The effect of climate change on the biodiversity of a multilayer network of plant-plant and plant-pollinator interactions

Abstract

Pollinators are highly under threat, causing a risk for biodiversity, ecosystem stability, food security and CO2 sequestration. Pollinators have a mutualistic interaction with plants (plants benefit from pollinator, pollinators from nectar). Recent studies show soil organisms determine aboveground plant species composition. This is caused by the plant-soil negative feedback: The soil becomes less suitable for a plant species by growing there. Plant diversity and interactions that are mediated via the soil can be modelled in a plant-plant network. Increasing temperatures and increasing or decreasing moisture content cause changes in the abundances of soil organisms. Because some of the mutualists and pathogens increase and others decrease, the hypothesis is that the heterogeneity in the competitive interaction strengths of this plant-plant network will therefore increase with climate change (some will increase, others decrease). Changes in the plant biodiversity, caused by these changes in the soil, might affect the pollinator biodiversity. To study the effect of this climate induced increased heterogeneity on plant and pollinator biodiversity, a new multi-layer model was created. The model combines the plant-plant network with a mutualistic plant-pollinator network. The study shows that plant richness will decrease because the plant-plant networks become increasingly unstable with changing climate. Also, both plant and pollinator densities will become less even, what might generate a higher risk of extinction by other factors. Furthermore, climate induced soil modifications might make plant communities more dependent on the pollinator network to generate network stability. Therefore, soil conservation and restoration will improve plant richness conservation and might also improve pollinator richness.