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Alex Zvoleff *1 , Li An * 2011 AAAS Annual Meeting, Washington DC

The ChitwanABM: Modeling Population-Environment Interactions and their Implications in the Chitwan Valley, Nepal. Alex Zvoleff *1 , Li An * 2011 AAAS Annual Meeting, Washington DC San Diego State University; San Diego, USA. 1 azvoleff@mail.sdsu.edu. Outline. Introduction Study Site

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Alex Zvoleff *1 , Li An * 2011 AAAS Annual Meeting, Washington DC

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  1. The ChitwanABM: Modeling Population-Environment Interactions and their Implications in the Chitwan Valley, Nepal Alex Zvoleff*1, Li An* 2011 AAAS Annual Meeting, Washington DC San Diego State University; San Diego, USA. 1azvoleff@mail.sdsu.edu

  2. Outline • Introduction • Study Site • Methods: The ChitwanABM • Scenario Comparison • Conclusions AAAS Annual Meeting

  3. Introduction • Land-use and land-cover and human-decision making are intimately linked • Micro-level decision-making can lead to broader scale (“emergent”) patterns on the landscape • The link between these micro-scale decisions and the macro-scale landscape can be crucial for management AAAS Annual Meeting

  4. Research Question • How does micro-level demographic decision making impact macro-level land use and land cover (LULC)? • Objective: Focus on feedbacks between marriage timing and LULC AAAS Annual Meeting

  5. Study Site: Western Chitwan Valley, Nepal AAAS Annual Meeting

  6. Study Site: Western Chitwan Valley, Nepal AAAS Annual Meeting

  7. Study Site: Western Chitwan Valley, Nepal AAAS Annual Meeting

  8. Chitwan Valley Family Study • Longitudinal survey begun in 1996 • Focusing on social context and family formation • Human survey data • Three detailed interviews (1996, 2001, 2008) • Household registry (monthly since Feb. 1997) • Environmental data • Flora count (1996, 2000, 2007) • Neighborhood mapping (1997, 2000, 2007) AAAS Annual Meeting

  9. Chitwan Valley Family Study: Household Registry AAAS Annual Meeting

  10. Study Site: Overview • Population ≈ 250,000 • National park: 932 Km2 • Buffer zone: 766 Km2 • Forest resources important • 93% use fuelwood • 76% gather fuelwood • Ag. is dominant land-use • 80% of study area in 1996 AAAS Annual Meeting

  11. AGENT-BASED MODEL AAAS Annual Meeting

  12. Why an agent-based model? • Agent-based models (ABM) represent individual “agents” and model their interactions • ABM allows: • Representation of human-decision making • Consideration of feedbacks • Examination of system dynamics • Testing of alternative hypotheses AAAS Annual Meeting

  13. ChitwanABM Agent Hierarchy • 151 neighborhood agents • 1551 household agents • 8414 individual agents AAAS Annual Meeting

  14. Parameterization • Baseline probabilities calculated for: • Fertility • First birth timing • Desired number of children • Marriage • Migration • Mortality • Feedbacks alter the baseline probabilities • LULC determined by decisions of household agents AAAS Annual Meeting

  15. Parameterization: Mortality AAAS Annual Meeting

  16. Land-use/land-cover Classes • Land-use/land-cover classes • Agricultural vegetation • Non-agricultural vegetation • Private buildings • Public infrastructure • Other (ponds, silted riverbanks, etc.) AAAS Annual Meeting

  17. Land-use/land-cover Change – 1996-2006 AAAS Annual Meeting

  18. Objective: Explore Two Scenarios Scenario 1: Baseline scenario Scenario 2: LULC-marriage timing feedback scenario AAAS Annual Meeting

  19. Scenario 1 AAAS Annual Meeting

  20. Scenario 2 • Prior work (Yabiku 2007) has shown marriage timing • Highly correlated with age, sex, ethnicity • Positively related to agricultural land • Higher percentage agricultural land leads to earlier marriage (get married younger) • We explore two scenarios • Baseline scenario (no feedback) • Positive feedback of percent agricultural land on marriage AAAS Annual Meeting

  21. Scenario 2 AAAS Annual Meeting

  22. SCENARIO COMPARISON AAAS Annual Meeting

  23. Time Zero: Percent Vegetation AAAS Annual Meeting

  24. Scenario 1 (baseline): LULC AAAS Annual Meeting

  25. Scenario 1 (baseline) minus Scenario 2 (marriage) AAAS Annual Meeting

  26. DISCUSSION AAAS Annual Meeting

  27. Conclusions • Feedback of LULC on marriage timing: • Shows little impact at the aggregate level • Shows large impact spatially • Considering feedback • Agricultural areas grow quicker • Urbanized areas grow more slowly • Must consider spatial context of decision-making AAAS Annual Meeting

  28. Future Work • Incorporate additional feedbacks • LULC – first-birth timing • LULC – family size preferences • LULC – migration • Incorporate feedbacks between biomass harvesting ↔ ecosystem change AAAS Annual Meeting

  29. Acknowledgements With thanks to: With support from: • Dr. William Axinn, UM • Dr. Jianguo Liu, MSU • Dr. Lisa Pearce, UNC-Chapel Hill • Dr. Scott Yabiku, ASU • Dr. Dirgha Ghimire, UM • Dr. David López-Carr, UCSB • Binoj Shrestha, ISER-N • Krishna Shrestha, ISER-N AAAS Annual Meeting

  30. ChitwanABM is free and open-source: http://rohan.sdsu.edu/~zvoleff/ChitwanABM.php PyABM – an open-source ABM toolkit for Python (coming spring 2011): http://rohan.sdsu.edu/~zvoleff/PyABM.php Thank you. Questions?Email: azvoleff@mail.sdsu.edu AAAS Annual Meeting

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