uid=HFR,o=lter,dc=ecoinformatics,dc=org all public read doi:10.6073/pasta/de154dd2c57d434d49e4f08e0ad52e54 David Orwig https://orcid.org/0000-0001-7822-3560 David Foster https://orcid.org/0000-0003-1171-3762 Robert Cook Researcher Peter Del Tredici Researcher Heidi Lux Researcher Richard Schulhof Researcher 2023 English

Hemlock Hill at Harvard University's Arnold Arboretum is located in Jamaica Plain and has long been considered a remnant of the forest primeval in the heart of Boston. Eastern hemlocks have dominated the flanks and crest of this hill for centuries, despite experiencing many past disturbances. Following the 1997 snowstorm, the introduced hemlock woolly adelgid (HWA) was discovered on downed branches. Since the discovery of HWA at the Arboretum, an action committee was formed to develop plans for managing Hemlock Hill to meet the new threat. Over 1800 hemlock trees were tagged, measured for diameter, assigned a crown health rating, and mapped with GPS coordinates. Various chemical and biological control treatments were attempted to control the spread of HWA at the arboretum, with mixed success. From 1998 to 2002, 263 trees have died or were removed due to poor health. Of the remaining 1600+ trees, 70% are rated as being in poor condition. Since this is a heavily used portion of the Arboretum, which is part of the Boston Parks Department, the decision has been made to remove many of the dead and dying trees to reduce risks posed to the general public by falling limbs. This unfortunate turn of events provides us with an unusual opportunity to examine the environmental impacts of hemlock death and hemlock removal in an urban environment, including soil nutrient cycling, microclimate changes, and vegetation succession, especially the spread of invasive species. During 2004, six 15 x 15 m plots were fenced off, and baseline data on soil nutrient cycling, microclimate, and vegetation information was collected from each. Analyses of these baseline data are underway. Hemlocks are currently being removed from 4 plots, and 2 will remain untouched as control plots. Slash in the cut plots is either being chipped and left on site or removed so that we can investigate what impact these post-cut inputs have on ecosystem and vegetation trajectories. We will continue with data collection on vegetation and ecosystem parameters following harvesting, especially the spread of invasive plant species. Data from this project will provide a nice comparison to the rural cutting and girdling that is ongoing at HF this winter (see Barker-Plotkin et al. abstract). Simultaneously, we are investigating the resistance of Chinese hemlock (Tsuga chinensis) to HWA. This species, which was planted on Hemlock Hill in 1999, continues to demonstrate resistance to HWA and plantings have begun on some sections of the hill.

hemlock hemlock woolly adelgid successional dynamics timber harvest tree mortality urban LTER controlled vocabulary disturbance 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=hf061 Arnold Arboretum (Jamaica Plain MA). Coordinates based on WGS84 datum. -71.12413 -71.12413 +42.29754 +42.29754 52 52 meter 2004 2007 genus Adelges species tsugae hemlock woolly adelgid genus Betula species lenta black birch genus Tsuga species canadensis eastern hemlock 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

Nitrogen mineralization was measured using 4 closed-topped cores at each of six 15 x 15 m plots. Sampling occurred at 5-week intervals during each growing season with one set of cores left over winter. An additional assessment of forest floor N availability and mobility was determined from mixed-bed cation + anion resin bags that were buried for 6-month intervals at the organic layer-mineral layer interface (ca. 5 cm) in each sampling plot. Soil temperature at 1 and 5 cm depths were measured at each soil sampling plot every 30 minutes throughout the growing season using iButton temperature data loggers. Soil samples were returned to the laboratory on ice and processed the next day. Organic and mineral soils were passed through a 5.0 mm mesh screen, weighed for total mass, and subsampled for gravimetric moisture and inorganic N. NH4-N and NO3-N were extracted from all soils using 1M KCl and from resin bags using 2M KCl and concentrations were determined colorimetrically with a Lachat flow-injection 8500 autoanalyzer. We determined the following properties of soils collected during our initial sampling at each site: organic matter by loss on ignition (5.5 hrs at 550 deg C), pH in a soil and CaCl2 slurry (1:10 organic soil:solution; 1:4 mineral soil:solution), and total C and N content by dry combustion with our Fisons CHN autoanalyzer. Soil texture texture was determined on mineral soils in each subplot. Bulk density of organic and mineral horizons was determined from dried samples from each subplot using a soil sampling corer of known volume. Remaining organic and mineral soils were air-dried and stored in our sample archive. Vegetation was sampled in six 15 x 15 m plots systematically located across the northern slope of Hemlock Hill. Prior to cutting, all trees (stems at least 8 cm dbh) were tagged, measured for diameter, assigned a crown health rating, and mapped with GPS coordinates. The presence of all vascular plant species in each plot were recorded, along with slope, aspect, and topographic position, and saplings (less than 8 cm dbh and more than 1.4 m tall) were tallied by species. Ten 1-m2 subplots were established at randomly selected subplot (5 x 5 m) corners set up for soils analyses (see below) to assess understory vegetation. In each subplot, percent cover of seedling, herb, and shrub species were estimated using a Braun-Blanquet scale.

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. hf061-01-bulk-density.csv soil bulk density hf061-01-bulk-density.csv 591 290c4883eb695e60012bfa5f62acb7c8 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-01-bulk-density.csv plot number of plot (1-6) number of plot (1-6) subplot number of subplot (2-48). Each plot has 2 subplots, where samples were collected. number of subplot (2-48) horizon soil horizon. samples were separated into mineral (M) and organic (O) horizons at each subplot. M mineral O organic core.length length of soil core centimeter 0.01 real NA missing value dry.mass air dry weight of soils gram 0.01 real NA missing value bulk.density bulk density gramsPerCubicCentimeter 0.01 real NA missing value 24 hf061-02-soil-temp.csv soil temperature hf061-02-soil-temp.csv 20891299 f0aa28ad450cdea8dd5782cba8c96296 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-02-soil-temp.csv datetime date and time of collection YYYY-MM-DDThh:mm year collection year for data set. Soil temperatures are collected April-October. YYYY month month month day day of month day time time, 12-hour hh:mm am.pm am or pm am or pm site site code. See site description data for additional information on sites and codes. C1 Control 1 C2 Control 2 C3 Control 3 C4 Control 4 CH1 Chipped 1 CH2 Chipped 2 CH3 Chipped 3 CH4 Chipped 4 L1 Logged 1 L2 Logged 2 L3 logged 3 L4 Logged 4 horizon soil horizon ORG organic MIN mineral temp average hourly soil temperature celsius 0.1 real NA missing value 398136 hf061-03-soil-moisture.csv soil moisture hf061-03-soil-moisture.csv 4360 003c14941f52d70ba95b751e5d50b954 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-03-soil-moisture.csv year year of sample collection YYYY month month when sample was collected, actual dates vary from year to year. month hor soil horizon O organic M mineral plot number of 1 x 1 m subplot within each plot plot number treatment experimental manipulation C Control L Logged Ch Chipped moisture total evaporable moisture content of sample for 2004, 2005 and 2006. gram 0.01 real NA missing value 180 hf061-04-soil-ph.csv soil pH hf061-04-soil-ph.csv 1000 b44cda8ab8a477a97e8086c521897ccc 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-04-soil-ph.csv plot number of plot (1-6) number of plot (1-6) sub number of subplot (2-51). Each plot has 4 subplots, where samples were collected. number of subplot (2-51) trmt type of treatment applied to the plot type of treatment applied to the plot horizon soil horizon M mineral O organic avg.ph average soil pH of 2 replicate samples dimensionless 0.01 real NA missing value 48 hf061-05-soil-cn.csv soil carbon and nitrogen hf061-05-soil-cn.csv 594 3ff067e2b6c5c6d5d719c9f6f91798d0 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-05-soil-cn.csv plot number of plot (1-6) number of plot (1-6) sub number of subplot (2-51) number of subplot (2-51) horizon soil horizon M mineral O organic c.n index of the ratio of total C (mg C/g resin) divided by total N (mg N/g resin) milligramPerGram 0.01 real NA missing value 42 hf061-06-nmin.csv nitrogen mineralization hf061-06-nmin.csv 54262 3f5357165bcd578643cfa3139da853c3 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-06-nmin.csv year sample collection year YYYY hor soil horizon O organic M mineral subplot subplot. There are 4 subplots in each plot (1-32) subplot treatment experimental Treatment C Control L Logged Ch Chipped core.in date soil incubation began , in situ YYYY-MM-DD core.out date soil care incubation ended YYYY-MM-DD incubation number of days Final core was in the soil number 1 whole NA missing value no3.n final core – initial core extracted Nitrogen in the form of nitrate gramsPerGram 0.01 real NA missing value nh4.n final core – initial core extracted Nitrogen in the form of ammonium milligramPerKilogram 0.01 real NA missing value no3.n.area final core – initial core extracted Nitrogen in the form of ammonium kilogramsPerHectare 0.01 real NA missing value nh4.n.area final core – initial core extracted Nitrogen in the form of nitrate kilogramsPerHectare 0.01 real NA missing value 960 hf061-07-resin.csv resin data hf061-07-resin.csv 3039 5c9c6ee0bbca8b593738491e91c5661f 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-07-resin.csv season season. Resin bags are deployed in the soil from May-October (GS) and October- May (OW). Year values are the sum of the growing season and the following winter. OW over winter GS growing season YEAR year start.date start date YYYY end.date end date YYYY plot plot number of 15x15 m ( n = 2) plot number treatment experimental treatment applied to each plot C Control L Logged Ch Hemlock chips applied nh4.n Nitrogen in the form of ammonium captured in resin. Values are the average of values from 4 resin bags in each plot. microgramsPerGram 0.01 real NA missing value no3.n Nitrogen in the form of nitrate captured in resin. Values are the average of values from 4 resin bags in each plot. microgramsPerGram 0.01 real NA missing value ion.n Ammonium + Nitrate captured in resin. Values are the average of values from 4 resin bags in each plot. microgramsPerGram 0.01 real NA missing value 72 hf061-08-seedling-dens.csv seedling density hf061-08-seedling-dens.csv 296858 b69785a80e062a3ef1b9afc815a1b15e 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-08-seedling-dens.csv year year sample was taken YYYY date.sampled date sampled YYYY-MM-DD plot number of plot (1-6) number of plot (1-6) subplot number of subplot (1-211). Each plot has 10, 1x1 m subplots, where samples were collected. number of subplot (1-211) species species code (first two letters of Genus and species). See species key. species code density seedling density number 0.1 real NA missing value 9840 hf061-09-cover.csv cover hf061-09-cover.csv 1388786 cb3f56ff25528521394e93f4798c4579 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-09-cover.csv veg.type vegetation type seedling Tree Seedling shrub Shrub herb Herbacecous fern Ferns and Allies year year sample was taken YYYY date.sampled date sampled YYYY-MM-DD plot number of plot (1-6) number of plot (1-6) subplot number of subplot (1-211). Each plot has 10, 1x1 m subplots, where samples were collected. number of subplot (1-211) species species code (first two letters of Genus and species). See species key species code cover percent cover using a Braun-Blanquet scale dimensionless 0.1 real NA missing value 38160 hf061-10-species-key.csv species key hf061-10-species-key.csv 8741 4cd5b99d4c043c819184994cc280bce1 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p06/hf061/hf061-10-species-key.csv veg.type vegetation type vegetation type latin.abbr Latin abbreviation (first two letters of Genus and species) Latin abbreviation latin.comp complete Latin name complete Latin name common.name common name common name 166 invasive regional soil long-term measurement milligramPerGram