Browsing by Autor "Marc Cotter"

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Complexity of cacao production systems affects terrestrial ant assemblages
(Elsevier BV, 2023) Chloé Durot; Miguel Limachi; Kazuya Naoki; Marc Cotter; Natacha Bodenhausen; Luis Marconi; Laura Armengot
• Terrestrial ant species richness, composition and trophic roles were analysed. • Ants were sampled four times in a long-term trial comparing cacao production systems. • Ant species richness did not differ between production systems. • Ant composition differed according to the management intensity of the systems. Given the rapid changes in tropical agricultural production, the evaluation of different management practices has gained interest to determine the effects of land-use change on biodiversity. The conversion of forests into agricultural land is one of the main drivers of diversity loss. Agroforestry systems have been shown as a promising option to provide suitable yields in addition to conserving biodiversity. In this study we compared species richness and community composition of terrestrial ants in six different systems in a long-term experimental site established in 2009 in Bolivia: a full-sun monoculture and an agroforestry system under conventional management, a full-sun monoculture and an agroforestry system under organic management, a highly diverse and dense agroforestry system without external inputs and a secondary forest. Using pitfall traps, we sampled ants four times during a seven-year period (2015-2021). We collected a total of 85 ant species belonging to 6 sub-families and 41 genera. More than 80% of the species were recorded in less than 10% of the traps. Species richness did not significantly differ between the systems. However, species composition mainly differed between the fallow and the production systems, and within the latter, it followed the management intensity gradient, i.e., complex agroforestry, agroforestry and monocultures. The indicator species analysis clearly showed species exclusively associated with one or more production systems, whereas others were only associated with the secondary forest. Species with specialised trophic roles were more frequent in forest and agroforestry systems. Our results showed that the disturbance generated by cultivation was the main driver differentiating ant communities, but also reinforced the importance of the complexity and management intensity of the production system. These results have strong implications for landscape management and highlights the importance of preserving natural patches of forest but also diverse and complex agroforestry systems within the agricultural matrix for ant diversity conservation.
Successional agroforestry promotes biomass carbon storage in cocoa production systems: results from a long-term system comparison experiment on organic and conventional systems
(Elsevier BV, 2025) Hans‐Martin Krause; Stéphane Saj; Johanna Rüegg; Ulf Schneidewind; Sina Lory; Marc Cotter; Wiebke Niether; Monika Schneider; Johannes Milz; Georg Cadisch
Agroforestry systems are perceived as an effective approach to store carbon in agroecosystems by building tree biomass and raising soil organic carbon (SOC) stocks. This is especially evident in the tropics, where the cultivation of cash crops such as cacao in agroforestry systems is increasingly used. Among agroforestry systems, organic management, which avoids synthetic inputs for crop protection and fertilization, and the concept of successional agroforestry (SA), which aims to increase carbon storage by using high initial tree densities and intensive pruning without external inputs, have gained interest as alternatives to monocultures with less environmental impact. To assess the temporal development of carbon storage of differently managed agroforestry systems, we revisited a 14-year field experiment located in the Alto Beni Region of Bolivia to quantify biomass and SOC stocks in five distinct cocoa production systems. The field experiment includes SA as well as organic and conventional monocultures (OM and CM) and agroforestry systems (OA and CA). We found that all agroforestry systems increased carbon stocks in the biomass and the soil, especially in the particulate organic matter fraction. No significant effect of organic management practices was observed. After 14 years, the highest biomass carbon was observed in the SA system and topsoil SOC stocks increased significantly in SA and CA. Our findings emphasize the potential to enhance carbon accumulation in agroforestry systems with high initial tree density and rigorous pruning, even without additional fertilizer or synthetic plant protection inputs. • Agroforestry enhances soil and biomass carbon stocks compared to cacao monocultures • No effect of organic management on soil and biomass carbon within agroforestry systems. • Greatest gains of biomass carbon in successional agroforestry systems