Ecological Archives E090-162-D1

Steven E. Travers and Kelsey L. Dunnell. 2009. First-flowering dates of plants in the Northern Great Plains. Ecology 90:2332.


Emerging evidence of global climate change associated with increases in greenhouse gases have led to an increase in the number of studies examining biotic responses to increasing global temperatures and other changes in climate (Cleland et al. 2007). Since the beginning of the industrial revolution and the subsequent increase in global surface temperatures, a wide variety of organisms have shifted their natural range boundaries towards the poles or shifted their phenological patterns (Walther et al. 2002). Taxa living in regions with dramatic seasonal patterns, in particular, have been shown to initiate life history phases such as flowering or migration to earlier dates than those in the past century. As spring arrives earlier at relatively high latitudes (Schwartz et al. 2006) and elevations (Inouye et al. 2002, 2003) characterized by distinct climate seasonality, biologists are documenting earlier flowering times and migrant arrival times. These shifts in phenology are ecologically significant because of the potential for disruptions of inter and intra-specific interactions (e.g., pollination) that depend on coevolved timing patterns.

Research of phenological shifts in response to climate change is limited by the availability of long-term data. Understanding how biota are shifting the timing of their life history patterns over the time that climate has been changing is dependent on comparing current phenological patterns to past phenological patterns. In North America, there are few published data sets available that provide information on the timing of phenophases for specific taxa in a specific region (but see Bradley et al. 1999, Miller-Rushing and Primack 2008). Our goal here is to provide raw data from a 51 year observational study by O. A. Stevens of first-flowering times in North Dakota and Minnesota.

In 1910, O. A. Stevens began recording the first-flowering times of herbaceous and woody plant species in the prairies in North Dakota. The majority of his observations were made within 15 miles of Fargo, North Dakota. He eventually recorded data for 753 species of plants by the time he stopped in 1961. The observations he made represent a valuable glimpse into the phenological patterns of plant species in the past century of a region characterized by extremely cold and relatively long winters. Here we have transcribed his hand-written notes in order to make these data available to investigators interested in climate change and its effects on phenology.


A. Data set identity: Common name, Latin name, Family name, and date of first flowering time for plant species in Northern Red River Valley and North Dakota broadly from 1910 to 1961.

B. Data set identification code: FFDND.txt

C. Data set description

Principal Investigator: Steven E. Travers, Department of Biological Sciences, North Dakota State University, Fargo, ND 58105. Queries regarding the data set can be directed to:

Abstract. Phenological observations of plant flowering patterns provide useful information for studying the ecological impact of global climate change over long-term periods. However, the long-term data sets with which meaningful comparisons can be made are rare, especially in the less-populated Northern Great Plains region of North America. Here we present the observations of first-flowering time of native and nonnative plant species in North Dakota and Minnesota over the course of 51 years in the last century. Orin A. Stevens recorded the first-flowering time of 753 species in the vicinity of Fargo, North Dakota, USA, and throughout North Dakota from 1910 to 1961. These data offer baseline indications of both the timing of first flowering and the presence/absence for a wide variety of plants in a region of North America with a relatively short growing season.

D. Key words: climate change; flowering time; Great Plains; phenology; tallgrass prairie.


A. Overall project description

Identity: Common name, Latin name, Family name, and date of first flowering time for plant species in Northern Red River Valley and greater North Dakota from 1910 to 1961.

Originator: Steven E. Travers, Department of Biological Sciences, North Dakota State University, Fargo, ND 58105

Period of Study: 1910–1961

Objectives: To describe patterns in flowering phenology and relate timing of first flower to environmental variables.

Abstract: same as above.

Source(s) of funding: Data collection, transcription, and verification have been supported by NSF Epscor fund 0814442.

B. Specific subproject description

Site description: All plants included in the data set were observed within either a 15 mile radius of Fargo, North Dakota or within North Dakota boundaries as indicated in the data set. The Fargo observations (F) were made predominantly at two sites: (a) campus of North Dakota State University (46°53.4228N, 96°47.88594W); and (b) Bluestem Prairie Nature preserve (46˚ 51.458 N, 96˚ 28.211 W).

Site type: Fargo and Bluestem Prairie observation sites are in the Red River Valley which historically was at the eastern basin edge of ancient Lake Agassiz. It is an area characterized by flat topography, agricultural land, riparian corridors, and remnant Tallgrass prairie patches at the margin of the eastern deciduous forests of Minnesota. The ND or greater North Dakota collection sites (the towns of Minot, Wahpeton, Hankinson, Oakes, Streeter, Valley City, Ambrose, Kenmare, Minot, Granville, Page, Wimbledon, Courtenay, Fessenden, Kensal, Sheyenne, Jamestown, Oakes, Kathryn, Glen Ullin, Washburn, Bottineau, Lisbon, Mandan, Bismarck, Rugby, Williston, Hettinger, Bowman, Tappen, and Marmarth) are all characterized as temperate steppe or grassland. These sites are generally dominated by C3 grasses including Bouteloua spp. and Agropyron spp. as well as Andropogon gerardii. The coordinates for the four corners of the North Dakota region that was sampled are the following: (46°4'13"N 96°54'5"W; 48°57'15"N 103°28'59"W; 46°17'41"N 103°55'23"W; 48°33'40"N 97°10'46"W).

Geography: The geography of the sampling area is divided into three broad regions: the Red River Valley in the eastern most portions of the state where the Bluestem Prairie preserve and North Dakota State University (NDSU) are located; a middle region from the Red River Valley to the Missouri river; and a western region from the Missouri River to the western border of the state. Bluestem Prairie preserve is located on rolling topography of Campbell Beach or strandline of Lake Agassiz, a glacial lake that existed over 9,000 years ago. Elevation change at this site is minimal (900–1100 feet). The middle region is characterized by gently rolling prairie and numerous ponds in the aftermath of glaciations. West of the Missouri there is little evidence of glaciations and the geography is more typical of the Missouri plateau with badlands. The elevational range across all of the North Dakota sampling area is 800–3000 feet.

Habitat: The Red River Valley study sites are in the transitional zone between typical tall grass prairie habitat and more mesic forested regions to the east. There are two riparian corridors surrounding the Red River and Buffalo River. The two regions farther west are more characteristic of mixed grass prairie where Tallgrass species give way to shorter grasses as the annual precipitation drops off on a westward transect.

Geology: The sampling sites are all characterized by underlying sedimentary bedrock from ancient shallow seas that covered the Great Plains. The underlying geology of the eastern region is typical of glacial till regions. Deposits of sand, gravel, and clay were left by massive ice sheets that covered the entire sampling region east of the Missouri River. The Red River Valley was influenced by the formation of glacial Lake Agassiz. The middle region up to the Missouri River was also glaciated and is characterized by terminal moraines and closed depressions that have become lakes, the “Coteau du Missouri”. The western region was protected from ice sheets and has been defined more by erosional cutting of the many tributaries of the Missouri river. The deeply cut landscape includes badlands made up mainly of clay and silt (Trimble 1980).

Watersheds/hydrology: The drainage of the eastern region is bisected by the Red River of the North and is characterized by periodic flooding. The Bluestem Prairie preserve is flat bottomland bordered by a smaller stream, the Buffalo River. The central Coteau region of North Dakota is the direct result of “dead-ice” moraine deposits at the terminus of ice sheets that covered the eastern region. These glacial features scooped out depressions and created thousands of ponds and small lakes through the region. The unglaciated region to the west of the Missouri River receives relatively little precipitation due to the rain shadow created by the Rocky Mountains. However, the landscape is dissected by numerous tributaries of the Missouri, Little Missouri, Knife, and Cannonball rivers.

Site history: The two sampling areas in the Red River Valley region are adjacent to the Fargo-Moorhead metropolitan areas. However, both sites would have been rural when the majority of this sampling was conducted. The Bluestem Prairie preserve is a 490-ha section of native tall grass prairie that historically was used only for hay production and pasture for grazing livestock prior to 1970. The land was acquired by the Nature Conservancy of Minnesota in 1970. Since then the open regions have been managed for invasive species with a mixture of periodic burning (4-year intervals) and mowing. The NDSU campus was formed in 1890 in the center of a large expanse of wheat fields. Samples were also collected in the rail yards which ran adjacent to campus. The native flora observed in the other two regions of North Dakota would have been isolated to remnant prairie and riparian areas interspersed with agricultural fields.

Climate: There is a decrease in annual precipitation from east to west across the sampling area. The western region on the Missouri plateau averages 13 to 15 inches annually. The central region averages 17 to 20 inches annually. The Red River Valley region averages 20 to 23 inches annually. Approximately 75% of the annual precipitation across the sampling area is in the growing season between April and September. Winters are characterized by steady subzero temperatures and snowpack for most of the winter months. The last frost is typically between April and June and the first between August and October. In Fargo, the average minimum temperature per year since 1881 is -29.3˚ F and the average maximum is 97.9˚ F. The average median temperature per year has increased from 37.9˚ F in 1881 to 43.3˚ F in 2007 (A. Akyuz, ND State Climatologist, personal communication). Average winter temperatures in the western region of North Dakota can be as much as 6˚ F warmer than in the Red River Valley. In spring and early summer the trend is reversed where the eastern region is on average 2 degrees warmer than the west.

Experimental design: These data are the result of a long-term survey of flowering plants restricted to the region within a 15 mile radius of Fargo, ND, where indicated, and throughout North Dakota.

Design characteristics: N/A

Sampling methods: Sampling consisted of visual observations made by Stevens (OAS) on regular field trips during the course of the study.; Based on sample dates, field trips were made two or three times per week from April through September, from 1910 to 1961, to sites either within the Fargo vicinity study area or more broadly in North Dakota. The goal of the data collection was to observe and record the first date of flowering for herbaceous and woody plants in the area surrounding Fargo and throughout the state. We determined site locations by comparing hand written notes to lists compiled by OAS that were specific to the Fargo area. These data have been compiled elsewhere in summary form (Stevens 1921, 1956, 1961). However, here we provide raw data transcribed from handwritten field notes that describe year to year variation in first flowering date by species.

Taxonomy and systematics: Names for flowering plant species follow Stevens (1963). Revisions have been incorporated by comparison to current nomenclature in Van Bruggen (1985).

Permit history: N/A

Legal/organizational requirements: None

Project personnel: Steven Travers, Kelsey Dunnell, and O. A. Stevens


A. Status

Latest Update: The data spans the period of 1910–1961. Data collection by direct observation of flowering time in the Red River Valley region was re-initiated in spring 2007 and will be added as collected and verified. Flowering times between 1961 and 2007 are unavailable from direct observation. However, we will be compiling data from that time period by using plant specimens in the NDSU herbarium and can make those data available.

Latest Archive date: 10 September 1961

Metadata status: The metadata are complete and up to date.

Data verification: Hand written notes were transcribed from original material into Excel files.  These data entries were then checked for copying errors and matched against the original data.


Storage location and medium: Original Excel file exists on laboratory computers in the Plant Ecology Lab at North Dakota State University.  The original notes from OAS are stored in University Archives, North Dakota State University.

Contact person: Steven E. Travers, Department of Biological Sciences, North Dakota State University, Fargo, ND 58105. Email:

Copyright restrictions: None.

Proprietary restrictions: None.

Costs: None.


A. Data Set File

Identity: FFDND.txt

Size: File is 753 records not including header row. Each row has 58 cells. Total size is 168 kb.

Format and Storage mode: ASCII text, tab delimited. No compression scheme was used.

Header information: See variable names in Section B.

Alphanumeric attributes: mixed.

Special characters/fields: Missing data denoted as “.”.

Authentication procedures: See Section III. A.

B. Variable information: Data are organized vertically by species and sorted alphabetically by family. Flowering times are listed horizontally by year.

Genus: Genus name of plant observed flowering. Original nomenclature used by O. A. Stevens in notebooks is recorded.

Species: Original specific epithet of species observed flowering according to O. A. Stevens in notes.

Common names: Common names have been derived from Stevens (1963) and the Plants Database website of the U.S. Department of Agriculture ( by matching the scientific names listed in Stevens’ notes.

Family: Family name of species based on current treatment (Van Bruggen 1985).

Synonym: Alternate Latin names for species based on current treatment (Van Bruggen 1985).

Site: The location of flowering plants.  Species observed at either of the two Fargo area sites (NDSU and Bluestem Prairie) are indicated by an “F”.  Species that were observed in North Dakota but not clearly indicated in Stevens’ notes as observed in Fargo are indicated by “ND”.

1910–1961: The year in the column header indicates the year of plant observation.  The date in each cell indicates the first day of the year on which that species was observed flowering.


A.Data acquisition

Data forms: Paper notebooks

Location of completed data forms: The papers of O. A. Stevens, University Archives, North Dakota State University, Fargo, ND 58105

Data entry/verification procedures: The original data was recorded by hand in notebooks by O. A. Stevens.  These data were transcribed and entered into electronic MS Excel files by SET and KLD.

B. Quality assurance/quality control procedures: Data entries in Excel files were reviewed and corrected by an assistant.

C. Related material: The entire collection of O. A. Stevens’ notes, letters, and publications on many aspects of natural history in the Great Plains is stored at the NDSU University Archives.

D. Computer programs and data processing algorithms: N/A

E. Archiving: N/A

F. Publications using the data set:

Stevens, O. A. 1921. Plants of Fargo, North Dakota, with dates of flowering. American Midland Naturalist 7:54–62; 79–100; 135–156.

Stevens, O. A. 1956. Flowering dates of weeds in North Dakota. North Dakota Agricultural Experiment Station, Bimonthly Bulletin 18:209–213.

Stevens, O. A. 1961. Plants of Fargo, North Dakota. American Midland Naturalist 66:171–177.

G. Publications using the same sites: N/A

H. History of data set usage

Data request history: N/A

Data set update history: N/A

Review history: N/A

Questions and comments from secondary users: N/A


We thank Gary Clambey for introducing us to the phenological work conducted in the Red River Valley of the North over the last century. O. A. Stevens (1885–1980) was a superb naturalist and tireless biologist at North Dakota State University for over 50 years. The research presented here was supported by NSF Epscor grant EPS-0814442.


Bradley, N., A. Leopold, et al. 1999. Phenological changes reflect climate change in Wisconsin. Proceedings of the National Academy of Sciences 96:9701–9704.

Cleland, E. E., I. Chuine, et al. 2007. Shifting plant phenology in response to global change. Trends in Ecology and Evolution 22:357–365.

Inouye, D. W., M. A. Morales, et al. 2002. Variation in timing and abundance of flowering by Delphinium barbeyi Huth (Ranunculaceae): the roles of snowpack, frost, and La Nina, in the context of climate change. Oecologia 130:543–550.

Inouye, D. W., F. Saavedra, et al. 2003. Environmental influences on the phenology and abundance of flowering by Androsace septentrionalis (Primulaceae). American Journal of Botany 90:905–910.

Miller-Rushing, A., and R. Primack. 2008. Global warming and flowering times in Thoreau's Concord: a community perspective. Ecology 89:332–341.

Schwartz, M. D., A. Ahas, et al. 2006. Onset of spring starting earlier across the Northern Hemisphere. Global Change Biology 12:343–351.

Stevens, O. A. 1963. Handbook of North Dakota Plants. North Dakota Institute for Regional Studies, Fargo, North Dakota, USA.

Trimble, D. 1980. The Geologic Story of the Great Plains. Geological Survey Bulletin 1493. United States Government Printing Office.

Van Bruggen, T. 1985. The Vascular Plants of South Dakota. Iowa State University Press, Ames, Iowa, USA.

Walther, G. R., E. Post, et al. 2002. Ecological responses to recent climate change. Nature 416(6879):389–395.

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