对 PSII 热胁迫具有更高抵抗力的成分的转变。这一结果表明，苔藓可能会以与维管植物明显不同的方式对气候变化做出响应，并且在 S. caninervis 中观察到的 CO₂ 诱导的光合作用耐热性可能会对未来的荒漠生物地球化学产生影响。
