DOI: 10.5061/dryad.3j9kd51p1
title: Woody phenology and weather data related to Trelease Woods, Urbana, IL, USA 1883-1912, 1949-1964, and 1993-2023

description: In this study, weekly phenological observations throughout spring and
 autumn were made annually over 31 years for 22 woody plant taxa of
 multiple growth forms in Trelease Woods, a mature old-growth deciduous
 forest remnant near Urbana, Illinois, USA. The growth forms included
 canopy trees, saplings, sub canopy treelets, shrubs, and vines. Data
 collection began in the spring of 1993 and continued through the end of
 autumn 2023. The phenological data set is paired with weather data
 collected from a nearby weather station in Champaign, Illinois. These two
 data sets were used to determine if dates of phenological events and
 durations of phenophases were changing over time, possibly in connection
 with changing weather related to global climate change. To supplement
 these phenological data, two older phenological data sets are made
 available here. First, Charles Smith, Woods Custodian at the University of
 Illinois, made comparable observations from 1949 to 1964 of seven of the
 same phenological events on six of the same woody species. Data were
 collected from Trelease Woods and Brownfield Woods. The latter is an
 old-growth forest separated by 2 km from Trelease Woods, and the two sites
 were connected in a larger forest before the mid-19th century. Second,
 Thomas Mikesell, a farmer from Ohio, USA, made comparable observations
 from 1883 to 1912 of six of the same phenological events on 11 of the same
 woody species. Mikesell’s data were collected in a deciduous forest near
 Wauseon, Ohio, USA. Because of the distance between the Mikesell study
 site and the site of the current study in Urbana, Illinois, to compare the
 two data sets, adjustments were made to the event dates in the Mikesell
 data set based on bioclimatic laws. Comparison of the current data to
 those collected by Charles Smith and Thomas Mikesell provides evidence as
 to whether the trends in phenological event dates observed from 1993 to
 2023 held consistent when investigated at longer time scales.
description: Field observations of spring phenology of mature individuals of
 22 woody taxa (21 species and 1 genus which may have represented multiple
 species) were made in Trelease Woods, Champaign Co., Illinois, USA from
 1993-2023. Also, observations were made of saplings of three of the canopy
 tree species. The study site is the north half of a 24.5 ha fragment of
 temperate mature deciduous forest, dominated by sugar maple near Urbana,
 Illinois, USA.  Elevation varies by less than 5 m across the study
 area. The phenological status of each individual was
 recorded by the same observer (CKA) weekly from February to June of each
 year. Measurements were recorded and later analyzed, at the individual
 plant level. Within each of three vegetative phases, Bud Swell (BS), Bud
 Burst (BB), and Leaf Expansion (LE), three dates were noted (e.g., BS1
 (1/3 of units exhibit event), BS2 (2/3 completed event), BS3 (all
 completed event), each date being one event); the exception was flowering
 for which only beginning (FL1) and ending of flowering (FL2) were
 recorded. Species classified as Late Flowering were not observed in all
 years.  Middle events (e.g., BS2) were not used in any analyses but were
 critical in determining, by simple linear interpolation, estimated dates
 of non-observed events that passed in the one week between
 observations. From these data, durations (number of
 days) of phenophases for each individual were calculated: Bud Swell, Bud
 Burst, Leaf Expansion, Flowering, and Overall Spring Phenology.
 Species were analyzed together in seasonal groups. For most
 events, species were grouped as early or late. <em>Aesculus
 glabra</em> (canopy trees and saplings) were usually analyzed as a
 separate group(s) because of their very early phenology.
 We used linear mixed-effects models to analyze data from 1993 to
 2021 to test for phenological changes through time, and the weather
 variables that had the most predictive power of phenological
 events.
description: # Woody phenology and weather data related to Trelease Woods, Urbana, IL,
 USA 1883-1912, 1949-1964, and 1993-2023 ### Authors Carol K. Augspurger,
 Department of Plant Biology, University of Illinois Urbana-Champaign,
 [carolaug@illinois.edu](mailto:carolaug@illinois.edu) David N. Zaya,
 Illinois Natural History Survey, University of Illinois Urbana-Champaign,
 [dzaya1@illinois.edu](mailto:dzaya1@illinois.edu) ##### References
 Augspurger, C. K. and D. N. Zaya. 2020a. Concordance of long-term shifts
 with climate warming varies among phenological events and herbaceous
 species. Dryad. Dataset.
 [https://doi.org/10.5061/dryad.mcvdncjxh](https://doi.org/10.5061/dryad.mcvdncjxh) Augspurger, C. K. and D. N. Zaya. 2020b. Concordance of long-term shifts with climate warming varies among phenological events and herbaceous species. Ecological Monographs 90: e01421. Hopkins, A. D. 1920a. The Bioclimatic Law. Journal of the Washington Academy of Sciences 10:34–40. Hopkins, A. D. 1920b. The Bioclimatic Law. Monthly Weather Review 10:355–355. Hopkins, A. D. 1938. Bioclimatics: A science of life and climate relations. United States Department of Agriculture, Miscellaneous Publication No. 280. United States Department of Agriculture, Washington, D.C., USA. Richardson, A. D., K. Hufkens, X. Li, and T. R. Ault. 2019. Testing Hopkins’ Bioclimatic Law with PhenoCam data. Applications in Plant Sciences 7(3): e1228. Smith, J.W. 1915. Phenological dates and meteorological data recorded by Thomas Mikesell at Wauseon, Fulton County, Ohio. Monthly Weather Review Supplement 2:21-93. ## **Version changes** **2024-06-07:** We added two additional years of phenology data (2022, 2023) to the data collected from Trelease Woods. **2025-09-11:** One of the datasets (“Augspurger1889-1912MikesellPhenology.csv”, formerly “Augspurger1889-1912MikesellPhenologyDatesComparisons.csv”) records the day of year for spring and autumn events in 11 tree species. In that dataset, we corrected errors with day of year measurements due to leap years and three other transcription errors. Additionally, we changed some of the extraneous columns and names, but the core data in that dataset remains the same. ## Data Set 1 Phenological Observations of Woody Species: Spring 1993-2023 Trelease Woods Carol K. Augspurger and David N. Zaya File Name: **Augspurger1993-2023WoodyPhenologySpringDates.csv** ### Description of the data and file structure: Each unique event in a specific year (e.g., 1993-BS1) is labeled in the top row of its column of data. The unique number assigned to each individual is on one row of this column: 'Ind. No.'. A value in a cell is the day of the year in one year of one individual exhibiting one event. From these data, durations (number of days) of phenophases for each individual were calculated. The phenophase durations calculated were Bud Swell, Bud Burst/Leafing Out, Leaf Expansion, Flowering, and overall Spring Phenology. NA indicates empty cells. Descriptive statistics summarizing each event for all individuals for a given species for each year are provided, as well as the total number of individuals. Also included are species nomenclature (following USDA, NRCS 2024) and growth form. Literature Cited: USDA, NRCS. 2024. The PLANTS Database ([http://plants.usda.gov](http://plants.usda.gov), 22 January 2024). National Plant Data Team, Greensboro, NC 27401-4901 USA. Relationship between data files: 'Data Set 2' has the same file structure and information as this data set ('Data Set 1'), except the observations were made annually from July - December to obtain autumn phenological data on the same individuals. Both 'Data Set 1' and 'Data Set 2' are needed to calculate the duration of the growing season. These two data sets were used in combination with 'Data Set 5' to find weather predictors for specific event dates. ## Data Set 2 Phenological Observations of Woody Species: Autumn 1993-2023 Trelease Woods Carol K. Augspurger and David N. Zaya File Name: **Augspurger1993-2023WoodyPhenologyAutumnDates.csv** ### Description of the data and file structure: Each unique event in a specific year (e.g.,1993-LC1) is labeled in the top row of its column of data. The unique number assigned to each individual is on one row of this column: 'Ind. No.'. A value in a cell is the day of the year in one year of one individual exhibiting one event. From these data, durations (number of days) of phenophases for each individual were calculated. The phenophase durations calculated were Leaf Coloration, Leaf Drop, and overall Autumn Phenology. Descriptive statistics summarizing each event for all individuals for a given species for each year are provided, as well as the total number of individuals. Also included are species nomenclature (following USDA, NRCS 2024) and growth form. NA indicates empty cells. Literature Cited: USDA, NRCS. 2024. The PLANTS Database ([http://plants.usda.gov](http://plants.usda.gov), 22 January 2024). National Plant Data Team, Greensboro, NC 27401-4901 USA. Relationship between data files: 'Data Set 1' file has the same structure and information as this data set ('Data Set 2'), except the observations were made annually from February - June to obtain spring phenological data on the same individuals. Both 'Data Set 1' and 'Data Set 2' are needed to calculate the duration of the growing season. These two data sets were used in combination with ‘Data Set 5’ to find weather predictors for specific event dates. ## Data Set 3 Smith Phenology in Trelease Woods and Brownfield Woods: 1949-1964 Carol K. Augspurger and David N. Zaya File Name: 'Augspurger1949-1964SmithPhenologyDates.csv' ### Description of the data and file structure: Field observations of phenology were made for six woody species in Trelease Woods (TW), nearby Brownfield Woods (BW), or a non-specified location (N-S) near Urbana in Champaign Co., Illinois, USA, from 1949-1964 by Charles Smith, Woods Custodian at the University of Illinois. The seven events observed are: Begin Budburst (BB1), End Leaf Expansion (LE3), Begin Leaf Coloration (LC1), Begin Leaf Drop (LD1), End Leaf Drop (LD3), Begin Flowering (FL1), and End Flowering (FL2). Each unique event (e.g., LC1) is labeled in the top row of its column of data. A cell number is the day of the year of one event in one year. Descriptions of events used by Smith and Augspurger differ slightly and are noted below. Also included are species nomenclature (following USDA, NRCS 2024) and growth form. Smith did not describe whether the number represents the first (or last) individual of a species or the general perceived ‘average’ of the species. The frequency of observation and the number of individuals on which a given datum is based are unknown. For species that can reach the canopy, it is assumed the data represent canopy-sized individuals and not saplings. Differences between means of 1946-1964 vs. 1993-2021 were tested for each event in each species by t-tests. NA indicates empty cells. Comparison of the description of events by the two data collectors. * EVENT Augspurger's description of the event Smith's description of the event * BB1 First leaf tips visible beyond bud scales Bursting of leaf buds * LE3 Leaves fully expanded Leaves fully grown * LC1 Begin leaf coloration Leaves begin to color * LD1 Begin leaf drop Leaves begin to fall/wither * LD3 End leaf drop Leaves all fallen or withered * FL1 First flowers Beginning of flowers * FL2 No flowers End of flowering (seven days added to census date to add one week to the date the last flower was seen) Literature Cited USDA, NRCS. 2024. The PLANTS Database ([http://plants.usda.gov](http://plants.usda.gov), 22 January 2024). National Plant Data Team, Greensboro, NC 27401-4901 USA. Relationship between data files: Data from the files for 'Data Set 1' and 'Data Set 2' were used to compare with 'Data Set 3'. Unpublished data from Charles Smith (1949-1964) were made available from the files of the Natural Areas Manager, University of Illinois, Urbana, IL, USA. ## Data Set 4 Mikesell Phenology in Wauseon, Ohio, USA: 1883-1912 Carol K. Augspurger and David N. Zaya File Name: 'Augspurger1889-1912MikesellPhenology.csv' ### Description of the data and file structure: Thomas Mikesell's original phenological data for field observations of 11 woody species for 1883-1912 were extracted from Smith (1915). Each row represents one year of data for one species, and phenological dates are given for up to three events: Begin Leaf Expansion (LE1), End Leaf Expansion (LE3), and End Leaf Coloration (LC3). Original values for phenological events of Mikesell's years represent the mean date of the year for each species in each year for Begin Leaf Expansion (LE1_Date and LE1_DOY, fourth and fifth columns), End Leaf Expansion (LE3_Date and LE3_DOY, eighth and ninth columns), and End Leaf Coloration (LC3_Date and LC3_DOY, twelfth and thirteenth columns). Also shown are the adjusted dates of Mikesell’s data based on Hopkins’ Bioclimatic Law (Hopkins 1920a, b, 1938) and Richardson et al.’s (2019) revisions of the law, to make the values from Ohio comparable to the current study’s data collected in Illinois. The adjustments based on Hopkins Law were applied only to spring events (LE1 and LE3), while the Richardson et al. (2019) adjustments were applied to all events (LE1, LE3, and LC3) and growing season duration (GrowingSeason_Richardson, fifteenth column). Column headings provide the event and, if applicable, the reference used for Bioclimatic adjustment (Hopkins or Richardson). Adjusted Growing Season (GrowingSeason_Mikesell, fifteenth column) was calculated as (LC3_Richardson - LE1_Richardson), which are the values in the fourteenth and seventh columns, respectively. ``` We included species nomenclature (following USDA, NRCS 2024) and growth form, as well as common names. ``` Literature Cited: Hopkins, A. D. 1920a. The Bioclimatic Law. Journal of the Washington Academy of Sciences 10:34–40. Hopkins, A. D. 1920b. The Bioclimatic Law. Monthly Weather Review 10:355–355. Hopkins, A. D. 1938. Bioclimatics: A science of life and climate relations. United States Department of Agriculture, Miscellaneous Publication No. 280. United States Department of Agriculture, Washington, D.C., USA. Richardson, A. D., K. Hufkens, X. Li, and T. R. Ault. 2019. Testing Hopkins’ Bioclimatic Law with PhenoCam data. Applications in Plant Sciences 7(3): e1228. Smith, J.W. 1915. Phenological dates and meteorological data recorded by Thomas Mikesell at Wauseon, Fulton County, Ohio. Monthly Weather Review Supplement 2:21-93. USDA, NRCS. 2024. The PLANTS Database ([http://plants.usda.gov](http://plants.usda.gov), 22 January 2024). National Plant Data Team, Greensboro, NC 27401-4901 USA. Relationship between data files:\ Data from 'Data Set 1' and 'Data Set 2' were used to compare with 'Data Set 4'. Relevant data from those two files are included in 'Data Set 4'. The Mikesell data presented here are available in the following publication: Smith, J.W. 1915. Phenological dates and meteorological data recorded by Thomas Mikesell at Wauseon, Fulton County, Ohio. Monthly Weather Review Supplement 2:21-93. ## Data Set 5 Temperature and precipitation data from Champaign, Illinois, USA, 1992-2023 Carol K. Augspurger and David N. Zaya File Name: 'Augspurger1992-2023WeatherTemperature_Precipitation.csv' ### Description of the data and file structure: Daily weather data from Champaign, Illinois, USA, are provided here. These weather data were used to predict dates of phenological events in 22 woody taxa in Trelease Woods near Urbana, Illinois. This weather station is approximately 8 km southwest of Trelease Woods. The weather station is part of the National Weather Service Cooperative Observer Program (US-COOP, [https://www.weather.gov/coop/](https://www.weather.gov/coop/)). Data were obtained by the authors through the Midwestern Regional Climate Center ([http://mrcc.purdue.edu/](http://mrcc.purdue.edu/)) using the cli-MATE Online Data Portal. The weather station's name is ‘CHAMPAIGN 3S’, and the NWS Coop Number is 118740. The original data set included daily precipitation measured in inches, maximum daily temperature measured in degrees Fahrenheit, and minimum daily temperature measured in degrees Fahrenheit. We used these columns to calculate precipitation and temperature in metric units (cm, degrees Celsius). The file format is comma-separated values (CSV), and column definitions follow. * year – the year of the daily observation. * month – the month (as a number) of the daily observation. * day – the day of the month of the daily observation. * precip.inch – the amount of daily precipitation, measured in inches. * max.t.f – the daily maximum temperature, measured in degrees Fahrenheit. * min.t.f – the daily minimum temperature, measured in degrees Fahrenheit. * precip.cm – the amount of daily precipitation, measured in centimeters. This was calculated from ‘precip.inch’ by dividing by 2.54. * max.t.c – the daily maximum temperature, measured in degrees Celsius. This was calculated from ‘max.t.f’ by subtracting 32, and then dividing the result by 1.8. * min.t.c – the daily minimum temperature, measured in degrees Celsius. This was calculated from ‘min.t.f’ by subtracting 32, and then dividing the result by 1.8. * DayOfYear – The day of the year for the daily observation. This was determined by setting January 1st as day 1 and taking into consideration leap day. Relationship between data files: Data from 'Data Set 5', through 2021, were analyzed, along with event dates from 'Data Set 1' and 'Data Set 2' (both through 2021) to determine which weather variables were the most predictive of event dates. Links to other publicly accessible locations of the data: The data can be obtained from the Midwest Regional Climate Center using the cli-MATE Online Data Portal. ## Other Data Sources The data on woody plant phenology from the current study were collected from the same study site as the herbaceous plant phenology data described by and published in Augspurger and Zaya (2020a, b). Thomas Mikesell’s data were obtained from Smith (1915). Bioclimatic laws used for event date adjustments to the Mikesell data were derived from Hopkins (1920a), Hopkins (1920b), Hopkins (1938), and Richardson et al. (2019). Weather data for Champaign, Illinois, USA were collected from a station that is part of the National Weather Service Cooperative Observer Program (US-COOP, [https://www.weather.gov/coop/](https://www.weather.gov/coop/)), and data were obtained through the Midwestern Regional Climate Center ([http://mrcc.purdue.edu/](http://mrcc.purdue.edu/)).