Biodiversity patterns and trophic interactions in human-dominated tropical landscapes in Sulawesi (Indonesia): plants, arthropods and vertebrates

Abstract

SummaryThe need to capture primary production in order to sustain and improve economic livelihoods has lead to increasing conversion of natural habitat and intensification of agricultural practices in many parts of the world including most tropical regions. Understanding how these processes affect ecosystems and their functioning, in particular in the high-diversity ecosystems of the tropics, has become a key issue in ecological research. In this chapter, our focus is on the agriculture-forest landscapes of Central Sulawesi, Indonesia, an island widely known for its endemic yet still poorly known flora and fauna. The rise of the region to one of the largest cacao producing areas in the world is at the core of recent land-use change and intensification processes. Covering plants (trees, rattan palms, herbs, bryophytes) and several invertebrate (ants, dung beetles, cacao insect herbivores, fruit-feeding butterflies, parasitic Hymenoptera, spiders) and vertebrate groups (amphibians, birds, murids, reptiles), we give an in-depth overview of the determinants of biodiversity in cacao landscapes, including both management and landscape-scale variables into our analyses. Results show that shaded agroforests host a rich community of species. By adopting a large-scale study design we showed that proximity of natural forest is a key predictor for species richness of plants, invertebrates and vertebrates alike. Endemics and forest specialists benefit most from indigenous shade tree cover and proximity to natural forest. Importantly, several functionally important groups such as insectivorous and seed-dispersing birds benefit from tall shade trees, shade tree diversity and proximity to forest edge, while parasitoid diversity is greatest close to natural forests. Available data on the effects of landuse change in cacao landscape of Central Sulawesi is increasing. Change in landscape configuration and management practices are being clearly reflected in the composition of species communities, with likely impacts on ecosystem services such as pest control and pollination. More knowledge is needed especially in terms of species interactions and ecosystem functioning, but also on how existing knowledge can contribute to effective conservation in human-dominated landscapes outside protected areas.

Multifunctional shade-tree management in tropical agroforestry landscapes - a review

“…Shaded cacao agroforestry suffers less from insect pest problems (Rice & Greenberg 2000), for example, suckers such as thrips and mirid bugs (Schroth et al. 2000), and leaf herbivory (Clough, Faust & Tscharntke 2009b; Clough et al. 2010), although pathogens such as the black pod disease Phytophtora sp.…”

Camera transects as a method to monitor high temporal and spatial ephemerality of flying nocturnal insects

“…This is of great consequence, not only for the conservation of arthropod diversity, but also because insects play an important role in ecosystem functioning as pollinators, herbivores, detritivores and by facilitating nutrient cycling (Hallmann et al, ; Mattson & Addy, ; Ollerton, Winfree, & Tarrant, ; Yang & Gratton, ). Insects are also an important food resource for both invertebrates and vertebrates including fish, amphibians, reptiles, birds and mammals (Baxter, Fausch, & Saunders, ; Clough et al, ; Losey & Vaughan, ). Insects impact the spatial distribution of nutrients between ecosystems by redistributing nutrients from one system to another during outbreaks and emergence events.…”

Ant seed predation, pesticide applications and farmers' income from tropical multi‐cropping gardens

“…Ineffective pesticide application not only has implications for seed protection, but also suggests that, if invasive ant species are not controlled by pesticides, there are implications for crop production because these ants might act as a pests directly on crops (e.g. protecting sap‐sucking insects; Behera et al ., ) by culling parasitized Homoptera (Ness & Bronstein, ) or by introducing diseases (Clough et al ., ; Wielgoss et al ., ).…”