The influence of biodiversity-friendly ranching practices on dung beetle diversity in a Mexican mountainous tropical landscape

Abstract

Tropical montane cloud forest (TMCF) has been reduced to riparian vegetation remnants, and small patches surrounded by different land uses and human settlements. In agricultural and highly disturbed TMCF landscapes, the conservation of species diversity depends partially on management decisions made by landowners. This study compared the influence of 15 different ranching management practices (biodiversity-friendly or unfriendly) on the species and functional diversity of dung beetles associated with TMCF in a Mexican mountainous tropical landscape. Cattle pastures were divided into six groups (G) based on management practices friendly or unfriendly to dung beetle diversity. The most common biodiversity-friendly practices were livestock intensification (animal rotation and stocking) for grass recovery, (ii) organic fertilizer use, and (iii) the presence of shade trees. In contrast, agrochemical use, percentage of grass surface coverage, use of external food supplements, and the amount of disturbance were considered to be unfriendly biodiversity practices. G1 was a technified ranch experiencing frequent use of agrochemicals, had disturbed conditions with more than 40% of grass surface coverage, and used more practices unfriendly to biodiversity. In contrast, G4 had more than 50% biodiversity-friendly practices and pasture group G6 was characterized by low animal loading, total grass surface coverage and technification. In these pastures, ranchers did not use herbicides and used local resources as food supplements. A total of 2218 beetles belonging to 19 species were captured. G2 pastures had higher species diversity, while G1 pastures had the lowest. G6 pastures had the highest diversity of large, medium and coprophagous beetles, whereas G1 pastures showed the lowest. Agrochemical applications and pasture disturbance were the key results from management decisions influencing dung beetle diversity. Implications for insect conservation: Animal rotations, tree presence in grazing areas, and organic fertilizer applications were the most influential management decisions for improving conservation of dung beetles in the Mexican TMCF landscape studied. These practices should be favored by management strategies. Cattle pastures with higher frequencies of agrochemical applications and degree of disturbance showed the lowest dung beetles species diversity, and diversity of large and coprophagous species, likely implying greater negative effects on ecosystem functions and services. As such, these practices should be diminished.