DOI: 10.5061/dryad.dz08kps1m
title: Experimental dataset for the effect of chilling on budburst

description: We obtained available information from 23 experimental studies about
 chilling effects in budburst and established an experimental database of
 budburst date for 50 temperate and boreal species from 33 provenance
 origins (94 species-provenance combinations).
description: To identify phenological experiments that manipulated chilling
 and forcing, we searched both ISI Web of Science and Google Scholar with
 TOPIC = (budburst OR leaf out OR flowering OR phenology) AND chilling. The
 initial searches yielded more than 200 papers. Subsequently, we reviewed
 and assessed each paper strictly. The papers that were included in the
 analyses needed to meet the following criteria: (1) focusing on plant
 species existing in the ground phenological dataset; (2) testing for the
 effects of chilling on budburst, leaf-out or flowering; (3) having at
 least 3 chilling treatments. As a result, only 23 papers were included in
 the analyses. These papers first exposed dormant twigs
 or seedlings to different periods of natural low temperatures in the field
 or artificial low temperatures in the refrigerator and then to different
 forcing temperature and photoperiod regimes in growth chambers. The most
 important response data in these papers are days to budburst and duration
 of chilling treatments (i.e., starting and ending date of chilling
 treatments). We used GetData Graph Digitizer
 (http://www.getdata-graph-digitizer.com/index.php) to scrape these
 response data from the figures of each paper or directly extract the data
 from the tables of each paper whenever possible. For studies
 simultaneously testing the effects of photoperiod on budburst timing, we
 only retained the results under long photoperiod treatment (removing the
 data under short photoperiod), so as to mirror the photoperiod in natural
 conditions. Many papers reported the degree days to budburst rather than
 the days to budburst. In these cases, we converted the degree days to
 budburst to days to budburst according to the forcing treatments in the
 experiments and algorithms of degree-day (i.e., starting date and
 temperature threshold). Meanwhile, we added relevant information to the
 response data according to the contents of each paper, including the
 sampling site of plant materials, sampling year and date, provenance
 origin of plant materials, chilling temperature (natural chilling or
 experimental chilling), forcing temperature, and forcing
 photoperiod. Following the above processes, we
 constructed an experimental dataset involving 50 temperate woody species.
 Because different provenances of the same species may vary in their
 phenological response to chilling (Alberto, et al., 2013; Guo, et al.,
 2020; Thibault, et al., 2020), we compared the experimental data with the
 observation data at the provenance level. As a result, 94
 species/provenances (64 in Europe and 30 in North America) were analyzed
  For each species/provenance in the experimental data, we determined the
 leaf morphology (coniferous or broadleaved species), plant material (twig
 or seedling), types of chilling treatment (natural chilling or artificial
 chilling), types of forcing treatment (different day/night temperature or
 constant temperature).
description: Microsoft Excel is required to open
 the data files.  
description: # Experimental dataset for the effect of chilling on budburst The
 explanations to the headers of the supplementary_data Source original
 reference (see Table S1) genus: genus name species: species name BBCH:
 BBCH code of phenological event in the experiment Prov_code: The code to
 distinguish different provenances prov_lat: latitude of provenance origin
 prov_lon: longitude of provenance origin sam_lat: latitude of the sampling
 site sam_lon: longitude of the sampling site sampleyear: the year to
 sample the plant material; 999 represent unknown sampleday: the day of
 year to sample the plant material chilling_T: the temperature the plant
 materials were chilled ("natural " represent that the plant
 materials were chillled in natural conditions ) chilling_day: number of
 days from 1 Nov to the date when plant materials were moved to forcing
 condition forcing_T: the temperaure of the forcing treatments
 ("natural " represent that the plant materials were forced in
 natural conditions ) forcing_photoperiod: the daylength of the forcing
 treatments ("natural " represent that the plant materials were
 forced in natural conditions ) forcing_day: number of days to budburst
 since the date when plant materials were moved to forcing condition CA5:
 chilling accumulation calculated by chilling algorithm with Tc=5C CA7:
 chilling accumulation calculated by chilling algorithm with Tc=7C
 GDD5Jan1: forcing requirement calculated by forcing algorithm with Tb=5C
 and t1=1 January GDD0Jan1: forcing requirement calculated by forcing
 algorithm with Tb=0 C and t1=1 January GDD5Feb1: forcing requirement
 calculated by forcing algorithm with Tb=5C and t1=1 February leaf
 morphology: 1, broadleaved species; 2 conifers Experimental materials:  1,
 twig; 2, seedling chilling treatments: 1, natural; 2, artifical forcing
 treatments: 1, diurnal temperature range (DTR)&gt;0; 2 DTR=0 The
 description of each file and the explanations to the headers in data.zip:
 all_data.xlsx: The chilling accumulation and forcing requirements in
 observational and experimental dataset for each species.    
 CA_obs: chilling accumulation in the observational dataset based on the
 optimal combination of chilling and forcing algorithm     FR_obs: forcing
 requirement in the observational dataset based on the optimal combination
 of chilling and forcing algorithm     CA_exp: chilling accumulation in the
 experimental dataset based on the optimal combination of chilling and
 forcing algorithm     FR_exp: forcing requirement in the experimental
 dataset based on the optimal combination of chilling and forcing algorithm
     sheet name: genus name + species name + Prov_code all_station.xlsx:
 The latitude and longitude of observational and experimental sites and
 their sample size.     lat_obs: latitude of stations in the observational
 dataset     lon_obs: longitude of stations in the observational dataset  
   lat_exp: latitude of provenance origin in the experimental dataset    
 lon_exp: longitude of provenance origin in the experimental dataset    
 N_obs: the sample size of the observational dataset     N_exp: the sample
 size of the experimental dataset results_eu+mat.csv/results_US+mat.csv:
 The parameters of CA-FR curves according to experimental and observational
 dataset.     genus: genus name     species: species name     BBCH: BBCH
 code of phenological event in the experiment     prov: The code to
 distinguish different provenances     lat: mean latitude of provenance
 origin     lon: mean longitude of provenance origin     phylum: 1,
 angiosperm; 2, gymnosperm     material: 1, twig; 2, seedling  
   chilling_type: 1, natural; 2, artifical     forcing_type: 1, diurnal
 temperature range (DTR)&gt;0; 2 DTR=0     distance: Geographical distance
 between provenance origins in the experimental datasets and stations in
 the observational datasets (km)     a_exp: parameter a of CA-FR curve
 fitted from experimental data     b_exp: parameter b of CA-FR curve fitted
 from experimental data     c_exp: parameter c of CA-FR curve fitted from
 experimental data     RMSE_exp: root-mean-square error (RMSE) of CA-FR
 curve fitted from experimental data     R2_exp: Coefficient of
 determination of CA-FR curve fitted from experimental data    
 a_obs: parameter a of CA-FR curve fitted from all observational data    
 b_obs: parameter b of CA-FR curve fitted from all observational data    
 c_obs: parameter c of CA-FR curve fitted from all observational data    
 RMSE_obs: root-mean-square error (RMSE) of CA-FR curve fitted from all
 observational data     R2_obs: Coefficient of determination of CA-FR curve
 fitted from all observational data     miniFR_exp: the minimum FR in the
 experimental dataset     CR_exp: chilling requirement in experimental
 data, chilling requirement is defined as the amount of chilling required
 for endodormancy release     CS_exp: chilling sensitivity in experimental
 data, chilling sensitivity is defined as the sensitivity of FR to CA under
 intermediate chilling conditions     miniFR_obs: the minimum FR in the
 observational dataset     CR_obs: chilling requirement in observational
 data, chilling requirement is defined as the amount of chilling required
 for endodormancy release     CS_obs: chilling sensitivity in observational
 data, chilling sensitivity is defined as the sensitivity of FR to CA under
 intermediate chilling conditions     Similarity: Absolute difference in
 the CA-FR curves between observations and experiments, defined as the mean
 absolute relative difference in FR under different chilling conditions  
   ca_method: 1, CA5; 2, CA7     fr_method: 1, GDD5Jan1; 2, GDD0Jan1; 3,
 GDD5Feb1     MATexp: mean annual temperature in experimental stations    
 MATobs: mean annual temperature in observational stations    
 heatstress: difference in mean temperature between the chilling treatment
 and forcing treatment averaged from all sampling dates
 results_eu_20231129.csv/results_US_20231129.csv: The parameters of CA-FR
 curves and the indictors of chilling effects according to experimental and
 observational dataset, which can be directly used to draw figures
 by 2_visualization.R     The explaination of duplicate headers are the
 same as those in results_eu+mat.csv/results_US+mat.csv     minCA_obs: the
 minimum CA in the observational dataset     maxCA_obs: the maximum CA in
 the observational dataset     MATdiff: MATexp minus MATobs  
   similarity_dir: Directional difference in the CA-FR curves fitted from
 experimental data and all observational data  
   similarity_sample: Absolute difference in the CA-FR curves fitted from
 experimental data and 1000 random samples in observational data  
   similarity_sample_dir: Directional difference in the CA-FR curves fitted
 from experimental data and 1000 random samples in observational data  
   CR_sample: chilling requirement in observational data (averaged from
 1000 random samples)     CS_sample: chilling sensitivity in observational
 data (averaged from 1000 random samples)     SD_similarity_sample:
 standard derivation of absolute difference in the CA-FR curves fitted from
 experimental data and 1000 random samples in observational data  
   SD_similarity_sample_dir: standard derivation of directional difference
 in the CA-FR curves fitted from experimental data and 1000 random samples
 in observational data     SD_CR_sample: standard derivation of chilling
 requirement in 1000 random samples     SD_CS_sample: standard derivation
 of chilling sensitivity in 1000 random samples     RMSE_sample: 
 mean root-mean-square error (RMSE) of CA-FR curve fitted from 1000 random
 samples     R2_sample: Coefficient of determination of CA-FR curve fitted
 from 1000 random samples     SD_RMSE_sample: standard derivation
 of root-mean-square error (RMSE) of CA-FR curve fitted from 1000 random
 samples     SD_R2_sample: standard derivation of coefficient of
 determination of CA-FR curve fitted from 1000 random samples .csv files in
 par_EU and par_USA folders: the parameters of CA_FR curves fitted from
 1000 random samples in observational dataset.     filename: genus name +
 species name + Prov_code     a_obs: parameter a of CA-FR curve fitted from
 each random sample     b_obs: parameter b of CA-FR curve fitted from
 each random sample     c_obs: parameter c of CA-FR curve fitted from
 each random sample     R2_obs: coefficient of determination of CA-FR
 curve fitted from each random sample     RMSE_obs: root-mean-square error
 (RMSE) of CA-FR curve fitted from each random sample lifefrom_data.csv:
 the lifefrom of investigated species. DBS: deciduous broadleaf shrub; DBT:
 deciduous broadleaf tree; ECT: evergreen conifer tree. Rows 1-64
 correspond to species-provenance in results_eu_20231129.csv, and rows
 65-94 correspond to species-provenance in results_US_20231129.csv. The
 description of each Matlab .m file: (1) a_extract_phedata: extract all
 phenological data from the original PEP725 dataset. (2) b_a_selectdata:
 select the phenological events investigated. (3) b_b_eobosdata: extract
 temperature data from the meteorological datasets. (4) c_a_selectspecies:
 select the species investiagted in the observational datasets based on the
 experimental datasets. (5) c_b_calculateCDGDD: calculate chilling
 accumulation and forcing requirements of obervational data (6)
 c_c_compareBBCH: compare the forcing requirement of different phenological
 events so as to calibrate the experimental data when different spring
 events were recorded between experiments and observations (7)
 d_compareCDGDD1: compare the chilling and forcing curves between
 obervations and experiments The description of each R software .R file:
 (1) 1_data: compare the chilling effects between observations and
 experiments (2) 2_visualization: Code for drawing figures in manuscript
 and supplementary materials.