For data content questions, contact Niwot LTER data manager
For methodology questions, contact Hope Humphries
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Permanent 1-m^2 plots were established beside each of the 88 Saddle grid stakes in 1989 by Marilyn Walker, who led the sampling effort until 1997. Each plot was located within 2 m of the stake, but always in the same vegetation type as that associated with the stake. The distance and direction from the grid stake were randomly selected, and thus varied from plot to plot. Point quadrat measurements have been made at irregular intervals from 1989 to the present (1989, 1990, 1995, 1997, 2006, 2008, and yearly from 2010 onward). The point-quadrat technique used was identical to that described by Auerbach (1992) for sampling in 1989 to 1997: The point-quadrat method was used for estimating plant cover. The aluminum point-quadrat frame was 1 m^2 in size, with double-layer filament spaced 10 cm apart to make a 10 x 10 cm grid, for a total of 100 sample points per plot. Before sampling, the point-quadrat frame was leveled and plots were permanently marked in the following manner. Aluminum tags were nailed into the ground so that a frame could be repositioned in the same location from year to year; i.e., tags with a hole in the middle were used to define the locations for the point frame legs and four tags with a "X" stamped on them (positioned somewhere inside each of the frame corners) were used to define alignment of the frame by positioning the string crossings over these "X"s. Plant genus and species were recorded for top and bottom hits at each point for 1990-1997 data. In 1989, middle hits were also recorded. A plant species hit occurs when a plant part touches a thin metal stick placed at the intersection of 2 filaments in the quadrat. If plant parts of a given species touch the stick at multiple places, only one hit is recorded. In the next sampling year, 2006, and continuing to the present, all hits were recorded at each point, but frame distances were not measured. In addition, exact repositioning of the frame was not possible in some plots due to absence or relocation of tags. Data are formatted as one species hit per row (“string of pearls’).
Study sites were the 88 Niwot Ridge Saddle grid points. Original plot sheets, data entry spreadsheets, data collection/entry notes, and additional point-quadrat technique descriptions are stored with the NWT LTER data manager.
1989 - ongoing
yearly from 2010
year, plot number, point identification number, hit type, species code, species name
Elevation: 3500 m
Niwot Ridge (USFS - UNESCO Biosphere Reserve)
Located in: USFS - UNESCO Biosphere Reserve
(Click to learn more about these locations)
More data from: Saddle
Core Data Set: yes Core Area: Populations
Discipline: Plant/vegetation ecology
Award Or Grant: DEB1027341
The data in this file through 1997 were manually entered from field data sheets by data management personnel using an EasyEntry form. Subsequently, data were entered into Excel spreadsheets formatted to replicate plot sheets. Point records were converted to plant cover using macros. The resulting files were processed and/or archived on the NWT LTER server.
Data for 1989 and 1990 had originally been provided by the Joint Facility for Regional Ecosystem (JFREA) via FTP. More detailed information regarding the original entry of this data into Excel spreadsheets is on file in the JFREA Laboratory. Due to inconsistencies in format and entry
of this data, as well as the discovery of several errors, the 1989 and 1990 data were re-entered by data management personnel in the winter of 1995-1996. The format of the data was modified slightly at this time, so the entire data section of this file was replaced, and appropriate
modifications were made to the documentation section as well.
The plots are numbered the same as the grid stake numbers except for the "A" row plots. Plot numbers 101, 201, 301, 401, 501, 601, 701, and 801, correspond to grid stakes 10A, 20A, 30A, 40A, 50A, 60A, 70A, and 80A, respectively. There are 100 "points" in each of the 88 point quadrat plots, resulting in 8800 unique point identification numbers.
Point identification numbers begin in the southwest corner of the plot at grid stake 1 and mimic the numbering pattern of the grid stakes, so that point identification number 11 is directly north of point ID 1 and point ID 8800 is in the northeast corner of the plot at grid stake 80A (801).
Metadata for the full scientific names corresponding to the species codes can be found in http://niwot.colorado.edu/meta_data/pspecies.mw.meta.txt.
Disturbance conditions were not recorded as a separate category, but rather were collapsed into the species codes.
All chew and nest disturbances were recorded as litter, while all runway, mound, and cast disturbances were recorded as soil. Before sampling, stakes of rebar were positioned in the tundra outside each corner of the plot and string was tied around the rebar to cordone off each plot. Aluminum tags marked with the plot number and investigator were attached to the southwest corner rebar.
Ancillary information relating to plots recorded in 1989-1997 are available at:
In 2006 and thereafter, species and nonspecies codes were recorded using USDA PLANTS codes. Codes used in earlier years were converted to these codes. Codes that begin with “2” are nonspecies. Also, lichens and mosses were not identified to species in these years.
All species identifications after 2011 should be considered PRELIMINARY, especially for Carex species. These and earlier data are subject to revision.
plant species composition, vascular, communities, vegetation, populations, point quadrat, saddle grid plots, Niwot Ridge LTER, NWT, long term
COL1. label=year, type=integer, units=none, missing value indicator=NaN, minimum=1989, maximum=, precision=1, definition=year (yyyy)
COL2. label=plot, type=integer, units=none, missing value indicator=NaN, minimum=1, maximum=801, precision=1, definition=plot number (eastern-most plots are 101, 201, 301, 401, 501, 601, 701, 801)
COL3. label=point, type=integer, units=none, missing value indicator=NaN, minimum=1, maximum=8800, precision=1, definition=point identification number across plots
COL4. label=hit_type, type=string, units=none, missing value indicator=NaN, minimum=bottom, maximum=top, precision=, definition=hit type (bottom, middle1, middle2, top)
COL5. label=USDA_code, type=string, units=none, missing value indicator=NaN, minimum=, maximum=, precision=, definition=USDA PLANTS database code
COL5. label=USDA_name, type=string, units=none, missing value indicator=NaN, minimum=, maximum=, precision=USDA PLANTS database species name
*Note: To ask a question about data content, please contact the data manager HERE
To ask a question about methodology, please contact Hope Humphries,
Auerbach, N. 1992. Effects of road and dust disturbance in minerotrophic and acidic tundra ecosystems, Northern Alaska. MS thesis, University of Colorado, Boulder. 253 pp.
Walker, D.A., B.E. Lewis, W.B. Krantz, E.T. Price, and R.D. Tabler. 1994. Hierarchic studies of snow-ecosystem interactions: A 100-year snow-alteration experiment. Pp. 407-414 In: Ferrik, M. (ed.). Proceedings of the Fiftieth Annual Eastern and Western Snow Conference, Quebec City, Quebec, Canada, 8-10 June 1993. 441 pp.
The initial iteration of the documentation section was created by Leanne Lestak on 18 March 1994, using the itexptqd.mw documentation section as a template. The initial iteration of the header section was generated, and all 1989 and 1990 data were appended to the data section on this date. Minor editorial revisions were made to the documentation section by RCI on 21 March 1994. The file was put under sccs control on that date as well. [RCI 21 March 1994] Minor editorial revisions to the documentation section were suggested by Marilyn Walker and added on 13 May 1994.[RCI
13 May 1994] Plot locations surveyed by Tim Bardsley and Mike Hartman on 6 July 1994 were added to the comments section on 13 July 1994. [RCI 13 July 1994] Plot locations surveyed by Tim Bardsley and Mike Hartman on 13 July 1994 were added to the comments section on 14 July 1994.[RCI 14 July 1994] Comments and data for the 1995 season were added on 14 December 1995.[MAH 14 December 1995] Ancillary metadata for the 1995 data was added to the comments section on 15 December 1995.[MAH 15 December 1995] Unknowns for stakes 60a, 70a, and 76 for 1995 were corrected, and the data for those stakes were reimported into the data section on 29 December 1995.[MAH 29 December 1995] A comment concerning the use of condition code 5 was added to the comments section on 8 January 1996.[MAH 8 January 1995] On 23 January 1996 Leanne Lestak noted that the plot number for point identification number 6214 for 1995 was incorrectly listed in this file as 26. This was changed to the correct plot number of 58 on 23 January 1996.[MAH 23 January 1996] The reference to Walker et al. (1994) was added to the citations section on 2 May 1996.[MAH 2 May 1996] The data section was deleted and replaced with a new data section on 9 May 1996, following the re entry of all 1989 and 1990 data. Appropriate changes were also made to the documentation section of this file at that time.[MAH 9 May 1996] On 2 August 1996 it was determined that the 1989 data contained an extra, empty column of data at the end of each record. This column was srtipped off, and the data re-inserted into the data section on 2 August 1996.[MAH 2 August 1996] Data for plot 37 recorded in 1996 were appended to the data section on 11 November 1996.[MAH 11 November 1996] Data for the 1997 field season were appended to the data section and ancillary metadata for 1997 were added to the comments section on 8 December 1997. Corrections for several plants that had been misidentified in earlier years were provided by Teresa Nettleton, and the appropriate changes were made on that date as well.[MAH 8 December 1997] It was determined that for the 1997 data, all Cladonia pocillum occurances had been given an incorrect numeric code of 289 instead of the correct code of 298. The 1997 data were reprocessed, and replaced in the data section of this file on 14 January 1998. Corrections for the conditions of several plants from 1995 and 1997 were provided by Teresa Nettleton, and the appropriate changes were made on that date as well.[MAH 14 January 1998] Corrections for several height measurements on the 1997 hard copy data sheets were provided by Teresa Nettleton. The appropriate changes were made, and the data were reprocessed and replaced in the data section of this file on 24 March 1998.[MAH 24 March 1998] Miscellaneous comments and additional present species from 1997 were appended to the comments section on 15 August 2000.[MAH 15 August 2000]. Missing data for 1989, plots 2-19 were inserted into the data section.[TMA 17 April 2006] Data for plot 10A for 1989 were inserted into the data section.[TMA 11 September 2007]. Data were reformatted to remove heights and condition classes, middle heights for 1989 were incorporated, and species numbers were converted to USDA PLANTS codes with associated names. All lichen and moss hits were converted to generic “2MOSS” and “2LICHN” designations for consistency with post-1997 data. Data for 2006 to 2014 were added. Column data were edited to reflect the new format.[HCH 30 December]
Humphries, Hope. Walker, Marilyn. 2017. Plant species composition data for Saddle grid plots from 1989 - ongoing, yearly from 2010. http://niwot.colorado.edu
This material is based upon work supported by the National Science Foundation under Cooperative Agreement #DEB-1637686. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necesarily reflect the views of the National Science Foundation.
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