uid=HFR,o=lter,dc=ecoinformatics,dc=org all public read doi:10.6073/pasta/9632df53e5161476303819695cecabfc Julia Wheeler Kristina Stinson Natalie Gonzalez Researcher 2023 English

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.

aboveground biomass climate change maple recruitment seedlings soil temperature soil warming LTER controlled vocabulary primary production LTER core area Harvard Forest HFR LTER USA HFR default

This dataset is released to the public under Creative Commons CC0 1.0 (No Rights Reserved). Please keep the dataset creators informed of any plans to use the dataset. Consultation with the original investigators is strongly encouraged. Publications and data products that make use of the dataset should include proper acknowledgement.

Creative Commons Zero v1.0 Universal https://spdx.org/licenses/CC0-1.0.html CC0-1.0 https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=hf291 Harvard Forest Experimental Lath Houses. Coordinates based on WGS84 datum. -72.19 -72.19 +42.53 +42.53 330 330 meter 2015 2015 genus Acer species rubrum red maple complete Information Manager Harvard Forest

324 North Main Street Petersham MA 01366 USA

(978) 724-3302 hf-im@lists.fas.harvard.edu Harvard Forest

324 North Main Street Petersham MA 01366 USA

(978) 724-3302 (978) 724-3595 https://harvardforest.fas.harvard.edu

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.

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.

Harvard Forest

324 North Main Street Petersham MA 01366 USA

(978) 724-3302 (978) 724-3595 https://harvardforest.fas.harvard.edu https://ror.org/059cpzx98 pointOfContact The Harvard Forest Long-Term Ecological Research (LTER) program examines ecological dynamics in the New England region resulting from natural disturbances, environmental change, and human impacts. National Science Foundation LTER grants: DEB-8811764, DEB-9411975, DEB-0080592, DEB-0620443, DEB-1237491, DEB-1832210. hf291-01-maple-germ.csv germination day hf291-01-maple-germ.csv 103 396c6969782e9d453f425b7f72fbfbc9 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p29/hf291/hf291-01-maple-germ.csv treatment treatment Control control Warmed heated NA missing value mean mean day of germination in 2015; average day of germination for each treatment nominalDay 0.0001 real NA missing value n number of pots number 1 natural NA missing value sd standard deviations of average germination day for seedlings in each treatment dimensionless 0.000001 real NA missing value sem standard error of average germination day for seedlings in each treatment dimensionless 0.0000001 real NA missing value 2 hf291-02-maple-temp.csv soil temperature hf291-02-maple-temp.csv 3954 4a6ba0208f413e7e7a7f248e42bbd8d7 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p29/hf291/hf291-02-maple-temp.csv treatment treatment heated heated unheated control NA missing value doy day of year soil temperature measurement was taken nominalDay 1 natural NA missing value temp.mean mean daily temp soil temperature for each treatment celsius 0.00000001 real NA missing value temp.am mean temperature for each treatment measured in the morning celsius 0.00000001 real NA missing value temp.pm mean temperature for each treatment measured in the afternoon celsius 0.00000001 real NA missing value 134 hf291-03-maple-germ-pheno.csv germination phenology hf291-03-maple-germ-pheno.csv 7220 a9ef6517b74a92925a4619a4abd5d333 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p29/hf291/hf291-03-maple-germ-pheno.csv trt.pot treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling NA missing value treatment treatment Control control GM garlic mustard extract added Warmed heated warm_GM heated and garlic mustard extract added NA missing value tray tray number (1-5), with 5 trays for each treatment type tray number (1-5), with 5 trays for each treatment type NA missing value pot pot number (1-8), with each pot containing one individual seedling pot number (1-8), with each pot containing one individual seedling NA missing value trt.h heat treatment 0 no warming 1 warming added NA missing value trt.gm garlic mustard extract treatment 0 no garlic mustard extract 1 garlic mustard extract added NA missing value n.germ.max number of seeds germinating in individual pot (of 6) number 1 whole NA missing value n.germ.survival number of germinants surviving prior to thinning (of 6) number 1 whole NA missing value germ.doy day of year of seed germination nominalDay 1 natural NA missing value leaf.exp.doy day of year of first true leaf expansion nominalDay 1 natural NA missing value germ.doy.post.sow number of days between sowing and seed germination number 1 natural NA missing value leaf.exp.doy.post.sow number of days between sowing and leaf expansion number 1 natural NA missing value 160 hf291-04-maple-growth.csv growth hf291-04-maple-growth.csv 132054 47e802b39b2b6831b36a53e4596b55e8 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p29/hf291/hf291-04-maple-growth.csv trt.pot treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling NA missing value tray tray number (1-5), with 5 trays for each treatment type tray number (1-5), with 5 trays for each treatment type NA missing value pot pot number (1-8), with each pot containing one individual seedling pot number (1-8), with each pot containing one individual seedling NA missing value treatment treatment Control control Warmed heated NA missing value trt.h heating treatment 0 no warming 1 warming added NA missing value trt.gm garlic mustard extract treatment 0 no garlic mustard extract 1 garlic mustard extract added NA missing value doy.sow day of year seed sown in 2015 nominalDay 1 natural NA missing value doy.measured day of year 2015 measurements taken nominalDay 1 natural NA missing value doy.post.sow number of of days post sowing measurements taken number 1 natural NA missing value plant.height height measured from root collar to point where highest leaf pair meet millimeter 0.1 real NA missing value stem.width stem diameter just above root collar millimeter 0.1 real NA missing value bud.set occurence of bud set 0 bud set had not occurred 1 bud set had occurred NA missing value senescent occurence of leaf senescence 0 leaf senescence had not occurred 1 leaf senescence had occurred NA missing value n.leaf number of leaves counted dimensionless 1 whole NA missing value leaf.length length of largest leaf millimeter 0.1 real NA missing value leaf.width width of largest leaf millimeter 0.1 real NA missing value leaf.area length x width of largest leaf squareMillimeters 0.01 real NA missing value per.herb percent leaf tissue removed by insect herbivory dimensionless 0.01 real NA missing value per.herb.bin presence of leaf herbivory 0 leaf herbivory absent 1 leaf herbivory present NA missing value per.mil percent leaf tissue damaged by powdery mildew dimensionless 0.01 real NA missing value per.mil.bin presence of powdery mildew damage 0 powdery mildew damage absent 1 powdery mildew damage present NA missing value per.brown percent leaf tissue damaged by pathogen infection dimensionless 0.1 real NA missing value per.dam.gen percent leaf tissue damaged by all damage types dimensionless 0.1 real NA missing value main.root.len length of main root millimeter 0.1 real NA missing value long.sec.root.len length of longest secondary root millimeter 0.1 real NA missing value note note post measurements were taken after the seedling was harvested Free text (unrestricted) .* NA missing value 1440 hf291-05-maple-height.csv seedling height hf291-05-maple-height.csv 676 5a904227b7baa8d88b4a522599413d4f 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p29/hf291/hf291-05-maple-height.csv treatment type of treatment Control control Warmed heated NA missing value doy.sow day of year seed sown in 2015 nominalDay 1 natural NA missing value doy.obs day of year 2015 measurements taken nominalDay 1 natural NA missing value doy.post.sow number of days post sowing measurements were taken number 1 natural NA missing value mean mean height measured from root collar to point where highest leaf pair meet; mean stem height for all seedlings within the treatment millimeter 0.01 real NA missing value n number of seedlings (sample size) number 1 natural NA missing value sd standard deviations of average stem height for seedlings in each treatment dimensionless 0.01 real NA missing value sem standard error of average stem height for seedlings in each treatment dimensionless 0.01 real NA missing value 16 hf291-06-maple-leaf-count.csv leaf count hf291-06-maple-leaf-count.csv 578 1c12b99ffebafc928bbecedc19757eda 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p29/hf291/hf291-06-maple-leaf-count.csv treatment full treatment names for figures Control control Warmed heated NA missing value mean mean leaf count; mean leaf count for all seedlings within the treatment number 0.01 real NA missing value n number of seedlings (sample size) number 1 natural NA missing value sd standard deviations of average leaf count for seedlings in each treatment dimensionless 0.01 real NA missing value sem standard error of average leaf count for seedlings in each treatment dimensionless 0.01 real NA missing value doy.obs day of year 2015 measurements taken nominalDay 1 natural NA missing value doy.sow day of year seed sown in 2015 nominalDay 1 natural NA missing value doy.post.sow number of days post sowing measurements taken nominalDay 1 natural NA missing value 14 hf291-07-maple-leaf-area.csv leaf area hf291-07-maple-leaf-area.csv 644 ca9a7a900b1865b48e67660c0a5fe695 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p29/hf291/hf291-07-maple-leaf-area.csv treatment full treatment names for figures Control control Warmed heated NA missing value doy.sow day of year seed sown in 2015 nominalDay 1 natural NA missing value doy.obs day of year 2015 measurements taken nominalDay 1 natural NA missing value doy.post.sow number of days post sowing measurements taken number 1 natural NA missing value mean mean largest leaf area from length x width of largest leaf; mean largest leaf area for all seedlings within the treatment squareMillimeters 0.01 real NA missing value n number of seedlings (sample size) number 1 natural NA missing value sd standard deviations of average leaf area for seedlings in each treatment dimensionless 0.01 real NA missing value sem standard error of average leaf area for seedlings in each treatment dimensionless 0.01 real NA missing value 14 hf291-08-maple-biomass.csv biomass hf291-08-maple-biomass.csv 9838 cd30f92ea96ea986746a6f92eced2136 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p29/hf291/hf291-08-maple-biomass.csv trt.pot treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling treatment combined with tray number and individual pot number; doubles as unique identifier for each individual seedling NA missing value tray tray number (1-5), with 5 trays for each treatment type tray number (1-5), with 5 trays for each treatment type NA missing value pot pot number (1-8), with each pot containing one individual seedling pot number (1-8), with each pot containing one individual seedling NA missing value 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 NA missing value treatment full treatment names for figures Control control Warmed heated NA missing value trt.h heat treatment 0 no warming 1 warming added NA missing value trt.gm garlic mustard extract treatment 0 no garlic mustard extract 1 garlic mustard extract added NA missing value plant.height.final stem height from root collar to set terminal bud after harvest (november 2015) millimeter 0.1 real NA missing value stem.width.final stem width at root collar after harvest (november 2015) millimeter 0.1 real NA missing value main.root.len length of main root millimeter 0.1 real NA missing value long.sec.root.len length of longest secondary root millimeter 0.1 real NA missing value n.branches number of secondary branches off main root number 1 natural NA missing value root.mass dry root mass milligram 0.0001 real NA missing value wood.mass dry stem mass milligram 0.0001 real NA missing value 160 community short-term measurement