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Harvard Forest Data Archive

HF096

Nitrogen Cycling Dynamics in Sarracenia Purpurea at Harvard Forest 2004-2005

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Data

Overview

  • Lead: Aaron Ellison
  • Investigators: Jessica Butler
  • Contact: Aaron Ellison
  • Start date: 2004
  • End date: 2005
  • Status: completed
  • Location: Harvard Forest Greenhouse
  • Latitude: +42.53
  • Longitude: -72.19
  • Elevation: 330 meter
  • Taxa: Sarracenia purpurea (northern pitcher plant)
  • Release date: 2007
  • Revisions:
  • EML file: knb-lter-hfr.96.15
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: physiological ecology, population dynamics and species interactions
  • LTER core area: inorganic nutrients
  • Keywords: carnivorous plants, nitrogen cycling, nitrogen-15
  • Abstract:

    In nutrient poor systems, plants employ many strategies in order to acquire and recycle scarce nutrients, including nitrogen. Low leaf N content is associated with low photosynthetic rates, but carnivorous plants have unusually low photosynthetic rates given their N content. The northern pitcher plant Sarracenia purpurea readily uses any available nitrogen: NH4 and NO3 dissolved in precipitation; N mineralized from captured prey; the scant N in saturated peat; and N remobilized from storage. However, the dynamics of N cycling within S. purpurea are poorly understood.

    We conducted two greenhouse experiments to examine N-cycling dynamics of S. purpurea at the whole-plant and individual-leaf levels. In the first experiment we assessed assimilation, translocation, storage, and remobilization of 15N supplied to pitchers and roots. In the second experiment, we examined how 15N assimilated by the first pitcher produced at the start of the growing season contributed to the production and maintenance of subsequent pitchers, roots, and rhizomes.

    Patterns of N cycling were similar at the individual-leaf and whole-plant level. Pitchers assimilated 55 - 69% of available 15N and served both as the largest sink for newly assimilated N (more than 90% of the 15N assimilated during 2004) and the largest source of N remobilization the following spring. In contrast, N assimilated by roots was low and accounted for less than 2.5% of the overall S. purpurea N budget. S. purpurea uses both stored N and newly-acquired N throughout the growing season. The importance of stored N decreases throughout the growing season as newly assimilated N contributes more to later pitcher production.

  • Methods:

    We conducted two 15N labelling experiments using 5 atom% 15NH4-15NO3. All S. purpurea plants used in these experiments were five years old and were grown in a greenhouse with milled sphagnum (Spagnum magellanicum Brid.) as the growth medium (10 x 10 cm pots).

    Experiment One: Dynamics of root and pitcher-assimilated N

    One hundred S. purpurea plants were randomly assigned to one of four treatments: Control (no N added), Root-fed ('R-fed,' N added to growing medium), Pitcher-fed ('P-fed,' N added to individual pitchers), and Root + pitcher-fed ('RP-fed,' N added both to growth medium and pitchers). To trace the fate of previously assimilated 15N, nutrient solution containing 5 atom% 15N was supplied throughout the 2004 growing season, whilst natural abundance 15N-nutrient solution was supplied in 2005. Production of new pitchers by all plants in each treatment group was monitored throughout the experiment. Once a new pitcher had fully opened and hardened (about 2 weeks after opening) it received a modified Hoagland's nutrient solution containing: 457.19 mmol m-3 NH4NO3 (provided as 5 atom% 15NH4-15NO3), 138.59 mmol m-3 MgSO4, 69.29 mmol m-3 KH2PO4, 352.97 mmol m-3 CaCl2, 353.08 mmol m-3 KCl, 32.41 mmol m-3 H2BO3, 6.40 mmol m-3 MnCl2, 0.56 mmol m-3 ZnCl2, 0.21 mmol m-3 CuCl2, 0.07 mmol m-3 Na2MoO, 14.56 mmol m-3 Na2HPO4, and 14.02 mmol m-3 FeSO4. Root-fed plants received a dilute Hoagland's solution (15:1 dilution) applied directly to the peat once the plant's first pitcher had fully established.

    Nutrient addition took place twice weekly. Individual pitchers received a volume of nutrient solution equal to two-thirds the volume of that particular pitcher; volumes ranged from 0.5 mL to 7 mL. At each feeding, the solution added the previous time was withdrawn from pitchers and replaced with fresh nutrient solution. R-fed plants were fed twice each week with 75 mL of nutrient solution. Distilled-deionized water (dd-H2O) was added to control pitchers and pots not receiving nutrients. The milled sphagnum was kept moist by watering with dd-H2O as necessary. All pitchers were plugged with a fine nylon mesh screen to reduce prey capture. Each R-fed plant received 3.51 mg of N throughout the growing season, which represented an average of 54% (range: 26.2% to 92.9%) of those plants' N pools. The total N fed to pitchers at the end of labelling averaged 6.15 mg N, which represented 46% (range: 42.4 - 49.4%) of those plants' N pools.

    Five randomly chosen plants from each treatment were harvested at each of five destructive harvests: 1) Mid-growing season 2004 (June), when fourth pitchers had formed but not been treated/fed, 2) End of growing season 2004 (early October), 3) Dormancy (mid-January 2005), 4) Mid-growing season 2005 (June), when third pitchers had formed but not yet been fed, and 5) End of growing season 2005 (late September). Fewer plants were harvested in some cases due to damage caused by scale in the greenhouse.

    Pitcher heights were measured (+ or - 1 mm) before each plant was harvested and at the end of each growing season. During harvests, pitchers, roots, and rhizomes were separated and thoroughly washed in tap water, followed by several rinses in dd-H2O. Plant parts were dried for 48 hours at 65 deg C, weighed (+ or - 0.001 g), and ground to a fine powder using a Wig-L-Bug grinder (Bratt Technologies, LCC. East Orange, NJ). Subsamples (~2 mg) were then weighed into 8 x 5 mm tin capsules (Elemental Microanalysis, Mason Ohio) and analyzed for total N and 15N abundance at Yale University on a Finnigan DELTAplus Advantage continuous flow isotope ratio mass spectrometer and element analyzer.

    Experiment Two: Fate of N assimilated by first pitcher

    Fifteen S. purpurea plants received a similar treatment to the P-fed treatment described above for Experiment One. However, in this experiment, only the first pitcher formed on each plant received 15N-enriched nutrient solution, whilst the remaining pitchers received nutrient solutions containing natural abundance 15N. Three destructive harvests were used to quantify the fate of 15N assimilated by first pitchers (5 replicate plants at each harvest): 1) when third pitchers had formed and opened (Harvest 1), 2) when fourth pitchers had formed and opened (Harvest 2), and 3) when fifth pitchers had formed and opened (Harvest 3). This allowed us to examine translocation of N obtained by the first pitcher into subsequent pitchers, roots, and rhizomes. Pitchers that had opened just before each harvest period are referred to as 'target pitchers' (e.g., the third pitcher is the target pitcher in Harvest 1). Harvest procedures were identical to those described above for Experiment One. Three unlabelled control plants were harvested at the end of the experiment to assess natural 15N abundance.

  • 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. 2007. Nitrogen Cycling Dynamics in Sarracenia Purpurea at Harvard Forest 2004-2005. Harvard Forest Data Archive: HF096.

Detailed Metadata

hf096-01: experiment one

  1. treat: treatment
    • Pfed: 15N tracer fed to pitchers
    • Rfed: 15N tracer fed to root systems
    • RPfed: 15N tracer fed to root systems and pitchers
  2. harvest: time when each plant was harvested
    • 1: June 2004
    • 2: early Oct. 2004
    • 3: mid Jan. 2005
    • 4: June 2005
    • 5: late Sept. 2005
  3. pit.15n.fed: amount of 15N-NH4NO3 tracer fed to pitchers during 2004 growing season in mg (unit: milligram / missing value: NA)
  4. rt.15n.fed: amount of 15N-NH4NO3 tracer fed to root systems during 2004 growing season (unit: milligram / missing value: NA)
  5. plant.n: mg of nitrogen (N) within entire plant (unit: milligram / missing value: NA)
  6. plant.15n: mg of 15N tracer within entire plant (unit: milligram / missing value: NA)
  7. pit.n.04: mg of N in pitchers produced during 2004 growing season (unit: milligram / missing value: NA)
  8. pit.15n.04: mg of 15N tracer in pitchers produced during 2004 growing season (unit: milligram / missing value: NA)
  9. pit.n.05: mg of N in pitchers produced during 2005 growing season. Note: "NA" appears for harvests 1 through 3 because those plants were harvested prior to the 2005 growing season. (unit: milligram / missing value: NA)
  10. pit.15n.05: mg of 15N tracer in pitchers produced during 2005 growing season. Note: "NA" appears for harvests 1 through 3 because those plants were harvested prior to the 2005 growing season. (unit: milligram / missing value: NA)
  11. rt.n: mg of N in root system (unit: milligram / missing value: NA)
  12. rt.15n: mg of 15N tracer in root system (unit: milligram / missing value: NA)
  13. rh.n: mg of N in rhizome (unit: milligram / missing value: NA)
  14. rh.15n: 15N in rhizome (unit: milligram / missing value: NA)

hf096-02: experiment two

  1. harvest: time when each plant was harvested
    • 1: two weeks after the third pitcher had formed
    • 2: two weeks after the fourth pitcher had formed
    • 3: two weeks after the fifth pitcher had formed
  2. p1.15n.fed: ug of 15N tracer fed to first pitchers (unit: microgram / missing value: NA)
  3. plant.15n: ug of 15N tracer within entire plant (unit: microgram / missing value: NA)
  4. p1.mass: biomass of first pitcher in g (unit: gram / missing value: NA)
  5. p1.n: mg of N in first pitcher (unit: milligram / missing value: NA)
  6. p1.15n: ug of 15N tracer in first pitcher (unit: microgram / missing value: NA)
  7. p2.mass: biomass of second pitcher in g (unit: gram / missing value: NA)
  8. p2.n: mg of N in second pitcher (unit: milligram / missing value: NA)
  9. p2.15n: ug of 15N tracer in second pitcher (unit: microgram / missing value: NA)
  10. p3.mass: biomass of third pitcher in g (unit: gram / missing value: NA)
  11. p3.n: mg of N in third pitcher (unit: milligram / missing value: NA)
  12. p3.15n: ug of 15N tracer in third pitcher (unit: microgram / missing value: NA)
  13. p4.mass: biomass of fourth pitcher in g (unit: gram / missing value: NA)
  14. p4.n: mg of N in fourth pitcher (unit: milligram / missing value: NA)
  15. p4.15n: ug of 15N tracer in fourth pitcher (unit: microgram / missing value: NA)
  16. p5.mass: biomass of fifth pitcher in g (unit: gram / missing value: NA)
  17. p5.n: mg of N in fifth pitcher (unit: milligram / missing value: NA)
  18. p5.15n: ug of 15N tracer in fifth pitcher (unit: microgram / missing value: NA)
  19. rt.mass: biomass of root system in g (unit: gram / missing value: NA)
  20. rt.n: mg of N in root system (unit: milligram / missing value: NA)
  21. rt.15n: ug of 15N tracer in root system (unit: microgram / missing value: NA)
  22. rh.mass: biomass of rhizome in g (unit: gram / missing value: NA)
  23. rh.n: mg of N in rhizome (unit: milligram / missing value: NA)
  24. rh.15n: mg of 15N tracer in rhizome (unit: milligram / missing value: NA)