Von Thünen’s Rings

In 1948 James Conant, President of Harvard, abolished the university’s Geography Department with the comment, “Geography is not a University subject”. There was still an independent Institute of Geographical Exploration on campus, which had strong ties with the abolished department. In 1951 its owners donated the institute to the university, which immediately closed down its building and fired its staff.

Other U.S. colleges followed Harvard’s example and downgraded geography as an academic subject. I don’t think this explains the truly astounding lack of geographical knowledge in the U.S., but it surely didn’t help. The explanation has probably to do with, yes, geography, North America is a very large island.

There are some neat ideas in economic geography, e.g. Christaller’s Central Place Theory, and von Thünen’s rings. Von Thünen’s model is based on his concept of Land Rent,

R = Y(p-c) – Yfm

R = Rent per unit of land.
Y = Yield per unit of land.
p = market price per unit of yield.
c = Average production costs per unit of yield.
m = Distance from market.
f = Freight rate per unit of yield and unit of distance.

Different land uses have different rent-distance functions. The model predicts a concentric land use structure in circles or rings around a city, with dairies and truck farms producing high value or perishable crops close to the city, grains produced further out on cheaper land, and livestock still further out.

In both Japan and China, rice, although a tropical crop, is moving north, out of industrial zones. A similar process is taking place in Washington State, where dairies are moving east. In these cases, production is moving out of climatically better suited zones to less suited zones. The process can be understood in terms of von Thünen’s model.

If you have ever hiked in New England, you have probably come across the remains of abandoned farm houses in what is now again woodland. Once the railroads opened up the Midwest, New England farmers couldn’t compete. Reversal is possible.

If a population grows at 3% per year, and agricultural yields grow by 2%, more cropland is needed. If the population grows by 3%, and agricultural yields grow by 4%, less land is needed. The area needed to feed one person started shrinking about 50 years ago. Total cropland is shrinking in many countries, including Europe and China. As croplands shrinks, conservation becomes less expensive in the outer von Thünen rings.


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