Thorley Rachel M S, Taylor Lyla L, Banwart Steve A, Leake Jonathan R, Beerling David J
Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
Kroto Research Institute, University of Sheffield - North Campus, Sheffield, S3 7HQ, UK.
Plant Cell Environ. 2015 Sep;38(9):1947-61. doi: 10.1111/pce.12444. Epub 2014 Nov 7.
On million-year timescales, carbonate rock weathering exerts no net effect on atmospheric CO2 concentration. However, on timescales of decades-to-centuries, it can contribute to sequestration of anthropogenic CO2 and increase land-ocean alkalinity flux, counteracting ocean acidification. Historical evidence indicates this flux is sensitive to land use change, and recent experimental evidence suggests that trees and their associated soil microbial communities are major drivers of continental mineral weathering. Here, we review key physical and chemical mechanisms by which the symbiotic mycorrhizal fungi of forest tree roots potentially enhance carbonate rock weathering. Evidence from our ongoing field study at the UK's national pinetum confirms increased weathering of carbonate rocks by a wide range of gymnosperm and angiosperm tree species that form arbuscular (AM) or ectomycorrhizal (EM) fungal partnerships. We demonstrate that calcite-containing rock grains under EM tree species weather significantly faster than those under AM trees, an effect linked to greater soil acidification by EM trees. Weathering and corresponding alkalinity export are likely to increase with rising atmospheric CO2 and associated climate change. Our analyses suggest that strategic planting of fast-growing EM angiosperm taxa on calcite- and dolomite-rich terrain might accelerate the transient sink for atmospheric CO2 and slow rates of ocean acidification.
在百万年的时间尺度上，碳酸盐岩风化对大气二氧化碳浓度没有净影响。然而，在数十年至数百年的时间尺度上，它有助于人为二氧化碳的封存，并增加陆地-海洋碱度通量，抵消海洋酸化。历史证据表明这种通量对土地利用变化敏感，最近的实验证据表明树木及其相关的土壤微生物群落是大陆矿物风化的主要驱动因素。在这里，我们综述了林木共生菌根真菌潜在增强碳酸盐岩风化的关键物理和化学机制。我们在英国国家松树园正在进行的实地研究证据证实，形成丛枝菌根（AM）或外生菌根（EM）真菌共生关系的多种裸子植物和被子植物树种会增加碳酸盐岩的风化。我们证明，外生菌根树种下含方解石的岩石颗粒风化速度明显快于丛枝菌根树种下的，这种效应与外生菌根树种导致的更大土壤酸化有关。随着大气二氧化碳上升和相关气候变化，风化及相应的碱度输出可能会增加。我们的分析表明，在富含方解石和白云石的地形上战略性种植快速生长 的外生菌根被子植物类群可能会加速大气二氧化碳的短期汇，并减缓海洋酸化速度。
