Linking leaf-level morphological and physiological plasticity to seedling survival and growth of introduced Canadian sugar maple to elevated precipitation under warming

Abstract

Global climate change will lead to new combinations of temperature and precipitation patterns. Extreme precipitation events will become more common by the late 21st century due to anthropogenic warming, particularly in high latitudes; however, the specific responses of high latitude species are mostly unknown. We employed an introduction trial by transplanting temperate sugar maples (Acer saccharum Marsh) from three provenances of their native ranges within Canada, which had a mean annual temperature (MAT) ranging from 3.0 to 9.4 ℃, and mean annual precipitation (MAP) from 520 to 1190 mm. These maples were transplanted to four sites in subtropical China with a MAT of 15.8–16.2 ℃ and a MAP of 913 mm, 1001 mm, 1172 mm, 1490 mm, respectively. We measured the survival and growth of the first-year seedlings of all provenances, as well as the survival, growth, and leaf morphological and physiological traits of the seedlings of Ontario provenance after four years of acclimation. We found that the first-year survival and growth of all provenances increased with the MAP at the planting sites, peaked at 1172 mm, and then decreased at the 1490 mm MAP site, with the seedlings of Ontario provenance had the best overall survival and growth rates across all of the sites. At the end of the 4th growing season, the seedlings of the Quebec and Manitoba provenances died off, and the survival- and growth-MAP relationships of the Ontario provenance mirrored those observed in the first year. For the Ontario provenance at year 4, the major vein density, stomatal density and size, and non-structural carbohydrates (NSC) changed significantly with MAP at the introduced sites. Principal component analysis indicated that seedling survival was negatively associated with stomatal size, density and starch content and that growth was positively related to leaf major vein density and negatively to soluble sugar and NSC. Our results indicate that changes in the precipitation range determined the performance of introduced sugar maple at the introduced sites. A moderate increase in precipitation was observed to ameliorate heat stress and benefit plant growth; however, excessive water could result in a fatal effect. Moreover, our findings suggest that the plasticity of leaf morphological and physiological traits influenced the survival and growth of the introduced sugar maple under future precipitation and warming.