This readme.txt file was generated on 2024-07-06 by Wesley J. Glisson Recommended citation for the data: Glisson, Wesley J.; Nault, Michelle; Jurek, Chris; Fischer, Eric; Lund, Keegan; Bloodsworth Cattoor, Kylie; Londo, April; Kovar, Nicole, Hauck-Jacobs, Emelia; Egdell, Rod; McComas, Steve; Fieldseth, Eric; Larkin, Daniel J. (2024). Data supporting: Evaluation of a decade of management of a North American aquatic invasive species (Nitellopsis obtusa) highlights scale-dependent effectiveness and monitoring gaps. Retrieved from the Data Repository for the University of Minnesota (DRUM) https://doi.org/10.13020/vjxh-5p45. ------------------- GENERAL INFORMATION ------------------- 1. Title of Dataset Data supporting: Evaluation of a decade of management of a North American aquatic invasive species (Nitellopsis obtusa) highlights scale-dependent effectiveness and monitoring gaps 2. Author Information Principal Investigator Contact Information Name: Wesley J. Glisson Institution: Department of Fisheries, Wildlife and Conservation Biology & Minnesota Aquatic Invasive Species Research Center, University of Minnesota-Twin Cities Address: 2003 Upper Buford Circle, St. Paul, MN 55113, USA Email: wjglisson@gmail.com ORCID: https://orcid.org/0000-0002-2540-3696 Associate or Co-investigator Contact Information Name: Michelle Nault Institution: Bureau of Water Quality, Wisconsin Department of Natural Resources Address: 101 S Webster Street, Madison, WI 53703, USA Email: Michelle.Nault@wisconsin.gov Associate or Co-investigator Contact Information Name: Chris Jurek Institution: Minnesota Department of Natural Resources Address: 500 Lafayette Road, St. Paul, MN 55155, USA Email: christine.jurek@state.mn.us Associate or Co-investigator Contact Information Name: Eric Fischer Institution: Indiana Department of Natural Resources Address: 402 W Washington Street, Indianapolis, IN 46204, USA Email: efischer@dnr.in.gov Associate or Co-investigator Contact Information Name: Keegan Lund Institution: Minnesota Department of Natural Resources Address: 500 Lafayette Road, St. Paul, MN 55155, USA Email: keegan.lund@sepro.com Associate or Co-investigator Contact Information Name: Kylie Bloodsworth Cattoor Institution: Minnesota Department of Natural Resources Address: 500 Lafayette Road, St. Paul, MN 55155, USA Email:kylie.cattoor@state.mn.us Associate or Co-investigator Contact Information Name: April Londo Institution: Minnesota Department of Natural Resources Address: 500 Lafayette Road, St. Paul, MN 55155, USA Email: april.londo@state.mn.us Associate or Co-investigator Contact Information Name: Nicole Kovar Institution: Minnesota Department of Natural Resources Address: 500 Lafayette Road, St. Paul, MN 55155, USA Email: nicole.kovar@state.mn.us Associate or Co-investigator Contact Information Name: Emelia Hauck-Jacobs Institution: Minnesota Department of Natural Resources Address: 500 Lafayette Road, St. Paul, MN 55155, USA Email: emelia.hauck-jacobs@state.mn.us Associate or Co-investigator Contact Information Name: Rod Egdell Institution: Indiana Department of Natural Resources Address: 402 W Washington Street, Indianapolis, IN 46204, USA Email: REdgell@dnr.in.gov Associate or Co-investigator Contact Information Name: Steve McComas Institution: Blue Water Science Address: 550 Snelling Ave S, Ste 101, Saint Paul, MN 55116, USA Email: mccomas@pclink.com Associate or Co-investigator Contact Information Name: Eric Fieldseth Institution: AIS Consulting Address: 6544 Co. Rd. 6 NW Annandale, MN 55302, USA Email: AISConsultingMN@gmail.com Associate or Co-investigator Contact Information Name: Daniel J. Larkin Institution: Department of Fisheries, Wildlife and Conservation Biology & Minnesota Aquatic Invasive Species Research Center, University of Minnesota-Twin Cities Address: 2003 Upper Buford Circle, St. Paul, MN 55113, USA Email: djlarkin@umn.edu ORCID: https://orcid.org/0000-0001-6378-0495 3. Date published or finalized for release: 2024-12-05 4. Date of data collection: 2009 - 2022 5. Geographic location of data collection: Lakes with Nitellopsis obtusa in Indiana, Minnesota, and Wisconsin, USA. 6. Information about funding sources that supported the collection of the data: Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Minnesota Aquatic Invasive Species Research Center and the Legislative-Citizen Commission on Minnesota Resources. 7. Overview of the data: Nitellopsis obtusa (starry stonewort) is an invasive macroalga subject to substantial control efforts in the Midwestern United States; however, there has not been systematic evaluation of treatment effectiveness. We synthesized management approaches and outcomes using monitoring performed over a decade-long period across 38 lakes in Indiana, Wisconsin, and Minnesota. We compiled all available point-intercept (PI) survey data from lakes where N. obtusa was known to occur since the year the species was first discovered in each state (Indiana, 2008; Wisconsin, 2014; Minnesota, 2015) until 2018 (Indiana) and 2019 (Wisconsin and Minnesota). These data comprised raw survey and summary data from whole-lake PI surveys, as well as targeted sub-PI surveys within managed areas. We compiled all available information on N. obtusa management for the time periods encompassing the survey data. Management data were collected from: 1) pesticide application records (PARs; Minnesota), 2) chemical treatment and mechanical harvesting records (Wisconsin), 3) aquatic vegetation management plans (AVMPs; Indiana), and 4) direct knowledge of known management events (all states). We compiled as much information as possible for each management action on each lake. For hand pulling, we additionally compiled all available data on the biomass of N. obtusa removed during each event; we included all such data through 2022. -------------------------- SHARING/ACCESS INFORMATION -------------------------- 1. Licenses/restrictions placed on the data: _______ 2. Links to publications that cite or use the data: ______ 3. Was data derived from another source? No 4. Terms of Use: Data Repository for the U of Minnesota (DRUM) By using these files, users agree to the Terms of Use. https://conservancy.umn.edu/pages/policies/#drum-terms-of-use --------------------- DATA & FILE OVERVIEW --------------------- 1. File List A. Filename: Nobtusa_mgmt_2024_all_management.csv Short description: Data for all known management of Nitellopsis obtusa in Indiana, Minnesota, and Wisconsin 2009-2019. B. Filename: Nobtusa_mgmt_2024_wholeLake_PI.csv Short description: Whole-lake point intercept (PI) survey and management data used to analyze response of Nitellopsis obtusa frequency of occurrence and abundance to management with algaecides. C. Filename: Nobtusa_mgmt_2024_BA.csv Short description: Data for analysis of before-after (BA) Nitellopsis obtusa management within managed areas; see table S4 in the Supplementary Materials of the manuscript cited below. D. Filename: Nobtusa_mgmt_2024_BA_caseStudies.csv Short description: Data for analysis of before-after (BA) Nitellopsis obtusa management case studies. E. Filename: Nobtusa_mgmt_2024_handpull_biomass.csv Short description: Biomass removal data for Nitellopsis obtusa handpulling in three Minnesota Lakes, 2017-2022. F. Filename: Nobtusa_mgmt_2024_BACI_Koronis.csv Short description: Biomass data for before-after control-impact (BACI) analysis of Nitellopsis obtusa management in Lake Koronis, Minnesota. G. Filename: Nobtusa_mgmt_2024_BACI_BigMuskego.csv Short description: Biomass data for before-after control-impact (BACI) analysis of Nitellopsis obtusa management in Big Muskego Lake, Wisconsin. H. Filename: Nobtusa_mgmt_2024_BACI_LittleMuskego.csv Short description: Presence-absence data for before-after control-impact (BACI) analysis of Nitellopsis obtusa management in Little Muskego Lake, Wisconsin I. Filename: Nobtusa_mgmt_2024_all_csvs.zip Short description: single folder of all spreadsheets. 2. Relationship between files: Lake names, counties, and states are consistent across all data files. -------------------------- METHODOLOGICAL INFORMATION -------------------------- 1. Description of methods used for collection/generation of data: For a description of the methods used for collection/generation of data please see: Glisson, W. J., M. Nault, E. Fischer, K. Lund, K. Bloodsworth Cattoor, A. Londo, N. Kovar, E. Hauck-Jacobs, R. Egdell, S. McComas, E. Fieldseth, and D. J. Larkin. 2024. Evaluation of a decade of management of a North American aquatic invasive species (Nitellopsis obtusa) highlights scale-dependent effectiveness and monitoring gaps. FACETS. 2. Methods for processing the data: For a description of the methods used for processing the data please see: Glisson, W. J., M. Nault, E. Fischer, K. Lund, K. Bloodsworth Cattoor, A. Londo, N. Kovar, E. Hauck-Jacobs, R. Egdell, S. McComas, E. Fieldseth, and D. J. Larkin. 2024. Evaluation of a decade of management of a North American aquatic invasive species (Nitellopsis obtusa) highlights scale-dependent effectiveness and monitoring gaps. FACETS. 3. Instrument- or software-specific information needed to interpret the data: NA 4. Standards and calibration information, if appropriate: NA 5. Environmental/experimental conditions: NA 6. Describe any quality-assurance procedures performed on the data: All data were checked for accuracy and consistency upon entry and analysis. 7. People involved with sample collection, processing, analysis and/or submission: All coauthors contributed to these steps. ---------------------------------------------------------------------------------- DATA-SPECIFIC INFORMATION FOR: Nobtusa_mgmt_2024_all_management.csv ---------------------------------------------------------------------------------- 1. Number of variables: 28 2. Number of cases/rows: 397 (excluding column headers) 3. Missing data codes: NA: Used when the column is not applicable to the row of data. E.g., the amount of copper used for a management action such as hand-pulling. not reported: Used when the data for the given non-numeric column is applicable to the row of data, but the data was not included in available reports. (blank): Used when no data exists for the given column. Similar to "not reported", but this value is used for rows with numeric data. 4. Variable List A. state = The U.S. state where the lake is located; IN = Indiana, MN = Minnesota, and WI = Wisconsin. B. lake = The name of the lake where Nitellopsis obtusa management occurred. C. county = The county where the lake is located. D. year_discovered = The year that Nitellopsis obtusa was confirmed to be present in the lake. E. management_year = The year that Nitellopsis obtusa management was conducted. F. mgmt_startDate_reported = The reported starting date of management. Occasionally this was "unknown" for a given management_year, or was reported as a month only. Most management (e.g., algaecide treatment), started and ended on the same date. G. mgmt_startDate = The starting date of management used for processing and analyzing the data. If only management month was reported, we used the midpoint of the month. If only the management year was reported (i.e., "unknown" in column mgmt_startDate_reported), then 15 July of that year was used. See publication for additional details. H. mgmt_startDateKnown_estimated = Whether or not mgmt_startDate was estimated (yes or no). I. mgmt_dateRange = The range of dates reported for management events lasting more than a single day. J. mangement_type = The type of management action performed. K. algaecide_1 = The first reported and primary algaecide used for treatment. L. algaecide_2 = The second reported and secondary algaecide used for treatment. M. algaecide_3 = The third reported and any remaining algaecide(s) used for treatment. N. cu_algaecide_used = Whether or not a copper-based algaecide was used: 1 = yes, 0 = no. O. acres_managed = The surface acres of the waterbody included in the given management action. P. quantity_algaecide_1 = The amount of algaecide_1 applied, in gallons (gal), quarts (qt), or pounds (lbs). Q. quantity_algaecide_2 = The amount of algaecide_2 applied, in gallons (gal), quarts (qt), or pounds (lbs). R. quantity_algaecide_3 = The amount of algaecide_3 applied, in gallons (gal), quarts (qt), or pounds (lbs). S. cu_conc_gal_per_acre_feet: The concentration of copper applied (in gallons/acre-feet) for algaecide treatments with copper-based products. This value is the target concentration of the treatment, unless copper concentration monitoring data were available, in which case the intial value from the monitoring data was used. T. cu_conc_ppm: The concentration of copper applied (in parts per million [mg/L]) for algaecide treatments with copper-based products. This value is the target concentration of the treatment, unless copper concentration monitoring data were available, in which case the initial value from the monitoring data was used. U. cu_product_quantity = The amount of copper-based product applied in gallons (gal), quarts (qt), or pounds (lbs). If product amount was not reported or was reported inconsistly, minimum values for these amount were calculated using available data. See publication for further details. V. mgmt_acre_feet = The volume of water (in acre-feet) treated for algaecide applications. W. mgmt_avg_depth_ft = The average depth (in feet) of the managed area. X. cu_product_lbs = Pounds (lbs) of copper-based product used. Applies only to granular-based applications of copper-based algaecides. If copper-based algaecide quantity (cu_product_quantity) was not reported, then a minimum quantity value was calculated using available data (e.g., product, area treated, and product concentration). Y. cu_product_gal = Gallons (gal) of copper-based product used. Applies only to liquid-based applications of copper-based algaecides. If copper-based algaecide quantity (cu_product_quantity) was not reported, then a minimum quantity value was calculated using available data (e.g., product, area treated, and product concentration). Z. cu_lbs_per_product_amount = The product-label-specified ratio of elemental copper (in pounds [lbs]) to unit of product (either gallons or pounds). These values were taken directly from available algaecide product labels. AA. cu_lbs = The pounds (lbs) of elemental copper applied for the treatment. This value is calculated based on the most complete available data. For example, if the amount of product applied was available, (cu_product_quantity), this was multiplied by cu_lbs_per_product_amount. If the amount of product was not reported, we used application rates (either cu_conc_gal_per_acre_feet or cu_conc_ppm) and the volume of the treatment area (mgmt_acre_feet) to calculate the amount of product applied. If neither the product amount or volume of the treatment area (mgmt_acre_feet) were available, we used the application rate (either cu_conc_gal_per_acre_feet or cu_conc_ppm) and surface area managed (acres_managed). AB. water_temp_F = Water temperature (in Fahrenheit) recorded during the given management event ---------------------------------------------------------------------------------- DATA-SPECIFIC INFORMATION FOR: Nobtusa_mgmt_2024_wholeLake_PI.csv ---------------------------------------------------------------------------------- 1. Number of variables: 26 2. Number of cases/rows: 103 (excluding column headers) 3. Missing data codes: NA; used for columns Nobtusa_nRD and Nobtusa_nRD_nz. See column-specific notes below for details. 4. Variable List A. ssw_survey_id = Unique combination of state, lake name, and date for each survey. B. lakeID = The combination of state, lake name, and county. C. state = The U.S. state where the lake is located; IN = Indiana, MN = Minnesota, and WI = Wisconsin. D. lake = The name of the lake where the Nitellopsis obtusa survey and management occurred. E. County = The county where the lake is located. F. lake_size_acres = The size of the lake in surface acres. G. year_discovered = The year that Nitellopsis obtusa was confirmed to be present in the lake. H. survey_year = The year in which the survey occurred. I. survey_dateStart = The date in which the point intercept survey began (MM/DD/YYYY). J. survey_dateEnd = The date in which the point intercept survey was finished (MM/DD/YYYY). K. survey_points = The number of sampling points included in the point intercept survey. L. Nobtusa_pres = The number of points in the survey where Nitellopsis obtusa was observed. M. Nobtusa_notpres = The number of points in the survey where Nitellopsis obtusa was not observed. N. Nobtusa_freq = Nitellopsis obtsua frequency of occurrence: the number of sampling points where N. obtusa was found divided by the total number of survey points (Nobtusa_pres/survey_points). O. Nobtusa_nRD = The mean rake density in the survey. Rake density is an abundance metric measured on an ordinal, 1–3, scale, with 1 indicating small fragment(s) present, 3 indicating a fully covered rake-head, and 2 indicating an intermediate abundance level. The mean rake density values for this variable includes sampling points where no Nitellopsis obtusa was found (Nobtusa_notpres). "NA" indicates that no rake density data where collected or available for the surveys, and hence, a mean rake density value could not be calculated. P. Nobtusa_nRD_nz = The mean rake density where Nitellopsis obtusa was present in the survey. Rake density is an abundance metric measured on an ordinal, 1–3, scale, with 1 indicating small fragment(s) present, 3 indicating a fully covered rake-head, and 2 indicating an intermediate abundance level. The mean rake density values for this variable excludes sampling points where no Nitellopsis obtusa was found (Nobtusa_notpres). "NA" indicates either 1) no rake density data where collected or available for the survey, and hence, a mean rake density value could not be calculated, or 2) There was no N. obtusa detected in the survey (and, thus, both Nobtusa_pres and Nitellopsis_obtusa_nRD = 0). Q. acres_mgmt_alg_sum = The summed surface acreage of all algaecide treatments conducted prior to the survey. R. prop_acres_mgmt_alg_sum = The proportion of the lake surface area treated with algaecide prior to the survey (acres_treated_herb_sum / lake_size_acres). S. acres_mgmt_other_sum = The summed surface acreage of all non-algaecide management conducted prior to the survey. T. mangement_type = The type(s) of management actions performed prior to the survey. U. survey_dayofyear = The numeric day of the year on which the survey was conducted. V. years_since_infested = The number of years since the the lake was confirmed to be infested with Nitellopsis obtusa. Values range from 0 (survey conducted in the same year as the lake was confirmed to be infested) to 9. W. mgmt_beforeSurvey = A binary variable indicating whether or not any management occured prior to the survey that year. Only surveys that included at least one algaecide treatment are included in the data. X. pamas_scaled = prop_acres_mgmt_alg_sum scaled to have mean = 0 and standard deviation = 1. Y. ysi_scaled = years_since_infested scaled to have mean = 0 and standard deviation = 1. Z. sdoy_scaled = survey_dayofyear scaled to have mean = 0 and standard deviation = 1. ---------------------------------------------------------------------------------- DATA-SPECIFIC INFORMATION FOR: Nobtusa_mgmt_2024_BA.csv ---------------------------------------------------------------------------------- 1. Number of variables: 12 2. Number of cases/rows: 42 (excluding column headers) 3. Missing data codes: NA; for the variable "rake_density" NA indicates that the variable could not be calculated because there was no Nitellopsis obtusa present in the survey. 4. Variable List A. state = The U.S. state where the lake is located. Either Minnesota or Wisconsin. B. lake = The name of the lake where the surveys and algaecide treatments occurred. C. year = The year in which the treatment and survey occurred (YYYY). D. comparison_ID = Unique combination of state, lake, year, and in some instances, treatment area ("a" or "b"). This is used to identify pairs of before and after surveys for each unique treatment. E. treatment_dates = Date(s) of algaecide treatments (MM/DD/YYYY). F. algaecide = The name(s) of the algaecide products applied for treatment of Nitellopsis obtusa. Combinations of algaecides are indicated with a "+". G. survey_date = The date of the survey (MM/DD/YYYY). H. ba = Either "before" or "after" indicating whether the survey was conducted before or after treatment occurred. I. survey_points = The number of sampling points included in the survey. J. Nobtusa_pres = The number of sampling points in the survey where Nitellopsis obtusa was observed. K. Nobtusa_notpres = The number of sampling points in the survey where Nitellopsis obtusa was not observed. L. rake_density = The mean rake density (where Nitellopsis obtusa was present) in the survey. Rake density is an abundance metric measured on an ordinal, 1–3, scale, with 1 indicating small fragment(s) present, 3 indicating a fully covered rake-head, and 2 indicating an intermediate abundance level. ---------------------------------------------------------------------------------- DATA-SPECIFIC INFORMATION FOR: Nobtusa_mgmt_2024_BA_caseStudies.csv ---------------------------------------------------------------------------------- 1. Number of variables: 10 2. Number of cases/rows: 18 (excluding column headers) 3. Missing data codes: No missing data. 4. Variable List A. state = The U.S. state where the lake is located. Either Minnesota or Wisconsin. B. lake = The name of the lake where the surveys and management occurred. C. survey_year = The year the survey was conducted in format YYYY. D. case_study_ID = Unique combination of state, lake, and year used to identify pairs of before and after surveys for each unique case study. E. management = The type of management conducted for control of Nitellopsis obtusa. F. survey_date = The date of the survey (MM/DD/YYYY). G. ba = Either "before" or "after" indicating whether the survey was conducted before or after management occurred. H. survey_points = The number of sampling points included in the survey. I. Nobtusa_pres = The number of sampling points in the survey where Nitellopsis obtusa was observed. J. Nobtusa_notpres = The number of sampling points in the survey where Nitellopsis obtusa was not observed. ---------------------------------------------------------------------------------- DATA-SPECIFIC INFORMATION FOR: Nobtusa_mgmt_2024_handpull_biomass.csv ---------------------------------------------------------------------------------- 1. Number of variables: 5 2. Number of cases/rows: 39 (excluding column headers) 3. Missing data codes: No missing data 4. Variable List A. lake = The name of the lake where handpulling occurred. B. date = Date of biomass removal (MM/DD/YYYY). C. year = Year of biomass removal (YYYY). D. collector = The entity that collected the biomass data. AIS_Consulting = AIS Consulting; BWS = BlueWater Science; MNDNR = Minnesota Department of Natural Resources. E. biomass_removed_g = The amount of Nitellopsis obtusa biomass (in grams) removed during the handpull event. --------------------------------------------------------------------------------- DATA-SPECIFIC INFORMATION FOR: Nobtusa_mgmt_2024_BACI_Koronis.csv ---------------------------------------------------------------------------------- 1. Number of variables: 10 2. Number of cases/rows: 227 (excluding column headers) 3. Missing data codes: NA = no data (for "biomass_g"), or variable not calculated (for "biomass_g_m2", "biomass_g_ln" and "biomass_g_m2_ln") 4. Variable List A. site = Name of the site. Also indicates whether the site was a treatment (includes the word "treatment") or untreated reference (includes the word "reference) site. Treatment and untreated reference sites were not the same each year, so the treatment and reference locations only apply to the year in which they were sampled. B. point = The sampling point number within the site that indicates where a Nitellopsis obtusa biomass sample was collected. Note that the numbers are not always sequential because some points were not sampled if the the point could not be reached (e.g., too shallow). C. site_point = Unique combination of site and point. D. date = Date of sample collection (MM/DD/YYYY). E. year = Year of sample collection (YYYY). F. ba = Either "before" or "after" indicating whether the biomass sample was collected before or after treatment occurred. G. weight_g = Weight (in grams) of Nitellopsis obtusa biomass collected at the point location. H. weight_g_ln = The natural log of "weight_g" after adding 1 g. I. weight_g_m2 = Weight (in grams) per meter^2 of Nitellopsis obtusa biomass collected at the point location. J. weight_g_m2_ln = The natural log of "weight_g_m2" after adding 1 to the value of "weight_g_m2". ---------------------------------------------------------------------------------- DATA-SPECIFIC INFORMATION FOR: Nobtusa_mgmt_2024_BACI_BigMuskego.csv ---------------------------------------------------------------------------------- 1. Number of variables: 9 2. Number of cases/rows: 48 (excluding column headers) 3. Missing data codes: No missing data 4. Variable List A. site = Name of the site. B. point = The sampling point number within the site that indicates where a Nitellopsis obtusa biomass sample was collected. C. site_point = Unique combination of site and point. D. date = Date of sample collection (MM/DD/YYYY). E. algaecide = Algaecide product used for treatment. F. type = Either "treatment" for a point that occurred within a treated site or "reference" for a point that occurred in the untreated reference site. G. ba = Either "before" or "after" indicating whether the biomass sample was collected before or after treatment occurred. H. weight_g = Weight (in grams) of Nitellopsis obtusa biomass collected at the point location. I. weight_g_ln = The natural log of "weight_g" after adding 1 g. ---------------------------------------------------------------------------------- DATA-SPECIFIC INFORMATION FOR: Nobtusa_mgmt_2024_BACI_LittleMuskego.csv ---------------------------------------------------------------------------------- 1. Number of variables: 8 2. Number of cases/rows: 99 (excluding column headers) 3. Missing data codes: No missing data 4. Variable List A. site_type = The type of site. Either "treatment" for sites that were treated or "ref" for those not treated. B. point = The sampling point number within the site that indicates where Nitellopsis obtusa data was collected. C. site_type_point = Unique combination of site_type and point. D. date = Date of sample collection (MM/DD/YYYY). E. ba = Either "before" or "after" indicating whether presence/absence was collected before or after treatment occurred. F. depth_ft = Depth (in feet) of the point location where presence/absence data were collected. G. Nobtusa_pres = Indicates whether Nitellopsis obtusa was observed at the point location: 1 = yes, 0 = no.* H. Nobtusa_notpres = The opposite of the variable above (Nobtusa_pres); indicates whether Nitellopsis obtusa was not observed at the point location.* *For site_type_point "treatment_119" on date 5/22/2016 (row 17) Nobtusa_pres was changed from 1 to 0 in the data here (with a corresponding change to Nobtusa_notpres) because all values in the "before" & "treatment" group had a value of 1, which resulted in the failure of the logistic regression model (i.e., a generalized linear model with binary response variable) applied to the data. This specific point was chosen for this adjustment because it had a value 0 in the "after" & "treatment" group.