突然想到，这种动物M应该叫megafauna，叫巨兽，里面有一个词叫Pleistocene epoch，叫更新世。在WIKI上找了一点儿关于megafauna如何影响环境变化的，跟原文有点儿联系，可以作为背景知识，希望JJ整理者能看到~Effect on methane emissionsLarge populations of megaherbivores have the potential to contribute greatly to the atmospheric concentration of methane, which is an important greenhouse gas. Modern ruminantherbivores produce methane as a byproduct of foregut fermentation in digestion, and release it through belching. Today, around 20% of annual methane emissions come from livestock methane release. In the Mesozoic, it has been estimated that sauropods could have emitted 520 Tg of methane to the atmosphere annually,[39] contributing to the warmer climate of the time (up to 10 C warmer than at present).[39][40] This large emission follows from the enormous estimated biomass of sauropods, and the fact that methane production by individual herbivores is believed to scale almost linearly with mass.[39] Recent studies have indicated that the extinction of megafaunal herbivores may have caused a reduction in atmospheric methane. This hypothesis is relatively new.[41] One study examined the methane emissions from the bison that occupied the Great Plains of North America before contact with European settlers. The study estimated that the removal of the bison caused a decrease of 2.2 Tg/yr. This is a proportionally large change for the time period.[42] Another study examined the change of methane concentration in the atmosphere at the end of the Pleistocene epoch after the extinction of megafauna in the Americas. After early humans migrated to the Americas ~13,000 BP, their hunting and other associated ecological impacts led to the extinction of many megafaunal species in the region. Calculations suggest that this extinction decreased methane production by ~9.6 Tg/yr. This suggests that the absence of megafaunal methane emissions may have contributed to the abrupt climatic cooling at the onset of the Younger Dryas.[41] The decrease in atmospheric methane that occurred at that time, as recorded inice cores, was 2-4 times more rapid than any other decrease in the last half million years, suggesting a unique mechanism was at work.[41]
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
楼主
