【森林碳循环预测】Peter B. Reichab1 Roy L. Richa Xingjie Luc Ying-Ping Wangd and Jacek Oleksynae. Biogeographic variation in evergreen conifer needle longevity and impacts on boreal forest carbon cycle projections. PNAS 2014 13703–13708 doi: 10.1073-pnas.1216054110
Abstract
Leaf life spanis an important plant trait associated with interspecific variation in leaf organismal and ecosystem processes. We hypothesized that intraspecific variation in gymnosperm needle traits with latitude reflects both selection and acclimation for traits adaptive to the associated temperature and moisture gradient. This hypothesis was supported because across 127 sites along a 2160-km gradient in North America individuals of Picea glauca Picea mariana Pinus banksiana and Abies balsamea had longer needle life spanand lower tissue nitrogen concentration with decreasing mean annual temperature. Similar patterns were noted for Pinus sylvestris across a north–south gradient in Europe. These differences highlight needle longevity as an adaptive feature important to ecological success of boreal conifers across broad climatic ranges. Additionally differences in leaf life spandirectly affect annual foliage turnover rate which along with needle physiology partially regulates carbon cycling through effects on gross primary production and net canopy carbon export. However most if not all global land surface models parameterize needle longevity of boreal evergreen forests as if it were a constant. We incorporated temperature-dependent needle longevity and %nitrogen
