uid=BNZ,o=lter,dc=ecoinformatics,dc=org all public read knb-lter-bnz.238.10 David W. Valentine

Department of Forest Sciences University of Alaska Fairbanks O'Neill Bldg Fairbanks AK 99775-7200 United States

(907) 474-7614 (907) 474-6184 dvalentine@alaska.edu http://www.uaf.edu/snras/departments/forestry/faculty/valentine/ Bonanza Creek LTER Data Manager

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 jpdowning@alaska.edu http://www.lter.uaf.edu 2007-03-01 This database reports soil respiration before and after the 1999 Frostfire experimental burn in watershed C4 of the Caribou-Poker Creeks Research Watershed. We measured soil respiration in three replicate pairs of sites (planned burned, control) in two vegetation types (black spruce, mixed hardwoods) using a LiCor 6262 infrared gas analyzer attached to semi-automated chambers (3 replicate chambers per site). Measurements began in summer 1998 and continued each growing season through 2004; in addition, we measured winter respiration during winter 1998-1999 using a different chamber design on top of the snow pack. All of the black spruce sites were located on Helmer's Ridge; the mixed hardwood sites initially were located on the east side of the C4 watershed or just outside its eastern boundary. Following the 1999 fire, all of the mixed hardwood sites were moved burned and unburned areas near the main trail ascending Helmer's Ridge. soil respiration wildfires Biogeochemistry

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http://www.lter.uaf.edu/data_detail.cfm?datafile_pkey=238 1998-06-24 2004-09-15

Completed

Bonanza Creek LTER Data Manager

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 jpdowning@alaska.edu http://www.lter.uaf.edu Bonanza Creek LTER

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 Bonanza Creek LTER

This work focused on two major vegetation types occurring in the C4 watershed within the CPCRW: closed canopy black spruce (CBS sites) and mixed hardwood (MH sites). Within each, we selected three replicate burn (B) and control (C sites). The experimental Frostfire burn in July 1999 did not burn any of the planned mixed hardwood burn sites and lightly burned one of the planned black spruce burn sites. The mixed hardwood sites (1-3) were abandoned and new sites (4-6) were established in and near the actual burned areas. Also, CBS-B4 was established to replace the lightly burned CBS-B2 site.

Summer: A chamber collar was permanently installed in each of 3 quadrants within each site. Each collar consisted of a rectangular polyethylene storage container from which the bottom had been removed; the remaining walls of the collar were inserted ~1 cm into the soil. Soil respiration was measured using a field-portable LiCor 6262 infrared gas analyzer plumbed to a chamber lid with a baffled fan to ensure a well-mixed headspace. At each sampling location, the lid was clipped onto the collar and allowed to equilibrate in the open position. Then the lid was cycled automatically 3 times between the open position (30 seconds) and the closed position (90 seconds), during which headspace [CO2] was continuously monitored in a closed loop with the LiCor. Calculation of respiration rate required three measurements: 1) the average rate of change in headspace CO2 concentration during the closed periods (only linear changes were used). 2) the volume of the chamber, measured as ?effective? volume? once each growing season based on the dilution of an injection of a known quantity of CO2 into the chamber headspace 3) the area of ground enclosed by the chamber, calculated based on the dimensions of the chamber collar (0.166 m2 in summer, 0.0716 m2 in winter) In later parts of the study, we also used shaded chambers in black spruce areas to zero out photosynthetic CO2 uptake and clipped plots in which all vascular vegetation was clipped at ground level. Both of these variants are noted in the dataset. Winter measurements also used a closed loop chamber system with a LiCor 6262, but did not use the buried chamber collars. Instead, a portable ~0.3 m diameter chamber was placed on the snow surface, and the CO2 efflux was calculated based on the slope of the headspace CO2 change during the 90 s enclosure. Instrumentation used: LiCor 6262

1998-06-24 2004-09-15

Generally biweekly during growing seasons; sampling was more intensve in 2000 and less intensive in 2004. One winter season (1999-2000) is also reported at a generally monthly frequency.

238_soil_respiration_new.csv 238_soil_respiration_new.csv 1 \n \n column , http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-bnz..&urlTail=/ascii/files/238_soil_respiration_new.csv Site Site Site of the observation String Site of the observation Quad Quad Quad number String Quad number Ch Ch Vascular plants inside chamber clipped or intact String A unclipped B clipped MeasType MeasType Dark (shaded) or transparent chamber String D dark L light (transparent) DateTime DateTime Date of observation string ddmmyyyy Resp Resp Soil respiration rate float mgCm^-2h^-1 real RespSE RespSE Std Error of the mean for soil respiration measurements float mgCm^-2h^-1 real