DOI: 10.5061/dryad.c59zw3r69
title: The timing of leaf senescence relates to flowering phenology and functional traits in 17 herbaceous species along elevational gradients

description: 1. Leaf senescence is a major event in a plant’s life history as autumn
 marks the end of the growing season. The optimal timing of leaf senescence
 is crucial to both, minimize risks of low temperature events and maximize
 carbon gain during the growing season. As abiotic conditions are currently
 changing at unprecedented rates, it is important to study how leaf
 senescence of different species is responding to these changes in order to
 forecast future growing season length and carbon sequestration potentials.
 In contrast to flowering phenology, data on autumn events is scarce and
 even more so for herbaceous than for woody plants, thus more information
 on this phenological stage is urgently needed. 2. We studied leaf
 senescence of 632 populations from 17 herbaceous species located along
 elevational gradients. We focussed on the beginning (5% of the population
 senesce, LS5) and peak (50% senesce, LS50) of leaf senescence. To see
 whether we can predict species-specific changes, we studied the link
 between LS5 and LS50 and flowering phenology as well as leaf functional
 traits related to plant performance. We looked at first and last flowering
 day and flowering duration as well as the traits specific leaf area, leaf
 dry matter content, area based leaf nitrogen and carbon content, carbon
 isotope discrimination (Δ13C), and the stomatal pore area index. 3. We
 found species-specific slopes of the beginning of leaf senescence along
 the elevational gradient. The peak of leaf senescence was uniformly
 delayed with increasing elevation across all species. Flowering phenology
 as well as leaf functional traits had a close relationship with leaf
 senescence and thus can be used to forecast species-specific responses to
 changes in abiotic conditions. High SLA and high leaf nitrogen were
 related to earlier senescence while high LDMC, high Δ13C and high SPI to
 later senescence. 4. Synthesis: The link between senescence, flowering
 phenology and plant functional traits will help to fine-tune predictions
 of future growing season length and ecosystem function. To date, most
 analyses are based on spring phenology and traits, for which data is more
 abundant than data on autumn senescence.
description: This is the phenological data used in the manuscript. Phenology
 was monitored weekly on the two mountains at each elevational band, i.e.
 every 100 m increase in elevation during the growth phase in two
 consecutive years (2012 and 2013). Up to three subpopulations per species,
 which were located on separate grasslands at least 50 m apart were
 monitored on each elevational band (1024 subpopulations in total). We
 monitored phenology on the population scale, as repeated measurements of
 the same, marked individuals of herbaceous plants in meadows are not
 feasible. Subpopulations were formed by at least 20 individuals; monitored
 population sizes as well as the area covered by the populations differed
 between species. At each census the percentage of each subpopulation
 showing leaf senescence displayed either as dead leaves or visual
 colouring was recorded. We selected two different levels of leaf
 senescence: the beginning of leaf senescence defined as the day when 5% of
 the leaves within a subpopulation showed visually observable leaf
 senescence (LS_5), and the day, where 50% of the leaves within a
 subpopulation showed visually observable leaf senescence (LS_50). For
 both, the day of the year is given. Equally, we here report day of first
 flowering (FFD), day of last flowering (LFD) and flowering duration (FD)
 observed on the same populations.
description: Not all subpopulations or species reached LS_50 during the time
 of observation, so they were only included in the LS_5 analysis.
 Additionally, not all species could be observed in both years and both
 elevational gradients.