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Chapter source: 90 4. THE EFFCT OF DEFOLIATION MANAGEMENT PRACTISES ON SOIL RESPIRATION OF DIFFERENT ORIGIN AND SOIL BIOCHEMICAL PROPERTIES O. Gavrichkova, M. C. Moscatelli, S. Grego, R. Valentini. Soil carbon mineralization in a mediterranean pasture: effect of grazing and mowing management practices. Agrochimica 52, 285- 296.
4.1. Introduction Land-use changes are considered the most dominant component of global change in terms of impact on terrestrial ecosystems, profoundly altering land cover, vegetation composition and biochemical cycles (Walker et al., 1999). Besides land-use change, land management may have a significant effect on the CO2 efflux from soil especially in the short-term (Bahn et al., 2006). Land- use change and management practices can affect soil carbon storage by altering the input rates of organic matter and by changing its decomposability (Cambardella and Elliot, 1992; Moscatelli et al., 2007). In grassland ecosystems a very little quantity of organic carbon is stored in the above ground biomass and more than 90% is concentrated in roots and soils (Burke et al., 1997; Parton et al., 1993). Because of the soil significant capacity to store carbon, grasslands associated with a proper management are considered to be potential carbon sequestrators (Post et al., 1982; Degryze et al., 2004; Sun et al., 2004). Management practices, based on defoliation such as mowing and grazing account for about 20% of the global terrestrial ice-free surface. Historically also Mediterranean grasslands were used for cattle grazing and hay production. Ecosystems under grazing and mowing regimes are usually characterized by increased soil organic carbon content: a large amount of data show that such kind of management, based on defoliation, may substantially influence the below-ground food-web, and thus SOM (soil organic matter) transformation and nutrient cycling (Mikola et al., 2001; Bardgett et al., 1998). Maintenance of SOM and the quality of soil are the key factors in the sustainability of such ecosystems (Conant et al., 2001) and productivity of plant communities (Bending et al., 2000). However, there is still a dearth of clear information on the effect of defoliation of grassland plants on grassland C cycling, soil biochemical properties and the role of soil organisms in aboveground-belowground feedbacks in grazed and mowed grasslands as different studies show contrasting results (Guitian and Bardgett 2000). Some ecological studies stated that experimental clipping usually reduces CO2 efflux from soil by 21-49% despite the fact that it increases the soil temperature (Bremer et al., 1998; Wan and Luo, 2003). This decrease was mainly explained by the sensitivity of roots and microbes to the reduction in photosynthetic C supply from aboveground and to the decrease in rhizodeposition process and thus in the amount of easily available C substrates (Craine et al., 1999; Bahn et al., 2006; Zhou et al., 2007). Mawdsley and Bardgett (1997) however conclude that defoliation of Trifolium repens increases the rhizosphere microbial biomass and activity, whereas defoliation of Lolium perenne had a little effect on soil organisms. Uhlirova et al. (2005) and Zhou (2007) report mowing as a most suitable grassland management as it increased soil microbial biomass and consequently labile carbon pool and enhanced SOM transformation. Soils, under free grazing, on the contrary, tended to loose soil organic matter and reduce labile C availability (Lal, 2002; Zhou, 2007; Stark and Kytoviita, 2006). Bardgett and Leemans (1995) and 91
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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
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 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 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
Page 118 and 119: Rice C.W., Moorman T.B., Beare M, 1
Page 120 and 121: 120
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
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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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