| Data Set Citation |
Rowlings D of Institute for Sustainable Resources, Queensland University of Technology.Daily GHG fluxes from a subtropical rainforest. Mooloolah, Queensland, 2007-2009 [ARC Discovery].
Rowlings.22.9
(http://www.n2o.net.au/knb/metacat/Rowlings.22.9/default).
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| Data Set Owner(s): |
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Individual: | Dr. David Rowlings |
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Organization: | Institute for Sustainable Resources, Queensland University of Technology |
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Position: | Principal Investigator |
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| Gardens Point campus, 2 George St, |
| Brisbane, Queensland 4001 Australia |
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| Associated Party: |
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Individual: | Ms. Siobhann McCafferty |
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Organization: | Institute for Future Environments, Queensland University of Technology |
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Position: | Data Librarian |
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| 2 George Street, |
| Brisbane, QLD 4000 Australia |
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| Abstract: |
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| Soil-atmosphere exchange of CO2, CH4 and N2O was measured over two consecutive years from a subtropical rainforest in South-Eastern Queensland, Australia using an automated sampling system. Interannual variation in fluxes of all gases over the 2 years was minimal despite large discrepancies in rainfall, while a pronounced seasonal variation could only be observed for CO2 fluxes. High infiltration, drainage and subsequent high soil aeration under the rainforest limited N2O loss while promoting substantial CH4 uptake. The average annual N2O loss of 0.5 ± 0.1 kg N2O-N ha-1 over the two year measurement period was at the lower end of reported fluxes from rainforest soils. The rainforest soil functioned as a sink for atmospheric CH4 throughout the entire two year period despite periods of substantial rainfall. A clear linear correlation between soil moisture and CH4 uptake was found. Rates of uptake ranged from greater than 15 g CH4-C ha-1 day-1 during extended dry periods to less than 2-5 g CH4-C ha-1 day-1 when soil water content was high. The calculated annual CH4 uptake at the site was 3.65 kg CH4-C ha-1 year-1. This is amongst the highest reported for rainforest systems, reiterating the ability of aerated subtropical rainforests to act as substantial sinks of CH4.
A spatial study involving 30 manual chambers distributed across three remnant rainforest sites with similar vegetation and climatic conditions showed N2O fluxes almost 8 times higher and CH4 uptake reduced by over one third as clay content of the rainforest soil increased from 12% to 23%. An exponential relationship was found between N2O flux and percent clay content (r2 = 0.57) across the 30 chambers. This demonstrates that for some rainforest ecosystems soil texture and related water infiltration and WFPS constraints may play a more important role in controlling fluxes than either vegetation or seasonal variability. |
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| Keywords: |
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- N2O
- Nitrous oxide
- CH4
- CO2
- Subtropical gallery rainforest
- Soil texture
- Auto Chambers
- Mooloolah
- QLD
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| Thesaurus: | anzsrc-for |
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| License and Usage Rights: |
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| permission required from data owner |
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| Geographic Coverage: |
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Geographic Description: | Mooloolah, Queensland |
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Bounding Coordinates:
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| West: | 152.97 degrees
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| East: | 152.97 degrees
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| North: | -26.76 degrees
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| South: | -26.76 degrees
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| Temporal Coverage: |
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Begin:
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End:
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| Contact: |
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Individual: | Professor Peter Grace |
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Organization: | Institute for Sustainable Resources, Queensland University of Technology |
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Position: | Director ISR |
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Address: |
| 2 George St, |
| Brisbane, Queensland 4001 Australia |
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| Methods Info: |
| Step 1: |
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Description:
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| Automatic Chambers |
This system consisted of pneumatically operated static chambers (non-steady-state, non-through-flow), linked to an automated sampling system and a gas chromatograph. The clear acrylic glass chambers covered a surface area of 0.25 m2 (500 mm x 500 mm) with a height of 150 mm and were secured to stainless steel bases inserted permanently into the soil to a depth of 100 mm. Three replicate sampling chambers were randomly placed within an area roughly 5 x 4 metres within a larger 20 m x 30 m experimental plot. A transparent tinted plastic coating was placed on the lids to reduce heat build-up within the chambers when closed. A tipping bucket rain gauge (Davis Instruments Corp. CA, USA) connected to the system allowed for automated opening of the lids during rainfall events.
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| Step 2: |
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Description:
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| Greenhouse Gas Flux Measurement |
Nitrous oxide and CH4 concentrations were determined using a gas chromatograph (SRI GC8610, Torrance, CA, USA) equipped with 63Ni Electron Capture Detector for N2O and a Flame Ionisation Detector for CH4. Carbon dioxide was measured continuously with a non dispersive infrared CO2 analyser (LI-820; LI-COR, Lincoln Nebraska, USA). To minimize interference from moisture vapour and CO2 on N2O measurement, a precolumn filled with sodium hydroxide coated silica was installed ahead of the analytical column and changed regularly.A full measurement cycle for flux determination commenced with lid closure and finished when the lids opened 48 minutes later. The lids remained open for a further 96 minutes before the commencement of the next cycle. Fluxes of N2O, CH4 and CO2 were calculated from the slope of the linear increase or decrease in concentrations within the chambers over the closure time. An optimization function was used that selected the best regression coefficient (r2) from either 3 or 4 of the measured gas concentrations. Flux rates were discarded if the r2 was <0.81 for N2O and CH4 and <0.90 for CO2. The flux rate was then calculated and corrected for air temperature during measurement and site pressure using the procedure outline by Barton et. al. (2008).
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Instrument(s):
| Gas chromatograph (SRI GC8610, Torrance, CA, USA) equipped with 63Ni Electron Capture Detector for N2O and a Flame Ionisation Detector for CH4. |
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Instrument(s):
| Non dispersive infrared CO2 analyser (LI-820; LI-COR, Lincoln Nebraska, USA). |
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Description:
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| Water Content and Soil Temperature |
A FDR (EnviroSCAN Sentek, Stepney, South Australia) moisture probe located centrally to the chambers recorded half-hourly readings of volumetric water content (5-10 cm) while soil temperature (10 cm) was measured at 5 minute intervals (Hobo Pendant temperature/light data logger, Onset Computer Corporation).
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Instrument(s):
| A FDR moisture probe (EnviroSCAN Sentek, Stepney, South Australia). |
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Instrument(s):
| Hobo Pendant temperature/light data logger, Onset Computer Corporation. |
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Description:
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| Climate Data Collection |
For climate data an automatic weather station (Davis Instruments Corp. CA, USA) installed nearby recorded half-hourly rainfall, temperature, relative humidity and wind speed and direction values
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Instrument(s):
| A FDR moisture probe (EnviroSCAN Sentek, Stepney, South Australia). |
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Instrument(s):
| Hobo Pendant temperature/light data logger, Onset Computer Corporation. |
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Sampling Area And Frequency:
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| 01 March 2007 - 28 February 2009
Humid subtropical, Mooloolah, Queensland, Australia. |
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Sampling Description:
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| Access Control: |
| Auth System: | knb |
| Order: | allowFirst |
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[all]
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[read]
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