Duration of Cattle Ranching Affects Dung Beetle Diversity and Secondary Seed Removal in Tropical Dry Forest Landscapes

Abstract

Cattle ranching is an economic activity responsible for the loss of large extensions of tropicaldry forest around the world. Several studies have demonstrated that the use of inadequate practicesof this activity in tropical forests (e.g., fire, agrochemicals, and lack of rotational grazing systems ofcattle in pastures) have negative consequences on dung beetle diversity and their ecological functions.In the present study, the influence of the cattle ranching duration gradient on the diversity of dungbeetles and seed removal was evaluated. This study was carried out in pastures with different timesof establishment of cattle ranching (between 4 and 40 years) in a tropical dry forest of Mexico. Overall,the species richness of dung beetles was similar along the gradient of grazing ages. However, thediversity of common (q1) and dominant (q2) species decreased and was associated with an increasingabundance of exotic species and a decreasing abundance of native species. Seed removal was mainlycarried out by four beetle species, among which the exotic species Digitonthophagus gazella was themost important. The results establish that the duration of cattle ranching primarily influences thecomposition of dung beetle communities, as reflected in changes in the structure and function oftheir assemblages in the pastures. Although native dung beetles persist at low abundances along thisgradient, the consequences of land use changes are undeniable in other similar ecosystems wherethese species could definitively disappear.