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Harvard Forest Data Archive

HF193

Food Web of Sarracenia Purpurea in United States and Canada since 1999

Related Publications

Data

Overview

  • Lead: Aaron Ellison, Nicholas Gotelli
  • Investigators: Benjamin Baiser, Leszek Bledzki, Hannah Buckley, Jessica Butler, Thomas Miller
  • Contact: Aaron Ellison
  • Start date: 1999
  • End date: 2011
  • Status: completed
  • Location: Hawley Bog (Hawley MA), Molly Bog (Morristown VT), Swift River Bog (Belchertown MA), Canada, United States
  • Latitude: +30.74 to +58.49
  • Longitude: -122.54 to -61.88
  • Elevation: 9 to 685 meter
  • Taxa: Fletcherimyia fletcheri (pitcher-plant fly), Habrotrocha rosa (rotifer), Metriocnemus knabi (pitcher-plant midge), Sarracenia purpurea (pitcher plant), Sarraceniopus gibsoni (pitcher-plant mite), Wyeomyia smithii (pitcher-plant mosquito)
  • Release date: 2012
  • Revisions:
  • EML file: knb-lter-hfr.193.8
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement, modeling
  • Research topic: biodiversity studies; physiological ecology, population dynamics and species interactions
  • LTER core area: populations
  • Keywords: carnivorous plants, food webs, insects, morphology, species interactions
  • Abstract:

    How food webs are structured and how their structure and dynamics vary through time and space is a central focus of research in community ecology. We documented structural variation in the aquatic food web inhabiting pitcher-shaped leaves of the carnivorous pitcher plant Sarracenia purpurea across the geographic range of the plant (from Florida north to Labrador and west to British Columbia); examined temporal variation in this food web with detailed experiments in Massachusetts and Vermont; experimentally manipulated top-down and bottom-up processes in this food web in Massachusetts; and developed a dynamic simulation model of this food web that incorporates metacommunity dynamics.

  • Methods:

    Temporal variation in the structure of the Sarracenia food web

    We studied temporal dynamics in the Sarracenia food web in 1999 and 2000 at Hawley Bog and Molly Bog. In mid-May of each summer, we located 80 non-flowering adult plants (rosette diameter at lease 100mm) and assigned them at random to one of four treatment groups. Different plants were used in the two summers. In the first three treatment groups, we only used the first pitcher produced by each plant, whereas in treatment four, we used every pitcher produced by each plant. Treatment 1 plants were one set of controls: the first pitcher was allowed to accumulate an inquiline community from the day it opened. As soon as they opened, the first pitcher of treatment 2 plants were plugged with glass wool to prevent initial inquiline colonization and prey capture. The glass wool was removed three weeks later, and then inquilines were allowed to accumulate. Treatment 3 was identical to treatment 2, except that the glass wool was removed six weeks after the leaf opened. Thus, treatments 1-3 assessed the direct effect of leaf age on inquiline community assembly and structure. Pitchers of treatment 4 plants were allowed to accumulate inquilines from the day they opened, but in this case we measured food web composition of all the pitchers. Since pitchers are produced sequentially, this treatment allowed us to assess the effect of time of year (seasonal progression) on food web assembly in pitchers of constant age (new pitchers). It also served as a contrast for pitchers in treatments 2 and 3. This contrast allowed us to distinguish the effect of pitcher age on inquiline communities (treatments 2 and 3) from the effect of time of year (treatment 4 pitchers that opened at the same time that pitchers in treatments 2 and 3 were opened for colonization). Each week, we non-destructively sampled the inquiline communities in all open pitchers in all treatments. In the field, we removed the contents of each pitcher using an aspirator. The contents were placed into a petri dish on which we had inscribed a grid of 1 x 1mm squares. Fly larvae were counted and measured (from digitized photographs in 1999 and estimated to the nearest 1mm in 2000). The number of prey captured in each weekly interval was estimated by counting and identifying (to order) prey head capsules. After counting larvae and prey, we returned the liquid and the inquilines to the pitcher. A 1ml subsample of well-mixed pitcher fluid was returned to the laboratory, where we counted the number of rotifers, mites, and protozoa under a Wild zoom dissecting microscope (25x oculars). One ml of distilled water was added to each pitcher to replace the liquid taken for the microscopic subsampling. We also measured pitcher characteristics: pitcher length, mouth diameters (two perpendicular), and pitcher width. The entire study population was mapped at the end of each summer so we could test for spatial autocorrelation in plant characteristics and inquiline community structure.

    Spatial variation in the structure of the Sarracenia food web

    Between 1 May and 14 September 2001, we sampled 39 known, undisturbed populations distributed throughout the range of Sarracenia purpurea. Site-selection criteria included population size (more than 50 plants), ability of the population to sustain the damage of destructive sampling and accessibility, and permit availability. Only natural, rather than introduced, populations were sampled. The latitude, longitude and elevation of each population were determined using the satellite global positioning system. We standardized our sampling at different sites by choosing leaves that were c. 4 weeks old, by visiting each site approximately 1 month following flowering and choosing the first, usually largest pitcher, of the new season’s growth. Flowering time was determined through herbarium or other records for each area or estimated from sites at similar latitudes.

    At each site, we laid a 1-m-wide belt transect across the longest axis of the Sarracenia population. If this axis was longer than 100 m, we used a 100-m transect centered on this axis. This transect was then divided into 20 equally spaced marks (maximum of 5 m apart), and the nearest pitcher plant to each mark was identified. For each of these 20 plants, we measured the maximum diameter of the rosette. For the first (largest) pitcher of the current year, we measured (± 1 mm) the pitcher length, diameter of the pitcher mouth, the thickness of the pitcher lip, the maximum width of the pitcher, and the width of the wing (keel). We visually estimated percentage cover of vegetation in a 1-m2 quadrat centered on each plant. Because there was no consistent set of co-occurring species across the range of S. purpurea, we distinguished percentage cover of functional groups: trees, shrubs, terrestrial or aquatic forbs, graminoids, ferns, lycopods, Sphagnum, other bryophytes, fungi, and lichens. We took five pore-water samples, evenly spaced across the sample transect. Fifty-mL water samples were extracted using clean Tygon tubing from 50 cm long 3 2.5 cm diameter capped and perforated PVC tubes that were sunken into the peat. For each sample, we measured pH and calcium (mg/L) with Orion ion-sensitive electrodes (Thermo Electron Corp, Woburn, Massachusetts, USA), and phosphate (PO4-P), nitrate (NO3-N), and ammonium (NH4-N) (all in mg/L) spectrophotometrically using US-EPA standard methods. Pore-water samples were not taken in eight southern sites, due to insufficient water availability in the drier sandy soils.

    Using consistent sampling protocols, several research teams collected samples at widely separated sites, so that temporal biases introduced by travel schedules were minimized. At each site, the 20 pitchers and their contents were collected across the population, each from a different plant. We counted and identified all invertebrates in each pitcher and the rotifers in a 0.1-mL subsample. The protozoa in a standard 0.1-mL subsample of pitcher fluid were counted, and each was identified to genus where possible. Bacteria grown on Plate Count Agar using three replicate plates at two dilutions were grouped into morphological colony types. For each site, two measures of species richness were generated: (1) site richness, which was calculated as the total number of species encountered across all 20 sampled plants, and (2) pitcher richness, which was calculated as the average number of species encountered in pitchers within each site.

    Bottom-up and top-down processes in the Sarracenia food web

    Bottom-up effects - pulse experiment: We used a factorial response-surface design in a “pulse” experiment in which 5 levels each of NH4NO3 (4.687, 9.375, 18.75, 37.5, and 75.0 mM N) and PO4 (0.625, 1.25, 2.5, 5.0, and 10.0mM P) and controls (dH2O) were added biweekly to each pitcher. 130 non-flowering plants were randomly assigned to one of five groups of 26 plants. Each plant within a group was randomly assigned a nutrient treatment (one of the 25 possible N  P combinations or the dH2O control). Beginning on 4 June 2001, 20 ml of nutrient solution was added once to each pitcher 2-3 days after it had opened and fully hardened. Plants were checked every three days for new leaf production. Every three weeks (25 June, 16 July, 6 August, 27 August, and 17 September 2001), a complete set of 26 plants was harvested. At each harvest, pitcher fluid was pipetted into sterile tubes (one tube/leaf) and measured for pH, dissolve oxygen (mg/L), and concentration of NO3-N, NH4-N, PO4-P and Ca+2; macroinvertebrates (Metriocnemus knabi, Wyeomyia smithii, and Fletcherimyia fletcheri) were collected, identified, counted, and sorted by instar; number of microinvertebrates (Habrotrocha rosa, Sarraceniopus gibsoni) in a 1-ml subsample were counted; head capsules of captured prey were counted; and plant morphology was measured. All pitchers were dried at to constant mass 70oC, weighed, ground, and assayed for tissue nutrient content (mg/kg of C, H, N, P, K, Ca, and Mg).

    Bottom-up effects - press experiment: Concomitant with the pulse experiment, we haphazardly located 26 non-flowering plants and randomly assigned them to one of the same nutrient treatments as in the pulse experiment. Two-three days after each pitcher had opened and hardened, 20 ml of nutrient solution was added to it, and the 20-ml level marked on the side of the pitcher with indelible ink. Every two weeks, the pitcher fluid and associated food web and prey head capsules were pipetted out of each life and into a petri dish. Numbers and instars of each macroinvertebrate were counted in the field, and returned to the pitcher. Microinvertebrates and protozoa were counted in the lab in 1-ml subsamples. After field counts of invertebrates, the pitcher fluid was poured back into the pitcher and additional nutrient solution was added to maintain the fluid level at 20 ml. On 17 September, all pitchers were harvested, measured, and assayed as in the pulse experiment.

    Bottom-up x top-down interactions, and interactions with the plant. In 2004, we used a four-level factorial/response-surface experiment with 212 non-flowering plants assigned randomly to unique combinations of treatments. The first level was used to assess the influence of pitchers themselves on inquiline community dynamics. Pitcher interiors were either fitted with intact polyethylene tubes (2.2 cm diameter) (liquid closed to effects of pitcher; N = 64 plants), fitted with polyethylene tubes that had holes punched out of them (polyethylene control; N = 64 plants), or left without polyethylene tubes (unmanipulated control; N = 64 plants). The second level examined the effects of N deposition. One of eight different concentrations of inorganic nitrogen (NH4NO3: 0, 1.56, 3.1, 6.25, 12.5, 25, 50, or 100 mg N/L) was added to a randomly selected plant; there were N = 8 replicates of each N concentration in each set of 64 tube/tube control/no tube treatments. The third level examined effects of prey availability (organic nutrients). Supplemental prey (10 fruit flies/week) were added to one-half of each inorganic N  tube combination. The fourth level assessed the influence of the top predator on the development of the pitcher plant food web. Second instar Fletcherimyia fletcheri larvae were either removed from (one-half of each N  tube  fruit-fly treatment combination) or added to pitchers (one-half of each N x tube x fruit-fly treatment combination). In total, this response-surface design resulted in N = 2 plants in each tube x N x fruit-fly x F. fletcheri combination. We also haphazardly chose 20 additional plants as unmanipulated controls.

    This experiment was initiated on 23 June 2004, once pitchers had fully opened and hardened (one to two weeks after opening). At the start of the experiment, all pitchers were emptied, rinsed with deionized water, and the appropriate treatment combinations applied. Each week between the end of June and mid-August, fruit flies and NH4NO3 were replenished. Based on the results of the 2001 experiments, we assumed there would be constant uptake of NH4NO3 in the pitchers containing tubes with holes or no tubes at all. Therefore, we supplied an equivalent NH4NO3-N load each week by supplying pitchers small aliquots (1 to 3 mL depending on volume of liquid initially added to each pitcher) of an NH4NO3 solution of higher concentration than the designated treatment concentration. Plant liquid volume was maintained at two-thirds full by adding nutrient solutions, followed by deionized water when necessary. In contrast, plants containing intact polyethylene tubes were not able to assimilate NH4NO3 supplied to the tubes; therefore we used the same concentration of NH4NO3 and simply topped off each tube to two-thirds full for each pitcher (as in the press experiment described above), assuming loss due to volatilization and bacterial utilization was small compared to plant assimilation. Weekly visits were also used to assess the development of food webs by gently shaking pitchers to bring any inquilines to the surface and recording presence or absence of F. fletcheri, W. smithii, and M. knabi.

    One treated plant from each treatment combination (96 pitchers) and half the unmanipulated controls were harvested four weeks after the start of the experiment (21 July), and the remaining plants were harvested on 10 August 10. At each harvest, food webs and pitchers were assayed as described above.

    Modeling the Sarracenia food web using metacommunity dynamics

    We modeled the assembly of pitcher plant metacommunities using seven different models: four single-factor models (patch dynamics, species sorting, mass effects, neutral) and three hybrid models (species sorting + mass effects; neutral model + structured dispersal; neutral model + species sorting). The different models were implemented by altering specific aspects of local dynamics. For patch similarity, we altered resource availability such that similar patches had the same amount of resources and different patches varied in resource availability. Species differences related to dispersal differences (patch dynamics) and patch differences (species sorting and mass effects) were implemented by adjusting the Lotka-Volterra competition coefficients. Finally, we altered the relative time scale of local and regional dynamics by changing the number of Lotka-Volterra iterations between dispersal events.

  • Use:

    This dataset is released to the public under Creative Commons license CC BY (Attribution). Please keep the designated contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement.

  • Citation:

    Ellison A, Gotelli N. 2012. Food Web of Sarracenia Purpurea in United States and Canada since 1999. Harvard Forest Data Archive: HF193.

Detailed Metadata

hf193-01: food web structure, 1999

  1. site: site name
    • hawley: Hawley Bog
    • molly: Molly Bog
  2. date: date
  3. treatment: treatment code
    • 1: first leaf control
    • 2: first leaf unplugged after 3 weeks
    • 3: first leaf unplugged after 6 weeks
    • 4: all leaves used
  4. plant: plant number within treatment
  5. leaf: leaf number
  6. variable: item measured
    • Fletcherimyia: larvae of Fletcherimyia fletcheri
    • Habrotrocha: rotifers Habrotrocha rosa
    • Metriocnemus: larvae of Metriocnemus knabi
    • Sarraceniopus: mites Sarraceniopus gibsoni
    • Wyeomyia: larvae of Wyeomyia smithii
    • other: miscellaneous other species
    • headcap: head capsules of prey items
    • rotvol ml: volume of liquid taken for rotifer sample
    • volume ml: volume of liquid in the pitcher on the measurement date
  7. value: measured value of variable. Counts of Fletcherimyia, Wyeomyia, Sarraceniopus, other, headcap (integer). Numbers per rotvol of Habrotrocha (integer). Volume of volume ml (real).

hf193-02: sizes of Diptera larvae, 1999

  1. site: site name
    • hawley: Hawley Bog
    • molly: Molly Bog
  2. date: date
  3. treatment: treatment code
    • 1: first leaf control
    • 2: first leaf unplugged after 3 weeks
    • 3: first leaf unplugged after 6 weeks
    • 4: all leaves used
  4. plant: plant number within treatment
  5. leaf: leaf number
  6. photoroll: identifier for which roll of film
  7. photoframe: identifier for which image within photoroll
  8. wyeo.len: length of Wyeomyia smithii larva (unit: millimeter / missing value: NA)
  9. wyeo.headw: width of Wyeomyia smithii head capsule at widest point (unit: millimeter / missing value: NA)
  10. met.len: length of Metriocnemus knabi (unit: millimeter / missing value: NA)
  11. met.headw: width of Metriocnemus knabi head capsule at widest point (unit: millimeter / missing value: NA)
  12. flet.len: length of Fletcherimyia fletcheri (unit: millimeter / missing value: NA)
  13. flet.headw: width of Fletcherimyia fletcheri head capsule at widest point (unit: millimeter / missing value: NA)

hf193-03: locations and sizes of leaves, 1999

  1. site: site name
    • hawley: Hawley Bog
    • molly: Molly Bog
  2. treatment: treatment code
    • 1: first leaf control
    • 2: first leaf unplugged after 3 weeks
    • 3: first leaf unplugged after 6 weeks
    • 4: all leaves used
  3. plant: plant number within treatment
  4. leaf: leaf number
  5. xcoord: x-coordinate of plant (arbitrary origin) (unit: meter / missing value: NA)
  6. ycoord: y-coordinate of plant (arbitrary origin) (unit: meter / missing value: NA)
  7. length: length of pitcher, from base to top of hood (unit: millimeter / missing value: NA)
  8. diamlong: diameter of pitcher mouth, longer of two, and perpendicular to diamshort (unit: millimeter / missing value: NA)
  9. diamshort: diameter of pitcher mouth, shorter of two, and perpendicular to diamlong (unit: millimeter / missing value: NA)

hf193-04: food web structure, 2000

  1. site: site name
    • hawley: Hawley Bog
    • molly: Molly Bog
  2. date: date
  3. treatment: treatment code
    • 1: first leaf control
    • 2: first leaf unplugged after 3 weeks
    • 3: first leaf unplugged after 6 weeks
    • 4: all leaves used
  4. plant: plant number within treatment
  5. leaf: leaf number
  6. variable: item measured
    • flet.Xmm: larvae of Fletcherimyia fletcheri, where X their the length in mm
    • wyeo.Xmm: larvae of Wyeomyia smithii, where X is their length in mm
    • wyeo.pup: pupae of Wyeomyia smithii
    • met.Xmm: larvae of Metriocnemus knabi, where X is their length in mm
    • met.pup: pupae of Metriocnemus knabi
    • hab.per05ml: rotifers Habrotrocha rosa per 0.5 mL of liquid
    • sarraceniopus: mites Sarraceniopus gibsoni
    • protists: total protozoa per 0.5 mL of liquid
    • headcap: head capsules of prey items
    • vol.ml: volume of liquid in the pitcher on the measurement date
  7. value: measured value of variable: integer or real (see variable for details). Counts of flet.Xmm, wyeo.Xmm, wyeo.pup, met.Xmm, met.pup, hab.per05ml, sarraceniopus, protists, headcap (integer). Volume of vol.ml (real).
  8. notes: additional observations

hf193-05: sites sampled, 2001

  1. site: site number sampled in continental survey of Sarracenia food webs, 2001
  2. code: site code
  3. place: site name
  4. wetland: type of wetland at site
  5. date: date sampled
  6. lat: degrees north latitude (unit: degree / missing value: NA)
  7. long: degrees west longitude (unit: degree / missing value: NA)
  8. stnelev: elevation (m a.s.l.) at nearest weather station (unit: meter / missing value: NA)
  9. area.ha: area of site (unit: hectare / missing value: NA)
  10. subsp: species of subspecies of S. purpurea
    • rosea: S. rosea (formerly S. purpurea spp. venosa var. burkii)
    • venosa: S. purpurea ssp. venosa
    • purpurea: S. purpurea ssp. purpurea
  11. plant.m2: density of plants (per m2) at the site, measured along the transect (unit: numberPerMeterSquared / missing value: NA)
  12. soil: soil: one of sand, peat, mud, or floating mat
  13. ph: pore-water pH (unit: dimensionless / missing value: NA)
  14. po4: pore-water PO4 (unit: milligramsPerLiter / missing value: NA)
  15. nh4: pore-water NH4 (unit: milligramsPerLiter / missing value: NA)
  16. no3: pore-water NO3 (unit: milligramsPerLiter / missing value: NA)
  17. ca: pore-water Ca+2 (unit: milligramsPerLiter / missing value: NA)

hf193-06: pitchers sampled, 2001

  1. site: site number for pitchers sampled in the continental survey of Sarracenia food webs, 2001
  2. code: site code
  3. pno: pitcher number
  4. nolv: number of pitchers on the plant (unit: number / missing value: NA)
  5. nowlv: number of water-filled pitchers on the plant (unit: number / missing value: NA)
  6. lfwr: number of flowers on the plant (unit: number / missing value: NA)
  7. fwrng: flowering status
    • 1: flowering this year
    • 2: flowered in previous years
    • 3: flowering this year and in previous years
    • 4: no evidence of current or previous flowering
  8. leaflen: length of the longest pitcher (base to hood) on the plant (unit: centimeter / missing value: NA)
  9. rosette: maximum rosette diameter of the plant (unit: centimeter / missing value: NA)
  10. age: age of pitcher sampled
    • 1: first pitcher of the year
    • 2-6: younger pitchers (ordered from oldest to youngest)
  11. lfyr: year of leaf sampled
    • 1: current year's pitcher
    • 2: previous year's pitcher
  12. lipwdt: width of the pitcher lip (unit: millimeter / missing value: NA)
  13. aphgt: height of pitcher mouth from the ground (unit: centimeter / missing value: NA)
  14. apwdt: width of pitcher mouth (unit: centimeter / missing value: NA)
  15. lfynss: ratio of pitcher keel at widest part of pitcher / pitcher width at widest part including the keel (unit: dimensionless / missing value: NA)
  16. vol: volume of liquid in the pitcher (unit: milliliter / missing value: NA)
  17. btn: length of pitcher from base to neck (top of petiole at base of hood), measured up the back of the leaf (unit: centimeter / missing value: NA)
  18. nta: length of hood (unit: centimeter / missing value: NA)
  19. wab: width of pitcher measured at widest part of pitcher (unit: centimeter / missing value: NA)
  20. color: dominant pitcher color
    • 0: green
    • 1: red
  21. veins: number of clear red veins across the widest part of the pitcher (unit: number / missing value: NA)

hf193-07: food web composition of pitchers sampled, 2001

  1. site: site number for pitchers sampled in the continental survey of Sarracenia food webs, 2001
  2. code: site code
  3. pno: pitcher number
  4. taxon: taxon encountered in the food web. If num.per.mL = 0, then omitted from file to reduce size. See hf193-12-species-master-list.csv.
  5. num.per.ml: number of taxon per mL (unit: numberPerMilliliter / missing value: NA)

hf193-08: food web and nutrient pulse manipulation experiment, 2001 at Swift River Bog

  1. plant: plant number
  2. leafnum: leaf number (1, last leaf) on the plant
  3. nlevel: level of Nitrogen addition
  4. plevel: level of Phosphorus
  5. nstart: amount of Nitrogen added (unit: millimole / missing value: NA)
  6. pstart: amount of Phosphorus added (unit: millimole / missing value: NA)
  7. harvest: harvest number
    • 1: 25 June 2001
    • 2: 16 July 2001
    • 3: 6 August 2001
    • 4: 27 August 2001
    • 5: 17 September 2001
  8. leafage: number of days leaf had been open (unit: nominalDay / missing value: NA)
  9. o2.harvest: concentration of oxygen (O2) in pitcher fluid at harvest (unit: milligramsPerLiter / missing value: NA)
  10. temp: temperature of pitcher fluid at harvest (unit: celsius / missing value: NA)
  11. vol: volume of pitcher fluid at harvest (unit: milliliter / missing value: NA)
  12. maxvol: volume of pitcher at harvest (unit: milliliter / missing value: NA)
  13. leaflen: length of pitcher from base to hood (unit: millimeter / missing value: NA)
  14. leafwid: maximum width of pitcher in center (unit: millimeter / missing value: NA)
  15. keelwid: maximum width of keel of pitcher, adjacent to leafwidmm (unit: millimeter / missing value: NA)
  16. diam1: diameter of pitcher mouth, longer of two (mm), and perpendicular to diam2mm (unit: millimeter / missing value: NA)
  17. diam2: diameter of pitcher mouth, shorter of two (mm), and perpendicular to diam1mm (unit: millimeter / missing value: NA)
  18. wetmass: fresh mass of pitcher (unit: gram / missing value: NA)
  19. drymass: oven-dry mass of pitcher (unit: gram / missing value: NA)
  20. area: surface area of pitcher (unit: centimeterSquared / missing value: NA)
  21. totmidge: number of individual Metriocnemus knabi larvae per pitcher (unit: number / missing value: NA)
  22. roti.ml: number of Habrotrocha rosa rotifers per mL of pitcher fluid (unit: numberPerMilliliter / missing value: NA)
  23. mites.ml: number of Sarraceniopus gibsoni rotifers per mL of pitcher fluid (unit: numberPerMilliliter / missing value: NA)
  24. totmosq: number of individual Wyeomyia smithii larvae per pitcher (unit: number / missing value: NA)
  25. totfletch: number of individual Fletcherimyia fletcheri larvae per pitcher (unit: number / missing value: NA)
  26. proto.ml: number of protozoa per mL of pitcher fluid (unit: numberPerMilliliter / missing value: NA)
  27. totheads: number of prey head capsules per pitcher (unit: number / missing value: NA)
  28. ph: pH of pitcher fluid at harvest (unit: dimensionless / missing value: NA)
  29. p.harvest: Phosphorus concentration of pitcher fluid at harvest (unit: milligramsPerLiter / missing value: NA)
  30. n.harvest: Nitrogen concentration of pitcher fluid at harvest (unit: milligramsPerLiter / missing value: NA)
  31. ca.harvest: Calcium concentration of pitcher fluid at harvest (unit: milligramsPerLiter / missing value: NA)

hf193-09: food web and nutrient press manipulation experiment, 2001 at Swift River Bog: monitoring (pre-harvest) data

  1. plant: plant number
  2. leafnum: leaf number (1, last leaf used) on the plant
  3. nlevel: level of Nitrogen addition
  4. plevel: level of Phosphorus addition
  5. nstart: amount of Nitrogen added (unit: millimole / missing value: NA)
  6. pstart: amount of Phosphorus added (unit: millimole / missing value: NA)
  7. leafopendate: date leaf opened and available for manipulation
  8. sampledate: date leaf contents sampled
  9. variable: item measured
    • vol_ml: volume of liquid in the pitcher on the measurement date
    • wyeo.Xmm: larvae of Wyeomyia smithii, where X is their length in mm
    • wyeo.pup: pupae of Wyeomyia smithii
    • met.Xmm: larvae of Metriocnemus knabi, where X is their length in mm
    • flet.Xmm: larvae of Fletcherimyia fletcheri, where X their the length in mm
    • heads.ants: number of head capsules of ant prey
    • heads.coll: number of head capsules of collembola prey
    • heads.flies: number of head capsules of fly prey
    • heads.spiders: number of head capsules of spider prey
    • mitesperml: mites Sarraceniopus gibsoni per mL of liquid
    • rotiperml: rotifers Habrotrocha rosa per mL of liquid
    • protperml: total protozoa per mL of liquid
  10. value: measured value of variable: integer or real (see variable for details). Counts (integer) of all variables except for vol.ml, volume of vol.ml.

hf193-10: food web and nutrient press manipulation experiment, 2001 at Swift River Bog: harvest data

  1. plant: plant number
  2. leafnum: leaf number (1, last leaf used) on the plant
  3. nlevel: level of Nitrogen
  4. plevel: level of Phosphorus
  5. nstart: amount of Nitrogen added (unit: millimole / missing value: NA)
  6. pstart: amount of Phosphorus added (unit: millimole / missing value: NA)
  7. leafopendate: date leaf opened and available for manipulation
  8. sampledate: date leaf contents harvested
  9. variable: item measured
    • vol.ml: volume of liquid in the pitcher on the measurement date
    • wyeo.Xmm: larvae of Wyeomyia smithii, where X is their length in mm
    • wyeo.pup: pupae of Wyeomyia smithii
    • met.Xmm: larvae of Metriocnemus knabi, where X is their length in mm
    • flet.Xmm: larvae of Fletcherimyia fletcheri, where X their the length in mm
    • heads.ants: number of head capsules of ant prey
    • heads.coll: number of head capsules of collembola prey
    • heads.flies: number of head capsules of fly prey
    • heads.spiders: number of head capsules of spider prey
    • mitesperml: mites Sarraceniopus gibsoni per mL of liquid
    • rotiperml: rotifers Habrotrocha rosa per mL of liquid
    • protperml: total protozoa per mL of liquid
    • pH: pH of pitcher fluid
    • PmgperL: concentration of phosphate (PO4) in the pitcher fluid (mg/L)
    • NH4mgperL: concentration of ammonium (NH4) in the pitcher fluid (mg/L)
    • NO3mgperL: concentration of nitrate (NO3) in the pitcher fluid (mg/L)
    • CamgperL: concentration of calcium (Ca+2) in the pitcher fluid (mg/L)
    • o2mgperL: concentration of dissolved oxygen (O2) in the pitcher fluid (mg/L)
    • tempC: temperature of the pitcher fluid when ions were measured (oC)
  10. value: measured value of variable: integer or real (see variable for details). Volume of vol.ml.

hf193-11: food web and nutrient and prey and predator manipulation experiment, 2004 at Swift River Bog: harvest data

  1. harvestdate: one of two harvest dates
  2. plant: plant number
  3. leafnum: leaf number (1, last leaf used) on the plant
  4. tubetreat: tube treatment
    • full: tubes without holes
    • holes: tubes with holes
    • none: no tubes
    • ctrl: randomly harvested unmanipulated plant
  5. n.conc: concentration of NH4NO3 added (mg N/L) (unit: milligramsPerLiter / missing value: NA)
  6. n.added: total amount of N solution added from start of experiment to harvest (unit: milliliter / missing value: NA)
  7. dm.added: supplemental prey added as 10 Drosophila melanogaster (fruit fly) adults each week
    • 0: not added
    • 1: added
  8. ff.added: top predator (Fletcherimyia fletcheri) added to pitcher
    • 0: not added
    • 1: added
  9. variable: item measured
    • preymass: mass of prey in tube or pitcher at harvest (mg)
    • Flet.instar: instar of Fletcherimyia fletcheri individual at harvest, if present; NA if absent
    • Wyeo.inst4: number of Wyeomyia smithii pupae at harvest
    • Wyeo.inst3: number of third-instar Wyeomyia smithii larvae at harvest
    • Wyeo.inst2: number of second-instar Wyeomyia smithii larvae at harvest
    • Wyeo.inst1: number of first-instar Wyeomyia smithii larvae at harvest
    • Met.inst2: number of second-instar Metriocnemus knabii larvae at harvest
    • Met.inst1: number of first-instar Metriocnemus knabii larvae at harvest
    • lflength: length of pitcher from base to hood (mm)
    • leafdiam1: diameter of pitcher mouth, longer of two (mm), and perpendicular to leafdiam2 (real)
    • leafdiam2: diameter of pitcher mouth, shorter of two (mm), and perpendicular to leafdiam1 (real)
    • leafwid: width of pitcher at widest point (mm)
    • keelwid: width of pitcher keel at widest point (mm)
    • leafmass: mass of pitcher at harvest (g)
    • preymass.b: in pitchers with full tubes, mass off prey in pitcher below the tube (mg); NA for all other treatments
    • Fletinst.b: in pitchers with full tubes, instar of Fletcherimyia fletcheri at harvest, if present; NA if not present and in all other treatments.
    • Wyeo.inst4.b: in pitchers with full tubes, number of Wyeomyia smithii pupae at harvest; NA for all other treatments
    • Wyeoinst3.b: in pitchers with full tubes, number of third-instar Wyeomyia smithii larvae at harvest; NA for all other treatments
    • Wyeo.inst2.b: in pitchers with full tubes, number of second-instar Wyeomyia smithii larvae at harvest; NA for all other treatments
    • Wyeo.inst1.b: in pitchers with full tubes, number of first-instar Wyeomyia smithii larvae at harvest; NA for all other treatments
    • Met.inst2.b: in pitchers with full tubes, number of second-instar Metriocnemus knabi larvae at harvest; NA for all other treatments
    • Metinst1.b: in pitchers with full tubes, number of first-instar Metriocnemus knabi larvae at harvest; NA for all other treatments
  10. value: measured value of variable: integer or real (see variable for units)

hf193-12: species master list

  1. row: value 1-63, corresponding to the rows (and columns) of nocomp_matrix.csv and withcomp_matrix.csv
  2. abbreviation: species abbreviation, used in FTN-spList.csv, GEO-spList.csv and QUS-spList.csv
  3. taxon: species taxon, expansion of abbreviation

hf193-13: model files

  • Compression: zip
  • Format: zip
  • Type: zip file