Reviews and syntheses: VOC emissions from soil cover in boreal and temperate natural ecosystems of the Northern Hemisphere

[摘要] Plant litter decomposition is a biogeochemical process underlying the carboncycle in terrestrial ecosystems and between the biosphere and theatmosphere. For the latter, it serves as one of the most important sourcesof not only carbon dioxide but also volatile organic compounds (VOCs),which have not yet been taken into account in atmospheric models for variouspurposes and scales, from local to regional and global. This reviewowes its appearance to the growing interest in decaying leaf litter andliving forest floor cover as a hitherto unaccounted for source ofphotochemically active components of the Earth's atmosphere. This interestis understandable if we take into account the size of this source: forterrestrial ecosystems, the global production of litter is 10  ×  10 16  g dry matter. The living vegetation cover of the soil on theforest floor, mainly comprising mosses and small shrubs, should also beregarded as a potentially significant source of atmospheric VOCs, as itstotal biomass may be comparable to or even exceed that of canopy foliage,which is considered the main source of these compounds. This implies a needto integrate these sources into biogenic VOC emission models, which in turnrequires extensive research on these sources to understand the conditionsand factors that influence VOC emissions. The decomposition of leaf litter,accompanied by the release of VOCs, is a very complex process that dependson a number of biological, chemical and physical environmental factors, butlittle information is currently available on the role each plays. Equallylimited is information on the chemical composition and emission rates ofVOCs from these sources. The review focuses on the main gaps in our knowledge of the sources ofbiogenic VOCs under the forest canopy, and we are confident that fillingthem will make a significant contribution to solving such an important taskas closing the global organic carbon budget.

[学科分类] 大气科学