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48 Q10 R 2 p Rs 2.51 0.77 0.000 Ra 2.23 0.60 0.05 Rh 2.72 0.71 0.000 Table 1. Overall (2006-2008) Q10 values obtained from the response of soil respiration of different origin to changes in soil temperature. The data at SWC20%) 2.97 0.92 2.20 0.71 3.22 0.85 April-June 1.77 0.65 2.27 0.3 1.67 0.28 July-September 0.37 0.52 3.32 0.26 0.18 0.44 October-Jannuary 6.69 0.91 1.77 0.42 12.18 0.91 Table 2. Soil respiration Q10 values calculated for each treatment (total soil respiration (Rs); root-derived respiration (Ra); microbial-derived respiration (Rh) for various periods of the growing season 2007. MBC variation is represented in figure 9. October experienced higher values of MBC in confront with June. µg Biomass (C g -1 ) 800 700 600 500 400 300 200 100 0 +21% June October Fig. 9 Changes in microbial biomass C (MBC) during the growing season 2006 (± SE). % indicates an augment in MBC, taking June sampling as a reference.
The influence of moisture on soil respiration was more complex than temperature. In order to remove the temperature effect and examine the single moisture effect on soil CO2 efflux, soil respiration was normalized by soil temperature at a reference value 15 o C: Rx15= RxQ10 (15-T)/10 where Rx15 is the normalized respiration flux, Rx is the measured respiration, T is the measured soil respiration. normalized CO 2 (µmol m -2 s -1 ) 10 8 6 4 2 0 10 15 20 25 30 35 40 45 -2 Rs Rh Ra SWC (%) Fig. 10 Normalized total, root- and microbial-derived soil respiration vs. soil moisture measured in 2006-2007- 2008. From figure 10 is clear that soil moisture had two opposite effects on total and microbial soil respiration. When soil moisture was below critical value (below 25%), soil respiration increased with moisture, but it decreased when the soil moisture was greater than 35%. The negative correlation at high levels of SWC is probably associated with a decrease in soil air porosity and oxygen availability in soils which influence negatively microbial decomposition activity. No negative effect of high SWC was observed on root-derived respiration. To verify the effect photosynthetic C supply on soil CO2 efflux of different origin the data from the partitioning experiment were plotted vs. GPP from the eddy covariance. Pearson correlations were performed between the means of normalized and non normalized values of root- derived respiration fluxes and the mean values of GPP 0–7 days prior to each respiration measurement date. Linear regressions analyses were performed for the days where Pearson correlations showed peak values. Significant correlations between GPP and root-derived respiration were observed. Peaks in correlation strength correspond to time shifts between the C uptake through 49
Page 1: !!"% ( !"+ "!$ (!'! ,' - !"+ "!$ ##
Page 4 and 5: explain diurnal and seasonal change
Page 6 and 7: sull’intensità del flusso respir
Page 8 and 9: 8 3.2.4. Data analyses and definiti
Page 11 and 12: 1. INTRODUCTION AND OVERVIEW 11
Page 13 and 14: times as much carbon as the terrest
Page 15 and 16: Fig. 3 Different soil C pools with
Page 17 and 18: 1.3. Soil respiration sources Soil
Page 19 and 20: conditions, like soil type, plants
Page 21 and 22: For grasslands, the nature, frequen
Page 23 and 24: (a) (b) (c) Fig.7 Amplero (AQ, Ital
Page 25 and 26: magnitude of root respiration and o
Page 27 and 28: efficiency, indicating future posit
Page 29 and 30: approaches for studying of the cont
Page 31 and 32: Houghton R.A., 2003. Revised estima
Page 33: Vleeshouwers L.M., Verhagen A. 2002
Page 36 and 37: 2.1. Introduction 36 Soil respirati
Page 38 and 39: 38 In the year 2005 ten PVC collars
Page 40 and 41: 2.2.4. Biochemical analyses Microbi
Page 42 and 43: 42 Variation of soil respiration fr
Page 44 and 45: CO 2 efflux (mmol m -2 s -1 ) 44 CO
Page 46 and 47: 46 All diurnal measurements of root
Page 50 and 51: the photosynthesis and its followin
Page 52 and 53: 2.3.3. Inter-annual variation of so
Page 54 and 55: 54 RS RHET 8 6 6 4 25 4 2 2 25 20 T
Page 56 and 57: 2.4. Discussion 2.4.1. Partitioning
Page 58 and 59: measurements, the possibility to fi
Page 60 and 61: and Schlesinger, 1992; Moyano et al
Page 62 and 63: Janssens I.A., Pilegaard K., 2003.
Page 64: Xu X., Kuzyakov Y., Wanek W., Richt
Page 67 and 68: 3.1. Introduction Soil respiration
Page 69 and 70: Our experiment was conducted in a m
Page 71 and 72: Lactic acid 13 C 13 CO2 Root-derive
Page 73 and 74: At the end of the process, the subl
Page 75 and 76: where, MAs - the mean age of the co
Page 77 and 78: 13C of respiration ( o / oo ) 155 1
Page 79 and 80: Total Label Recovered (TLR, %) Ra R
Page 81 and 82: GPP (mmol m -2 s -1 ) 25 20 15 10 5
Page 83 and 84: frequent and possibly they missed t
Page 85 and 86: 3.4.3. Destructive vs. Non-destruct
Page 87 and 88: Gavrichkova O., Kuzyakov Y., 2008.
Page 90 and 91: Chapter source: 90 4. THE EFFCT OF
Page 92 and 93: Bardgett et al. (1997) showed that
Page 94 and 95: 94 Partitioning plots were installe
Page 96 and 97: Microbial C was calculated as a dif
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taken from 1 µg N-NO2 ml -1 soluti
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ates between clipped and unclipped
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Fig. 7 Total (Rs), root (Ra)- and m
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104 Rh, (CO 2 , mmolm -2 s -1 ) 7 6
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Fig. 11 Cumulative microbial respir
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108 After the calculation of synthe
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Fig. 16: a) Relationship between sy
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an annual mowing the measurement wa
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mineral N available to plants and N
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Cambardella C.A., Elliott E.T., (19
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Rice C.W., Moorman T.B., Beare M, 1
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120
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5.1. Introduction 122 Nitrogen (N)
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specie, c) an additional aim was to
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5.2.4. Sampling and analyses 126 Na
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the differences between N and contr
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130 specific root respiration (max
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Fig. 4 a) Intensity of 14 CO2 efflu
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Fig. 6 a) values above zero: root-d
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136 Zea mays: A clear diurnal dynam
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plants. The growth stage could cont
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nitrates. At temperatures of 15 - 2
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experiment could be responsible for
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Horwath W.R., Pretziger K.S., Paul,
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146
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148 6.1 . Introduction In studies o
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Regression analyses technique, whic
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152 The respiratory response with g
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154 100% 80% 60% 40% 20% 0% 85% 13%
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6.3.2. 2008: Mesh- exclusion vs. re
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6.4. Discussion 6.4.1. Mesh-exclusi
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introduction in a small soil sample
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component, expressing a total soil
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Kucera C.L., Kirkham D.R., 1971. So
Page 166:
Acknowledgements This work was poss
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