The NEW ZEALAND model (Figure IV-14) simulates the main aspect of the agricultural-based economy of New Zealand in its history. Colonists from England and Scotland transported their sheep-based economy to the new land in the 18th and 19th centuries, exporting some wool as a cash crop. Around 1900 refrigerated ships were developed and lamb became a major export. Money received in exchange bought fuels, goods, and services, making a prosperous economy, up until the Arab oil embargo raised oil prices sharply in 1972.

The simulation (Figure IV-14b) has sheep developing on pastures receiving government-supplied fertilizer from the towns. Some agricultural products are used in town and the rest exported. Although calibrated with stock (sheep and cattle), other agricultural products behave similarly. Thus, the model is general in representing features of agricultural role in national economic development.

Starting with virgin soils, the initial effect of the sheep is to reduce the nutrients in the soil and lose productivity. As exports allow a fossil fuel based economy to develop, more fertilizer is bought from outside and production rises. With more purchases of fuels and goods and services, urban assets increase. The simulation has a switch, which increases exports after 1912. Urban assets rise until 1972 when foreign import prices rise sharply. The model stops in 1978. Here you can discuss alternatives and then continue the simulation for different conditions.

Examples of Countries Which Export Agricultural Products

Many "third world" countries fall in this category of countries that export goods from their environment. If they use their products at home, they can stimulation their economies much more. Developed nations like New Zealand and even the United States are exporting commodities like wood and wheat that would give them more value if they processed them and then exported the final products.

"What If" Experimental Problems

1. The original program contains one scenario for continuing the simulation after 1978. If nothing is changed - sheep are exported; goods and services are imported; and there is a brain drain - what happens to the economy?
   


2. If agriculture is reorganized with less exports and more products used at home, and "brain" drain due to emigration of educated people is stopped, what will happen? To stop exports of sheep (K6*S and X4*S) and to stop the brain drain (X1*A), type the following three statements K6 = 0; X4 = 0; X1 = 0 Then run.
   


3. Let's look at the likely scenario in which phosphate fertilizer imports become more expensive by year 2000. How do you predict this will change the economy if it is added to the program in question 14.2? Add another statement to decrease the import of phosphate in year 2000: IF (T>148) THEN X2 = 6.5E-5 Then run again.

COMPUTER MINIMODELS AND SIMULATION EXERCISES FOR SCIENCE AND SOCIAL STUDIES

Howard T. Odum* and Elisabeth C. Odum+
* Dept. of Environmental Engineering Sciences, UF
+ Santa Fe Community College, Gainesville

Center for Environmental Policy, 424 Black Hall
University of Florida, Gainesville, FL, 32611
Copyright 1994

Autorização concedida gentilmente pelos autores para publicação na Internet
Laboratório de Engenharia Ecológica e Informática Aplicada - LEIA - Unicamp
Enrique Ortega
Mileine Furlanetti de Lima Zanghetin
Campinas, SP, 20 de julho de 2007