RAINFOR GEM Intensive Plots Manual (pdf) - University of Oxford

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numbers_observer, e.g. “cax_22.11.04_PA_1-25_paulo”) then press Y/R on the EGM-4 to commence the datatransfer. Open the saved file in Excel to verify that all the data has been transferred successfully. If the datatransfer is not successful try again a few times, check the USB to Serial connection, try other USB to Serialconverter cables, and/or try other Com Ports (File → Preferences → Com Port) 103 .Under default settings the EGM-4 will record each measurement for 120 sec (= 24 records) or a change inchamber CO 2 concentration of 50 ppm, whichever comes first. The EGM can store a maximum of 1000records, therefore if flux rates are not unusually high so that every measurement proceeds for the full period of120 sec, a maximum of 36 measurements (full records) may be stored. If measurements proceed beyond thispoint the EGM-4 will begin to overwrite the oldest stored data: DO NOT LET THIS HAPPEN! ALWAYS SAVEALL DATA FROM EACH MEASUREMENT IN A FILE.Any problems with the EGM-4 or SRC-1, PP Systems are at 110 Haverhill Road, Suite 301, Amesbury, MA01913, USA, Tel: +1 978 834 0505, Email: support@ppsystems.com.*** PLEASE REMEMBER WHEN USING AN IRGA MACHINE: ****** !! NO SMOKING !! ***n.b. EGM-4 machines record CO 2 flux in units of g CO 2 m -2 h -1 and 1 g CO 2 m -2 h -1 is equivalent to(12.011/44.01=)0.27 g C m -2 h -1 or (1000000/(44.01*60*60)=)6.31 µmol C m -2 s -1 .103 Sometimes the computer is unable to open the Com Port because the port the program is using is not the same as the one thecomputer has made available. If so, look in My Computer → Properties → Hardware → Device Manager, check Ports (COM & LPT)and see if the number is different from that in the Transfer Program, then right click on the Port → Properties → Port Settings →Advanced Options and change the number to the desired one and click OK.74
CO 2 efflux calculationsWhile the EGM-calculated values are useful (and should be noted), you should always directly calculate yourfluxes from the raw data (the .dat file). To do so, take only the last 10 records of any individual measurement,verify that there is an approximately linear increase in CO 2 over time (open the .dat file in Excel and check byplotting CO 2 concentration (“CO2 Ref”) against time (“Input E”)), and use the following equation 104 105 :RucCPV10 1d= *g CO 2 m -2 h -1t10− C− t144.01* 0.36( Ta+ 273.15) A RuWhere R uc is uncorrected CO 2 efflux (g CO 2 m -2 h -1 ), t 10 and t 1 are the times (sec) since that measurement beganat records 10 and 1 chosen respectively (e.g. record 1 could be 86 s after measurement began and record 10 thefinal record of this measurement after 124 s), C 10 and C 1 are CO 2 concentrations (ppmv) at times t 10 and t 1 , P isambient pressure at time t 10 (mb, e.g. ~1013.25 mb at sea level) and T a is air temperature at time t 10 (°C). TheSRC-1 chamber volume V d is 0.0012287 m 3 from measurement of the SRC-1 and the upper part of the adapter104 The Ideal Gas Law states that n moles of any gas at ambient pressure P mb and temperature T a °C will occupy Vol m 3 whereVolnR( T + 273.15)u a= (R u =8.31432 J mol -1 K -1 is the Universal Gas Constant). Therefore, at time t 1 the CO 2 occupies a volumeCV1000000100Pn R1 1 u a+d( T 273.15)= m 3 .100PBetween times t 1 and t 10 the CO 2 concentration rises from C 1 to C 10 ppmv, so the number of moles CO 2 that enter thechamber during this time is10− nC10 − C1100P1Vd1000000 R−u( T + 273.15) ( t t )Aa1C10− C1= V1000000C10− C1100P1Vd* 44.01*36001000000 Ru( Ta+ 273.15) ( t10− t1) AC10− C1P 273Ruc* *t − t 1000 T + 273dRu( T + 273.15)75100Pn mol CO 2 . This equates to a molar flux of101amol CO 2 m -2 s -1 . The molar mass of CO 2 is 44.01 g/mol so this is equivalent tog CO 2 m -2 h -1 .44.01*3.6105 Metcalfe et al. (2009) hadd* *( ) A 22. 41101aV= g CO 2 m -2 h -1 but the 22.41 L there was forold Standard Temperature and Pressure (0°C, 1013 mb) when it should have been for new STP (0°C, 1000 mb) which would havebeen 22.7 L. These forms are essentially equivalent through the value of R u ≈100*22.41/273.
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Measuring Tropical ForestCarbon All
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ContentsTHE RAINFOR-GEM INTENSIVE C
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The RAINFOR-GEM Intensive Carbon Mo
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What are the RAINFOR-GEM protocols?
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Where can I get data from existing
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Two RAINFOR-GEM hectare plots in th
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1.2 Setting out the plotSubplot cor
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An example surveying path (cf. Cond
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Required for jobs that can be sched
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Tree #487 in Fragment E plot where
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1.4 Tagging small trees*** Note tha
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does, measure underneath the lean o
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Measuring a liana at three points i
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BOX 2: Five unusual trees.Example 1
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Example 3: Here is a large liana on
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1.5 Tree heightTree height should b
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1.6 Sketch map of the plotAt this p
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2. BELOW GROUND MEASUREMENTSWe star
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Next, insert the cylindrical core i
Page 41 and 42: BOX 3: How to make an in-growth cor
Page 43 and 44: 2.2 RhizotronsRoot observation pits
Page 45 and 46: sure that it covers the hole but no
Page 47 and 48: An example rhizotron transparency f
Page 49 and 50: Analysis: First, calculate the sum
Page 51 and 52: A metallic rhizotron as in use at t
Page 53 and 54: 2.3 Coarse rootsNeither in-growth c
Page 55 and 56: 3. CO 2 EFFLUX3.1 Total soil CO 2 e
Page 57 and 58: 3.2 Stem CO 2 effluxFirst, choose t
Page 59 and 60: e related to stem growth) to check
Page 61 and 62: Equipment: IRGA and SRC-1, PVC coll
Page 63 and 64: Control No litter Double litterNo e
Page 65 and 66: the S3 hole. Finally, discard the l
Page 67 and 68: 3.4 Coarse woody debris (CWD) CO 2
Page 69 and 70: 4.2 Coarse woody debris (CWD) surve
Page 71 and 72: all of the large, marked wood piece
Page 73 and 74: Equipment: 25 litter traps per ha (
Page 75 and 76: this select the straight line drawi
Page 77 and 78: http://www.eci.ox.ac.uk/research/ec
Page 79 and 80: • The tripod is level so that the
Page 81 and 82: 8. WEATHER AND CLIMATELocal climate
Page 83 and 84: Luiz Aragão repairing an understor
Page 85 and 86: 10. DATA ENTRY AND SERVER UPLOADA c
Page 87 and 88: APPENDIX I: RAINFOR-GEM Fieldwork c
Page 89 and 90: APPENDIX II: How to use an EGM-4 In
Page 91: • Remember to change the switch i
Page 95 and 96: The volume V airspace (stippled) be
Page 97 and 98: CO 2 flux measurements with EGM: A
Page 99 and 100: Downloading dataEGM memory can stor
Page 101 and 102: APPENDIX III: Possible schedule of
Page 103 and 104: Gerwing JJ, Schnitzer SA, Burnham R
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