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Harvard Forest Data Archive

HF275

Predator Contributions to Belowground Responses to Climate Warming at Harvard Forest 2014

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Data

Overview

  • Lead: Shannon Pelini, Audrey Maran
  • Investigators: Robert Baroudi, Heather Clendenin, Laura Figueroa
  • Contact: Shannon Pelini
  • Start date: 2014
  • End date: 2014
  • Status: completed
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.53
  • Longitude: -72.19
  • Elevation: 340 meter
  • Taxa: Pardosa spp. (wolf spider)
  • Release date: 2016
  • Revisions:
  • EML file: knb-lter-hfr.275.2
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: physiological ecology, population dynamics and species interactions
  • LTER core area: populations, organic matter
  • Keywords: air temperature, arthropods, communities, climate change, insects, microbial biomass, soil respiration, soil temperature
  • Abstract:

    Identifying the factors that control soil CO2 emissions will improve our ability to predict the magnitude of climate change-soil ecosystem feedbacks. Despite the integral role of invertebrates in belowground systems, they are excluded from climate change models. Soil invertebrates have consumptive and non-consumptive effects on microbes, whose respiration accounts for nearly half of soil CO2 emissions. By altering the behavior and abundance of invertebrates that interact with microbes, invertebrate predators may have indirect effects on soil respiration. We examined the effects of a generalist arthropod predator on belowground respiration under different warming scenarios. Based on research suggesting invertebrates may mediate soil CO2 emission responses to warming, we predicted that predator presence would result in increased emissions by negatively affecting these invertebrates. We altered the presence of wolf spiders (Pardosa spp.) in mesocosms containing a forest floor community. To simulate warming, we placed mesocosms of each treatment in ten open-top warming chambers ranging from 1.5 to 5.5° C above ambient at Harvard Forest, MA. As expected, CO2 emissions increased under warming and we found an interactive effect of predator presence and warming, though the effect was not consistent through time. The interaction between predator presence and warming was the inverse of our predictions: mesocosms with predators had lower respiration at higher levels of warming than those without predators. Carbon dioxide emissions were not significantly associated with microbial biomass. We did not find evidence of consumptive effects of predators on the invertebrate community, suggesting that predator presence mediates response of microbial respiration to warming through non-consumptive means. In our system we found a significant interaction between warming and predator presence that warrants further research into mechanism and generality of this pattern to other systems.

  • Methods:

    Overview

    We built mesocosms simulating a forest floor invertebrate community within plastic 18.9 L buckets. We added equal volume layers (5200 mL) of sieved and homogenized soil in each bucket, with a sand layer at the bottom, followed by a layer of mineral soil and organic soil. Each bucket contained a red maple (Acer rubrum) sapling (15-25 cm in height), a pvc soil collar, a microrhizon sampler (Soil Moisture Inc. Santa Barbara, CA), 2 grams of leaf litter, three millipedes, three earthworms, and natural densities of springtails, mites, and enchytraeid worms. To half of the buckets, we added a wolf spider (Pardosa sp.) as our "predator treatment". All mesocosms were surrounded with a fine mesh throughout the experiment. We placed 3 mesocosms without predators and 3 mesocosms with predators in each warming chamber (9 levels of warming, 1.5 to 5.5° C above ambient) and in one control chamber on Prospect Hill tract. This made for a total of 60 mesocosms.

    Weekly Measurements

    We measured efflux using a LI-6400 (LICOR, Lincoln, NE) with the soil respiration attachment. The LI-6400 also recorded soil temperature and air temperature in the soil respiration attachment. During the CO2 efflux measurements, we also recorded moisture using a Hydrosense moisture probe, plant leaf number and stem height. Three times a week, we collected soil solution using the microrhizon samplers, which were analyzed for dissolved NO3-, NH4+, total reducing sugars, and total free primary amines using fluorometric and colorimetric methods and analyzed on a Shimadzu TOC-VCPN analyzer (Shimadzu Scientific Instruments Inc. Columbia, MD, USA).

    Mesocosm Harvest

    We destructively sampled 20 of the mesocosms (one of each treatment) on 7/10/2014 and the remaining 40 on 9/10/2014. From each mesocosm, we recorded the density of springtails, mites, and enchytraeids, the remaining number of worms and millipedes, and took soil cores. Using the soil cores, we used fumigation-extraction to determine microbial carbon biomass and microbial nitrogen biomass. The extracts from this process were analyzed on a Shimadzu TOC-VCPN analyzer.

  • 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:

    Pelini S, Maran A. 2016. Predator Contributions to Belowground Responses to Climate Warming at Harvard Forest 2014. Harvard Forest Data Archive: HF275.

Detailed Metadata

hf275-01: mesocosm weekly measurements

  1. datecode: code for date of data collection. Two digit year code, followed by the two digit month number, and two digit day number.
  2. date: date of data collection
  3. week: week of data collection
  4. time: time of data collection
  5. datetime: date and time of data collection
  6. mesocosm.id: unique id for the mesocosm
  7. number: number of the mesocosm only
  8. chamber: warming chamber number
  9. target.warming: target warming level of the chamber (degrees C above ambient) (unit: celsius / missing value: NA)
  10. warming: actual average degrees above C of the chamber over the course of the experiment (unit: celsius / missing value: NA)
  11. predator.pa: predator treatment
    • 0: no predator
    • 1: predator
  12. efflux1: first of 3 efflux (micromole CO2 per meter squared per second) measurements taken on each day. The Li-6400 always took three measurements, one right after the next. (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  13. efflux2: second of 3 efflux (micromole CO2 per meter squared per second) measurements taken on each day (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  14. efflux3: third of 3 efflux (micromole CO2 per meter squared per second) measurements taken on each day (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  15. effluxavg: average of the three efflux (micromole CO2 per meter squared per second) measurements (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  16. soiltemp: temperature of soil at approximately 8 cm depth (unit: celsius / missing value: NA)
  17. airtemp: temperature of the air in the soil measurement chamber of the LI-6400 during measurement (unit: celsius / missing value: NA)
  18. moisture: soil moisture (% VWC) reading taken at time of the efflux measurement (unit: dimensionless / missing value: NA)
  19. plant: state of the plant
    • A: alive
    • D: dead
  20. leaf: number of leaves on the plant (unit: number / missing value: NA)
  21. stem: height of stem of the plant (unit: centimeter / missing value: NA)
  22. nh4: NH4 (micromole per liter) on the efflux measurement day (unit: micromolePerLiter / missing value: NA)
  23. no3: NO3 (micromole per liter) on the efflux measurement day (unit: micromolePerLiter / missing value: NA)
  24. tfpa: total free primary amines (micromole per liter) on the efflux measurement day (unit: micromolePerLiter / missing value: NA)
  25. trs: total reducing sugars (micromole per liter) (unit: micromolePerLiter / missing value: NA)
  26. harvest.date: date that the mesocosm was harvested
  27. weather: simple description of the weather on the efflux measurement day

hf275-02: mesocosm measurements at harvest

  1. date: date the mesocosm was harvested
  2. mesocosm.id: unique id for the mesocosm
  3. number: number of the mesocosm only
  4. chamber: warming chamber number
  5. warming.target: the target warming level of the chamber (degrees C above ambient) (unit: celsius / missing value: NA)
  6. warming: actual average degrees above C of the chamber over the course of the experiment (unit: celsius / missing value: NA)
  7. predator.pa: predator treatment
    • 0: no predator
    • 1: predator
  8. wetwt: weight of soil sample from mesocosm before drying (unit: gram / missing value: NA)
  9. drywt: weight of soil sample from mesocosm after drying (unit: gram / missing value: NA)
  10. microbes.c: micrograms of microbial carbon per gram of soil (unit: microgramsPerGram / missing value: NA)
  11. microbes.n: micrograms of microbial nitrogen per gram of soil (unit: microgramsPerGram / missing value: NA)
  12. worms: number of worms counted in all soil (unit: number / missing value: NA)
  13. sprintailcount1: number of springtails counted in one 15 mL subsample (unit: number / missing value: NA)
  14. potwormcount1: number of potworms (enchytraeids) counted in one 15 mL subsample (unit: number / missing value: NA)
  15. mitecount1: number of mites counted in one 15 mL subsample (unit: number / missing value: NA)
  16. sprintailcount2: number of springtails counted in second 15 mL subsample (unit: number / missing value: NA)
  17. potwormcount2: number of potworms counted in second 15 mL subsample (unit: number / missing value: NA)
  18. mitecount2: number of mites counted in second 15 mL subsample (unit: number / missing value: NA)
  19. sprintailcount3: number of springtails counted in third 15 mL subsample (unit: number / missing value: NA)
  20. potwormcount3: number of potworms counted in third 15 mL subsample (unit: number / missing value: NA)
  21. mitecount3: number of mites counted in third 15 mL subsample (unit: number / missing value: NA)
  22. springtailavg: average of number of springtails found in the three subsamples (unit: number / missing value: NA)
  23. potwormavg: average of number of potworms found in the three subsamples (unit: number / missing value: NA)
  24. miteavg: average of number of mites found in the three subsamples (unit: number / missing value: NA)
  25. effluxavg: average efflux for this mesocosm over the course of the experiment (micromole CO2 per meter squared per second) (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
  26. effluxlast: efflux measurement taken before harvest (unit: micromolePerMeterSquaredPerSecond / missing value: NA)