Wilder Benjamin T, Hultine Kevin R, Dorshow Wetherbee Bryan, Vanderplank Sula E, López Blanca R, Medel-Narváez Alfonso, Marvan Monica, Kindl Kristen, Musgrave Aryn, Macfarlan Shane, Ezcurra Exequiel
Next Generation Sonoran Desert Researchers, Tucson, Arizona, USA.
Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, Arizona, USA.
Glob Chang Biol. 2025 May;31(5):e70217. doi: 10.1111/gcb.70217.
A shift to greater aridification in dry regions of the world is ongoing and rapidly increasing in intensity, including in the biodiverse Sonoran Desert of the Southwest United States and northern Mexico. In addition to experiencing over two decades of drought, the Sonoran Desert is facing anomalous heat events that are increasing in frequency, evidenced in a record hot and dry period from 2020 to 2021. This article evaluates the impacts of the 2020-2021 region-wide heat and drought event at three scales: (1) a landscape level assessment of ecosystem stress across the entirety of the Sonoran Desert based on precipitation and temperature data from meteorological stations and a satellite-derived vegetation health index (VHI), (2) assessments of stress on iconic columnar cacti and succulent trees, and (3) mechanistic plant responses to extreme heat and drought, and secondary biotic stressors from insect attacks. 2020 was the hottest and driest year since 1980 across the Sonoran Desert region, and vegetation health, determined from VHI, was also near its lowest point. Field-based assessments of columnar cacti across the Sonoran Desert revealed high levels of acute plant stress, including cactus scorching, defined by rapid onset of discolored photosynthetic tissue that leads to permanent photosynthetic dysfunction and increased plant mortality. Tissue scorching corresponded with a three-fold increase in mortality of giant cactus species across the region relative to background levels following 2020-2021. Likewise, repeated plant health surveys show a persistent legacy of the 2020-2021 anomaly, resulting in a marked reduction in the current health and survival of the iconic giant saguaro (Carnegiea gigantea) in the northern Sonoran Desert. This multi-scale assessment of previously anomalous heat and drought events on succulent desert plants shows landscape-wide impacts that could fundamentally reshape populations of these keystone species and the communities that depend on them.
世界干旱地区正朝着更加干旱的方向转变，且强度在迅速增加，包括美国西南部和墨西哥北部生物多样的索诺兰沙漠。除了经历二十多年的干旱外，索诺兰沙漠还面临着异常炎热事件，其发生频率不断增加，2020年至2021年创纪录的炎热干燥时期就是明证。本文从三个尺度评估了2020 - 2021年全区域高温和干旱事件的影响：（1）基于气象站的降水和温度数据以及卫星衍生的植被健康指数（VHI），对整个索诺兰沙漠生态系统压力进行景观层面评估；（2）评估标志性柱状仙人掌和肉质树所受的压力；（3）植物对极端高温和干旱以及昆虫攻击等次生生物胁迫源的机制性反应。2020年是自1980年以来索诺兰沙漠地区最热、最干旱的年份，根据VHI确定的植被健康状况也接近最低点。对索诺兰沙漠各地柱状仙人掌的实地评估显示，植物遭受了高水平的急性胁迫，包括仙人掌焦枯，其表现为光合组织迅速变色，导致永久性光合功能障碍并增加植物死亡率。2020 - 2021年后，该地区巨型仙人掌物种的死亡率相对于背景水平增加了两倍，组织焦枯与之相对应。同样，多次植物健康调查显示，2020 - 2021年异常情况留下了持久影响，导致索诺兰沙漠北部标志性巨型树形仙人掌（巨人柱）目前的健康状况和存活率显著下降。这种对肉质沙漠植物先前异常高温和干旱事件的多尺度评估表明，其影响范围广泛，可能从根本上重塑这些关键物种的种群以及依赖它们的群落。
