Parker Thomas C, Clemmensen Karina E, Friggens Nina L, Hartley Iain P, Johnson David, Lindahl Björn D, Olofsson Johan, Siewert Matthias B, Street Lorna E, Subke Jens-Arne, Wookey Philip A
Biological and Environmental Sciences, University of Stirling, Stirling,, FK9 4LA, UK.
Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, SE-75007, Sweden.
New Phytol. 2020 Sep;227(6):1818-1830. doi: 10.1111/nph.16573. Epub 2020 May 12.
In arctic ecosystems, climate change has increased plant productivity. As arctic carbon (C) stocks predominantly are located belowground, the effects of greater plant productivity on soil C storage will significantly determine the net sink/source potential of these ecosystems, but vegetation controls on soil CO efflux remain poorly resolved. In order to identify the role of canopy-forming species in belowground C dynamics, we conducted a girdling experiment with plots distributed across 1 km of treeline birch (Betula pubescens) forest and willow (Salix lapponum) patches in northern Sweden and quantified the contribution of canopy vegetation to soil CO fluxes and belowground productivity. Girdling birches reduced total soil CO efflux in the peak growing season by 53%, which is double the expected amount, given that trees contribute only half of the total leaf area in the forest. Root and mycorrhizal mycelial production also decreased substantially. At peak season, willow shrubs contributed 38% to soil CO efflux in their patches. Our findings indicate that C, recently fixed by trees and tall shrubs, makes a substantial contribution to soil respiration. It is critically important that these processes are taken into consideration in the context of a greening arctic because productivity and ecosystem C sequestration are not synonymous.
在北极生态系统中，气候变化提高了植物生产力。由于北极碳（C）储量主要位于地下，植物生产力提高对土壤碳储存的影响将显著决定这些生态系统的净汇/源潜力，但植被对土壤CO排放的控制仍未得到很好的解决。为了确定形成树冠的物种在地下碳动态中的作用，我们在瑞典北部1公里长的树线桦树（Betula pubescens）森林和柳树（Salix lapponum）斑块中进行了环剥实验，并量化了树冠植被对土壤CO通量和地下生产力的贡献。环剥桦树使生长旺季的土壤总CO排放减少了53%，鉴于树木仅占森林总叶面积的一半，这一减少量是预期的两倍。根系和菌根菌丝体的产量也大幅下降。在生长旺季，柳树灌木对其斑块中的土壤CO排放贡献了38%。我们的研究结果表明，树木和高大灌木最近固定的碳对土壤呼吸有很大贡献。在北极绿化的背景下考虑这些过程至关重要，因为生产力和生态系统碳固存并非同义词。
