志留纪—泥盆纪维管植物的辐射演化及对陆地碳库的潜在影响OA

Vascular plants,as the major clade of land plants,represent the most important plant group that colonized the land during the Paleozoic.Fossil records demonstrate that vascular plants first appeared in the Silurian and then underwent significant radiation during the Devonian.Plants from the Silurian-Devonian periods represent the ancestors or stem groups of modern lineages such as the lycopsids,equisetopsids,filicopsids,and seed plants,foreshadowing their earliest differentiation.The total genus-level diversity of vascular plants gradually increased from the Silurian,reached the first peak during the Pragian,which was then followed by two decline-rise fluctuations,with one peak registrated during the late Givetian and another peak during the late Famennian.The vegetation types of the Silurian to Early Devonian include rhyniopsid herblands,zosterophyllopsid herblands and zosterophyllopsid-early euphyllo-phyte mixed herblands,with sporadic occurrences of shrubs and wetlands.During the Middle and Late Devonian,herblands,wetlands and shrubs continued to develop,while emerged new vegetation types such as cladoxylopsid forests,lycopsid forests,and progymnosperm forests.Along with the Silurian-Devonian radiation of vascular plants,the vegetation carbon stock significantly expanded,and the soil inorganic carbon stock also increased,as indicated by the dramatic increase of calcareous paleosols.Some Lower Devonian paleosols have inorganic carbon densities comparable to the modern maximum values.Since the Middle Devonian,the records of coal(paleo-histosols)gradually increased,indicating a significant rise in the amount of soil organic carbon.The increase of terrestrial carbon burial during the Silurian-Devonian was indicated by the accumulation of carbon-rich soils such as histosols and calcareous soils.Through diagenesis,carbon from surface system was converted into paleosols as a part of the lithosphere carbon stock,with an effect of long-term carbon sequestration.Future efforts,on one side,should be put into the systematics and classification of plant fossils,and as well as the study of paleobotanical community ecology and the classification of early vegetation.On the other side,the reconstruction of whole-plants and their communities,model simulations,and other methods could be conducted to estimate the vegetation carbon stocks of different time intervals.The information of surface soil carbon storage of different time intervals and burial efficiency of paleosols should be used to constrain the carbon cycle processes in Earth System models.