Department of Biology, Stanford University, Stanford, CA 94305.
Department of Environmental Sciences and Lake Erie Center, University of Toledo, Toledo, OH 43606.
Proc Natl Acad Sci U S A. 2023 Oct 24;120(43):e2306815120. doi: 10.1073/pnas.2306815120. Epub 2023 Oct 16.
Recent global changes associated with anthropogenic activities are impacting ecological systems globally, giving rise to the Anthropocene. Critical reorganization of biological communities and biodiversity loss are expected to accelerate as anthropogenic global change continues. Long-term records offer context for understanding baseline conditions and those trajectories that are beyond the range of normal fluctuation seen over recent millennia: Are we causing changes that are fundamentally different from changes in the past? Using a rich dataset of late Quaternary pollen records, stored in the open-access and community-curated Neotoma database, we analyzed changes in biodiversity and community composition since the end Pleistocene in North America. We measured taxonomic richness, short-term taxonomic loss and gain, first/last appearances (FAD/LAD), and abrupt community change. For all analyses, we incorporated age-model uncertainty and accounted for differences in sample size to generate conservative estimates. The most prominent signals of elevated vegetation change were seen during the Pleistocene-Holocene transition and since 200 calendar years before present (cal YBP). During the Pleistocene-Holocene transition, abrupt changes and FADs were elevated, and from 200 to -50 cal YBP, we found increases in short-term taxonomic loss, FADs, LADs, and abrupt changes. Taxonomic richness declined from ~13,000 cal YBP until about 6,000 cal YBP and then increased until the present, reaching levels seen during the end Pleistocene. Regionally, patterns were highly variable. These results show that recent changes associated with anthropogenic impacts are comparable to the landscape changes that took place as we moved from a glacial to interglacial world.
最近与人类活动相关的全球变化正在影响全球生态系统，引发了人类世。随着人为的全球变化继续，生物群落和生物多样性的急剧重组和丧失预计将加速。长期记录为了解基线条件和那些超出最近几千年正常波动范围的轨迹提供了背景：我们是否正在引起与过去变化根本不同的变化？利用 Neotoma 数据库中公开获取和社区管理的丰富的第四纪花粉记录数据集，我们分析了自北美更新世末期以来生物多样性和群落组成的变化。我们测量了分类学丰富度、短期分类学损失和增益、首次/末次出现（FAD/LAD）以及突然的群落变化。对于所有分析，我们都包含了年龄模型不确定性，并考虑了样本量的差异，以生成保守的估计。在全新世过渡期间和距今 200 个日历年（cal YBP）以来，最明显的植被变化信号是在全新世过渡期间和距今 200 个日历年（cal YBP）以来看到的。在全新世过渡期间，突然的变化和 FAD 升高，从 200 到 -50 cal YBP，我们发现短期分类学损失、FAD、LAD 和突然变化增加。分类学丰富度从约 13000 cal YBP 下降到约 6000 cal YBP，然后增加到现在，达到更新世末期的水平。在区域上，模式变化很大。这些结果表明，与人为影响相关的近期变化与我们从冰川期到间冰期世界转变时发生的景观变化相当。
