| dc.description.abstract | Since modern days, anthropogenic activity significantly alters the nitrogen (N) and phosphorus (P) cycle, and these changes are substantially affecting terrestrial plant communities. Along with potassium (K), N and P are key nutrients limiting plant growth. Plants occupy distinct niches along N:P ratio gradients, and their physiological adaptation to these environments could potentially help us understand current and future species composition within N- and P-limited soils. This is especially important due to the high concentration of threatened P-limited areas. It has been suggested that belowground rooting behaviour is oriented along a slow to fast growing spectrum. However, such one-dimensional view has not been able to explain the variation in root traits adequately. An improved two-dimensional conceptual framework was introduced to understand resource acquisition by incorporating plants’ ability to cooperate with fungi. This framework discerned two largely independent gradients using four core traits: a conservation and a collaboration gradient. This framework has not been assessed from a nutrient stoichiometric perspective, neither has it been used to better understand the threatened status of species. For this, we retrieved twelve belowground traits from trait databases and linked them to a European-wide field dataset of 991 vegetation recordings with species composition, site productivity and biomass nutrient contents of herbaceous plant communities. First, our results confirm that threatened species tend to be concentrated in P-limited sites and species richness was highest at low productivity. Second, threatened species compared to non-threatened species do not possess different belowground traits. Third, using four core traits we demonstrate that a conservation and collaboration gradient can be identified on plant community level. Finally, we show that plant communities adopt a fast and do-it-yourself to a slow and outsourcing belowground strategy along an increasing N:P gradient. However, mycorrhizal traits provide contrasting results, questioning present understanding of fungal importance for belowground nutrient acquisition. Our results imply that, in addition to the benefit for fast-growing species in a nutrient-enriching world, anthropogenic alterations in the nutrient balance may also heavily affect species fitness and survival due to their nutrient-specific rooting strategies. The biggest remaining question is whether species will be able to adapt to changes in nutrient stoichiometry and if they can, how fast this adaptation process will be. Our analysis on threatened species seem to indicate that the answer on this question is not to be found belowground, but much more research is needed. | |
