Sapwood Temperatures in Hemlock Trees at Harvard Forest HEM Tower 1997-1998

doi:10.6073/pasta/819fcd63dbd53b3918cd980e47e19e8f Sapwood Temperatures in Hemlock Trees at Harvard Forest HEM Tower 1997-1998 Julian Hadley 2023 English

Sapwood temperatures in four large hemlocks, 130-200 years old and about 40 to 90 cm basal diameter and 25 to 29 m tall, were measured in order to estimate sapwood respiration in these trees as part of a physiological model for hemlock forest carbon exchange. As expected, sapwood temperature varied most in small branches and least in the main bole of the tree near the ground. An additional finding from these measurements is that sapwood begins to freeze at -1 to -2 degrees C, as shown by a stabilization and in some cases an increase of about 1 degree C in sapwood temperature when air temperature cooled continuously to below this temperature range.

plant physiology temperature wood 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=hf156 Prospect Hill Tract (Harvard Forest). Coordinates based on WGS84 datum. -72.180 -72.180 +42.539 +42.539 355 355 meter 1997 1998 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

Type T (copper-constantan) thermocouples were made by twisting and then soldering 20 gauge thermocouple wire of this type, supplied by Omega, Stamford, CT, USA. Branches were selected in the upper, middle, and lower canopies of the four trees, on the S, W, N, and E sides of each tree, except that the side of each tree facing the canopy access tower in the middle were not sampled. Thermocouples were inserted either at the midpoint between the branch base and end, or at the furthest point that a person with feet resting on a branch base could reach. In the bole, thermocouples were inserted at 1.25 m above ground, at the level of the lowest live branches (15-18 m above ground), and about 2 m below the top of each tree, on the side of the tree facing the canopy-access tower. Holes 1.5 cm deep were drilled into the sapwood in order to insert the thermocouples. Thermocouples were connected to one of three dataloggers (Model CR10, Campbell Scientific, Logan, UT, USA) on the tower, by type T thermocouple extension wires, between 5 and 15 m long. Sapwood temperatures at each location was measured every 60 seconds, and an average calculated once per hour. Air temperature was measured and averaged at the same frequency, using a shaded 20-gauge thermocouple 22 m above ground, about midway the levels of upper- and mid-canopy sapwood thermocouples.

Harvard Forest Long-Term Ecological Research 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. hf156-01-sapwood-temp.csv sapwood temperature hf156-01-sapwood-temp.csv 9776195 7f3b619fca80efe07860298a9fa56274 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p15/hf156/hf156-01-sapwood-temp.csv datetime date and time YYYY-MM-DDThh:mm year year YYYY doy day of year nominalDay 1 natural NA missing value hour hour at end of measurement interval hh:mm ac.tair above canopy air temperature celsius 0.001 real NA missing value tree.num tree number tree number location location on tree UC upper canopy MC middle canopy LC lower conopy LB lower bole direction side of tree from which measurement was taken N north S south E east W west sapwood.temp sapwood temperature celsius 0.001 real NA missing value 190296