Flowering phenology traits of four plant communities in the high Andes of Chile

Two sites were selected in the middle part of the subalpine belt (Sites I and II) and two in the upper part of the alpine belt (Sites III and IV) in the Andes of Central Chile. On each site, 10 individuals were marked per plant species. The total numbers of species per site fluctuated from 20 to 36, with fewer species on the two upper alpine sites due to the lower species richness there. Rare species where 10 individuals could not be found were not included. As of snowmelt, the sites were visited at five-day intervals until the end of the flowering season, from September 11th, 2018, to May 15th, 2019, spanning a continuous period of 35 weeks. On each observation date, all individuals of a species that were in flower were registered and the number of open flowers per plant counted. For plants with very large number of flowers, the number of open flower-bearing branches was counted. For large flat cushion plants, flowering in 10 cm x 10 cm fixed quadrats running across the diameter of the cushion was recorded. For annual species where the density of individuals was very high, quadrats were used to quantity flowering.
Five calendar-based floral traits and six thermal sum-based traits were defined, giving a total of 11 flowering traits. The calendar-based traits were:
1. Calendar day to first individual per species that flowered (FFDOY)
2. Days from snowmelt to first flowering (FF)
3. Peak flowering plants (PFP), expressed as days from snowmelt to maximum number of plants in flower
4. Peak floral abundance (PFA), expressed as days from snowmelt to the maximum number of open flowers
5. Flowering season length (FSL)
Thermal sum-based traits were expressed in Growing Degree Days (GDD) which gave the accumulated heat required for achieving reproductive milestones (FF, PPF and PFA). The biofix day was the date of snowmelt. Following other alpine studies, GDDs were calculated for TBASE = 5 ◦C and TBASE = 0 ◦C (GDD0 and GDD5) using hourly temperatures recorded at 1.5 m a.g.l HOBO U23 Pro v2 battery-powered sensors. The two measures of GDD were calculated with HOBOware using the double sine method with no upper threshold. Calculation of GDD for the aforementioned reproductive milestones resulted in six GDD-based traits (GDD0FF; GDD5FF; GDD0PFP; GDD5PFP; GDD0PFA and GDD5PFA).
Additionally, Bayesian inference phylogenetic tree of the study site species is provided.