Department of Biology, Western University, London, ON, Canada.
Glob Chang Biol. 2013 Jul;19(7):2022-35. doi: 10.1111/gcb.12175. Epub 2013 Mar 25.
Ecosystems in the far north, including arctic and boreal biomes, are a globally significant pool of carbon (C). Global change is proposed to influence both C uptake and release in these ecosystems, thereby potentially affecting whether they act as C sources or sinks. Bryophytes (i.e., mosses) serve a variety of key functions in these systems, including their association with nitrogen (N2 )-fixing cyanobacteria, as thermal insulators of the soil, and producers of recalcitrant litter, which have implications for both net primary productivity (NPP) and heterotrophic respiration. While ground-cover bryophytes typically make up a small proportion of the total biomass in northern systems, their combined physical structure and N2 -fixing capabilities facilitate a disproportionally large impact on key processes that control ecosystem C and N cycles. As such, the response of bryophyte-cyanobacteria associations to global change may influence whether and how ecosystem C balances are influenced by global change. Here, we review what is known about their occurrence and N2 -fixing activity, and how bryophyte systems will respond to several key global change factors. We explore the implications these responses may have in determining how global change influences C balances in high northern latitudes.
北极和北方森林等偏远地区的生态系统是全球范围内重要的碳汇。全球变化预计会影响这些生态系统对碳的吸收和释放，从而可能影响它们是作为碳源还是碳汇。苔藓植物（即苔藓）在这些系统中具有多种关键功能，包括与固氮蓝藻的共生关系、作为土壤的热绝缘体，以及产生难分解的凋落物，这对净初级生产力（NPP）和异养呼吸都有影响。虽然地被苔藓植物通常在北方系统的总生物量中只占很小的比例，但它们的综合物理结构和固氮能力对控制生态系统碳氮循环的关键过程产生了不成比例的大影响。因此，苔藓-蓝藻共生体对全球变化的响应可能会影响生态系统碳平衡是否以及如何受到全球变化的影响。在这里，我们回顾了它们的发生和固氮活性的已知情况，以及苔藓系统将如何应对几个关键的全球变化因素。我们探讨了这些响应可能对确定全球变化如何影响高纬度地区碳平衡的影响。
