uid=HFR,o=lter,dc=ecoinformatics,dc=org all public read doi:10.6073/pasta/5867ab3f5de90cb2a7366660e06f8399 Peter Raymond https://orcid.org/0000-0002-8564-7860 William Sobczak Emery Boose https://orcid.org/0000-0003-4820-0231 Researcher 2023 English

Headwater streams make up greater than 80% of total channel length in the United States and play important roles in regulating nutrient, organic matter, and sediment fluxes from terrestrial to downstream ecosystems. Headwater streams are common features of many upland-forested watersheds in New England, yet are not explicitly factored into forest water, carbon, and nutrient budgets. Here we report on recent efforts to examine terrestrial and stream ecosystem linkages in carbon biogeochemistry in a hemlock-dominated watershed. A prototype stream biogeochemical system (SBS) was tested at the Harvard Forest LTER. The SBS allows a suite of stream water properties to be characterized in real-time over extended periods of time thus allowing questions to be asked at a wide range of time scales. The prototype SBS was field-tested in Bigelow Brook West on the Prospect Hill research tract at Harvard Forest. Bigelow Brook West was selected because the watershed’s hydrology, stream ecology, forest composition, land-use history, and carbon sequestration have been characterized, thus aiding the interpretation of SBS data and facilitating multi-disciplinary research. The prototype system monitors stream and air temperature, pCO2 , colored dissolved organic matter, total suspended sediments, PAR, water depth, pH, and dissolved O2. Independent estimates of organic and inorganic water chemistry were used to validate and interpret SBS data. Here we report on preliminary findings from the pilot SBS at Harvard Forest to highlight the usefulness of headwater stream chemistry data to a wide-diversity of ecosystem scientists. 1) Low pH constrains dissolved inorganic carbon solute fluxes to downstream ecosystems. 2) CO2 concentrations were always supersaturated in Bigelow Brook, averaging about 6x atmospheric values in summer, thus the stream is an important source of CO2 to the atmosphere. Variation in CO2 appears to be linked to multiple mechanisms including changes in stream temperature, soil CO2, and in-stream processes. 3) Diurnal variation in stream dissolved oxygen concentrations is linked to both in situ stream processes and watershed processes, such as evapotranspiration. 4) Colored dissolved organic matter (CDOM) concentrations were tightly linked to discharge with concentrations increasing with discharge. The surprising additive effect of increasing DOC concentration with discharge cause DOC fluxes to increase non-linearly with water fluxes in Bigelow Brook. 5) Low inorganic N and P concentrations suggest that organic N and P may account for a disproportionate fraction of N and P fluxes to downstream ecosystems. Preliminary SBS data have already altered our conceptual model regarding terrestrial and aquatic linkages in the Bigelow Brook watershed and have illuminated a fundamental lack of understanding of the mechanisms regulating diurnal and storm-driven stream water chemistry in hemlock-dominated watersheds.

biogeochemistry carbon carbon dioxide nitrogen oxygen ph phosphorus storms stream discharge LTER controlled vocabulary organic matter 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=hf043 Prospect Hill Tract (Harvard Forest). Coordinates based on WGS84 datum. -72.20 -72.17 +42.55 +42.53 280 420 meter 2006 2007 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

The proto-type system monitors stream and air temperature, pCO2 (IR detector with an air headspace equilibrator, gas standard tanks are included for standardized measurements), pH in triplicate (therefore allows for the calculation of carbonate alkalinity and dissolved inorganic carbon with monthly on site calibration), colored dissolved organic matter (CDOM; fluorescence measurement which can be used as a proxy for DOC), total suspended sediments (TSS), chlorophyll a (by fluorescence), PAR, water flux (estimated from water depth) and dissolved O2 (using an optode). The control unit (Campbell Scientific CR3000, with programmable valves) can be programmed to measure these variables at any time interval. The current system can run for ~1 month using two marine batteries and making measurements every 2 hours. In addition, we have independently characterized stream chemistry with monthly grab samples in which the following constituents are analyzed: dissolved organic C (Shimadzu high-temperature combustion), N, and P, and inorganic N and P (EPA methods 350.1, 353.2, and 365.1 using an Astoria2 segmented flow analyzer).

The Harvard Forest has initiated long-term hydrological studies on two small headwater streams in the Prospect Hill Tract. The upper watershed on Bigelow Brook (the focus of this biogeochemical data set) comprises 24 ha of upland forest with no large wetlands. For details see dataset HF070.

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. hf043-01-chemistry.csv water chemistry hf043-01-chemistry.csv 9618 2ae4fac4edab14e77576821510c33882 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p04/hf043/hf043-01-chemistry.csv stream stream location Head of Flow groundwater input to Bigelow Brook West Upper Weir headwaters of Bigelow Brook West Lower Weir downstream of beaver wetland along Bigelow Brook Bigelow Brook (East) Bigelow Brook East @ road Nelson Brook Nelson Brook weir date date YYYY-MM-DD am.pm am or pm AM ~ 10:00am PM ~ 4:00pm time time sampled during storm events hh:mm NA missing value doc dissolved organic carbon milligramsPerLiter 0.01 real NA missing value total.n NO3 + NH4 + Dissolved organic N milligramsPerLiter 0.001 real NA missing value no3 nitrate. Note: values below the detection limit of 0.02 mg/L are reported as 0.01 mg/L. milligramsPerLiter 0.001 real NA missing value nh4 ammonium. Note: values below the detection limit of 0.005 mg/L are reported as 0.001 mg/L. milligramsPerLiter 0.001 real NA missing value total.p PO4 + dissolved organic P microgramsPerLiter 0.1 real NA missing value po4 PO4. Note: values below the detection limit of 0.2 ug/L are reported as 0.1ug/L. microgramsPerLiter 0.1 real NA missing value bod biological oxygen demand (mg O2/ L) following 5 day incubation milligramsPerLiter 0.01 real NA missing value per.bioavailability doc (as a function of BOD and DOC concentration) dimensionless 0.01 real NA missing value 146 hf043-02-ph-temp.csv ph and temperature hf043-02-ph-temp.csv 28618 10c3be5a2e411e03c608a0b650f9f511 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p04/hf043/hf043-02-ph-temp.csv time date and time YYYY-MM-DDThh:mm NA missing value temp water temperature celsius 0.01 real NA missing value ph pH dimensionless 0.001 real NA missing value 970 hf043-03-co2.csv CO2 hf043-03-co2.csv 23818 cb76f27771e4545cc765792460080578 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p04/hf043/hf043-03-co2.csv time date and time YYYY-MM-DDThh:mm NA missing value co2 carbon dioxide micromole 0.01 real NA missing value 961 hf043-04-cdom-o2.csv cdom and O2 hf043-04-cdom-o2.csv 190988 69aa0af5004f1eb03259d8f97066f01e 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p04/hf043/hf043-04-cdom-o2.csv time date and time YYYY-MM-DDThh:mm NA missing value cdom colored dissolved organic matter millivolt 0.001 real NA missing value o2 dissolved oxygen micromole 0.1 real NA missing value temp water temperature celsius 0.001 real NA missing value per.sat.o2 percent saturation of dissolved oxygen dimensionless 0.001 real NA missing value 4565 watershed short-term measurement https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=hf070 micromole