Answer:
Based on the information provided, it is difficult to determine the specific change that has caused the decrease in crop variety and biodiversity in the region. However, there are several potential factors that could contribute to this change:
1. Climate change: Shifts in temperature and rainfall patterns can affect the suitability of certain crops for cultivation, leading to a decrease in crop variety.
2. Land use changes: Conversion of agricultural land for other purposes, such as urbanization or industrial development, can reduce the available area for crop cultivation and impact biodiversity.
3. Intensive farming practices: The use of monoculture and reliance on a few high-yielding crop varieties can lead to a loss of crop diversity over time.
4. Pest and disease outbreaks: The emergence of new pests or diseases that affect specific crops can result in decreased crop variety if farmers are forced to abandon susceptible crops.
5. Economic factors: Changes in market demand and consumer preferences may influence farmers' decisions on which crops to grow, leading to a reduction in crop variety.
It is important to conduct further investigation and analysis to determine the specific factors contributing to the decrease in crop variety and biodiversity in the region. Local environmental and agricultural experts would be better equipped to provide a comprehensive assessment based on the specific context and conditions of the region.