ProteaNet - Protea networks in time and space: resource-driven dynamics of interacting plant, pollinator and seed predator communities in South African Fynbos (DFG-Project)

Interactions within and between plant and animal communities are key for the temporal dynamics of terrestrial ecological systems. Thus far, we largely lack a mechanistic understanding of what drives the coupled dynamics of plant and animal communities. Here, we aim to study the long-term community dynamics of Protea shrubs, their mutualistic pollinators and antagonistic seed predators in fire-prone South African Fynbos. We build on high-resolution individual-level maps of 29 Protea communities produced by a previous project on spatial plant-animal interactions. To study long-term dynamics across multiple years, we will exploit the fact that growth and fecundity schedules of Protea individuals can be determined retrospectively and that the mapped communities cover the typical range of post-fire ages (4 to 28 years). First, we will test whether life histories of individual plants are determined by resource allocation and by resource-mediated interactions with pollinators, seed predators and other plants. To this end, we will relate fecundity schedules of mapped plant individuals to traits determining resource allocation and to the temporal dynamics of plant-based resource landscapes (e.g. nectar sugar, pollen, seed mass and seed nutrients). Second, we will record bird and insect pollinators as well as insect seed predators on Protea and will measure functional traits of animals. These data will serve to test whether the temporal dynamics of plant-based resource landscapes determines functional and interaction diversity of Protea-associated interaction networks. Third, two multi-species experiments will complement the observational studies of plant and animal communities. The first is a common-garden experiment testing whether interactions among Protea seedlings are determined by resource allocation traits and by trade-offs with the performance of adult plants. The second is a pollinator-exclusion experiment that will quantify the impact of different-sized pollinators on Protea fecundity in communities of different post-fire age. By combining observational and experimental approaches, the proposed project will provide new insights into how resources shape plant life histories and how they mediate direct and indirect interactions of plants with animal mutualists, antagonists and other plants. A resource-based understanding of plant-plant and plant-animal interactions will be an important step towards predicting the coupled dynamics of plant and animal communities.