Abstract ........................................................ 5
Contents ........................................................ 7
1 Introduction ................................................ 11
1.1 General introduction ................................... 11
1.2 Management components of grazing systems ............... 14
1.3 Research questions ..................................... 14
1.4 Modelling as a tool for analysing grazing systems ...... 16
1.5 Structure of this thesis ............................... 17
2 Simulation model ............................................ 19
2.1 General model outline .................................. 19
2.2 Model description ...................................... 21
2.2.1 Purpose ......................................... 21
2.2.2 Entities, state variables, and scales ........... 21
2.2.3 Process overview and scheduling ................. 22
2.2.4 Design concepts ................................. 25
2.2.5 Initialisation .................................. 26
2.2.6 Input data ...................................... 26
2.2.7 Submodels ....................................... 26
3 Pattern-oriented parameterisation for generic models ........ 35
3.1 Introduction ........................................... 35
3.2 Pattern-oriented parameterisation ...................... 37
3.2.1 Methods ......................................... 37
3.2.2 Results ......................................... 43
3.3 Sample application: Constant vs. adaptive stocking
management ............................................. 49
3.3.1 Methods ......................................... 50
3.3.2 Results ......................................... 51
3.4 Discussion ............................................. 54
4 Linking farmers' objectives and environmental constraints ... 59
4.1 Introduction ........................................... 59
4.2 Methods ................................................ 61
4.2.1 Model settings .................................. 61
4.2.2 Management strategies ........................... 61
4.2.3 Economic evaluation ............................. 62
4.2.4 Simulation settings ............................. 63
4.3 Results ................................................ 64
4.3.1 Herd and selling dynamics ....................... 64
4.3.2 Management aiming at maximum stable income ...... 65
4.3.3 Management for sustaining a minimum income ...... 67
4.3.4 Influence of climate change ..................... 68
4.3.5 Combining objectives ............................ 70
4.4 Discussion and conclusions ............................. 70
5 Adaptation of livestock management to spatio-temporal
heterogeneity ............................................... 75
5.1 Introduction ........................................... 75
5.2 Methods ................................................ 77
5.2.1 Management strategies ........................... 77
5.2.2 Ecological-economic evaluation .................. 79
5.2.3 Simulation settings ............................. 79
5.3 Results ................................................ 80
5.3.1 Performance of management strategies ............ 80
5.3.2 Spatio-temporal effects of grazing management ... 83
5.3.3 Robustness of strategies in a stochastic
environment ..................................... 89
5.4 Discussion ............................................. 92
6 Synthesis and outlook ....................................... 97
6.1 Methodical progress and achievements ................... 97
6.1.1 Model framework ................................. 97
6.1.2 Parameterisation of generic models .............. 98
6.2 Risk management in semi-arid grazing systems ........... 99
6.2.1 Management strategies for semi-arid grazing
systems ......................................... 99
6.2.2 Effect of climate conditions ................... 101
6.2.3 Importance of vegetation characteristics ....... 102
6.2.4 Socio-economic perspectives .................... 102
6.2.5 The relevance of rotational grazing ............ 103
6.3 Outlook and future research ........................... 104
6.3.1 Spatio-temporal heterogeneities on larger
scales and their potential for adaptation ...... 105
6.3.2 Remote sensing and semi-arid rangeland
modelling ...................................... 106
Bibliography .................................................. 109
Acknowledgements .............................................. 125
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