Department of Biology, University of New Mexico, Albuquerque, NM, USA.
Jornada Experimental Range, New Mexico State University, Las Cruces, NM, USA.
Glob Chang Biol. 2021 Sep;27(17):4005-4023. doi: 10.1111/gcb.15672. Epub 2021 Jun 10.
Regional long-term monitoring can enhance the detection of biodiversity declines associated with climate change, improving future projections by reducing reliance on space-for-time substitution and increasing scalability. Rodents are diverse and important consumers in drylands, regions defined by the scarcity of water that cover 45% of Earth's land surface and face increasingly drier and more variable climates. We analyzed abundance data for 22 rodent species across grassland, shrubland, ecotone, and woodland ecosystems in the southwestern USA. Two time series (1995-2006 and 2004-2013) coincided with phases of the Pacific Decadal Oscillation (PDO), which influences drought in southwestern North America. Regionally, rodent species diversity declined 20%-35%, with greater losses during the later time period. Abundance also declined regionally, but only during 2004-2013, with losses of 5% of animals captured. During the first time series (wetter climate), plant productivity outranked climate variables as the best regional predictor of rodent abundance for 70% of taxa, whereas during the second period (drier climate), climate best explained variation in abundance for 60% of taxa. Temporal dynamics in diversity and abundance differed spatially among ecosystems, with the largest declines in woodlands and shrublands of central New Mexico and Colorado. Which species were winners or losers under increasing drought and amplified interannual variability in drought depended on ecosystem type and the phase of the PDO. Fewer taxa were significant winners (18%) than losers (30%) under drought, but the identities of winners and losers differed among ecosystems for 70% of taxa. Our results suggest that the sensitivities of rodent species to climate contributed to regional declines in diversity and abundance during 1995-2013. Whether these changes portend future declines in drought-sensitive consumers in the southwestern USA will depend on the climate during the next major PDO cycle.
区域长期监测可以提高对与气候变化相关的生物多样性下降的检测能力，通过减少对时空替代的依赖和提高可扩展性，改善未来的预测。啮齿动物是干旱地区（占地球陆地表面 45%）多样且重要的消费者，这些地区的特点是水资源稀缺，而且气候越来越干燥，变化无常。我们分析了美国西南部草原、灌丛、生态交错带和林地生态系统中 22 种啮齿动物的丰度数据。两个时间序列（1995-2006 年和 2004-2013 年）与太平洋年代际振荡（PDO）的两个阶段相吻合，PDO 影响着北美西南部的干旱。从区域上看，啮齿动物物种多样性下降了 20%-35%，后期下降幅度更大。丰度也呈区域性下降，但仅在 2004-2013 年期间下降了 5%的被捕动物。在第一个时间序列（较湿润的气候）中，植物生产力超过气候变量，成为啮齿动物丰度的最佳区域预测因子，占 70%的分类群；而在第二个时期（较干燥的气候）中，气候对 60%的分类群的丰度变化解释最好。多样性和丰度的时间动态在不同的生态系统之间存在空间差异，新墨西哥州和科罗拉多州中部的林地和灌丛的下降幅度最大。在干旱加剧和干旱年际变率放大的情况下，哪些物种是赢家或输家，取决于生态系统类型和 PDO 的相位。在干旱条件下，显著的赢家（18%）比输家（30%）少，但在 70%的分类群中，赢家和输家的身份因生态系统而异。我们的研究结果表明，啮齿动物物种对气候的敏感性导致了 1995-2013 年期间区域多样性和丰度的下降。在未来的 PDO 周期中，这些变化是否预示着美国西南部干旱敏感消费者的未来下降，将取决于未来的气候。
