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quantities and changes of label in CO2 respired from weeks to month, otherwise a high concentrations of 13 C or continuous isotope labeling application in 13 C atmosphere should be applied, as it is a less sensitive tracer due its relatively high natural abundance. 68 Study Lag Method Ecosystem Horwath et al., (1994) 2 to 3d 14C Populus eumericana Mikan et al. (2000)
Our experiment was conducted in a mediterranean grassland (Amplero, Italy), aiming to cover the gap in the understanding of allocation patterns and speed of cycling of recently assimilated C in such type of ecosystems. Summarizing the above findings and uncertainties, the aims of the study were: • To monitor the dynamic of the 13 CO2 evolution from the soil, with and without shoots, aiming to get the peak of respiration of recently assimilated 13 C of root- and shoot-origin in situ under the real plant growing conditions. • To study temporal variation of source (photosynthetically active leaves)-sink (developing shoots, roots, leaves) interaction within the plant community: the fraction of new assimilated C respired below- vs. aboveground. • To compare the observed time lags obtained by non destructive technique of isotope pulse labeling with the results of widely diffused destructive technique, where the value of root- derived respiration is obtained by root-exclusion technique and is plotted vs. GPP from eddy covariance (performing both experiments in the same time). 3.2. Materials and Methods 3.2.1.Site description Amplero was established as a main CarboEurope site in central Italy near the city Collelongo (AQ) in the year 2002. A Mediterranean grassland site, located at 900 m a.s.l. Amplero is a nearly flat to gently south sloping (2-3%) doline bottom with an average annual temperature of 10°C and average annual precipitation of 1365 mm. The site is subjected to a long-term management since 1950, which consists in a once-a-year mowing during the peak of the growing season and the rest of the growing season the site is used as a pasture for cattle grazing. The soil is classified as Haplic Phaeozem (FAO classification) and contains 13% of sand, 33% of silt and 56% of clay, pHH2O of 6.6, total carbon (C) 3.48 % and total nitrogen (N) 0.28%. The plant cover is mainly represented by the following families: Caryophyllaceae (19%), Faseolaceae (30%) and Poaceae (34%). 69
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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
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 48 and 49: 48 Q10 R 2 p Rs 2.51 0.77 0.000 Ra
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: 3.1. Introduction Soil respiration
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
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
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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
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Acknowledgements This work was poss
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