Grassland Simulation Model, Softcover reprint of the original 1st ed. 1978
Ecological Studies Series, Vol. 26

Perspectives on the ELM Model and Modeling Efforts This volume is the major open-literature description of a comprehensive, pioneering ecological modeling effort. The ELM model is one of the major outputs of the United States Grassland Biome study, a contribution to the International Biological Program (IBP). Writing this introduction provides wel­ come personal opportunity to (i) review briefly the state of the art at the beginning of the ELM modeling effort in 1971, (ii) to discuss some aspects of the ELM model's role in relation to other models and other phases of the Grassland Biome study, and (iii) to summarize the evolution of ELM or its components since 1973. Pre-Program Historical Perspective My first major contacts with ecological simulation modeling were in 1960 when I was studying intraseasonal herbage dynamics and nutrient production on foothill grasslands in southcentral Montana, making year-round measurements of the aboveground live vegetation, the standing dead, and the litter. Limitations in funding and the rockiness of the foothill soils prevented measuring the dynamics of the root biomass, both live and dead. Herbage biomass originates in live shoots from which it could be translocated into live roots or the live shoots could transfer to standing dead or to litter. Standing dead vegetation must end up in the litter and the live roots eventually transfer to dead roots. Obviously, the litter and the dead roots must decay away.

1. Objectives and Structure for a Grassland Simulation Model.- 1.1 Introduction.- 1.2 Objective.- 1.3 Model Construction.- 1.4 Pawnee Site and Data.- 1.5 The Model.- 1.6 The Structure of ELM.- 1.7 Question Reviewed.- 1.8 Additional Trials.- 1.9 Conclusion.- References.- Appendix 1.A. SIMCOMP 3.0.- References.- 2. Abiotic Section of ELM.- 2.1 Introduction.- 2.2 Model Development.- 2.3 Validation of the Model.- 2.4 Verification of the Weather Simulator.- References.- 3. A Simulation Model for Grassland Primary Producer Phenology and Biomass Dynamics.- 3.1 Introduction.- 3.2 Literature Review.- 3.3 Phenology Submodel.- 3.4 Carbon Submodel.- 3.5 Conclusions.- References.- 4. A Mammalian Consumer Model for Grasslands.- 4.1 Introduction.- 4.2 Model Development and Overview.- 4.3 Biological Components.- 4.4 Results and Discussion.- 4.5 General Discussion.- References.- 5. Simulation of Grasshopper Populations in a Grassland Ecosystem.- 5.1 Introduction.- 5.2 Model Overview.- 5.3 Life-cycle Dynamics.- 5.4 Interactions.- 5.5 Results and Discussion.- References.- 6. A Simulation Model for Decomposition in Grasslands.- 6.1 Introduction.- 6.2 The Problem of Heterogeneous Substrates.- 6.3 Decomposition under Variable Conditions.- 6.4 Physical Transfers.- 6.5 Decomposer Biomass.- 6.6 Tuning the Model.- 6.7 Model Performance.- 6.8 Discussion.- References.- 7. A Grassland Nitrogen-flow Simulation Model.- 7.1 Introduction.- 7.2 Model Structure.- 7.3 Model Output.- 7.4 Discussion.- References.- 8. Simulation of Phosphorus Cycling in Semiarid Grasslands.- 8.1 Introduction.- 8.2 Review of Literature.- 8.3 Model Structure and Development.- 8.4 Soil Phosphorus Solubility and Plant Uptake.- 8.5 Plant Translocation and Utilization of Phosphorus.- 8.6 Decomposer Uptake and Turnover of Phosphorus.- 8.7 Mineralization of Organic Phosphorus.- 8.8 Model Simulation Results.- 8.9 Conclusions.- References.- 9. Sensitivity Analyses of the ELM Model.- 9.1 Introduction.- 9.2 Tomovi?’s Sensitivity Analysis.- 9.3 Parameter Perturbations.- 9.4 Discussion.- References.- 10. Critique and Analyses of the Grassland Ecosystem Model ELM.- 10.1 Introduction.- 10.2 Model Objectives.- 10.3 Analysis and Criticism of ELM in Relation to the Desired Goals of Modeling in the Grassland Biome Program.- References.- Author Index.