drivers of soil respiration of root and microbial ... - Unitus DSpace

More documents

Recommendations

Info

42 Variation of soil respiration from different sources together with soil temperature and soil water content during the measurement campaigns 2006-2008 is represented in figure 2. Calculated fluxes of various origin differed significantly in magnitude and showed also different annual course. Total soil respiration in 2006 peaked in the beginning of July, whereas in 2007 and 2008 the highest respiration was observed in the middle June, with the following decrease. After the period of the low fluxes in July and August which is associated with the low SWC and high soil temperatures soil respiration increased again (Fig. 2a and 2c). Microbial-derived respiration was generally much higher than the root-derived CO2 efflux (Fig.2b). Comprising a high proportion of total soil respiration, their annual courses were also similar. Root-derived respiration performed differently during various years. In 2007 and 2008 the maximum value was reached during the month of June followed by a decrease during the dry period. In 2006 root-derived respiration was increasing constantly up to the month of July. The decrease of root-derived respiration associated with drought was less pronounced than for total and microbial-derived respiration, in fact the relative contribution of root-derived respiration to the total CO2 efflux during this period increases (Fig.3). In the late summer, during the months of August and September root-derived respiration generally experienced the second peak. This period is associated with the mild temperatures and high SWC, which favour the re-growth and new onset of vegetation. Example of above- and belowground biomass changes in the year 2007 are shown in Figure 4 100% 80% 60% 40% 20% 0% 30.05.06 71% 24.07.06 29% 17.09.06 11.11.06 05.01.07 01.03.07 25.04.07 19.06.07 13.08.07 07.10.07 01.12.07 25.01.08 20.03.08 Ra Rh Fig. 3 Relative contribution of root and microbial-derived respiration to total CO2 efflux during three years of measurements. Percentage in the graph indicate an average contribution. 14.05.08 date 08.07.08
AG biomass (g m -2 ) 400 350 300 250 200 150 100 50 0 26.04.2007 15.05.2007 30.05.2007 16.06.2007 03.07.2007 12.07.2007 Fig. 4 Changes of the aboveground (AG) and belowground (BG) biomass (± SE) in the course of the growing season 2007. An average contribution of roots to total CO2 efflux from soil amounted to 30%. However the range of variation in root respiration contribution to Rs varied significantly in course of the growing seasons from 2 to 70% (Fig.3). 2.3.1. Diurnal variation of soil respiration of different origin Response of soil respiration of different origin to diurnal changes in soil temperature in 2007 and 2008 is represented in figure 5. The first observation which is possible to make from the graphs is that any of respiration sources do not follow diurnal patterns of soil temperature often decreasing suddenly under the high respiration rates, independently from the period of the growing season when the measurements were performed (Fig. 5: ex. 15 June, 11 July, 19 August; 11 November; 5 June; 2 August). Another important observation is that in different times of the day with similar temperatures soil respiration is different. Changes in SWC also failed to explain the diurnal variation in soil respiration fluxes, its fluctuations during the day were negligible (Fig. 6). 04.08.2007 20.08.2007 08.09.2007 23.10.2007 AGb BGb 05.11.2007 2000 1800 1600 1400 1200 1000 800 600 400 200 0 BG biomass (g m -2) 43
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 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 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
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
Page 140 and 141:
nitrates. At temperatures of 15 - 2
Page 142 and 143:
experiment could be responsible for
Page 144 and 145:
Horwath W.R., Pretziger K.S., Paul,
Page 146 and 147:
146
Page 148 and 149:
148 6.1 . Introduction In studies o
Page 150 and 151:
Regression analyses technique, whic
Page 152 and 153:
152 The respiratory response with g
Page 154 and 155:
154 100% 80% 60% 40% 20% 0% 85% 13%
Page 156 and 157:
6.3.2. 2008: Mesh- exclusion vs. re
Page 158 and 159:
6.4. Discussion 6.4.1. Mesh-exclusi
Page 160 and 161:
introduction in a small soil sample
Page 162 and 163:
component, expressing a total soil
Page 164 and 165:
Kucera C.L., Kirkham D.R., 1971. So
Page 166:
Acknowledgements This work was poss
show all

drivers of soil respiration of root and microbial ... - Unitus DSpace

Create successful ePaper yourself

Delete template?

Save as template?