Declining growth of deciduous shrubs in the warming climate of continental western Greenland

作者：Cassandra Gamm, Patrick F. Sullivan, Agata Buchwał, Roman J. Dial, Amanda Young, David A. Watts, Sean M. P. Cahoon, J. M. Welker, Eric Post · 发表于：Journal of Ecology · 年份：2017 · DOI：10.1111/1365-2745.12882 · 被引用次数：83 · 研究领域：Climate change and permafrost、Tree-ring climate responses、Geology and Paleoclimatology Research

Abstract Observational and experimental studies have generally shown that warming is associated with greater growth and abundance of deciduous shrubs in arctic ecosystems. It is uncertain, however, if this trend will persist in the future. Our study examined growth responses of deciduous shrubs to climate change over the late 20th and early 21st centuries near Kangerlussuaq in western Greenland. We combined shrub dendrochronology, stable isotope analysis and weekly measurements of leaf gas exchange to examine the drivers of secondary growth in two widespread and dominant deciduous shrub species: Salix glauca and Betula nana . Betula showed a dramatic growth decline beginning in the early 1990s, when correlations between growing season air temperature and growth shifted from neutral to strongly negative. Salix also showed a growth decline, but it began slightly later and was more pronounced among older stems. May–August mean air temperature of c . 7°C appeared to be an important threshold. Carbon isotope discrimination (∆ 13 C) in α‐cellulose of Salix growth rings declined strongly during the period of reduced growth, suggesting drought‐induced stomatal closure as a possible cause. Leaf gas exchange of Salix was also highly sensitive to seasonal variation in moisture availability. Betula growth declined more dramatically than Salix, but leaf gas exchange was less sensitive to moisture availability and there was less evidence of a ∆ 13 C trend. We hypothesize that the dramatic ...