Characterizing urbanization, and agricultural and conservation land-use change in Riverside County, California, USA

Monitoring trends in urbanization and land use related to population growth and changing social and economic conditions is an important tool for developing in land use and habitat conservation policy. We analyzed urbanization and agricultural land-use change in Riverside County, California from 1984 to 2002, comparing maps every two years on the basis of aerial photographs. Matrix analysis combined with information theory was applied to study land type conversion. Results showed that the total area of "Urban and Built-Up Land" increased the most whereas total area of "Prime Farmland" decreased most. Land-use characterized as "Grazing Land,""Farmland of Local Importance," and "Farmland of Statewide Importance" also decreased. Mean patch size also decreased for "Grazing Land,""Water Area,""Other Land," and "Prime Farmland." The diversity of land types decreased dramatically after 1992. Urbanization patterns were different among three city groups (Riverside City, Coachella Valley, and Blythe), indicating the different times for "leapfrog" development in the three areas. Furthermore, the unpredictability and change in composition of land use increased after 1996 due to intensified urbanization. If the current driving forces continue, our model projects that in 2020 the area of "Urban and Built-Up Land" may increase between 25% and 39% in comparison with 2002. Percentages of most agricultural land types are projected to decrease, especially "Farmland of Local Importance,""Prime Farmland," and "Farmland of Statewide Importance." If the county's goal is to preserve agricultural lands and natural biodiversity, while maintaining sustainable development, current land-use policies and practices should be changed. This study demonstrates new useful methods for monitoring and detection of change of land-use processes.