uid=HFR,o=lter,dc=ecoinformatics,dc=org all public read doi:10.6073/pasta/d767246af14d7cf2ab5537fbdffb889c Tara Sackett https://orcid.org/0000-0002-3615-4170 Nathan Sanders https://orcid.org/0000-0001-6220-6731 Aimee Classen https://orcid.org/0000-0002-6741-3470 Aaron Ellison https://orcid.org/0000-0003-4151-6081 2023 English

This study assessed how the change in leaf litter input and environmental conditions, from that of hemlock stands to earlier successional deciduous stands, will affect inorganic nitrogen availability at the interface of the mineral soil and LFH horizons. In early October 2007 we exchanged 0.5 x 0.5 m "loaves" of LFH horizons from hemlock and deciduous stands between forest types, while keeping control plots in the original forest stands. Inorganic nitrogen outputs from the litter loaves were monitored for 20 months using ion-exchange resins, removing and replacing the resins three times at 5 - 8 month intervals. Results indicated that there were differences between the control hemlock and deciduous loaves - NO3 and NH4 availability were higher in deciduous stands. However, the transfer of litter loaves from one stand type to another did not reveal changes in nutrient availability due to a shift in habitat. Rather, the methodology of moving litter loaves to a new site caused greater changes in nutrient availability, particularly over the summer months.

ammonium hemlock hemlock woolly adelgid leaf litter nitrate nitrogen LTER controlled vocabulary inorganic nutrients 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=hf179 Simes Tract (Harvard Forest). Coordinates based on WGS84 datum. -72.22 -72.22 +42.47 +42.47 200 240 meter 2007 2009 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

1. Study sites: At each of two sites (A and B) in the Simes Tract of Harvard Forest (see map) we located a deciduous and hemlock forest stand. At site A, the hemlock and deciduous stands were within 100 m of each other. At site B the stands were within 600 m of each other. 2. Plot selection: Within each stand we selected 18 0.5 x 0.5 m plots (total 72 plots). We chose plots haphazardly, but with the following restrictions: (a) Must only be underneath hemlock canopy in H stands, and underneath deciduous canopy in D stands. (b) Within a stand, must be separated at least 7-10 m. (c) Flat(tish) (d) Without small trees or shrubs (e) No visible rocks or tree roots. 3. Treatments: We used reciprocal switching of the LFH horizons in 0.5 x 0.5 m plots from deciduous and hemlock stands to investigate how a shift in litter inputs and environments would influence inorganic nitrogen availability. There were six treatments, each with 3 replicate in each site (n=6 total): (1) Deciduous to deciduous switch (DD-swi), (2) Deciduous to hemlock switch (DH-swi), (3) Hemlock to hemlock switch (HH-swi), (4) Hemlock to deciduous switch (HD-swi), (5) Hemlock control (no switch) (HH-con), (6) Deciduous control (no switch) (DD-con). 4. Plots: We cut the LFH "litter loaves" as follows: I measured out plots (0.5 m x 0.5 m) with a quadrant, made initial cut with a bread knife, and then final cuts with a flat-edged spade. Small roots were cut with a saw. Rocks were left behind because they were usually big. We cut down to above the mineral layer of soil, and so the loaf consisted mainly of LFH horizons, although some A horizon was included. Loaves were a mean of 12.6 plus or minus 0.3 (SE) cm (n=48) in height. Loaves were lifted out of the ground and placed on an aluminum sheet, on top of a square of plywood. We measured the height of the soil and litter layer on each of the four sides of the loaves, and the height at the centre of the loaf (to the nearest cm) (Table 1). A 4-sided "cookie cutter" of aluminum flashing was placed around the litter loaf so it wouldn’t fall apart or lose litter while being moved around. Undisturbed controls were flagged but not cut. Litter loaves were switched haphazardly (we only made sure that adjacent plots weren’t ending up near each other) within or between forest types within each site. No across site switches were made. We carried the loaves on the plywood to the plot where they would be placed. The aluminum flashing cookie cutter was taken off the loaf, it was lifted off the plywood, still on top of the aluminum sheet, and placed in the hole. We then slid out the aluminum sheet, settled the loaf into the ground, and flagged each corner of the plot. 5. Plot loss: In site A, a HH-con and HD-swi plot were lost as the following spring it turned out they had been placed in spot where there is a shallow vernal pool. 6. Measurement of inorganic N in soil solutions: Ion-exchange resin bags were made by using rubber tubing to form a ring with a surface area of 64 cm2, placing the rubber ring in the toe of an (unenforced) nylon stocking, and measuring out 15 mL of ion-exchange resin (MTO-Dowex MR-3 LCNG) into the nylon bag. Bags were tied off securely. One resin bag was inserted below each litter loaf on 1 November, 2007. Resin bags were removed and new ones inserted on 22 May 2008, 1 Oct 2008, and 4 July 2009. At the time of collection 1, resin bags had disappeared or been damaged from 4 plots; at the time of collections 2 and 3 from 2 plots. These data are missing from the dataset. 7. Soil samples: In July 2009 humus samples were taken from the bottom of the litter loaf (~ 20g) for inorganic N measurements. At this point the flags were removed from the plots. An inadequate quantity of soil was taken from 3 plots, these data are missing from the dataset.

Resins: To determine NO3 and NH4 adsorbed to the resin surface, resins were dried, and then extracted with 100 mL of 2M KCl. Upon addition of KCl, bottles were shaken manually, and then placed on an orbital shaker for an additional 45 minutes. Extracts were filtered through #1 Whatman filters and frozen until analysis. NO3 and NH4 concentrations were determined colourimetrically on a Lachat flow injection analyzer (Lachat Instruments, Milwaukee, WI, USA). Soils: To determine extractable NO3 and NH4 concentrations from the humic fractions, ~ 10 g (fresh weight) of soil was extracted with 100 mL of 2M KCl. Samples were shaken with KCl for 1 hour, allowed to settle overnight (refrigerated), and filtered through Whatman #2 filter paper. NO3 and NH4 concentrations were determined as for resin extracts.

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. hf179-01-sample.csv treatment and sample information hf179-01-sample.csv 2327 a1000d21b754c15346c5f08323606988 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p17/hf179/hf179-01-sample.csv plot number assigned to each sample plot for analyses number assigned to each sample plot for analyses site site A site A B site B origin habitat where litter loaf was removed from H hemlock D deciduous destination habitat where litter loaf was inserted H hemlock D deciduous sample description of field plot of origin and destination. C = control; H=hemlock; D=deciduous. description of field plot of origin and destination. C = control; H=hemlock; D=deciduous. disturbance whether litter loaves were switched or remained in place (disturbance control) switch litter loaves were switched control litter loaves remained in place (disturbance control) treatment code describing each of the six treatments DD_swi deciduous to deciduous switch DH_swi deciduous to hemlock switch HH_swi hemlock to hemlock switch HD_swi hemlock to hemlock switch HH_con hemlock control (no switch) DD_con deciduous control (no switch) 70 hf179-02-resin.csv resin data hf179-02-resin.csv 16525 e85482fb7de3b3224daf1a5381b6bbad 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p17/hf179/hf179-02-resin.csv collection collection 1 1st resin bag installation and collection period 2 2nd resin bag installation and collection period 3 3rd resin bag installation and collection period plot sample plot code sample plot code site site A site A B site B treatment code describing each of the six treatments DD_swi deciduous to deciduous switch DH_swi deciduous to hemlock switch HH_swi hemlock to hemlock switch HD_swi hemlock to hemlock switch HH_con hemlock control (no switch) DD_con deciduous control (no switch) date.install date resin bag buried YYYY-MM-DD date.remove date resin bag retrieved YYYY-MM-DD days number of days resin bags were buried number 1 whole NA missing value no3 NO2/NO3 measured by Lachat milligramsPerLiter 0.001 real NA missing value nh4 NH4 measured by Lachat milligramsPerLiter 0.001 real NA missing value no3.blank Lachat measurement of blank for NO2/NO3 milligramsPerLiter 0.0001 real NA missing value nh4.blank Lachat measurement of blank for NH4 milligramsPerLiter 0.0001 real NA missing value volume volume of KCl used to extract resin liter 0.1 real NA missing value no3.day NO2/NO3 standardized as μg /day adsorbed by resin microgramPerDay 0.0001 real NA missing value nh4.day NH4 standardized as μg /day adsorbed by resin microgramPerDay 0.0001 real NA missing value 202 hf179-03-soil.csv soil data hf179-03-soil.csv 4420 4062509b83255cf1f7ecb7f9b5e3ab75 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p17/hf179/hf179-03-soil.csv plot sample plot code sample plot code site site A site A B site B treatment code describing each of the six treatments DD_swi deciduous to deciduous switch DH_swi deciduous to hemlock switch HH_swi hemlock to hemlock switch HD_swi hemlock to hemlock switch HH_con hemlock control (no switch) DD_con deciduous control (no switch) no3 NO2/NO3 measured by Lachat milligramsPerLiter 0.0001 real NA missing value nh4 NH4 measured by Lachat milligramsPerLiter 0.0001 real NA missing value no3.blank Lachat measurement of blank for NO2/NO3 milligramsPerLiter 0.0001 real NA missing value nh4.blank Lachat measurement of blank for NH4 milligramsPerLiter 0.0001 real NA missing value volume volume of KCl used to extract soil liter 0.1 real NA missing value mass.soil dry weight soil extracted gram 0.0001 real NA missing value no3.soil μg NO2/NO3 per g dry weight soil microgramsPerGram 0.0001 real NA missing value nh4.soil μg NH4 per g dry weight soil microgramsPerGram 0.0001 real NA missing value 67 hf179-04-map.jpg hemlock litter loaf map hf179-04-map.jpg 161991 fc5dbc19a655bfa0e650b82ef8ac54c3 jpeg https://harvardforest.fas.harvard.edu/data/p17/hf179/hf179-04-map.jpg image invasive soil short-term measurement microgramPerDay