The impacts of tropical agriculture on biodiversity: a meta-analysis

1. Biodiversity underpins all food production and strengthens agricultural resilience to crop failure. However, agricultural expansion is the primary driver of biodiversity loss, particularly in the tropics where crop production is increasing and intensifying rapidly to meet a growing global food demand. It is therefore crucial to ask, how do different crops and crop production systems impact biodiversity?

2. We first use the FAO database of harvested crop area to explore temporal changes in crop area and intensification across the entire tropical realm. We show that the harvested area of tropical crops has more than doubled since 1961, with ever-increasing intensification. The harvested area in 2019 was 7.21 million km2 , equivalent to 5.5% of global ice-free land area, or 11.5% of land area in the tropics.

3. Second, we conducted a meta-analysis of 194 studies and 1,368 pairwise comparisons to assess the impact of tropical agriculture on biodiversity, comparing biodiversity values in food crop sites versus natural reference habitats.

4. Our meta-analysis shows that crop type, rotation time and level of shading are important determinants of biodiversity assemblages. Perennial tropical crops that are grown in shaded plantations or agroforests (e.g., banana and coffee) support higher biodiversity, while crops cultivated in unshaded and often homogeneous croplands (e.g., maize, sugarcane, and oil palm), and particularly annual crops, have impoverished biodiversity communities.

5. Policy implications: These findings inform our understanding of how different crops and crop production systems impact biodiversity, and may serve as a warning sign for agricultural systems that rely on the ecological functions provided by biodiversity.