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94 Partitioning plots were installed both, in MG and UM plots. Inside each fence were placed 2 complete partitioning plots: one in 2006 and one in 2007, the same was done for managed soil outside the fences. Modified after Leake et al. (2004) and Moyano et al. (2007, 2008) root-exclusion technique was used to partition the CO2 efflux from soil. A complete partitioning plot is shown in Fig.2 Fig.2 Schematic description of the modified root-exclusion technique. One complete partitioning plot is represented • Soil cores, 20 cm in diameter and 30 cm deep were sampled; the soil was sieved through 4 mm mesh and all the roots were carefully removed from the soil. • Half of the sampled soil was placed to the nylon meshes with 1µm pore size and returned to the study site. The CO2 measured from these meshes was considered as respiration associated with microbial decomposition of SOM – microbial-derived respiration (Rh) after disturbance. • Another half of the sampled and sieved soil was placed back without any barriers for the roots growing (bags with 1.0cm pore size). The CO2 efflux, coming from these bags is a sum of microbial and root-derived respiration (Rh+Ra). • Root-derived respiration was calculated as a difference between these two treatments: ((Rh+Ra)-Rh). • Total soil respiration (Rs) measured from the undisturbed soil was used as a control and in Summarizing: 1µm pore mesh combination with root-derived respiration was used to calculate the real microbial-derived respiration, excluding the effect of soil sieving: (Rs – Ra). 1µm = microbial-derived respiration (Rh), after disturbing 1 cm = sum of microbial and root-derived respiration (Rh+Ra) 1cm - 1µm = root-derived respiration (Ra) No mesh = control for total respiration (Rs) 1 cm pore mesh Control - Ra = microbial derived respiration (Rh), real one Rh Ra+Rh control
4.2.3. Soil chemical and biochemical properties Soil sampling was performed twice in the year 2006: just after the mowing at the end of June and four months after the mowing in the beginning of October. For each sampling date 16 soil cores were collected: 2 soil samples inside each fenced area, 8 in total (unmanaged, UM), and 2 soil samples outside the fences, 8 in total (mowed and grazed, MG). MG soils were sampled at least 5m away from the fences. The following analyses were performed: total organic C (TOC), total N (TN), microbial biomass C (MBC), extractable C (Cext), the potential microbial respiration measured during a 28 days incubation, short nitrification assay as a measure of nitrogen mineralization activity (SNA) and eight soil enzymatic activities related to C,N, P and S cycling. Physical analyses Soil water content 5 g field-moist soil samples were weighed in ceramic pots. Soils were placed in an oven at 105 °C. After 24 hours soils were removed from the stove and weighed again. Soil water content was referred to the fresh weight. Water holding capacity Soil samples were saturated with water in a cylinder. The cylinder was tapped in the bottom by filter paper until the excess water was drawn away by gravity. After 24 h, when equilibrium was reached, the water holding capacity was calculated based on the weight of the water held in the sample vs. the sample dry weight. Chemical analyses Total Organic Carbon (TOC) and Total nitrogen (TN) TOC and TN were determined only in June 2006 in 20 mg of dry soil after HCl addition with a C/N soil analyzer (FlashEA 1112 Series, Thermo Electron Corporation). Biochemical analyses Microbial Biomass C For MBC determination the Fumigation Extraction method (Vance et al., 1987) was used. In brief, two portions of moist soil (20 g oven-dry soil) were weighed, the first one (non fumigated) was immediately extracted with 80 ml of 0.5M K 2 SO 4 for 30 min by oscillating shaking at 200 rpm and filtered with filter paper (Whatman n. 42); the second one was fumigated for 24h at 25 °C with ethanol-free CHCl3 and then extracted as described above. Organic C in the fumigated and non fumigated extracts was determined after oxidation with 0.4 N K 2 Cr 2 O 7 at 100°C for 30 min. 95
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explain diurnal and seasonal change
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sull’intensità del flusso respir
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8 3.2.4. Data analyses and definiti
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1. INTRODUCTION AND OVERVIEW 11
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times as much carbon as the terrest
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Fig. 3 Different soil C pools with
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1.3. Soil respiration sources Soil
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conditions, like soil type, plants
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For grasslands, the nature, frequen
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(a) (b) (c) Fig.7 Amplero (AQ, Ital
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magnitude of root respiration and o
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efficiency, indicating future posit
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approaches for studying of the cont
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Houghton R.A., 2003. Revised estima
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Vleeshouwers L.M., Verhagen A. 2002
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2.1. Introduction 36 Soil respirati
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38 In the year 2005 ten PVC collars
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2.2.4. Biochemical analyses Microbi
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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 48 and 49: 48 Q10 R 2 p Rs 2.51 0.77 0.000 Ra
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Page 54 and 55: 54 RS RHET 8 6 6 4 25 4 2 2 25 20 T
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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
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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 96 and 97: Microbial C was calculated as a dif
Page 98 and 99: taken from 1 µg N-NO2 ml -1 soluti
Page 100 and 101: ates between clipped and unclipped
Page 102 and 103: Fig. 7 Total (Rs), root (Ra)- and m
Page 104 and 105: 104 Rh, (CO 2 , mmolm -2 s -1 ) 7 6
Page 106 and 107: Fig. 11 Cumulative microbial respir
Page 108 and 109: 108 After the calculation of synthe
Page 110 and 111: Fig. 16: a) Relationship between sy
Page 112 and 113: an annual mowing the measurement wa
Page 114 and 115: mineral N available to plants and N
Page 116 and 117: Cambardella C.A., Elliott E.T., (19
Page 118 and 119: Rice C.W., Moorman T.B., Beare M, 1
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Page 122 and 123: 5.1. Introduction 122 Nitrogen (N)
Page 124 and 125: specie, c) an additional aim was to
Page 126 and 127: 5.2.4. Sampling and analyses 126 Na
Page 128 and 129: the differences between N and contr
Page 130 and 131: 130 specific root respiration (max
Page 132 and 133: Fig. 4 a) Intensity of 14 CO2 efflu
Page 134 and 135: Fig. 6 a) values above zero: root-d
Page 136 and 137: 136 Zea mays: A clear diurnal dynam
Page 138 and 139: plants. The growth stage could cont
Page 140 and 141: nitrates. At temperatures of 15 - 2
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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
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Acknowledgements This work was poss
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