Modeling paleosol formation on the Chinese Loess Plateau during the Quaternary interglacials

Sommaire

CHAPTER 1.General introduction and objectives  .1
1.1 The importance of studying interglacial soil development in the Quaternary 2
1.2 The Quaternary paleosols formed on loess3
1.3 Study area - The Chinese Loess Plateau .6
1.3.1 Geography, climate and vegetation gradient .6
1.3.2 Quaternary loess-paleosol records in the Chinese Loess Plateau 8
1.3.3 Forcing factors of the Loess-paleosols sequences in China .13
1.4 Importance of linking climate evolution with paleosol development .14
1.4.1 Inconsistencies between global climate and Chinese paleosol .14
1.4.2 The necessity of combining soil-forming factors and dust addition in pedogenic processes in the CLP 16
1.5 Why modeling (paleo)soil evolution is important 17
1.5.1 Soil modeling and paleoclimate-paleosol relations18
1.5.2. Soil modeling and soil-based ecosystem services .18
1.6 Research gaps and questions and research objectives .19
1.7 Structure of this thesis 21
CHAPTER 2. Methodology: interglacial paleosol simulation setup, and the SoilGen2, LOVECLIM1.3 models .23
2.1 Interglacial simulation periods used in the study 24
2.2 Research design .28
2.3 The SoilGen2 model .29
2.4 The LOVECLIM1.3 model.33
2.5 Bias correction and downscaling the climate model outputs to the soil model input scale 34
CHAPTER 3. Calibrating SoilGen2 for interglacial soil evolution in the Chinese Loess Plateau considering soil parameters and the effect of dust addition rhythm 39
3.1 Introduction .42
3.2 Materials and methods44
3.2.1 Study locations and periods.44
3.2.2 The SoilGen2 model input data .45
3.2.3 Model calibration and parameters .47
3.3 Results and Discussion.54
3.3.1 Effect of dissolution constant of calcite and interception
evaporation loss on decarbonatization .54
3.3.2 Assessment of clay migration related model parameters56
3.3.3 Assessment of SOC related model parameters 58
3.3.4 Effect of dust deposition scenarios on the quality of the calibration result .61
3.4 Conclusions.66
CHAPTER 4. Driving factors of interglacial paleosol formation on the Chinese Loess Plateau and the effect of precession and ice sheets 69
4.1 Introduction .72
4.2 Material and methods .74
4.2.1 Locations and studied interglacials 74
4.2.2 Climate simulations75
4.2.3 The SoilGen2 model and Input data 76
4.2.4 Research layout .77
4.3. Results and discussion 80
4.3.1 Analysis of the driving factors of the changes in paleosol development 80
4.3.2 Paleosol response to the astronomical forcing 87
4.3.3 Paleoclimate-paleosol response to NH ice sheets 96
4.3.4 Comparison of simulated and observed S4 and S5-1 paleosols in the southeast CLP.108
4.4. Conclusions110
CHAPTER 5. Soil modeling for Soil Loss Tolerance estimations: Exploring natural baselines and long-term variations 113
5.1 Introduction .116
5.2 Materials and Methods120
5.2.1 Study locations and study periods .120
5.2.2 The SoilGen2 model and input data 121
5.2.3 Climate simulations123
5.2.4 Soil EB and SOC stocks, Ecosystems and scenario .124
5.3. Results and discussion 128
5.3.1. Spatio-temporal trends in simulated climate and vegetation 128
5.3.2 Soil EB and SOC stocks evolution and SLT 130
5.3.3 Soil ES evolution and SLT .142
5.3.4 Combining performance indices for ecosystem services 150
5.3.5 Concept of SLT under erosion/dust accumulation scenarios and semi-arid climate .152
5.4 Conclusions.154
CHAPTER 6. Conclusions  157
CHAPTER 7. Limitations, recommendations and perspectives .163
7.1 Paleosol evolution modeling - Scientific limitations 164
7.1.1 Input data .164
7.1.2 Climate and soil model limitations .165
7.1.3 Simulation limitations .171
7.2 Recommendations for future research .172
7.2.1 Future perspectives on model calibration and paleosol simulations 172
7.2.2 Future perspectives on soil-based ecosystem services 173