Leaf longevity in temperate evergreen species is related to phylogeny and leaf size
Leaf longevity (LL), the amount of time a photosynthetically active leaf remains on a plant, is an important trait of evergreen species, affecting physiological ecology and ecosystem processes. A long LL gives leaves more time to fix carbon but carries higher construction costs, while a short LL allows plants to respond more rapidly to changing environmental conditions. For many evergreen taxa, LL data are not readily available, and it is not known if LL is phylogenetically conserved. To address this gap, we measured LL for 169 temperate and boreal evergreen woody species at the Arnold Arboretum, a botanical garden in Boston, Massachusetts, along with metrics of leaf size and number known to be related to LL. We hypothesized that LL is phylogenetically conserved, and that longer LL is associated with a greater numbers of leaves, smaller leaves, and a colder hardiness zone of the species’ native range. We found that average LL ranged from 1.4 years in Rhododendron tomentosum to 10.5 years in Abies cilicia. LL was phylogenetically conserved, with some genera, such as Abies and Picea, exhibiting long LL (> 3 years) and others, such as Ilex and Rhododendron, exhibiting short LL (< 3 years). Leaf length was negatively correlated with LL in conifers, due to differences between Pinus and other genera; however, there was no correlation between LL and number of leaves. This study highlights the considerable variation and phylogenetic pattern in LL among temperate evergreen species, which has implications for carbon budgets and ecosystem models.
KeywordsLeaf aging Leaf lifespan Leaf senescence
We thank the Arnold Arboretum of Harvard University for permission for the fieldwork and sampling, and Irina Kadis of the Arnold Arboretum for help with the leaf length measurements. This study was funded by the BU Undergraduate Research Opportunities Program, and was carried out as part of a BU undergraduate honors thesis (LS) and a BU Academy senior thesis (SP). We acknowledge the use of data provided by the TRY initiative on plant traits (http://www.try-db.org). Helpful comments on the paper were provided by Abe Miller-Rushing, Pam Templer, and two anonymous reviewers.
Author contribution statement
RBP, LS and SP conceived and designed the study. LS and SP collected data. All authors analyzed the data and wrote the manuscript.
- Chapin FS, Lambers H, Pons TL (1998) Plant physiological ecology. Springer, New YorkGoogle Scholar
- Hothorn T, Bretz F, Westfall P (2008) Simultaneous inference in general parametric models. Biomed J 50:346–363Google Scholar
- Pinheiro J, Bates D, DebRoy S, Sarkar D, R Core Team (2017) nlme: linear and nonlinear mixed effects models. R package version 3.1-131. https://CRAN.R-project.org/package=nlme. Accessed 11 Jan 2019
- R Core Team (2017) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. http://www.R-project.org/. Accessed 11 Jan 2019
- Rehder A (1940) Manual of cultivated trees and shrubs, 12th edn. Macmillian Publishing, New YorkGoogle Scholar