Data from: Microsite availability, not floral herbivory, limits recruitment in peripheral native thistle populations
Data files
May 06, 2025 version files 600.63 KB
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Baregroundcover.csv
3.24 KB
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Plantcommunitybiomass.csv
3.86 KB
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Plattethistlefirstflowering.csv
10.68 KB
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Plattethistleseedlingestablishment.csv
178.45 KB
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Plattethistleseedproduction.csv
348.10 KB
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README.md
34.56 KB
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Soilhardness.csv
3.13 KB
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Soilmoisture.csv
18.62 KB
Abstract
Variation in insect herbivory can drive variation in plant fitness and population dynamics. However, our ability to predict the ecological contexts in which insect herbivores will reduce plant fitness or population growth is limited. In theory, populations at the periphery of a plant species’ biogeographic range, are expected to experience reduced herbivory. Further, in montane landscapes, elevation is expected to drive variation in abiotic conditions and variation in plant-insect interactions. Specifically, less insect herbivory may occur at cooler, higher elevations. To examine these predictions, we quantified effects of inflorescence- and seed-feeding insect herbivores in populations of the short-lived, monocarpic, perennial forb Cirsium canescens (Platte thistle) in montane grasslands in Colorado, USA. We asked: 1) Does insect flower head herbivory and predispersal seed predation limit Platte thistle lifetime seed production?, 2) Does this insect herbivory limit seedling recruitment?, 3) Does ecological context, including spatial - especially elevational - and temporal variation, affect the outcome of these interactions? We conducted insect exclusion experiments in three years at five sites over 52% of Platte thistle’s elevation range in our region. We compared both lifetime viable seed production and seedlings recruited between plants with ambient vs. insecticide-reduced levels of flower head herbivory. Insect herbivory on flower heads significantly reduced Platte thistle lifetime viable seed production at all sites, independent of elevation. Unexpectedly, however, increasing seed by reducing herbivory did not lead to a proportional increase in seedling recruitment. The relationship between viable seed production and seedling recruitment per plant was non-linear, decelerating across the range of seed production achieved by both plants exposed to and protected from flower head herbivory. While elevation altered Platte thistle flowering phenology, it did not influence insect damage, viable seed production, or seedling recruitment. These results show that flower head- and seed-feeding insect herbivores strongly reduced Platte thistle lifetime viable seed production, a key component of maternal fitness, in these peripheral populations. Yet, the herbivory did not determine population recruitment, suggesting post-dispersal processes limit recruitment here. Further, elevation did not drive context-dependent variation in the insect herbivore outcomes.
https://doi.org/10.5061/dryad.kh18932dc
ReadMe file for seven data sets associated with “Microsite availability, not floral herbivory, limits recruitment in peripheral native thistle populations.” by FL Russell, MR Taylor and SM Louda. The data sets are named; 1. ‘Plattethistleseedproduction.csv’, 2. ‘Plattethistleseedlingestablishment.csv’, 3. ‘Plattethistlefirstflowering.csv’, 4. ‘Plantcommunitybiomass.csv’, 5. ‘Baregroundcover.csv’, 6. ‘Soilhardness.csv’, 7. ‘Soilmoisture.csv’.
1. Data Set: ‘Plattethistleseedproduction.csv’
Data Description: These data are from experiments that examined the effects of insect floral herbivory and pre-dispersal seed predation on the number of viable seeds produced by Platte thistles (Cirsium canescens) along an elevation gradient in Caffee County, Colorado USA. Specifically, we were interested in addressing 1) how elevation affected Platte thistle viable seed production, 2) how insect herbivory on reproductive adult Platte thistles affected their viable seed production and 3) whether the effect of insect herbivory varied with elevation. Both experiments that contributed to this data set involved an insect exclusion treatment in which insect herbivory either was reduced on plants through insecticide application or the plants were not sprayed with insecticide and served as controls. Control plants either were entirely unmanipulated or were sprayed with water. In one experiment, seeds were pulled out of post-anthesis flower heads in the field to estimate viable seed production and then inserted back into the flower head to allow normal dispersal. This experiment was focused upon quantifying effects of insect floral herbivory and pre-dispersal seed predation on seedling establishment (see the file titled ‘Plattethistleseedlingestablishment.csv’). This experiment is referred to as ‘Project 1’ in the data set. In the other experiment, post-anthesis flower heads were collected from the plants and dissected in the lab to quantify viable seed production per flower head. This experiment is referred to as ‘Project 2’ in the data set. Both experiments occurred in 2017, 2018 and 2019, using different adult Platte thistle individuals in each year. The species is monocarpic. The experiment was replicated at five sites along the elevation gradient.
2. Data set: ‘Plattethistleseedlingestablishment.csv’
Data Description: These data are from an experiment that examined the effects of insect floral herbivory and pre-dispersal seed predation on the number of seedlings established by Platte thistle (Cirsium canescens) along an elevation gradient in Caffee County, Colorado USA. Specifically, we were interested in addressing 1) how elevation affected Platte thistle seedling recruitment, 2) how insect herbivory on reproductive adult Platte thistles affected their seedling recruitment and 3) whether the effect of insect herbivory varied with elevation. The insect exclusion experiment, involving insecticide application to manipulated plants, was conducted in 2017, 2018 and 2019. Control plants either were entirely unmanipulated or were sprayed with water. In the two growing seasons after experimental adult plants produced seed, we counted the number of Platte thistle seedlings within a 2 m radius surrounding the adult plant. For example, for experimental adult plants that produced seed in 2017, we counted seedlings in 2018 and 2019. The experiment was replicated at five sites along the elevation gradient.
3. Data set: ‘Plattethistlefirstflowering.csv’
Data Description: These data are a component of a larger study that examined the effects of insect herbivory on viable seed production and seedling recruitment by Platte thistle (Cirsium canescens) along an elevation gradient in Caffee County, Colorado USA. Specifically, we were interested in addressing 1) how elevation affected Platte thistle viable seed production and seedling recruitment, 2) how insect herbivory on reproductive adult Platte thistles affected their viable seed production and seedling recruitment and 3) whether the effect of insect herbivore varied with elevation. The insect exclusion experiment, involving insecticide application to manipulated plants, was conducted in 2017, 2018 and 2019. Control plants either were entirely unmanipulated or were sprayed with water. The experiment was replicated at five sites along the elevation gradient. The data in this file present Julian dates on which we detected the first (earliest) flower head to be flowering on each experimental plant. We defined ‘flowering’ as having a full circumference, around the flower head, of exerted florets. Each line in the data set represents a different reproductive, adult Platte thistle plant.
4. Data set: ‘Plantcommunitybiomass.csv’
Data Description: These data were collected in support of a larger study that examined the effects of insect herbivory on viable seed production and seedling recruitment by Platte thistle (Cirsium canescens) along an elevation gradient in Caffee County, Colorado USA. Specifically, we were interested in addressing 1) how elevation affected Platte thistle viable seed production and seedling recruitment, 2) how insect herbivory on reproductive adult Platte thistles affected their viable seed production and seedling recruitment and 3) whether the effect of insect herbivore varied with elevation. The data in this file present standing crop plant community biomass at each of the five study sites along the elevation gradient. Cattle were grazed at four of the five sites, so biomass was harvested inside 5 m X 5 m cattle exclosures. At the fifth site, no cattle exclosures were present, but plots for biomass harvesting were located in the same pattern as at sites with cattle exclosures. Biomass was harvested in three 50 cm X 50 cm plots per block within each block (exclosure). All living herbaceous biomass was harvested and new, ‘of-the-year’ growth on woody plants was harvested. Sampling occurred in three blocks (exclosures) per site in 2019 and two blocks in per site in 2020. Biomass was dried for 3 days at 60°C. Each line in the data set represents a different 50 cm X 50 cm plot within which biomass was harvested.
5. Data set: ‘Baregroundcover.csv’
Data Description: These data were collected in an experiment that examined the effects of rodent granivory / seedling herbivory and soil disturbance upon establishment of Platte thistle (Cirsium canescens) seedlings from seeds. This experiment was conducted immediately adjacent to the insect exclusion experiment that is the focus of the current manuscript, hence, bare ground cover in the plots of this rodent exclusion experiment is very similar to that in the insect exclusion experiment. To characterize bare ground cover at the site, we used only plots that were not experimentally disturbed. We did estimate bare ground cover in both plots that had rodent exclusion cages and plots that had no cages. Since plots with rodent exclusion cages and control plots are equally represented across all sites, considering the plots with cages in our bare ground estimates should not bias site- or elevation-based differences. Further, establishing the rodent exclusion cages did not generate soil disturbance because the cages were not sunken into the ground to prevent burrowing, rather they had long flanges around the sides that extended the distance a rodent would need to burrow to enter the plot. All plots were protected from cattle grazing by exclosures made of cattle panels. The plots in which we estimated bare ground were 50 cm X 50 cm and bare ground cover was sampled in two such plots per block. Cover was estimated by two people using cover cards that were equal to 1% and 10% of the area of the plot. Bare ground cover was estimated in 2017 (6 plots per site), 2018 (6 plots per site) and 2019 (4 plots per site). Different plots were sampled in each year.
6. Data set: ‘Soilhardness.csv’
Data Description: These data were collected in an experiment that examined the effects of rodent granivory / seedling herbivory and soil disturbance upon establishment of Platte thistle (Cirsium canescens) seedlings from seeds. This rodent exclusion experiment was conducted immediately adjacent to the insect exclusion experiment that is the focus of the current manuscript and, hence, soil characteristics in the plots of this experiment are very similar to that in the insect exclusion experiment. To characterize soil hardness at the site, we used only plots that were not experimentally disturbed. We did estimate soil hardness in both plots that had rodent exclusion cages and plots that had no cages. Since plots with rodent exclusion cages and control plots are equally represented across all sites, considering the plots with cages in our bare ground estimates should not bias site- or elevation-based differences. Further, establishing the rodent exclusion cages did not generate soil disturbance because the cages were not sunken into the ground to prevent burrowing, rather they had long flanges around the sides that extended the distance a rodent would need to burrow to enter the plot. All plots were protected from cattle grazing by exclosures made of cattle panels. The plots in which we estimated soil hardness were 50 cm X 50 cm and soil hardness was sampled in two such plots per block. Soil hardness was estimated in an unvegetated location as close to the center of the plot as possible. To quantify soil hardness, we used a ‘pocket penetrometer’ (Forestry Suppliers, Jackson MS USA) that measures hardness as the force required to push a piston 0.25 inches into the soil. Soil hardness was only sampled in August 2020.
7. Data set: ‘Soilmoisture.csv’
Data Description: These data were collected in an experiment that examined the effects of rodent granivory / seedling herbivory and soil disturbance upon establishment of Platte thistle (Cirsium canescens) seedlings from seeds. This rodent exclusion experiment was conducted immediately adjacent to the insect exclusion experiment that is the focus of the current manuscript and, hence, soil moisture in the plots of this experiment is very similar to that in the insect exclusion experiment. To characterize soil moisture at the site, we used only plots that were not experimentally disturbed. We did estimate soil moisture in both plots that had rodent exclusion cages and plots that had no cages. Since plots with rodent exclusion cages and control plots are equally represented across all sites, considering the plots with cages in our soil moisture estimates should not bias site- or elevation-based differences. Further, establishing the rodent exclusion cages did not generate soil disturbance because the cages were not sunken into the ground to prevent burrowing, rather they had long flanges around the sides that extended the distance a rodent would need to burrow to enter the plot. All plots were protected from cattle grazing by exclosures made of cattle panels. The plots in which we estimated soil moisture were 50 cm X 50 cm and soil moisture was sampled in two such plots per block. Soil moisture was estimated using a handheld TDR soil moisture sensor with 10 cm probes. Soil moisture was sampled in an unvegetated location as close to the center of the plot as possible. In 2017, soil moisture was sampled in six plots per site that were established in 2017. In 2018, soil moisture was sampled in six plots per site that were established in 2018. In 2019, soil moisture was sampled in 12 plots per site, which included plots established in 2017 and 2018. In 2020, soil moisture was sample in 16 plots per site, which included plots established in 2017, 2018 and 2019. In 2017, soil moisture was sampled in June and August. In 2018, soil moisture was sampled only in August. In 2019, soil moisture was sampled in May and June. In 2020, soil moisture was sampled in May, June and August.
Description of the data and file structure
1. Data Set: ‘Plattethistleseedproduction.csv’
In this data set, each row contains data for an individual flower head on an experimental plant. For example, rows 2 through 12 are all flower heads on experimental adult Platte thistle 35. The first row that contains data for a plant contains ‘whole plant’ data, such as root crown diameter, plant height etc., as well as data for the most apical flower head. For example, row 2 contains ‘whole plant’ data for plant 23 in columns F through Q and then again in column Y. In columns R through X, row 2 contains data that is specific to the most apical (Hd number 100) flower head. For flower heads on a plant that are not the most apical, their rows contain ‘NA’ in the columns for whole plant data because there was no reason to copy the whole plant data into the rows for every flower head on a plant.
Note that many of the variables (columns) in this data set are the same as in the data set titled ‘Plattethistleseedlingestablishment.csv.’
Definitions of variables (column titles)
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Project: This is the identifying number of the experiment in which the plant was included. As described above, in Project 1 viable seed production per plant was estimated by pulling seeds out of the flower head in the field and then returning them to the head to allow natural dispersal. Project 1 was most focused upon seedling establishment. In Project 2, viable seed production was estimated by collecting and dissecting post-anthesis flower heads in the lab. This project was exclusively focused upon viable seed production.
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Year: The year in which the plant was a reproductive adult and was either sprayed with insecticide or was included as a ‘control’ plant. This variable takes values 2017, 2018 and 2019, representing the three years in which the experiment was conducted.
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Site: The study site along the elevation gradient at which the plant occurred. The study sites are: Centerville (38°40’55.85’’N, 106°5’13.94’’W, elevation = 2435 m), Brown’s Creek (38°41’39.46’’N, 106°7’15.03’’W, elevation = 2502 m ), Lost Creek (38°45’29.85’’N, 106°9’26.14’’W, elevation = 2577 m), Forman ( 38°53’56.68’’N, 106°12’22.75’’W, 2665 m); and Forest Service (38°49’32.08’’N, 105°59’40.30’’W, 2776 m).
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Plant: The unique identifying number of the plant.
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FnlTrt: The level of the insect exclusion treatment that was randomly assigned to the plant. Randomization of treatment levels to plants was conducted within each site. The two treatment levels for this variable are ‘I’, for plants that were treated with insecticide, and ‘C’ for plants that were not treated with insecticide. Control (C) plants either experienced no manipulation or they were sprayed with water. We found no statistical differences in the performance of plants that were unmanipulated and plants that were sprayed with water, so we pooled them into a single ‘control’ treatment level.
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RtCrwn: The diameter of the root crown, measured in millimeters, using calipers inserted just below the soil surface
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PlntHgt: The perpendicular vertical distance from the ground to the highest point on the plant, measured in centimeters
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StmHgt: The distance along the stem from the ground to the base of the most apical flower head, measured in centimeters
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HdsFlrd: The number of flower heads on the plant that reached anthesis, meaning exerted yellow florets
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DamFlrHds: The number of flower heads on the plant that reached anthesis and showed clear, external evidence of insect herbivore damage
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LrgBud: The number of buds that were more than 10 cm in diameter, but did not flower
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DamLrgBud: The number of buds that were more than 10 cm in diameter, did not flower and showed clear external evidence of insect herbivore damage
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SmlBud: The number of buds that were less than 10 cm in diameter and did not flower
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DamSmlBud: The number of buds that were less than 10 cm in diameter, did not flower and showed clear external evidence of insect herbivore damage
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TotHds: The total number of flower heads produced by the plant. This is the sum of HdsFlrd + LrgBud + SmlBud.
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TDamHd: The total number of flower heads produced by the plant that showed clear external evidence of insect herbivore damage. This is the sum of DamFlrHds + DamLrgBud + DamSmlBud.
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NStg34: The number of flower heads that were still flowering, meaning still had florets that retained their yellow color, in the final census of the year in mid-August.
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HdN: The identifying number of the flower head. The flower head numbering scheme begins with the apical flower head on the main stem, numbered the 100 head. The terminal flower head on the first lateral branch is labelled 200. The terminal flower head on the second lateral branch is labelled 300 and so on down the lateral branches. The first axillary flower head on a lateral branch has a number that ends in ’10.’ So, the 210 flower head is the first axillary flower head on the first lateral branch. The 220 flower head would be the second axillary flower head on the first lateral branch.
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Stg: The developmental stage of the flower head at the final census of the year in mid-August. ‘1’ indicates a small bud (<10 cm diameter). ‘2’ indicates a large bud (>10 cm diameter). ‘3’ indicates a flower head that has florets exerted but not yet a full circumference of florets. ‘4’ indicates full flowering, meaning at least a full circumference of florets. ‘5’ indicates post-anthesis, meaning the florets have turned grey. ‘6’ indicates that the flower head is dispersing seeds.
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HdDam: A score indicating the severity of externally obvious insect herbivore damage to the flower head. ‘0’ indicates that no damage is present. ‘1’ indicates that it is ambiguous as to whether the flower head is damaged. We try to use ‘1’ rarely. ‘2’ indicates minor damage, less that 5% of the phyllaries show damage. ‘3’ indicates a medium amount of damage, more than 6% but less than 30% of phyllaries damaged. ‘4’ indicates severe damage, more than 30% of phyllaries damaged. ‘5’ indicates severe damage as a result of stem mining within 1 cm of the flower head. ‘6’ indicates severe damage due to a hole chewed into the interior of the flower head.
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RcEg: The number of ovipositions by the exotic, biocontrol weevil, Rhinocyllus conicus, on the flower head.
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FinPRGD: The estimated proportion of seeds in the flower head that are viable.
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EstSdProd: The estimated number of viable seeds produced by the flower head. This estimate includes values of zero viable seeds produced for early-season flower heads that were killed by us applying Tanglefoot to the flower heads in an attempt to reduce insect damage in 2018.
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EstSdProdTang: A second estimate of the number of viable seeds produced by the flower head. This estimate uses seed production by plants that we began spraying with insecticide upon noticing that Tanglefoot was damaging heads on our original plants to estimate possible seed production by heads killed by Tanglefoot on the original plants in 2018. ‘EstSdProdTang’ differs from ‘EstSdProd’ for 68 flower heads in 2018.
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TPltSDs: The estimated number of viable seeds produced by the plant. This is the sum of the number of viable seeds produced by each flower head on the plant. Specifically, it is the sum of the values in the ‘EstProdTang’ column across all flower heads on a plant.
2. Data set: ‘Plattethistleseedlingestablishment.csv’
In this data set, each row contains data for an individual flower head on an experimental plant. For example, rows 2 through 25 are all flower heads on experimental adult Platte thistle 23. The first row that contains data for a plant contains ‘whole plant’ data, such as root crown diameter, plant height etc., as well as data for the most apical flower head. For example, row 2 contains ‘whole plant’ data for plant 23 in columns E through P and then again in columns W and X. In columns Q through V, row 2 contains data that is specific to the most apical (Hd number 100) flower head. For flower heads on a plant that are not the most apical, their rows contain ‘NA’ in the columns for ‘whole plant’ data because there was no reason to copy the whole plant data into the rows for every flower head on a plant.
Note that many of the variables (columns) in this data set are the same as in the data set titled ‘Plattethistleseedproduction.csv.’
Definitions of variables (column titles)
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Year: The year in which the plant was a reproductive adult and was either sprayed with insecticide or was included as a ‘control’ plant. This variable takes values 2017, 2018 and 2019, representing the three years in which the experiment was conducted.
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Site: The study site along the elevation gradient at which the plant occurred. The study sites are: Centerville (38°40’55.85’’N, 106°5’13.94’’W, elevation = 2435 m), Brown’s Creek (38°41’39.46’’N, 106°7’15.03’’W, elevation = 2502 m ), Lost Creek (38°45’29.85’’N, 106°9’26.14’’W, elevation = 2577 m), Forman ( 38°53’56.68’’N, 106°12’22.75’’W, 2665 m); and Forest Service (38°49’32.08’’N, 105°59’40.30’’W, 2776 m).
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Plant: The unique identifying number of the plant.
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FnlTrt: The level of the insect exclusion treatment that was randomly assigned to the plant. Randomization of treatment levels to plants was conducted within each site. The two treatment levels for this variable are ‘I’, for plants that were treated with insecticide, and ‘C’ for plants that were not treated with insecticide. Control (C) plants either experienced no manipulation or they were sprayed with water. We found no statistical differences in the performance of plants that were unmanipulated and plants that were sprayed with water, so we pooled them into a single ‘control’ treatment level.
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RtCrwn: The diameter of the root crown, measured in millimeters, using calipers inserted just below the soil surface
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PlntHgt: The perpendicular vertical distance from the ground to the highest point on the plant, measured in centimeters
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StmHgt: The distance along the stem from the ground to the base of the most apical flower head, measured in centimeters
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HdsFlrd: The number of flower heads on the plant that reached anthesis, meaning exerted yellow florets
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DamFlrHds: The number of flower heads on the plant that reached anthesis and showed clear, external evidence of insect herbivore damage
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LrgBud: The number of buds that were more than 10 cm in diameter, but did not flower
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DamLrgBud: The number of buds that were more than 10 cm in diameter, did not flower and showed clear external evidence of insect herbivore damage
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SmlBud: The number of buds that were less than 10 cm in diameter and did not flower
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DamSmlBud: The number of buds that were less than 10 cm in diameter, did not flower and showed clear external evidence of insect herbivore damage
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TotHds: The total number of flower heads produced by the plant. This is the sum of HdsFlrd + LrgBud + SmlBud.
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TDamHd: The total number of flower heads produced by the plant that showed clear external evidence of insect herbivore damage. This is the sum of DamFlrHds + DamLrgBud + DamSmlBud.
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NStg34: The number of flower heads that were still flowering, meaning still had florets that retained their yellow color, in the final census of the year in mid-August.
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HdN: The identifying number of the flower head. The flower head numbering scheme begins with the apical flower head on the main stem, numbered the 100 head. The terminal flower head on the first lateral branch is labelled 200. The terminal flower head on the second lateral branch is labelled 300 and so on down the lateral branches. The first axillary flower head on a lateral branch has a number that ends in ’10.’ So, the 210 flower head is the first axillary flower head on the first lateral branch. The 220 flower head would be the second axillary flower head on the first lateral branch.
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Stg: The developmental stage of the flower head at the final census of the year in mid-August. ‘1’ indicates a small bud (<10 cm diameter). ‘2’ indicates a large bud (>10 cm diameter). ‘3’ indicates a flower head that has florets exerted but not yet a full circumference of florets. ‘4’ indicates full flowering, meaning at least a full circumference of florets. ‘5’ indicates post-anthesis, meaning the florets have turned grey. ‘6’ indicates that the flower head is dispersing seeds.
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HdDam: A score indicating the severity of externally obvious insect herbivore damage to the flower head. ‘0’ indicates that no damage is present. ‘1’ indicates that it is ambiguous as to whether the flower head is damaged. We try to use ‘1’ rarely. ‘2’ indicates minor damage, less that 5% of the phyllaries show damage. ‘3’ indicates a medium amount of damage, more than 6% but less than 30% of phyllaries damaged. ‘4’ indicates severe damage, more than 30% of phyllaries damaged. ‘5’ indicates severe damage as a result of stem mining within 1 cm of the flower head. ‘6’ indicates severe damage due to a hole chewed into the interior of the flower head.
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RcEg: The number of ovipositions by the exotic, biocontrol weevil, Rhinocyllus conicus, on the flower head.
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FinPRGD: The estimated proportion of seeds in the flower head that are viable.
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EstSdProd: The estimated number of viable seeds produced by the flower head.
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TPltSDs: The estimated number of viable seeds produced by the plant. This is the sum of the number of viable seeds produced by each flower head on the plant.
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TSdl: The estimated number of seedlings produced by the plant over the two growing seasons subsequent to flowering. Seedlings were counted in biweekly censuses during the growing seasons. This estimate is the sum of the maximum number of seedlings counted in any census in the first growing season plus the maximum number of seedlings counted in any census in the second growing season.
3. Data set: ‘Plattethistlefirstflowering.csv’
Definitions of variables (column titles)
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Year: The year in which the plant was a reproductive adult and was either sprayed with insecticide or was included as a ‘control’ plant. This variable takes values 2017, 2018 and 2019, representing the three years in which the experiment was conducted.
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Site: The study site along the elevation gradient at which the plant occurred. The study sites are: Centerville (38°40’55.85’’N, 106°5’13.94’’W, elevation = 2435 m), Brown’s Creek (38°41’39.46’’N, 106°7’15.03’’W, elevation = 2502 m ), Lost Creek (38°45’29.85’’N, 106°9’26.14’’W, elevation = 2577 m), Forman ( 38°53’56.68’’N, 106°12’22.75’’W, 2665 m); and Forest Service (38°49’32.08’’N, 105°59’40.30’’W, 2776 m).
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PlantID: The unique identifying number of the plant.
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InsctExclTrt: The level of the insect exclusion treatment that was randomly assigned to the plant. Randomization of treatment levels to plants was conducted within each site. The two treatment levels for this variable are ‘I’, for plants that were treated with insecticide, and ‘C’ for plants that were not treated with insecticide. Control (C) plants either experienced no manipulation or they were sprayed with water. We found no statistical differences in the performance of plants that were unmanipulated and plants that were sprayed with water, so we pooled them into a single ‘control’ treatment level.
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JulianDate: The number of days since January 1 until the earliest flower head on the plant to exert a complete circumference of florets was observed. ‘NA’ is inserted for experimental plants that died before they could flower.
4. Data set: ‘Plantcommunitybiomass.csv’
Definitions of variables (column titles)
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Site: The study site along the elevation gradient at which the plant occurred. The study sites are: Centerville (38°40’55.85’’N, 106°5’13.94’’W), Brown’s Creek (38°41’39.46’’N, 106°7’15.03’’W), Lost Creek (38°45’29.85’’N, 106°9’26.14’’W), Forman ( 38°53’56.68’’N, 106°12’22.75’’W); and Forest Service (38°49’32.08’’N, 105°59’40.30’’W).
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Elevation: The elevation of the each study site above sea level in meters. A single elevation was used per study site because there was only minor variation in elevation within a study site.
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Year: The year in which the 50 cm X 50 cm plot had biomass harvested. Data were collected in 2019 and 2020. Different blocks (exclosures) and, therefore, different 50 cm X 50 cm plots were harvested in each year.
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BlockID: The unique identifying number of the block (exclosure) within which three 50 cm X 50 cm plots were harvested.
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SampleID: The identifying number of the sample, meaning 50 cm X 50 cm plot, that was harvested and weighed. The same numbers for samples (1 through 3) were used in each block (exclosure). Therefore, a sample is uniquely identified by combining its BlockID and its SampleID.
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WholeMass: The mass in grams of the harvested plant biomass and the paper shopping bag in which it was collected in the field
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BagMass: The mass in grams of the paper shopping bag with the dried plant biomass removed.
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Biomass: The mass in grams of the dried plant biomass from the 50 cm X 50 cm plot.
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Biom1m: The mass in grams of the dried plant biomass from the 50 cm X 50 cm plot extrapolated to a 1 m2 area. In other words, the variable ‘Biomass’ multiplied by four.
5. Data set: ‘Baregroundcover.csv’
Definitions of variables (column titles)
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Site: The study site along the elevation gradient at which the plant occurred. The study sites are: Centerville (38°40’55.85’’N, 106°5’13.94’’W, elevation = 2435 m), Brown’s Creek (38°41’39.46’’N, 106°7’15.03’’W, elevation = 2502 m ), Lost Creek (38°45’29.85’’N, 106°9’26.14’’W, elevation = 2577 m), Forman ( 38°53’56.68’’N, 106°12’22.75’’W, 2665 m); and Forest Service (38°49’32.08’’N, 105°59’40.30’’W, 2776 m).
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Block: The unique identifying code of the block (exclosure) within which two plots were sampled for cover by bare ground.
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PlotID : The unique identifying number of the plot in which cover by bare ground was estimated.
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Disturbance: This is the level of the experimental disturbance treatment that the plot experienced. For characterizing bare ground cover at the site, we only used data from plots that were not experimentally disturbed (NoDist).
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RodentExcl: The level of the rodent exclusion treatment (Cage vs. NoCage) that was randomly assigned to the plot.
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PercBare: The percentage cover of each 50 cm X 50 cm plot that was bareground, as estimated by two people with cover cards.
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Year: The year in which cover by bare ground was estimated in the 50 cm X 50 cm plot.
6. Data set: ‘Soilhardness.csv’
Definitions of variables (column titles)
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Site: The study site along the elevation gradient at which the plot occurred. The study sites are: Centerville (38°40’55.85’’N, 106°5’13.94’’W, elevation = 2435 m), Brown’s Creek (38°41’39.46’’N, 106°7’15.03’’W, elevation = 2502 m ), Lost Creek (38°45’29.85’’N, 106°9’26.14’’W, elevation = 2577 m), Forman ( 38°53’56.68’’N, 106°12’22.75’’W, 2665 m); and Forest Service (38°49’32.08’’N, 105°59’40.30’’W, 2776 m).
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Block_ID: The unique identifying code of the block (exclosure) within which two plots were sampled for soil hardness.
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Plot_ID : The unique identifying number of the plot in which soil hardness was estimated.
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SoilDist: This is the level of the experimental disturbance treatment that the plot experienced. For characterizing soil hardness at the site, we only used data from plots that were not experimentally disturbed (NoDist).
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Excl: The level of the rodent exclusion treatment (Cage vs. NoCage) that was randomly assigned to the plot.
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Penet: The amount force required to push a piston into the soil to a depth of 0.25 inches, measured in tons per square foot.
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Month: All soil hardness measurements were taken in August
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Year: All soil hardness measurements were taken in 2020
7. Data set: ‘Soilmoisture.csv’
Definitions of variables (column titles)
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Site: The study site along the elevation gradient at which the plot occurred. The study sites are: Centerville (38°40’55.85’’N, 106°5’13.94’’W, elevation = 2435 m), Brown’s Creek (38°41’39.46’’N, 106°7’15.03’’W, elevation = 2502 m ), Lost Creek (38°45’29.85’’N, 106°9’26.14’’W, elevation = 2577 m), Forman ( 38°53’56.68’’N, 106°12’22.75’’W, 2665 m); and Forest Service (38°49’32.08’’N, 105°59’40.30’’W, 2776 m).
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Block_ID: The unique identifying code of the block (exclosure) within which two plots were sampled for cover by bare ground.
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Plot_ID : The unique identifying number of the plot in which cover by bare ground was estimated.
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Disturb: This is the level of the experimental disturbance treatment that the plot experienced. For characterizing soil moisture at the site, we only used data from plots that were not experimentally disturbed (NoDist).
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Excl: The level of the rodent exclusion treatment (Cage vs. NoCage) that was randomly assigned to the plot.
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SoilM: Soil moisture at 10 cm depth in the soil expressed as percent water by volume.
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Month: The month in which the soil moisture measurement was made.
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Year: The year in which the soil moisture measurement was made.
Sharing/Access information
Links to other publicly accessible locations of the data:
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Data was derived from the following sources:
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Code/Software
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The plant-based data sets (Plattethistleseedproduction.csv, Plattethistleseedlingestablishment.csv, Plattethistlefirstflowering.csv) are from experiments that examined the effects of insect floral herbivory and pre-dispersal seed predation on the number of viable seeds produced and the number of seedlings established by Platte thistles (Cirsium canescens) along an elevation gradient in Caffee County, Colorado USA. Specifically, we were interested in addressing 1) how elevation affected Platte thistle viable seed production, 2) how insect herbivory on reproductive adult Platte thistles affected their viable seed production and 3) whether the effect of insect herbivory varied with elevation. The experiments that contributed to this data set involved an insect exclusion treatment in which insect herbivory either was reduced on plants through insecticide application or the plants were not sprayed with insecticide and served as controls. Control plants either were entirely unmanipulated or were sprayed with water. In one experiment (Plattethistleseedlingestablishment.csv), seeds were pulled out of post-anthesis flower heads in the field to estimate viable seed production and then inserted back into the flower head to allow normal dispersal. This experiment was focused upon quantifying effects of insect floral herbivory and pre-dispersal seed predation on seedling establishment. Seedling establishment was monitored for two growing seasons after seed dispersal within a 2m radius circle of the parent plant. In the other experiment (Plattethistleseedproduction.csv), post-anthesis flower heads were collected from the plants and dissected in the lab to quantify viable seed production per flower head. Both experiments occurred in 2017, 2018, and 2019, using different adult Platte thistle individuals in each year. The species is monocarpic. The experiment was replicated at five sites along the elevation gradient. The plants used in the seedling establishment and seed production experiments were also monitored for flowering phenology (Plattethistlefirstflowering.csv)
The data that are contained in the data sets titled 'Platteplantcommunitybiomass.csv', 'Baregroundcover.csv', 'Soilhardness.csv', and 'Soilmoisture.csv' all provide environmental context for the two experiments described above. These environmental context data were collected in an experiment that was immediately adjacent to the two experiments described above at each study site. This adjacent experiment examined the effects of rodent granivory / seedling herbivory and soil disturbance upon establishment of Platte thistle (Cirsium canescens) seedlings from seeds. Environmental context data were only collected in plots that did not experience the soil disturbance manipulation.
- Russell, F. Leland; Taylor, Mason R.; Louda, Svata M. (2025). Microsite availability, not floral herbivory, limits recruitment in peripheral native thistle populations. Ecosphere. https://doi.org/10.1002/ecs2.70310