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Harvard Forest Data Archive

HF291

Red Maple Seedling Soil Warming Experiment in Harvard Forest Lath House 2015

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Data

Overview

  • Lead: Julia Wheeler, Kristina Stinson
  • Investigators: Natalie Gonzalez
  • Contact: Julia Wheeler
  • Start date: 2015
  • End date: 2015
  • Status: completed
  • Location: Harvard Forest Experimental Lath Houses
  • Latitude: +42.53
  • Longitude: -72.19
  • Elevation: 330 meter
  • Taxa: Acer rubrum (red maple)
  • Release date: 2017
  • Revisions:
  • EML file: knb-lter-hfr.291.2
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: physiological ecology, population dynamics and species interactions
  • LTER core area: primary production
  • Keywords: aboveground biomass, climate change, maple, recruitment, seedlings, soil temperature, soil warming
  • Abstract:

    Microhabitat environmental conditions are an important filter for seedling establishment, controlling the availability of optimal recruitment sites. Understanding how tree seedlings respond to warming soil temperature is critical for predicting population recruitment in the future hardwood forests of northeastern North America, particularly as environmental conditions and thus optimal microhabitat availabilities change. We examined the effect of 5˚C soil warming during the first growing season on germination, survival, phenology, growth, and stem and root biomass allocation in Acer rubrum (red maple) seedlings. While there was no effect of soil warming on germination or survival, seedlings growing in warmer soils demonstrated significantly accelerated leaf expansion, delayed autumn leaf senescence, and an extended leaf production period. Further, seedlings growing in warmer soils showed larger leaf area, stem and root structures at the end of the first growing season, with no evidence of biomass allocation tradeoffs. Results suggest A. rubrum seedlings can capitalize on soil warming by adjusting leaf phenology and leaf production, resulting in a longer period of carbon uptake and leading to higher overall biomass. The absence of growth allocation tradeoffs suggests A. rubrum will respond positively to increasing soil temperatures in northeastern forests, at least in the early life stages.

  • Methods:

    Experimental Design

    In June 2015, we filled 80 15.25 cm (6 inch diameter) pots with local soil sourced from the edge of the forest (less than 20 m from our experimental site, an area occupied by mature A. rubrum). We placed pots in dark plastic trays to standardize surface colour and drainage. There were two levels of soil temperature treatment in this experiment: unheated (ambient temperature) control pots, which we placed on bare dark gravel groundcover, and soil warming pots (+5˚C above ambient), which we placed on electric hydroponic heating mats (Root Radiance, China). We randomly assigned pots to one of the two treatments. The pots were slightly shaded under a 3m tall wooden lath structure, but were situated close together (in a 2×4 m area) in order to minimize variation in light and other microscale environmental conditions. In addition, we randomized pot position halfway through the growing season to minimize any effect of light variation.

    In the first week of June, we collected mature A. rubrum seeds in a single batch from a series of local A. rubrum trees (within 1 km of the experiment site). Acer rubrum germinates immediately after maturation (Walters and Yawney 1990), so we planted seeds one day after sampling. We planted six seeds in each pot (40 pots per treatment; total seed N=480) and marked the planted seeds with toothpicks to minimize the probability of counting an A. rubrum seed already present in the soil or from an outside seedfall. Four weeks after planting, we thinned germinants to one seedling per pot (N=80 seedlings) to eliminate the effects of intraspecific competition on experimental seedling growth. We monitored pots daily or every other day through the growing season, weeded as necessary to remove interspecific competitors and watered to saturation when needed.

    Field Data Collection

    After planting, we recorded day of onset of germination for each seed, in addition to total germination per pot (of six planted seeds). After germination, we recorded germinant survival over the first four weeks, and day of first true leaf expansion. Once per week until mid-August, we measured stem height, counted leaf number and measured the largest leaf area (leaf length x width) using calipers in order to determine the maximum number of leaves and the largest leaf size produced during the growing season. Since A. rubrum produces lobed leaves, our leaf measurements represent an approximation of individual leaf area. At the end of the growing season (early October), we measured total seedling height and stem diameter just above the root collar for each seedling using calipers. In early October, we also recorded leaf senescence on each seedling, where a seedling was defined as senescent if no green leaf tissue remained. In early November, we removed seedlings from pots and washed the roots to remove soil. We counted the number of branches from the main root, and measured the lengths of both the primary root and the longest secondary root using calipers. Root and stem tissues were then dried at 60˚C for 72 hours. We removed any senescent leaf tissue, and then weighed stem tissue and root tissue separately using an analytic balance. We calculated root-stem ratios as root dry mass divided by stem dry mass.

    We collected soil temperature data using a standard handheld soil probe at a depth of 5 cm in each pot containing experimental seedlings. We measured temperatures in a random sample of ten pots per treatment during each collection period. We collected temperature data daily during July to mid-August, and then every 2-3 days until late September.

  • 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:

    Wheeler J, Stinson K. 2017. Red Maple Seedling Soil Warming Experiment in Harvard Forest Lath House 2015. Harvard Forest Data Archive: HF291.

Detailed Metadata

hf291-01: germination day

  1. treatment: treatment
    • Control: control
    • Warmed: heated
  2. mean: mean day of germination in 2015; average day of germination for each treatment (unit: nominalDay / missing value: NA)
  3. n: number of pots (unit: number / missing value: NA)
  4. sd: standard deviations of average germination day for seedlings in each treatment (unit: dimensionless / missing value: NA)
  5. sem: standard error of average germination day for seedlings in each treatment (unit: dimensionless / missing value: NA)

hf291-02: soil temperature

  1. treatment: treatment
    • heated: heated
    • unheated: control
  2. doy: day of year soil temperature measurement was taken (unit: nominalDay / missing value: NA)
  3. temp.mean: mean daily temp soil temperature for each treatment (unit: celsius / missing value: NA)
  4. temp.am: mean temperature for each treatment measured in the morning (unit: celsius / missing value: NA)
  5. temp.pm: mean temperature for each treatment measured in the afternoon (unit: celsius / missing value: NA)

hf291-03: germination phenology

  1. trt.pot: treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling
  2. treatment: treatment
    • Control: control
    • GM: garlic mustard extract added
    • Warmed: heated
    • warm_GM: heated and garlic mustard extract added
  3. tray: tray number (1-5), with 5 trays for each treatment type
  4. pot: pot number (1-8), with each pot containing one individual seedling
  5. trt.h: heat treatment
    • 0: no warming
    • 1: warming added
  6. trt.gm: garlic mustard extract treatment
    • 0: no garlic mustard extract
    • 1: garlic mustard extract added
  7. n.germ.max: number of seeds germinating in individual pot (of 6) (unit: number / missing value: NA)
  8. n.germ.survival: number of germinants surviving prior to thinning (of 6) (unit: number / missing value: NA)
  9. germ.doy: day of year of seed germination (unit: nominalDay / missing value: NA)
  10. leaf.exp.doy: day of year of first true leaf expansion (unit: nominalDay / missing value: NA)
  11. germ.doy.post.sow: number of days between sowing and seed germination (unit: number / missing value: NA)
  12. leaf.exp.doy.post.sow: number of days between sowing and leaf expansion (unit: number / missing value: NA)

hf291-04: growth

  1. trt.pot: treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling
  2. tray: tray number (1-5), with 5 trays for each treatment type
  3. pot: pot number (1-8), with each pot containing one individual seedling
  4. treatment: treatment
    • Control: control
    • Warmed: heated
  5. trt.h: heating treatment
    • 0: no warming
    • 1: warming added
  6. trt.gm: garlic mustard extract treatment
    • 0: no garlic mustard extract
    • 1: garlic mustard extract added
  7. doy.sow: day of year seed sown in 2015 (unit: nominalDay / missing value: NA)
  8. doy.measured: day of year 2015 measurements taken (unit: nominalDay / missing value: NA)
  9. doy.post.sow: number of of days post sowing measurements taken (unit: number / missing value: NA)
  10. plant.height: height measured from root collar to point where highest leaf pair meet (unit: millimeter / missing value: NA)
  11. stem.width: stem diameter just above root collar (unit: millimeter / missing value: NA)
  12. bud.set: occurence of bud set
    • 0: bud set had not occurred
    • 1: bud set had occurred
  13. senescent: occurence of leaf senescence
    • 0: leaf senescence had not occurred
    • 1: leaf senescence had occurred
  14. n.leaf: number of leaves counted (unit: dimensionless / missing value: NA)
  15. leaf.length: length of largest leaf (unit: millimeter / missing value: NA)
  16. leaf.width: width of largest leaf (unit: millimeter / missing value: NA)
  17. leaf.area: length x width of largest leaf (unit: squareMillimeters / missing value: NA)
  18. per.herb: percent leaf tissue removed by insect herbivory (unit: dimensionless / missing value: NA)
  19. per.herb.bin: presence of leaf herbivory
    • 0: leaf herbivory absent
    • 1: leaf herbivory present
  20. per.mil: percent leaf tissue damaged by powdery mildew (unit: dimensionless / missing value: NA)
  21. per.mil.bin: presence of powdery mildew damage
    • 0: powdery mildew damage absent
    • 1: powdery mildew damage present
  22. per.brown: percent leaf tissue damaged by pathogen infection (unit: dimensionless / missing value: NA)
  23. per.dam.gen: percent leaf tissue damaged by all damage types (unit: dimensionless / missing value: NA)
  24. main.root.len: length of main root (unit: millimeter / missing value: NA)
  25. long.sec.root.len: length of longest secondary root (unit: millimeter / missing value: NA)
  26. note: note
    • post: measurements were taken after the seedling was harvested

hf291-05: seedling height

  1. treatment: type of treatment
    • Control: control
    • Warmed: heated
  2. doy.sow: day of year seed sown in 2015 (unit: nominalDay / missing value: NA)
  3. doy.obs: day of year 2015 measurements taken (unit: nominalDay / missing value: NA)
  4. doy.post.sow: number of days post sowing measurements were taken (unit: number / missing value: NA)
  5. mean: mean height measured from root collar to point where highest leaf pair meet; mean stem height for all seedlings within the treatment (unit: millimeter / missing value: NA)
  6. n: number of seedlings (sample size) (unit: number / missing value: NA)
  7. sd: standard deviations of average stem height for seedlings in each treatment (unit: dimensionless / missing value: NA)
  8. sem: standard error of average stem height for seedlings in each treatment (unit: dimensionless / missing value: NA)

hf291-06: leaf count

  1. treatment: full treatment names for figures
    • Control: control
    • Warmed: heated
  2. mean: mean leaf count; mean leaf count for all seedlings within the treatment (unit: number / missing value: NA)
  3. n: number of seedlings (sample size) (unit: number / missing value: NA)
  4. sd: standard deviations of average leaf count for seedlings in each treatment (unit: dimensionless / missing value: NA)
  5. sem: standard error of average leaf count for seedlings in each treatment (unit: dimensionless / missing value: NA)
  6. doy.obs: day of year 2015 measurements taken (unit: nominalDay / missing value: NA)
  7. doy.sow: day of year seed sown in 2015 (unit: nominalDay / missing value: NA)
  8. doy.post.sow: number of days post sowing measurements taken (unit: nominalDay / missing value: NA)

hf291-07: leaf area

  1. treatment: full treatment names for figures
    • Control: control
    • Warmed: heated
  2. doy.sow: day of year seed sown in 2015 (unit: nominalDay / missing value: NA)
  3. doy.obs: day of year 2015 measurements taken (unit: nominalDay / missing value: NA)
  4. doy.post.sow: number of days post sowing measurements taken (unit: number / missing value: NA)
  5. mean: mean largest leaf area from length x width of largest leaf; mean largest leaf area for all seedlings within the treatment (unit: squareMillimeters / missing value: NA)
  6. n: number of seedlings (sample size) (unit: number / missing value: NA)
  7. sd: standard deviations of average leaf area for seedlings in each treatment (unit: dimensionless / missing value: NA)
  8. sem: standard error of average leaf area for seedlings in each treatment (unit: dimensionless / missing value: NA)

hf291-08: biomass

  1. trt.pot: treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling
  2. tray: tray number (1-5), with 5 trays for each treatment type
  3. pot: pot number (1-8), with each pot containing one individual seedling
  4. trt: treatment
    • C: control
    • GM: garlic mustard
    • H: warmed 5 degrees Celsius above ambient
    • HGM: garlic mustard extracted added in addition to being warmed 5 degrees Celsius above ambient
  5. treatment: full treatment names for figures
    • Control: control
    • Warmed: heated
  6. trt.h: heat treatment
    • 0: no warming
    • 1: warming added
  7. trt.gm: garlic mustard extract treatment
    • 0: no garlic mustard extract
    • 1: garlic mustard extract added
  8. plant.height.final: stem height from root collar to set terminal bud after harvest (november 2015) (unit: millimeter / missing value: NA)
  9. stem.width.final: stem width at root collar after harvest (november 2015) (unit: millimeter / missing value: NA)
  10. main.root.len: length of main root (unit: millimeter / missing value: NA)
  11. long.sec.root.len: length of longest secondary root (unit: millimeter / missing value: NA)
  12. n.branches: number of secondary branches off main root (unit: number / missing value: NA)
  13. root.mass: dry root mass (unit: milligram / missing value: NA)
  14. wood.mass: dry stem mass (unit: milligram / missing value: NA)