McLean Bryan S, Ward Joy K, Polito Michael J, Emslie Steven D
Department of Biology and Museum of Southwestern Biology, University of New Mexico, MSC03-2020, Albuquerque, NM, 87131-0001, USA,
Oecologia. 2014 Aug;175(4):1117-27. doi: 10.1007/s00442-014-2982-y. Epub 2014 Jun 11.
Atmospheric CO2 cycles of the Quaternary likely imposed major constraints on the physiology and growth of C3 plants worldwide. However, the measured record of this remains both geographically and taxonomically sparse. We present the first reconstruction of physiological responses in a late Quaternary high-elevation herbaceous plant community from the Southern Rocky Mountains, USA. We used a novel proxy-fossilized tooth enamel of yellow-bellied marmots (Marmota flaviventris)-which we developed using detailed isotopic analysis of modern individuals. Calculated C isotopic discrimination (Δ) of alpine plants was nearly 2 ‰ lower prior to the Last Glacial Maximum than at present, a response almost identical to that of nonherbaceous taxa from lower elevations. However, initial shifts in Δ aligned most closely with the onset of the late Pleistocene bipolar temperature "seesaw" rather than CO2 increase, indicating unique limitations on glacial-age high-elevation plants may have existed due to both low temperatures and low CO2. Further development of system-specific faunal proxies can help to clarify this and other plant- and ecosystem-level responses to past environmental change.
第四纪的大气二氧化碳循环可能对全球范围内C3植物的生理和生长施加了主要限制。然而，对此的实测记录在地理和分类学上仍然很稀少。我们展示了美国落基山脉南部一个晚第四纪高海拔草本植物群落生理反应的首次重建。我们使用了一种新的代理指标——黄腹旱獭（Marmota flaviventris）的化石牙釉质，这是我们通过对现代个体进行详细的同位素分析而开发出来的。末次盛冰期之前高山植物的计算碳同位素分馏（Δ）比现在低近2‰，这一反应与低海拔非草本类群的反应几乎相同。然而，Δ的初始变化与晚更新世两极温度“跷跷板”的开始最为密切相关，而不是与二氧化碳的增加相关，这表明由于低温和低二氧化碳，冰川期高海拔植物可能存在独特的限制因素。特定系统动物代理指标的进一步发展有助于阐明这一点以及其他植物和生态系统层面过去对环境变化的反应。
