Data belonging with MSc thesis "Linking phosphorus acquisition strategies to the fungal collaboration gradient in grassland species"

The Root Economic Space (RES) framework contains a conservation gradient, which is a trade-off between fast and slow growth and a (fungal) collaboration gradient. This is the trade-off between an Arbuscular Mycorrhizal Fungi (AMF) symbiosis strategy (or ‘outsourcing’) or soil exploration through roots (or ‘do-it-yourself’ strategy). An addition to this framework has been proposed to include root exudates as a third strategy. However, in the framework, nutrient acquisition and their different solubilities have not yet been taken into account. So, we looked into how plastic the species are in their place along the gradient in with P sources. The five forb species (D. deltoides, R. acetosella, P. lanceolata, T. officinale, R. repens) native to Dutch grasslands were fertilized with either no additional phosphate (P), soluble P (Trisodium phosphate, TSP), or insoluble P (rock phosphate) in a greenhouse pot experiment. We found that the species D. deltoides and R. acetosella were not colonized by AMF, while the species P. lanceolata, T. officinale, and R. repens were. The species D. deltoides and R. acetosella had a higher SRL, but a lower RD compared to the species P. lanceolata, T. officinale and R. repens. There was no difference in the citric acid concentration between species or P source. We also found a significant influence of AMF colonization on the P-content of the plants, but not for root morphology or organic acid exudation. Within species, we found no differences between the different P-sources for any of the traits studied, which suggests that plants are plastic along the collaboration gradient. Thus we can confirm the fungal collaboration gradient of the RES framework, but we are yet unable to confirm the inclusion of root exudates into the RES.