Ecosystem services and biodiversity in Colombia: pollination in the Amazon livestock landscape

Agriculture, and livestock systems in particular, are major drivers of biodiversity loss. Global agricultural land expansion has been predominantly concentrated in the tropics, where biodiversity is high. In Colombia, the second most biodiversity country in the world, pasture expansion for livestock production has been responsible for the deforestation of considerable areas with hotspots in Amazonia. However, over the past 20 years, silvopastoral systems have been implemented to mitigate the negative environmental effects of conventional livestock production.
Nevertheless, little is known about the impact of sustainable practices such as silvopastoral systems on biodiversity, particularly on the flower-visiting insect communities and the ecosystem services they provide in the Colombian Amazon. To contribute to this research gap, I studied flower-visiting insects, their interactions with plants and their contribution to seed and fruit development in different land-use systems in a livestock landscape of Caquetá, a Department in the Colombian Amazon.
This research was divided into five chapters. In Chapter one I present a general introduction with a literature review on the challenges of biodiversity conservation and strategies to address biodiversity loss in the context of agriculture and sustainability. In chapter two I evaluated the diversity of flower-visiting insects in the productive livestock zone of Caquetá, exploring the impact of different livestock systems, the remnant tropical forests, and the environmental variables on the insect communities. I found that Forest and Scattered trees in pastures were the most diverse systems, and that canopy coverage and vegetation structure were significant variables on the diversity of flower-visiting insects.
In chapter three, I determined the structure of plant-insect networks in silvopastoral and conventional livestock systems which showed modularity characteristics. Scattered trees in pastures presented the most complex network, with the highest number of interactions and network size. In chapter four I evaluated the pollination services in silvopastoral arrangements with guava (Psidium guajava), pomo (Bellucia pentamera) and cupuassu trees (Theobroma grandiflorum) by measuring fruit and seed production when flowers were visited by insects. Although the flowers of the three plant species are hermaphroditic, the presence of flower visitors were essential for fruit development in guava and cupuassu trees, and for improving fruit quality in pomo trees. In addition, flower abundance and forest proximity were important variables that influenced the abundance of flower-visiting insects. Ultimately, chapter five shows the general discussion and conclusion of this research.
Overall, this research advances our understanding of ecosystem services in livestock landscapes and provides a basis for contributing to biodiversity conservation in the Colombian Amazon.