Research progresses on the impacts of volcanic eruptions on vegetation and terrestrial carbon cycle
The 1991 Pinatubo eruption caused a noticeable slowdown of the increase of atmospheric CO2 concentration,drawing attention to the impact of the Earth's interior on the biogeochemical cycle at the land surface through volcanoes.Since then,many studies have emerged which investigate the impacts of volcanoes on terrestrial ecosystems and to elucidate the underlying mechanisms.With advances in modelling tools and in collections of tree ring data,several pathways through which volcanoes affect the terrestrial ecosystems were revealed.In order to identify the gaps in current understanding and stimulate future studies,we provide a comprehensive review of the recent progress made and the known mechanisms underlying the volcanic impacts,focusing on the impacts of volcanoes on vegetation and terrestrial carbon cycle at regional to global scales.Previous studies have yielded a range of insights into the impacts of volcanoes on terrestrial ecosystems,in particular on the impact of volcanic stratospheric aerosols via changes in radiation and climate.The radiative impacts encompass a dimming effect and an increase of diffuse radiation.While the dimming effect decreases gross primary production(GPP)in ecosystems that are limited by radiation,the increase of diffuse radiation increases GPP because diffuse light distributes more evenly in vegetation canopy.The effect of diffuse ration on the GPP is much stronger than the dimming effect,resulting in an overall positive radiative effect on GPP.The diffuse radiation effect was estimated to have induced global net land C sink of～3.2 PgC a-1 global C sink during the 2 years after the Pinatubo eruption in 1991.However,this increase in C sink is short-lived and most of the sequestered C will be released back into the atmosphere gradually on a timescale of decades to centuries.The dimming effect of volcanic aerosols on the surface energy budget leads to further climatic effects,including a global cooling and changes of precipitation regimes at regional scales.The cooling interrupts the growth of wood,leading to abnormal tree rings in high latitudes and high elevation regions in the years following a volcanic eruption.At global scale,it reduces GPP in high latitudes and increases GPP in low latitudes.Meanwhile,the lower temperature decreases ecosystem respiration at global scale,resulting in an increased carbon sink.The precipitation regime changes caused by volcanoes can strongly affect vegetation growth in some regions.However,current understandings on the impacts of aerosols on precipitation remain poor,leading to significant uncertainty when assessing volcano impacts.Despite recent progresses,gaps remain in current studies.First,few efforts have been made to link volcano impacts at different scales and to synthesize the tree ring evidence and large-scale simulations.Second,large uncertainties in model-based quantification of volcano impacts on the land C cycle remain,which require further improvement of model processes on aerosol impacts on climate,especially on precipitation to reduce.Finally,many gaps still exist in current understandings:The responses of vegetation to volcano-induced climate extremes and local hydrological changes remain understudied.The recovery of ecosystem from the volcanic disturbances and the long-term fate of the C sink due to volcanic eruptions remain poorly quantified.The impacts of volcano on marine system and human societies are also important to understand the full volcano impacts on the C cycle.In the end,volcano impact studies need to be more related to policies for supporting evaluating climate and ecological risks,making adaptation policies,and also for developing more efficient and safe solar radiation management strategies.
Laboratory for Sciences of Climate and Environment,Institute Pierre-Simon Laplace,French Alternative Energies and Atomic Energy Commission/French National Centre for Scientific Research/Versailles-St-Quentin University,Gif sur Yvette 91191,France
万方数据
维普
