Urban gardens are temporally dynamic systems, with many (e.g., the Victory Gardens in the U.S. following WWII), sprouting, and then quickly disappearing in history, while others (e.g. the urban and periurban gardens of Cuba and Germany) seem more resistant to change. To understand why transitions to urban gardens are more permanent in some cases than others, we combine competitive population models and Markov-chain transition rules to describe the expansions of and transitions between a given set of land-use strategies (vacant lots, gardens and developed land). Growth and transitions of land-use states are determined by differences in land-use state utilities and government mandated land-reform standards.
Results/Conclusions
Relaxing static impressions of utility so that they change with economic conditions leads to complex dynamic consequences for urban gardens, including limit cycles. We find that supplementing the economy of land markets can lead to large-scale economic booms and busts and correspondingly large changes in land-use; results that are similar to trends seen during the subprime mortgage crisis of the U.S. in the early 2000s, and other cascading housing bubbles felt worldwide. Hence, simple population models can mimic the complex, large-magnitude fluctuations in urban land-use following economic collapse that have been observed to occur in many places and times in history. We find that reducing land tenure to medium levels may stabilize dominance of urban gardens in cities albeit at the cost of a slightly reduced, but more stable economy.